Best us obstetric dating scan viability

best us obstetric dating scan viability

WE OFFER. Obstetric. NEW Preeclampsia. Gynaecologic All early scans will include a transabdominal scan performed through your skin and requires a full bladder. It may be necessary to perform an internal or transvaginal scan. This is done after you have emptied your bladder The NT scan or 12 week scan is an ultrasound best performed in the first trimester between 11 weeks and 13 weeks 6 days. This scan is combined with a blood test that looks at 2 specific hormones of pregnancy, the free Beta hCG and PAPP-A. It is an extremely accurate non-invasive screening test that helps identify a fetus at risk for Down syndrome as well as other chromosomal conditions and some major structural abnormalities.

best us obstetric dating scan viability

Each ultrasound examination gives important information to the referring doctor. It is a snapshot in time. Your initial ultrasound is best performed 6-8 weeks after your last menstrual period (LMP).

At this scan we hope to: • Confirm a pregnancy • Confirm a normal intrauterine location. This is when the BhCG hormone levels are greater than 1000Ius – usually after 6 weeks • Confirm viability by demonstrating the presence of fetal heart motion • Determine the number of babies present • If more than one baby, determine their choronicity, identical/non-identical (fraternal) • Calculate the expected date of delivery (EDD) • Demonstrate a cause of bleeding in early pregnancy.

All early scans will include a transabdominal scan performed through your skin and requires a full bladder. It may be necessary to perform an internal or transvaginal scan. This is done after you have emptied your bladder. These internal scans do not present any harm to your baby and usually allow better visualisation.

On transvaginal scan at 5 weeks gestation, only a gestation sac will be seen. At around 6 weeks a yolk sac will become visible. At this time a small embryo becomes apparent and when it reaches 5+mm the heart beat should be visible. Doppler is used to hear the heart beat and measure the heart rate. The crown rump length (CRL) is the measurement taken from baby’s head to bottom.

This is used to calculate the expected due date. This measurement is used to date the pregnancy up until 14 weeks. The NT scan or 12 week scan is an ultrasound best performed in the first trimester between 11 weeks and 13 weeks 6 days. This scan is combined with a blood test that looks at 2 specific hormones of pregnancy, the free Beta hCG and PAPP-A. It is an extremely accurate non-invasive screening test that helps identify a fetus at risk for Down syndrome as well as other chromosomal conditions and some major structural abnormalities.

This ultrasound screening test does not have any side effects or complications. It will however only tell us if a fetus has an increased risk. The only way to diagnose Down syndrome or other chromosomal abnormalities is by having a diagnostic test (a CVS or amniocentesis). These tests are invasive and require a needle to be passed into the maternal abdomen and uterus and therefore carry a small risk of miscarriage.

Chromosomal abnormalities occur when there is a change in the number or structure of the chromosomes. Normally we have 46 chromosomes. We acquire 23 from our mum and 23 from our dad. They are numbered 1-22 and a pair of sex chromosomes. Boys have XY and girls XX. The most common chromosomal abnormality seen at birth is Down syndrome.

These babies have an extra number 21 chromosome giving a total of 47 chromosomes. Accredited practices To ensure your NT scan is performed correctly, it is important that you have your scan at an accredited ultrasound practice.

An NT computer program was developed by the London Fetal Medicine Foundation. This is available in Australia through the Royal College of Obstetricians and Gynaecologists. Strict auditing of sonographers and ultrasound practices is undertaken every year. This ensures that the NT scan test is being performed correctly. The sonographers at Newcastle Ultrasound for Women have full NT accreditation.

12 week NT scan advantages. These include: • To estimate individual risk for Trisomy 21 (Down syndrome), Trisomy 18 (Edward syndrome) and Trisomy 13 (Patau syndrome). • More accurately date the pregnancy • Diagnose multiple foetuses • Diagnose early pregnancy failure • Allow early detection of some major abnormalities including spina bifida. NT and Down syndrome In the first trimester there is a small amount of fluid beneath the skin at the back of the neck in all fetus’s.

This fluid is called the nuchal translucency (NT), and can be easily and accurately measured on ultrasound. When there is extra fluid and the NT measurement is thicker than normal, there is an association with chromosomal anomalies such as Down syndrome or some structural abnormalities.

Some babies with at thickened NT can be perfectly normal. The fluid itself is not an abnormality and does not harm the baby but is simply a sign of a potential problem. At the NT scan, the baby is measured from head to bottom to determine the crown-rump length (CRL) and the nuchal translucency is measured.

These measurements are entered into the FMF computer program with the patient’s date of birth and the first trimester biochemistry blood test. The computer then calculates the patient’s age related risk for Down syndrome and the new individual risk for this pregnancy. The results are then discussed with the patient. The combined NT result will provide the patient with a risk assessment. This will either be a high risk result (greater than 1 in 300) or low risk (less than 1 in 300).

Even with a low calculated risk, Down syndrome is not completely excluded and can still occur occasionally. Patient’s within the high risk group should then be offered further testing – NIPT, CVS or Amniocentesis. Free BhCG and PAPP-A Beta human chorionic gonadotrophin (free BhCG) and pregnancy associated plasma protein-A (PAPP-A) levels can be assessed from a blood test.

This is best done after 9 weeks and at least a week prior to the NT scan. The BhCG tends to be higher and PAPP-A tends to be lower in pregnancies affected by Down syndrome. Nuchal translucency accuracy When the ultrasound is combined with the first trimester blood test and nasal bone, the detection rate increases to 95%.

No screening test can give 100% detection. Preeclampsia is an illness which only occurs in pregnancy. It is sometimes referred to as preeclamptic toxaemia, PE or PET. It usually arises during the second half of the pregnancy and can affect both the mother and her unborn baby.

Preeclampsia symptoms include: • High blood pressure – 140/90 or greater • Headaches • Edema- accumulation of excess fluid especially concerning when it occurs in the face, around the eyes and in the hands • Changes in vision- flashing lights, auras or sudden onset of blurry vision • Protein in the urine.

In Australia, mild preeclampsia occurs in 5-10 % of pregnancies and severe preeclampsia in 1-2%. Preeclampsia and complications associated with this condition account for 15% of direct maternal mortality and 10% of perinatal mortality. Preeclampsia is the indication for 20% of labour inductions and 15% of Caesarean sections. It accounts for 5-10% of preterm deliveries. Worldwide, preeclampsia and its complications kill many tens of thousands of women and their babies every year.

In the past there was no way of screening for preeclampsia, but now screening can be performed at the 12-14 week scan. Women can be identified to be at high risk of developing the condition. The screening program can detect 90% of women who will go on to develop preeclampsia. The advantage of early screening for preeclampsia is that early administration of low dose aspirin to the pregnant mother is now known to improve the outcomes and reduce the complications in about 50% of affected pregnancies.

