Amniocentesis is a medical procedure used primarily in the prenatal diagnosis of genetic conditions. It has other uses such as in the assessment of infection and fetal lung maturity. Prenatal diagnostic testing, which includes amniocentesis, is necessary to conclusively diagnose the majority of genetic disorders, with amniocentesis being the gold-standard procedure after 15 weeks' gestation.
Selective reduction is the practice of reducing the number of fetuses in a multiple pregnancy, such as quadruplets, to a twin or singleton pregnancy. The procedure is also called multifetal pregnancy reduction. The procedure is most commonly done to reduce the number of fetuses in a multiple pregnancy to a safe number, when the multiple pregnancy is the result of use of assisted reproductive technology; outcomes for both the mother and the babies are generally worse the higher the number of fetuses. The procedure is also used in multiple pregnancies when one of the fetuses has a serious and incurable disease, or in the case where one of the fetuses is outside the uterus, in which case it is called selective termination.
Obstetric ultrasonography, or prenatal ultrasound, is the use of medical ultrasonography in pregnancy, in which sound waves are used to create real-time visual images of the developing embryo or fetus in the uterus (womb). The procedure is a standard part of prenatal care in many countries, as it can provide a variety of information about the health of the mother, the timing and progress of the pregnancy, and the health and development of the embryo or fetus.
Twin-to-twin transfusion syndrome (TTTS), also known as feto-fetal transfusion syndrome (FFTS), twin oligohydramnios-polyhydramnios sequence (TOPS) and stuck twin syndrome, is a complication of monochorionic multiple pregnancies in which there is disproportionate blood supply between the fetuses. This leads to unequal levels of amniotic fluid between each fetus and usually leads to death of the undersupplied twin and, without treatment, usually death or a range of birth defects or disabilities for a surviving twin, such as underdeveloped, damaged or missing limbs, digits or organs, especially cerebral palsy.
In obstetrics, gestational age is a measure of the age of a pregnancy taken from the beginning of the woman's last menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method, if available. Such methods include adding 14 days to a known duration since fertilization, or by obstetric ultrasonography. The popularity of using this measure of pregnancy is largely due to convenience: menstruation is usually noticed, while there is generally no convenient way to discern when fertilization or implantation occurred.
Hemolytic disease of the newborn (anti-Kell1) is the second most common cause of severe hemolytic disease of the newborn (HDN) after Rh disease. Anti-Kell1 is becoming relatively more important as prevention of Rh disease is also becoming more effective.
A nuchal scan or nuchal translucency (NT) scan/procedure is a sonographic prenatal screening scan (ultrasound) to detect chromosomal abnormalities in a fetus, though altered extracellular matrix composition and limited lymphatic drainage can also be detected.
Placental insufficiency or utero-placental insufficiency is the failure of the placenta to deliver sufficient nutrients to the fetus during pregnancy, and is often a result of insufficient blood flow to the placenta. The term is also sometimes used to designate late decelerations of fetal heart rate as measured by cardiotocography or an NST, even if there is no other evidence of reduced blood flow to the placenta, normal uterine blood flow rate being 600mL/min.
Stuart Campbell DSc FRCPEd FRCOG FACOG, was born in Glasgow, Scotland, and graduated from the medical school of Glasgow University. During his training he worked with Ian Donald, who had published some of the first papers on the use of ultrasound in obstetrics.
Maternal–fetal medicine (MFM), also known as perinatology, is a branch of medicine that focuses on managing health concerns of the mother and fetus prior to, during, and shortly after pregnancy.
Velamentous cord insertion is a complication of pregnancy where the umbilical cord is inserted in the fetal membranes. It is a major cause of antepartum hemorrhage that leads to loss of fetal blood and associated with high perinatal mortality. In normal pregnancies, the umbilical cord inserts into the middle of the placental mass and is completely encased by the amniotic sac. The vessels are hence normally protected by Wharton's jelly, which prevents rupture during pregnancy and labor. In velamentous cord insertion, the vessels of the umbilical cord are improperly inserted in the chorioamniotic membrane, and hence the vessels traverse between the amnion and the chorion towards the placenta. Without Wharton's jelly protecting the vessels, the exposed vessels are susceptible to compression and rupture.
Monoamniotic twins are identical or semi-identical twins that share the same amniotic sac within their mother's uterus. Monoamniotic twins are always monochorionic and are usually termed Monoamniotic-Monochorionic twins. They share the placenta, but have two separate umbilical cords. Monoamniotic twins develop when an embryo does not split until after formation of the amniotic sac, at about 9–13 days after fertilization. Monoamniotic triplets or other monoamniotic multiples are possible, but extremely rare. Other obscure possibilities include multiples sets where monoamniotic twins are part of a larger gestation such as triplets, quadruplets, or more.
Monochorionic twins are monozygotic (identical) twins that share the same placenta. If the placenta is shared by more than two twins, these are monochorionic multiples. Monochorionic twins occur in 0.3% of all pregnancies. Seventy-five percent of monozygotic twin pregnancies are monochorionic; the remaining 25% are dichorionic diamniotic. If the placenta divides, this takes place before the third day after fertilization.
The following outline is provided as an overview of and topical guide to obstetrics:
Twin anemia-polycythemia sequence (TAPS) is a chronic type of unbalanced fetal transfusion in monochorionic twins that results in polycythemia in the TAPS recipient and anemia in the TAPS donor due to tiny placental anastomoses. Post-laser TAPS and spontaneous TAPS are the two forms of TAPS. Unlike twin-to-twin transfusion syndrome, which arises when twin oligohydramnios polyhydramnios sequence (TOPS) is present, TAPS develops in its absence.
Charles Richard Whitfield FRCOG, FRCP(G) was a Northern Irish obstetrician and gynaecologist who was a pioneer of maternal-fetal (perinatal) medicine. His primary interest was in fetal medicine, a branch of obstetrics and gynaecology that focuses on the assessment of the development, growth and health of the baby in the womb. He was also an early proponent of subspecialisation within the fields of obstetrics and gynaecology, a practice that is common today.
Sally L. Collins BSc BMBCh DPhil FRCOG is a Professor of Obstetrics in the Nuffield Department of Women’s and Reproductive Health, University of Oxford and a Consultant Obstetrician and lead for the Placenta Accreta Service at Birmingham Women's Hospital. She is also a lecturer in Medical Sciences at St. Anne’s College, University of Oxford.
Beryl Rice Benacerraf was an American radiologist and professor of obstetrics, gynecology and reproductive biology and radiology at Harvard Medical School. She was a pioneer in the use of prenatal ultrasound to diagnose fetal abnormalities, including Down syndrome. In 2021, she was recognized as a "Giant in Obstetrics and Gynecology" by the American Journal of Obstetrics & Gynecology.
Liona Poon is an obstetrician-gynaecologist with clinical research interests devoted to improving women's and children's health. Poon is currently the Chairperson of the Department of Obstetrics and Gynaecology at the Chinese University of Hong Kong and a visiting professor at the Department of Women and Children's Health, King's College London.
Professor Aris T. Papageorghiou MBChB, MD, FRCOG, FAIUM (hon) is a Cypriot-German physician and researcher known for his work in maternal and perinatal health. He is a professor at the University of Oxford. and at St George's Hospital. He is also research director of the Oxford Maternal and Perinatal Health Institute and Reproductive Health and Editor in Chief of the British Journal of Obstetrics and Gynaecology