A trial using asprin in early pregnancy was performed. This was the ASPRE trial: Aspirin from 12 weeks – It examined the prophylactic use of low-dose aspirin from the first trimester in women at increased risk for preterm PE. Women with singleton pregnancies had screening by means of an algorithm that combines maternal factors (previous pregnancy outcomes, weight, smoker, diabetes, hypertension, previous preeclampsia or if mother had preeclampsia), mean arterial pressure (BP), uterine artery Pulsatility index (ultrasound doppler measurement) and maternal serum placental growth factor (PlGF) and pregnancy associated plasma protein (PAPP-A) at 11-14 weeks gestation.

Women with a risk for preterm preeclampsia of greater than 1:100 were invited to participate in a double-blind trial of aspirin (150mg/day) vs Placebo.

The results showed that preterm PE occurred in 1.6% of participants in the aspirin group as compared with 4.3% in the placebo group. The incidence of PE at less than 34 weeks was reduced by 82%. The trial showed that aspirin had no significant effect in reducing the risk of term PE. The study concluded that treatment with low-dose aspirin in women at high risk for preterm PE reduced substantially the incidence of this disease.

Contraindications to aspirin use include: sensitivity to aspirin, aspirin related asthma, previous gastrointestinal sensitivity, ulcers etc. Newcastle Ultrasound for Women now includes preeclampsia screening as part of the 12 week Nuchal scan. Referring doctors only need to ask for an NT scan on the referral form. There is no extra cost and it is covered partially by Medicare.

No extra time is allocated to the scan. What is involved: • In addition to the images and measurements taken during the NT scan, a Doppler measurement of the right and left Uterine arteries is taken to obtain a PI (pulsatility index) • The mother’s blood pressure is also taken on both arms • Information regarding maternal factors including weight, height, previous pregnancy information, smoker, diabetes, hypertension and previous preeclampsia or family history of preeclampsia are collected.

• Added to this are some blood test results including pregnancy associated plasma protein (PAPP-A) and maternal serum placental growth factor (PlGF). If the FTS bloods are sent to a Douglas or NSW pathology lab (Pathology North), they automatically include the PlGF measurement.

The same Fetal Maternal Foundation software that gives the risk of chromosomal abnormalities is used. By adding the PlGF, Uterine artery doppler PI measurements and the mother’s blood pressure, a risk for PE before 34 weeks, PE before 37 weeks and a Fetal growth restriction risk before 37 weeks is calculated. Unlike the chromosomal risk which is deemed to be high when greater than 1:300 for preeclampsia the high risk group is greater than 1:100.

This is printed in bold on the report. If the blood results are available on the day of the scan, our Sonographer will discuss the Nuchal and Preeclampsia results with the patient.

If a patient chooses to have a Genesyte or Harmony NIPT, it is still essential that they also have the FTS bloods (Bhcg, PAPP-A and PlGF) so that a Preeclampsia risk assessment can be reported. We believe every woman who chooses to have a 12-14 week scan should have preeclampsia screening included. It costs no more, is of no harm to her or the baby, and might just highlight the otherwise unknown risk of her developing preeclampsia.

To our knowledge, only a few places in Newcastle include preeclampsia screening. The sonographer performing the scan must be accredited by FMF, which runs through RANZCOG.

This new technology has only been available in Australia since 2012. NIPT is a maternal blood test that can be performed from 10 weeks gestation. It uses advanced genetic testing technology that allows for the detection and comparison of fetal DNA within the mother’s blood sample. There is no Medicare rebate available for this test at this time. There are no risks to the baby from this test. Currently it is the most accurate screening test for Down syndrome (Trisomy 21), Edward syndrome (Trisomy 18) and Patau syndrome (Trisomy 13).

NIPT allows for a >99% detection rate for Down syndrome, a 98% rate for Edward syndrome and a 80% detection rate for Patau syndrome.

There is a 93–95% detection rate for sex chromosome abnormalities including Turner syndrome and Klinefelters syndrome and >99% detection rate for fetal gender. NIPT is available for twin pregnancies and donor egg pregnancies. Gender detection is not available for twin pregnancies. This test has been validated for both high and low risk pregnancies, allowing patients to avoid the risk of miscarriage associated with the traditional invasive testing options of CVS and amniocentesis.

NIPT is not currently classified as a diagnostic test and therefore a positive result for Trisomy 21,18 or 13 will require confirmation by traditional invasive testing, CVS or amniocentesis. If the nuchal translucency measurement is >3.5mm or there is a fetal anomaly seen on scan, even if the risk for a chromosomal abnormality is deemed to be low, then invasive testing CVS or amniocentesis should be offered. Newcastle Ultrasound for Women recommends the GeneSyte NIPT screening test which can be performed at our Lingard practice.

This scan is also known as an anomaly scan and in Australia nearly all pregnancies undergo this scan at 19-20 weeks. No harmful effects of obstetric ultrasound have been shown in the past 30–40 years that it has been used routinely. You are welcome to bring your partner or support person to the scan. The scan is used to assess: • Placental position and cord insertion • Cervical length • Amniotic fluid volume • Fetal structural development including brain, face, spine, heart, lungs, stomach, kidneys, bladder, arms, legs, hands and feet • Fetal growth At Newcastle Ultrasound for Women, our lovely sonographers will talk you through the scan explaining exactly what is being imaged and measured.

You are welcome to ask questions. The majority of the scan is performed using 2D imaging (black and white) which is how we check for abnormalities and measure baby’s size. A 4D scan will also be performed when the baby is in a good position for this to be done. There are limitations with the 4D scan including baby’s position and cooperation as well as maternal size. We always try to capture the best images at the time.

At the conclusion of the scan you will be provided with thermal printed images, a USB containing all the images and a DVD of the scan. Detecting abnormalities You will be amazed at the amount of detail that can be often seen in the morphology scan. It is important to realise however, that not all parts of the baby show up well on ultrasound.

No ultrasound examination can ever guarantee a normal baby. The ultrasound scan is often limited by mum’s size, the position of the baby and an anterior placenta. Up to half of fetal heart defects will not be seen. Most of these are only minor. Many bone growth problems, including forms of dwarfism, will only be detectable late in pregnancy or after the baby is born.

Conditions such as cerebral palsy, blindness, deafness, autism and most skin and soft tissue lesions are never detected with ultrasound. Your obstetrician may refer you for a scan in the third trimester for a number of reasons which include: • If you have a low lying placenta on the 19–20 week scan • If you are clinically measuring too large or too small for dates • If you have had a small or large baby in the past • If you have high blood pressure • If you have diabetes or another medical condition • If you have pain in your abdomen • If you have had vaginal fluid loss • If you have premature contractions • If you are having twins etc • If you had a low PAPP-A at NT scan • If the umbilical artery contains only a single artery The ultrasound will be used to assess: • Fetal growth/size • The amount of amniotic fluid around baby • Doppler studies/blood flow patterns in the umbilical cord, middle cerebral artery in the brain and Ductus venosum.

• Placenta location • Fetal well-being Imaging the baby in the third trimester can be difficult as the baby occupies much more space in the uterus. This means in general we cannot see the baby as well as on earlier scans. The further into the pregnancy you go, the denser the bones become, which can shadow and obscure the view.

This is the case when looking at the fetal brain. Things like fingers and toes, hands and feet are also more difficult to assess.

The quality of the imaging depends on what position the baby is in and how cooperative the baby wants to be for us. The amount of amniotic fluid also affects the quality of the scan, more fluid is better.

If there is enough fluid in front of the fetal face amazing 4D images are possible. Assessing fetal well-being. Ultrasound is a major tool used to assess the fetal health by using Doppler assessment and evaluating the fetal biophysical profile. The ultrasound biophysical profile is a test that attempts to gauge whether or not the fetus is getting too little oxygen – fetal hypoxia.

The sonographer examines fetal movement, breathing movement, tone, amniotic fluid volume and heart rate variability. The baby has a number of mechanisms for coping with placental insufficiency.

These include: • Diverting blood flow to the brain and away from the kidneys and bowel. This then reduces the amount of urine and therefore the amniotic fluid around baby. The blood flows through the brain at reduced resistance and this can be measured using Doppler to assess the flow in the middle cerebral artery.

• When there is a significant problem with placental function there tends to be a decline in fetal movements. Initially, fetal chest or breathing movements disappear followed by limb and trunk movements. • Placental function can also be assessed by examining the blood flow through the umbilical cord artery. Increasing resistance to flow will initially be reflected in the cord Doppler readings showing a high resistance waveform.

In severe cases this is followed by absent or reverse flow in the artery during diastole. There are different types of twin pregnancies with some being more high risk. Dichorionic diamniotic (DCDA) twins DCDA twins can also be called fraternal twins.

The most likely scenario is 2 separate eggs are fertilized by 2 separate sperm. They are usually non-identical however approximately 10% may be identical if infact they are from one embryo which split very early in development.

DCDA twins have two placentas and two separate amniotic sacs. These babies will have different genetic material. DCDA twins are usually scanned monthly to assess growth and well being of each baby as well as to check cervical length. Monochorionic diamniotic (MCDA) twins Monochorionic twins occur when 1 egg and 1 sperm and therefore 1 embryo split to make 2 very early in development.

These babies therefore have identical genetic material and are identical in appearance. MCDA twins have a single placenta and 2 separate amniotic sacs. MCDA twins are routinely scanned every 2 weeks from 16-32 weeks to monitor for evidence of twin-twin transfusion syndrome. They are also monitored closely for growth, well being and maternal cervix length. Monochorionic monoamniotic (MCMA) twins MCMA twins have a single placenta and both babies share the same amniotic sac.

They are identical and share the same genetic material. MCMA twins are usually scanned weekly from 24 weeks until delivery – usually at 32 weeks. MCMA twins are at a greater risk for:

best us obstetric dating scan viability

best us obstetric dating scan viability - Baisez des femmes de votre région ce soir

best us obstetric dating scan viability

Main areas Prenatal care Prenatal care is important in screening for various complications of pregnancy. This includes routine office visits with physical exams and routine lab tests: First trimester • Complete blood count (CBC) • Blood type • General antibody screen ( indirect Coombs test) for HDN • Rh D negative antenatal patients should receive RhoGam at 28 weeks to prevent Rh disease. • Rapid plasma reagin (RPR) to screen for syphilis • Rubella antibody screen • Hepatitis B surface antigen • Gonorrhea and Chlamydia culture • PPD for tuberculosis • Pap smear • Urinalysis and culture • HIV screen Genetic screening for Down syndrome (trisomy 21) and trisomy 18, the national standard in the United States, is rapidly evolving away from the AFP-Quad screen for Down syndrome, done typically in the second trimester at 16–18 weeks.

The newer integrated screen (formerly called F.A.S.T.E.R for First And Second Trimester Early Results) can be done at 10 plus weeks to 13 plus weeks with an ultrasound of the fetal neck (thicker nuchal skin correlates with higher risk of Down syndrome being present) and two chemicals (analytes) PAPP-A and βHCG (pregnancy hormone level itself). It gives an accurate risk profile very early. A second blood screen at 15 to 20 weeks refines the risk more accurately. The cost is higher than an "AFP-quad" screen due to the ultrasound and second blood test, but it is quoted to have a 93% pick up rate as opposed to 88% for the standard AFP/QS.

This is an evolving standard of care in the United States. Second trimester • MSAFP/quad. screen (four simultaneous blood tests) (maternal serum AFP, inhibin A, estriol, & βHCG) – elevations, low numbers or odd patterns correlate with neural tube defect risk and increased risks of trisomy 18 or trisomy 21 • Ultrasound either abdominal or transvaginal to assess cervix, placenta, fluid and baby • Amniocentesis is the national standard (in what country) for women over 35 or who reach 35 by mid pregnancy or who are at increased risk by family history or prior birth history.

Third trimester • [Hematocrit] (if low, the mother receives iron supplements) • Group B Streptococcus screen. If positive, the woman receives IV penicillin or ampicillin while in labor—or, if she is allergic to penicillin, an alternative therapy, such as IV clindamycin or IV vancomycin. • Glucose loading test (GLT) – screens for gestational diabetes; if > 140 mg/dL, a glucose tolerance test (GTT) is administered; a fasting glucose > 105 mg/dL suggests gestational diabetes.

Most doctors do a sugar load in a drink form of 50 grams of glucose in cola, lime or orange and draw blood an hour later (plus or minus 5 minutes) ; the standard modified criteria have been lowered to 135 since the late 1980s Fetal assessments Obstetric ultrasonography is routinely used for dating the gestational age of a pregnancy from the size of the fetus, determine the number of fetuses and placentae, evaluate for an ectopic pregnancy and first trimester bleeding, the most accurate dating being in first trimester before the growth of the foetus has been significantly influenced by other factors.

Ultrasound is also used for detecting congenital anomalies (or other foetal anomalies) and determining the biophysical profiles (BPP), which are generally easier to detect in the second trimester when the foetal structures are larger and more developed. Specialised ultrasound equipment can also evaluate the blood flow velocity in the umbilical cord, looking to detect a decrease/absence/reversal or diastolic blood flow in the umbilical artery.

X-rays and computerized tomography (CT) are not used, especially in the first trimester, due to the ionizing radiation, which has teratogenic effects on the foetus. No effects of magnetic resonance imaging (MRI) on the foetus have been demonstrated, [11] but this technique is too expensive for routine observation. Instead, obstetric ultrasonography is the imaging method of choice in the first trimester and throughout the pregnancy, because it emits no radiation, is portable, and allows for realtime imaging.

The safety of frequent ultrasound scanning has not be confirmed. Despite this, increasing numbers of women are choosing to have additional scans for no medical purpose, such as gender scans, 3D and 4D scans. A normal gestation would reveal a gestational sac, yolk sac, and fetal pole. The gestational age can be assessed by evaluating the mean gestational sac diameter (MGD) before week 6, and the crown-rump length after week 6.

Multiple gestation is evaluated by the number of placentae and amniotic sacs present. Other tools used for assessment include: • Fetal screening is used to help assess the viability of the fetus, as well as congenital abnormalities.

• Fetal karyotype can be used for the screening of genetic diseases. This can be obtained via amniocentesis or chorionic villus sampling (CVS) • Foetal haematocrit for the assessment of foetal anemia, Rh isoimmunization, or hydrops can be determined by percutaneous umbilical blood sampling (PUBS), which is done by placing a needle through the abdomen into the uterus and taking a portion of the umbilical cord.

• Fetal lung maturity is associated with how much surfactant the fetus is producing. Reduced production of surfactant indicates decreased lung maturity and is a high risk factor for infant respiratory distress syndrome. Typically a lecithin: sphingomyelin ratio greater than 1.5 is associated with increased lung maturity.

• Nonstress test (NST) for fetal heart rate • Oxytocin challenge test Intercurrent diseases A pregnant woman may have intercurrent diseases, that is, other diseases or conditions (not directly caused by the pregnancy) that may become worse or be a potential risk to the pregnancy. • Diabetes mellitus and pregnancy deals with the interactions of diabetes mellitus (not restricted to gestational diabetes) and pregnancy.

Risks for the child include miscarriage, growth restriction, growth acceleration, feotal obesity (macrosomia), polyhydramnios and birth defects. • Systemic lupus erythematosus and pregnancy confers an increased rate of foetal death in utero and spontaneous abortion (miscarriage), as well as of neonatal lupus.

• Thyroid disease in pregnancy can, if uncorrected, cause adverse effects on foetal and maternal well-being. The deleterious effects of thyroid dysfunction can also extend beyond pregnancy and delivery to affect neurointellectual development in the early life of the child. Demand for thyroid hormones is increased during pregnancy, and may cause a previously unnoticed thyroid disorder to worsen. • Hypercoagulability in pregnancy is the propensity of pregnant women to develop thrombosis (blood clots).

Pregnancy itself is a factor of hypercoagulability (pregnancy-induced hypercoagulability), as a physiologically adaptive mechanism to prevent post partum bleeding. However, when combined with an additional underlying hypercoagulable states, the risk of thrombosis or embolism may become substantial. Induction and labour Induction is a method of artificially or prematurely stimulating labour in a woman.

Reasons to induce can include pre-eclampsia, foetal distress, placental malfunction, intrauterine growth retardation and failure to progress through labour increasing the risk of infection and foetal distresses. Induction may be achieved via several methods: • Disturbance of cervical memebranes • Pessary of Prostin cream, prostaglandin E 2 • Intravaginal or oral administration of misoprostol • Cervical insertion of a 30-mL Foley catheter • Rupturing the amniotic membranes • Intravenous infusion of synthetic oxytocin (Pitocin or Syntocinon) During labour, the obstetrician carries out the following tasks: • Monitor the progress of labour, by reviewing the nursing chart, performing vaginal examination, and assessing the trace produced by a foetal monitoring device (the cardiotocograph) • Provide pain relief, either by nitrous oxide, opiates, or by epidural anaesthesia done by anaesthestists, an anaesthesiologist, or a nurse anaesthetist.

• Caesarean section, if there is an associated risk with vaginal delivery, as such feotal or maternal compromise. Complications and emergencies The main emergencies include: • Ectopic pregnancy is when an embryo implants in the uterine (Fallopian) tube or (rarely) on the ovary or inside the peritoneal cavity. This may cause massive internal bleeding.

• Pre-eclampsia is a disease defined by a combination of signs and symptoms that are related to maternal hypertension. The cause is unknown, and markers are being sought to predict its development from the earliest stages of pregnancy.

Some unknown factors cause vascular damage in the endothelium, causing hypertension. If severe, it progresses to eclampsia, where seizures occur, which can be fatal. Preeclamptic patients with the HELLP syndrome show liver failure and Disseminated intravascular coagulation (DIC). The only treatment is to deliver the foetus. Women may still develop pre-eclampsia following delivery.

• Placental abruption is where the placenta detaches from the uterus and the woman and foetus can bleed to death if not managed appropriately. • Foetal distress where the foetus is getting compromised in the uterine environment. • Shoulder dystocia where one of the foetus' shoulders becomes stuck during vaginal birth. There are many risk factors, including macrosmic (large) feotus, but many are also unexplained. • Uterine rupture can occur during obstructed labour and endanger foetal and maternal life.

• Prolapsed cord can only happen after the membranes have ruptured. The umbilical cord delivers before the presenting part of the foetus. If the foetus is not delivered within minutes, or the pressure taken off the cord, the foetus dies. • Obstetrical hemorrhage may be due to a number of factors such as placenta previa, uterine rupture or tears, uterine atony, retained placenta or placental fragments, or bleeding disorders.

• Puerperal sepsis is an ascending infection of the genital tract. It may happen during or after labour. Signs to look out for include signs of infection (pyrexia or hypothermia, raised heart rate and respiratory rate, reduced blood pressure), and abdominal pain, offensive lochia (blood loss) increased lochia, clots, diarrhea and vomiting. Postnatal care Postnatal care is care provided to the mother following parturition. A woman in the Western world who is delivering in a hospital may leave the hospital as soon as she is medically stable and chooses to leave, which can be as early as a few hours postpartum, though the average for spontaneous vaginal delivery (SVD) is 1–2 days, and the average caesarean section postnatal stay is 3–4 days.

During this time the mother is monitored for bleeding, bowel and bladder function, and baby care. The infant's health is also monitored. Certain things must be kept in mind as the physician proceeds with the post-natal care.

• General condition of the patient. • Check for vital signs (pulse, blood pressure, temperature, respiratory rate, (pain) at times) • Palour? • Edaema? • Dehydration? • Fundus (height following parturition, and the feel of the fundus) (Per abdominal examination) • If an episiotomy or a C-section was performed, check for the dressing. Intact, pus, oozing, haematomas? • Lochia (colour, amount, odour)?

• Bladder (keep the patient catheterized for 12 hours following local anaesthesia and 24–48 hours after general anaesthesia) ? (check for bladder function) • Bowel movements? • More bowel movements? • Follow up with the neonate to check if they are healthy. Veterinary obstretics History Prior to the 18th century, caring for pregnant women in Europe was confined exclusively to women, and rigorously excluded men.

The expectant mother would invite close female friends and family members to her home to keep her company. Skilled midwives managed all aspects of the labour and delivery. The presence of physicians and surgeons was very rare and only occurred once a serious complication had taken place and the midwife had exhausted all measures to manage the complication.

Calling a surgeon was very much a last resort and having men deliver women in this era whatsoever was seen as offending female modesty. [3] Before the 18th century Obstetrics prior to the 18th and 19th centuries was not recognized as a specific specialty.

However, the subject matter and interest in the female reproductive system and sexual practice can be traced back to Ancient Egypt and Ancient Greece. Soranus of Ephesus sometimes is called the most important figure in ancient gynecology. Living in the late first century A.D.

and early second century he studied anatomy and had opinions and techniques on abortion, contraception –most notably coitus interruptus– and birth complications.

After the death of Soranus, techniques and works of gynecology declined but very little of his works were recorded and survived to the late 18th century when gynaecology and obstetrics reemerged. 18th century The 18th century marked the beginning of many advances in European midwifery. These advances in knowledge were mainly regarding the physiology of pregnancy and labour. By the end of the century, medical professionals began to understand the anatomy of the uterus and the physiological changes that take place during labour.

The introduction of forceps in childbirth also took place during the 18th century. All these medical advances in obstetrics were a lever for the introduction of men into an arena previously managed and run by women—midwifery. The addition of the male- midwife is historically a significant change to the profession of obstetrics. In the 18th century medical men began to train in area of childbirth and believed with their advanced knowledge in anatomy that childbirth could be improved.

In France these male-midwives were referred to as "accoucheurs". This title was later on lent to male-midwives all over Europe. The founding of lying-hospitals also contributed to the medicalization and male-dominance of obstetrics. These lying-hospitals were establishments where women would come to have their babies delivered, which had prior been unheard of since the midwife normally came to home of the pregnant woman.

This institution provided male-midwives or accoucheurs with an endless number of patients to practice their techniques on and also was a way for these men to demonstrate their knowledge. [11] Many midwives of the time bitterly opposed the involvement of men in childbirth. Some male practitioners also opposed the involvement of medical men like themselves in midwifery, and even went as far as to say that men-midwives only undertook midwifery solely for perverse erotic satisfaction. The accoucheurs argued that their involvement in midwifery was to improve the process of childbirth.

These men also believed that obstetrics would forge ahead and continue to strengthen. 19th century Even 18th century physicians expected that obstetrics would continue to grow, the opposite happened. Obstetrics entered a stage of stagnation in the 19th century, which lasted until about the 1880s. The central explanation for the lack of advancement during this time was substantially due to the rejection of obstetrics by the medical community.

The 19th century marked an era of medical reform in Europe and increased regulation over the medical profession. Major European institutions such as The College of Physicians and Surgeons considered delivering babies ungentlemanly work and refused to have anything to do with childbirth as a whole. Even when Medical Act 1858 was introduced, which stated that medical students could qualify as doctors, midwifery was entirely ignored. This made it nearly impossible to pursue an education in midwifery and also have the recognition of being a doctor or surgeon.

Obstetrics was pushed to the side. [11] By the late 19th century the foundation of modern-day obstetrics and midwifery began developing.

Delivery of babies by doctors became popular and readily accepted, but midwives continued to play a role in childbirth. Midwifery also changed during this era due to increased regulation and the eventual need for midwives to become certified. Many European countries by the late 19th century were monitoring the training of midwives and issued certification based on competency. Midwives were no longer uneducated in the formal sense. [12] As midwifery began to develop so did the profession of obstetrics near the end of the century.

Childbirth was no longer unjustifiably despised by the medical community as it once had been at the beginning of the century. But the specialty was still behind in its development stages in comparison to other medical specialities, and remained a generality in this era. Many male physicians would deliver children but very few would have referred to themselves as obstetricians. The end of the 19th century did mark a significant accomplishment in the profession with the advancements in asepsis and anaesthesia, which paved the way for the mainstream introduction and later success of the Caesarean Section.

[12] [11] Before the 1880s mortality rates in lying-hospitals would reach unacceptably high levels and became an area of public concern. Much of these maternal deaths were due to Puerperal fever, at the time commonly known as childbed fever. In the 1800s Dr. Ignaz Semmelweis noticed that women giving birth at home had a much lower incidence of childbed fever than those giving birth by physicians in lying-hospitals.

His investigation discovered that washing hands with an antiseptic solution before a delivery reduced childbed fever fatalities by 90%. [11] So it was concluded that it was physicians who had been spreading disease from one labouring mother to the next.

Despite the publication of this information, doctors still would not wash. It was not until the 20th century when advancements in aseptic technique and the understanding of disease would play a significant role in the decrease of maternal mortality rates among many populations. History of obstetrics in America The development of obstetrics as a practice for accredited doctors happened at the turn of the 18th century and thus was very differently developed in Europe and in the Americas due to the independence of many countries in the Americas from European powers.

“Unlike in Europe and the British Isles, where midwifery laws were national, in America, midwifery laws were local and varied widely”. [7] Gynaecology and Obstetrics gained attention in the American medical field at the end of the nineteenth century through the development of such procedures as the ovariotomy. These procedures then were shared with European surgeons who replicated the surgeries. It should be noted that this was a period when antiseptic, aseptic or anaesthetic measures were just being introduced to surgical and observational procedures and without these procedures surgeries were dangerous and often fatal.

Following are two surgeons noted for their contributions to these fields include Ephraim McDowell and James Marion Sims. Ephraim McDowell developed a surgical practice in 1795 and performed the first ovariotomy in 1809 on a 47-year-old widow who then lived on for thirty-one more years. He had attempted to share this with John Bell whom he had practiced under who had retired to Italy. Bell was said to have died without seeing the document but it was published by an associate in Extractions of Diseased Ovaria in 1825.

By the mid-century the surgery was both successfully and unsuccessfully being performed. Pennsylvanian surgeons the Attlee brothers made this procedure very routine for a total of 465 surgeries–John Attlee performed 64 successfully of 78 while his brother William reported 387– between the years of 1843 and 1883.

By the middle of the nineteenth century this procedure was successfully performed in Europe by English surgeons Sir Spencer Wells and Charles Clay as well as French surgeons Eugène Koeberlé, Auguste Nélaton and Jules Péan. J. Marion Sims was the surgeon responsible for being the first treating a vesicovaginal fistula –a condition linked to many caused mainly by prolonged pressing of the feotus against the pelvis or other causes such as rape, hysterectomy, or other operations– and also having been doctor to many European royals and the 20th President of the United States James A.

Garfield after he had been shot. Sims does have a controversial medical past. Under the beliefs at the time about pain and the prejudice towards African people, he had practiced his surgical skills and developed skills on slaves. [11] These women were the first patients of modern gynecology.

One of the women he operated on was named Anarcha, the woman he first treated for a fistula. [11] Historical role of gender Women and men inhabited very different roles in natal care up to the 18th century.

The role of a physician was exclusively held by men who went to university, an overly male institution, who would theorize anatomy and the process of reproduction based on theological teaching and philosophy. Many beliefs about the female body and menstruation in the 17th and 18th centuries were inaccurate; clearly resulting from the lack of literature about the practice.

Many of the theories of what caused menstruation prevailed from Hippocratic philosophy. Midwives of this time were those assisted in the birth and care of both born and unborn children, and as the name suggests this position held mainly by women. During the birth of a child, men were rarely present. Women from the neighbourhood or family would join in on the process of birth and assist in many different ways.

The one position where men would help with the birth of a child would be in the sitting position, usually when performed on the side of a bed to support the mother. Men were introduced into the field of obstetrics in the nineteenth century and resulted in a change of the focus of this profession.

Gynaecology directly resulted as a new and separate field of study from obstetrics and focused on the curing of illness and indispositions of female sexual organs. This had some relevance to some conditions as menopause, uterine and cervical problems, and childbirth could leave the mother in need of extensive surgery to repair tissue. But, there was also a large blame of the uterus for completely unrelated conditions.

This led to many social consequences of the nineteenth century. See also • Childbirth and obstetrics in antiquity • Henry Jacques Garrigues, who introduced antiseptic obstetrics to North America • Maternal-fetal medicine • Obstetrical nursing • Obstetric ultrasonography • Puerperum • Obstetrical complications <img src="//" alt="" title="" width="1" height="1" /> Image & Video Gallery

best us obstetric dating scan viability

The basic obstetric ultrasound examination provides an accurate and safe clinical assessment of the gravid uterus throughout a woman’s pregnancy including characterizing pregnancy location, identifying the number of embryos present, and aiding in the prenatal diagnosis of fetal anomalies.

In 2013, the American Institute of Ultrasound in Medicine (AIUM), in conjunction with the American College of Radiology (ACR) and the American College of Obstetricians and Gynecologists (ACOG), released updated Practice Guidelines for Performance of Obstetric Ultrasound Examinations. These guidelines describe the indications and key elements of 4 major types of obstetric ultrasounds, specifically the first trimester ultrasound, standard second or third trimester ultrasound, and limited and specialized ultrasound examinations.

[] Further details regarding specific information gathered in each type of ultrasound exam is described below. Also see the article . The first ­trimester basic ultrasound is typically performed to confirm a viable intrauterine pregnancy. The exam may be performed either trans-abdominally or trans-vaginally.

It is ideally performed before 13 weeks and 6 days of gestation. Ultrasound examination at this time aids in the clinical assessment of pelvic pain and/or vaginal bleeding in the setting of an early pregnancy because it can diagnose an extrauterine pregnancy or an abnormal pregnancy, such as a hydatidiform molar pregnancy, an anembryonic gestation or an incomplete versus complete abortion. A definitive diagnosis of an intrauterine pregnancy can be made when a gestational sac containing a yolk sac is visualized within the uterine cavity.

Without visualization of a yolk sac (or signs of a further developed pregnancy such as an embryo), the location of the pregnancy cannot be certain and further evaluation is warranted. In some cases where a pregnancy test is positive but there is no clear intrauterine pregnancy or extrauterine findings concerning for an ectopic pregnancy such as an adnexal mass on ultrasound, a patient may have a “pregnancy of unknown location.” It is important to consider the clinical context of a patient without a documented intrauterine pregnancy to guide further management.

This includes the patient’s symptoms (pelvic pain, vaginal bleeding), serial serum beta human chorionic gonadotropin levels (bHCG), and pelvic exam findings. Additionally, a first trimester ultrasound examination is useful to diagnose an “early pregnancy loss” which is defined by American College of Obstetricians and Gynecologists as a nonviable, intrauterine pregnancy with either an empty gestational sac, or a gestational sac containing an embryo or fetus without cardiac activity within the first 12 6/7 weeks of gestation.

[] The Society of Radiologists in Ultrasound Multispecialty Panel on Early First Trimester Diagnosis of Miscarriage and Exclusion of a Viable Intrauterine Pregnancy have published conservative guidelines to aid with clinical judgment in the diagnosis of an abnormal intrauterine pregnancy.

Diagnostic findings of an early pregnancy loss include: 1.) Crown-rump length of 7 mm or greater and no heartbeat, 2.) Mean sac diameter of 25 mm or greater and no embryo, 3.) the absence of cardiac activity in an embryo 2 weeks or more after a scan that showed a gestational sac without a yolk sac, and/or 4.) the absence of cardiac activity in an embryo 11 days or more after a scan that showed a gestational sac with a yolk sac.

[] Cardiac activity of an embryo is documented using 2-dimensional video clip or M-mode imaging. [] If no cardiac motion is seen on transvaginal ultrasound in an embryo less than 7 mm, a subsequent ultrasound in 1-2 weeks should be performed to assess for cardiac activity.

[] Additionally, if the patient’s clinical presentation suggests a miscarriage (i.e heavy vaginal bleeding) but she is stable for expectant management, a follow-up ultrasound performed 7-14 days after initial presentation to assess for interval changes and viability is also appropriate management.

[] In the setting of a confirmed viable intrauterine pregnancy, the first ­trimester ultrasound is utilized to provide an accurate gestational age assessment. When only a gestational sac and yolk sac are visualized, the mean gestational sac diameter may be used to estimate gestational age (Mean sac diameter (mm) + 30 = gestational age in days).

However, if an embryo is visualized then a crown-rump length (CRL) of the fetus should be used to determine an estimated due date because it is the most accurate measurement for establishing gestational age. [] An embryo should be visible by transvaginal ultrasonography with a mean gestational sac diameter of 25 mm or greater.

The crown rump length is the maximum length of the infant from cranium to caudal rump in a longitudinal plane. [, ] Measurements of the CRL are more accurate the earlier the first trimester ultrasound is performed. If the CRL measurement is greater than or equal to 84 mm (which corresponds to a gestational age of 14 and 0/7 weeks), second-trimester biometric parameters should be used for calculating the gestational age.

[] A reliable formula to calculate gestational age based on CRL is as follows: CRL (mm) + 42 days (+/- 3 days) = gestational age (days). [] In 2014, ACOG published a standardized approach for calculating a patient’s anticipated due date using both ultrasound estimates and menstrual history, specifically the patient’s first day of the last menstrual period.

[] If the patient is unsure of her last menstrual period (LMP) or has a history of irregular menstrual cycles, dating should be calculated based on ultrasound measurements. In general, ultrasound dating is used when the discrepancy between menstrual dating and ultrasound dating is greater than the precision of ultrasonography. [] First trimester calculations are more precise compared to later gestational ages.

Before 14 0/7 weeks gestation, the mean crown-rump length calculated has a precision of 5-7 days. [] Therefore, before 9 0/7 weeks gestation, the estimated due date should correspond to ultrasound measurements when there is more than a 5 day discrepancy between menstrual dating and ultrasound dating. [, ] Similarly, if the ultrasound dating between 9 0/7 weeks of gestation and 13 6/7 weeks gestation has more than a 7 day discrepancy from the menstrual dating, ultrasound measurements should be used to assign estimated due date.

[, ] In the second and third trimester, larger discrepancies reflect less precise measurements based on biometric parameters (see Table 1). In the setting of multifetal gestations, amnionicity and chorionicity should be documented. In the setting of desired genetic testing, nuchal translucency measurement aids in the screening assessment for fetal aneuploidy in conjunction with biomarkers. A first trimester ultrasound is also useful for the evaluation of maternal anatomy including assessment of the uterus, cervix and adnexal structures.

The presence of adnexal masses, ovarian cysts, and/or leiomyomas should be documented and followed throughout pregnancy. Second or third trimester ultrasound examinations use fetal biometry to assess fetal growth and also can provide detailed information on fetal anatomy. A standard obstetric ultrasound examination also may include an evaluation of fetal presentation(s), amniotic fluid volume, cardiac activity, and placentation.

After the first trimester, fetal biometry specifically measures the fetus’ biparietal diameter, head circumferences, abdominal circumference or average abdominal diameter and femoral diaphysis length. Fetal biometry may be utilized to establish an estimated due date for a pregnancy if no prior ultrasound measurement of the embryo was done. However the most accurate gestational age assessment is based on crown rump length measurement and the variability of gestational age estimations increases throughout pregnancy.

For this reason, the earliest available ultrasound should always be used to assign an estimated due date and any significant discrepancies between gestational age and fetal measurements on subsequent ultrasounds should raise suspicion for growth abnormalities. The approximate error in fetal weight prediction methods is approximately 15% and is influenced by patient body habitus, weight range of fetus, technical factors such as machine quality and experience of ultrasonographer.

[] In the third trimester, the femur length is the best single biometric measurement of gestational age. [] Assessment of fetal anomalies, also known as a fetal anatomic survey, should be performed after 18 weeks gestational age and ideally performed between 18-20 weeks gestational age. [] Although it may be possible to document anatomic structures before this time, the size, position, and movement of a fetus may limit a comprehensive examination of structures and therefore require repeat ultrasound examinations.

[] Additionally if a fetal anomaly is detected in this preferred gestational age window (18-20 weeks), termination of pregnancy may still be an option for the patient. The basic fetal anatomic examination includes assessment of the following structures: lateral cerebral ventricles, choroid plexus, midline falx, cavum septi pellucidi, cerebellum, cistern magna, upper lip, four-chamber view of heart as well as left and right ventricular outflow tracts, size and location of stomach, urinary bladder and ureters, spinal anatomy, extremities, and gender.

A more detailed anatomic survey may be indicated depending on the risk and concern for aneuploidy. The placenta should also be further characterized at this time, specifically noting its location and proximity to the internal cervical os as well as the number of vessels and insertion site of the umbilical cord [1,4].

[, ] Additionally, the second and third trimester basic ultrasound may also be used to diagnose or to monitor maternal anatomical problems, most notably cervical length in the setting of risk factors for preterm birth or cervical insufficiency. Ultrasound monitoring of fibroids and/or ovarian cysts is also important, but this is limited at later gestational ages due to the size of the gravid uterus. A limited or specialized ultrasound may be performed at any gestational age and is typically used to evaluate a specific clinical concern during prenatal care.

Some examples include assessment of cardiac activity when fetal heart tones are undetectable with external fetal monitoring devices to rule out fetal demise, notation of fetal presentation in setting of anticipated external cephalic version or to determine mode of delivery, and calculation of estimated fetal weight and amniotic fluid in setting of comorbidities that may predispose infants to growth abnormalities (eg chronic hypertension, pre-eclampsia, diabetes, multifetal gestation).

Fetal growth evaluations are typically performed at 3-4 week intervals and usually include an assessment of amniotic fluid as well. [] There are two main techniques to measure amniotic fluid in the second or third trimester, specifically single deepest pocket (SDP) or the amniotic fluid index (AFI). The SDP technique records the single largest vertical pocket of amniotic fluid without evidence of umbilical cord or fetal parts visualized in utero. The AFI technique is the summative measurement of the single deepest vertical pocket of fluid without evidence of cord or fetal parts noted in all four quadrants of the uterus.

Oligohydramnios, or significantly low amniotic fluid, is defined as an AFI less than 5 cm or a maximum vertical pocket less than 2 cm. Alternatively, polyhydramnios which is a term to describe an abnormally large amount of fluid, is defined by an AFI greater than 24 cm or a single deepest vertical pocket (SDP) greater than 8 cm.

[] In multifetal gestations, fluid evaluation should be performed using the single deepest pocket technique. Comparison of measurement techniques show that measurement of the single deepest pocket leads to fewer interventions (such as induction of labor for oligohydramnios) with no increase in poor perinatal outcomes.

[] Similar to a limited ultrasound exam, a detailed ultrasound examination is a supplemental tool to aid in the management of prenatal care in the setting of concern for fetal well-being due patient history, genetic screening abnormalities, or results of prior ultrasound exams.

For example, The CDC and ACOG recommend that pregnant women who live in or have traveled to areas with ongoing Zika virus exposure should undergo Zika virus serologic testing and fetal ultrasonography to screen for microcephaly or intracranial calcifications as early as 3-­4 weeks after symptoms or exposure. [, ] . However, the CDC warned that fetal ultrasounds might not detect abnormalities until late second or early third trimester of pregnancy. [, , ] Other examples of specialized ultrasound exams include fetal surveillance with a biophysical profile, fetal Doppler ultrasound for assessment of placental insufficiency, and a more detailed anatomy scan or fetal echocardiography in setting of concern for fetal anomaly.

The prenatal ultrasound examination has been proven safe to both mothers and fetuses. As with any clinical test or medical intervention, a risk ­to ­benefit analysis of the test should be considered and should only be performed when there is a medical/obstetric indication or clinical concern. Additionally, if a diagnostic ultrasound is required for patient care it should be done under the “as low as reasonably achievable principle” (ALARA principle) due to possible risks associated to the physical effects from the exam including mechanical vibrations or increase in temperature under exam conditions as well as unknown risks of ultrasound energy to fetus not yet documented in the literature.

[, ] Some ultrasonographic modalities, such as Doppler, deliver more energy to the area of interest and the use of those modalities should be reserved for specific clinical questions and an attempt made to limit their duration of use. In 1994 the Federal Drug Administration reported concern about the misuse of diagnostic ultrasound exams and equipment for non-medical purposes, specifically noting that the promotion, selling, or leasing of ultrasound equipment for “keepsake” fetal videos without a physician’s order may be in violation of local or state laws and regulations.

[] Obstetric ultrasound examination requires real-time two-dimensional imaging via a trans-abdominal or trans-vaginal approach in order to adequately assess pregnancy viability through cardiac activity and fetal movement.

There is currently no clinical evidence suggesting a clear advantage of three-dimensional imaging in prenatal diagnosis. [] The ultrasound transducer frequency must be selected to balance optimal beam penetration versus resolution, and therefore may vary based on a patient’s body habitus. For example, a lower-frequency transducer is beneficial in obese patients to allow for increased penetration and better imaging. Modern equipment typically includes a trans-abdominal transducer with 3 to 5 MHz frequency and a trans-vaginal transducer with 5-10 MHz frequency.

[] Modern ultrasound equipment has boundaries set by the manufacturer, limiting the fetal exposure to energy generated by the equipment. As with any medical equipment, adequate care and maintenance should be performed as per manufacturer recommendations.

Additionally, personnel involved with the use of ultrasound equipment should have appropriate training. Some ultrasound suites have quality ­assurance programs to evaluate performance of personnel and the ultrasound unit.

The AIUM has published specific training guidelines for physicians who perform and interpret obstetric ultrasound which includes the following minimum requirements to demonstrate a strong knowledge base, technical skill and competency.

[, ] Specifically for graduates of residency or fellowship programs to gain proficiency, the physician must perform at least 300 diagnostic ultrasounds.

Additionally, a minimum of 170 annual diagnostic obstetric ultrasound examinations is recommended to maintain the technical skills required for competency. [] Minimal preparation is required for a trans-abdominal or trans-vaginal ultrasound.

A fasting state is not required, in contrast to other ultrasound studies (eg, gallbladder ultrasonography). Some practitioners advise their patients to arrive to the ultrasound suite with a full bladder, but there is no consensus regarding this recommendation, especially for an obstetric ultrasound performed after 18 weeks’ gestation. If a trans-vaginal approach is to be used, the patient is asked to void just before the study to empty her bladder.

This minimizes discomfort and collapses the bladder for better visualization of pelvic organs. Ultrasound transducers require proper cleaning before and after each patient’s use to avoid risk of microbial transmission leading to infection. Transabdominal ultrasound transducers are typically cleansed with disposable antiseptic wipes and the clean transducer may be applied directly to the patient’s skin.

Conversely trans-vaginal ultrasound transducers require more extensive cleaning and sterilization. Specifically trans-vaginal transducers should be covered with a single-use disposal cover during the patient exam.

After the exam is completed, cleaning steps include removal of the disposal cover, cleansing with running water or a damp cloth to remove residual gel or debris from probe, followed by high-level disinfection chemical agents in accordance with FDA recommended guidelines.

[] • American Institute of Ultrasound in Medicine. AIUM practice guideline for the performance of obstetric ultrasound examinations. J Ultrasound Med. 2013 Jun. 32 (6):1083-101. . • Committee on Practice Bulletins—Gynecology. The American College of Obstetricians and Gynecologists Practice Bulletin no. 150.

Early pregnancy loss. Obstet Gynecol. 2015 May. 125 (5):1258-67. . • Doubilet PM, Benson CB, Bourne T, et al. Diagnostic criteria for nonviable pregnancy early in the first trimester. N Engl J Med. 2013 Oct 10. 369 (15):1443-51. . • Practice Bulletin No. 175 Summary: Ultrasound in Pregnancy. Obstet Gynecol.

2016 Dec. 128 (6):1459-1460. . • Committee opinion no 611: method for estimating due date. Obstet Gynecol. 2014 Oct. 124 (4):863-6. . • Goldstein SR, Wolfson R. Endovaginal ultrasonographic measurement of early embryonic size as a means of assessing gestational age. J Ultrasound Med. 1994 Jan. 13 (1):27-31. . • Petersen EE, Polen KN, Meaney-Delman D, et al.

Update: Interim Guidance for Health Care Providers Caring for Women of Reproductive Age with Possible Zika Virus Exposure - United States, 2016. MMWR Morb Mortal Wkly Rep. 2016 Apr 1. 65 (12):315-22. . • Practice Advisory: Updated Interim Guidance for Care of Women of Reproductive Age During a Zika Virus Outbreak. ACOG. Available at . June 23, 2016; Accessed: July 27, 2016. • Driggers RW, Ho CY, Korhonen EM, Kuivanen S, Jääskeläinen AJ, Smura T, et al.

Zika Virus Infection with Prolonged Maternal Viremia and Fetal Brain Abnormalities. N Engl J Med. 2016 Jun 2. 374 (22):2142-51. . • Kelly JC. Early Ultrasounds May Miss Zika-Induced Microcephaly. Medscape Medical News. Available at . April 15, 2016; Accessed: July 27, 2016.

• Fetal keepsake video. Food and Drug Administration. Available at . May 2011; Accessed: June 11, 2012. • AIUM official statement. Training guidelines for physicians who evaluate and interpret diagnostic obstetric ultrasound examinations. American Institute of Ultrasound in Medicine. Available at . October 31, 2015; Accessed: December 6, 2016. • Guidelines for Professional Working Standards. Ultrasound Practice. United Kingdom Association of Sonographers.

October 2008. • Preisler J, Kopeika J, Ismail L, Vathanan V, Farren J, Abdallah Y, et al. Defining safe criteria to diagnose miscarriage: prospective observational multicentre study. BMJ. 2015 Sep 23. 351:h4579. . • Brown T. Miscarriage Ultrasound Diagnosis May Still Need Rescan. Medscape Medical News. Available at . September 25, 2015; Accessed: July 27, 2016. • Sonek J, Nicolaides K.

Additional first-trimester ultrasound markers. Clin Lab Med. 2010 Sep. 30(3):573-92. . • McGahan JP. Sonography of the Fetal Heart. Findings on the Four Chamber View. March 1991. AJR: 156: • Dicke JM, Piper SL, Goldfarb CA. The utility of ultrasound for the detection of fetal limb abnormalities - a 20 year single center experience. Prenat Diagn.

2014 Dec 4. . • American Institute of Ultrasound in Medicine. AIUM practice guideline for the performance of obstetric ultrasound examinations. J Ultrasound Med. 2010 Jan. 29(1):157-66. . • Bignardi T, Condous G, Kirk E, Van Calster B, Van Huffel S, Timmerman D. Viability of intrauterine pregnancy in women with pregnancy of unknown location: prediction using human chorionic gonadotropin ratio vs. progesterone. Ultrasound Obstet Gynecol. 2010 Jun. 35(6):656-61. . • Practice Advisory: Updated Interim Guidance for Care of Women of Reproductive Age During a Zika Virus Outbreak.

ACOG. Available at . June 23, 2016; Accessed: July 27, 2016. Chief Editor Carl V Smith, MD The Distinguished Chris J and Marie A Olson Chair of Obstetrics and Gynecology, Professor, Department of Obstetrics and Gynecology, Senior Associate Dean for Clinical Affairs, University of Nebraska Medical Center Carl V Smith, MD is a member of the following medical societies: , , , , , , Disclosure: Nothing to disclose.

Additional Contributors Serdar H Ural, MD Associate Professor of Obstetrics and Gynecology and Radiology, Director, Division of Maternal-Fetal Medicine, Medical Director, Labor and Delivery Suite, Pennsylvania State University College of Medicine Serdar H Ural, MD is a member of the following medical societies: , , , , , Disclosure: Received honoraria from GSK for speaking and teaching; Received honoraria from J&J for speaking and teaching.

Pedro Roca, MD, MPH, FACOG Fellow in Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Hershey Medical Center, Pennsylvania State University College of Medicine Pedro Roca, MD, MPH, FACOG is a member of the following medical societies: , , , Disclosure: Nothing to disclose.

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