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.
Fetal distress, also known as non-reassuring fetal status, is a condition during pregnancy or labor in which the fetus shows signs of inadequate oxygenation. Due to its imprecision, the term "fetal distress" has fallen out of use in American obstetrics. The term "non-reassuring fetal status" has largely replaced it. It is characterized by changes in fetal movement, growth, heart rate, and presence of meconium stained fluid.
Chorionic villus sampling (CVS), sometimes called "chorionic villous sampling", is a form of prenatal diagnosis done to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus and testing it for chromosomal abnormalities, usually with FISH or PCR. CVS usually takes place at 10–12 weeks' gestation, earlier than amniocentesis or percutaneous umbilical cord blood sampling. It is the preferred technique before 15 weeks.
Polyhydramnios is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in about 1% of pregnancies. It is typically diagnosed when the amniotic fluid index (AFI) is greater than 24 cm. There are two clinical varieties of polyhydramnios: chronic polyhydramnios where excess amniotic fluid accumulates gradually, and acute polyhydramnios where excess amniotic fluid collects rapidly.
Oligohydramnios is a medical condition in pregnancy characterized by a deficiency of amniotic fluid, the fluid that surrounds the fetus in the abdomen, in the amniotic sac. It is typically diagnosed by ultrasound when the amniotic fluid index (AFI) measures less than 5 cm or when the single deepest pocket (SDP) of amniotic fluid measures less than 2 cm. Amniotic fluid is necessary to allow for normal fetal movement, lung development, and cushioning from uterine compression. Low amniotic fluid can be attributed to a maternal, fetal, placental or idiopathic cause and can result in poor fetal outcomes including death. The prognosis of the fetus is dependent on the etiology, gestational age at diagnosis, and the severity of the oligohydramnios.
The amniotic fluid is the protective liquid contained by the amniotic sac of a gravid amniote. This fluid serves as a cushion for the growing fetus, but also serves to facilitate the exchange of nutrients, water, and biochemical products between mother and 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.
Rupture of membranes (ROM) or amniorrhexis is a term used during pregnancy to describe a rupture of the amniotic sac. Normally, it occurs spontaneously at full term either during or at the beginning of labor. Rupture of the membranes is known colloquially as "breaking [one's] water," especially when induced rather than spontaneous, or as one's "water breaking". A premature rupture of membranes (PROM) is a rupture of the amnion that occurs at full term and prior to the onset of labor. In cases of PROM, options include expectant management without intervention, or interventions such as oxytocin or other methods of labor induction, and both are usually accompanied by close monitoring of maternal and fetal health. Preterm premature rupture of membranes (PPROM) is when water breaks both before the onset of labor and before the pregnancy's 37 week gestation. In the United States, more than 120,000 pregnancies per year are affected by a premature rupture of membranes, which is the cause of about one third of preterm deliveries.
Placental abruption is when the placenta separates early from the uterus, in other words separates before childbirth. It occurs most commonly around 25 weeks of pregnancy. Symptoms may include vaginal bleeding, lower abdominal pain, and dangerously low blood pressure. Complications for the mother can include disseminated intravascular coagulopathy and kidney failure. Complications for the baby can include fetal distress, low birthweight, preterm delivery, and stillbirth.
Prelabor rupture of membranes (PROM), previously known as premature rupture of membranes, is breakage of the amniotic sac before the onset of labor. Women usually experience a painless gush or a steady leakage of fluid from the vagina. Complications in the baby may include premature birth, cord compression, and infection. Complications in the mother may include placental abruption and postpartum endometritis.
Chorioamnionitis, also known as intra-amniotic infection (IAI), is inflammation of the fetal membranes, usually due to bacterial infection. In 2015, a National Institute of Child Health and Human Development Workshop expert panel recommended use of the term "triple I" to address the heterogeneity of this disorder. The term triple I refers to intrauterine infection or inflammation or both and is defined by strict diagnostic criteria, but this terminology has not been commonly adopted although the criteria are used.
Postterm pregnancy is when a woman has not yet delivered her baby after 42 weeks of gestation, two weeks beyond the typical 40-week duration of pregnancy. Postmature births carry risks for both the mother and the baby, including fetal malnutrition, meconium aspiration syndrome, and stillbirths. After the 42nd week of gestation, the placenta, which supplies the baby with nutrients and oxygen from the mother, starts aging and will eventually fail. Postterm pregnancy is a reason to induce labor.
An amniotic fluid embolism (AFE) is a life-threatening childbirth (obstetric) emergency in which amniotic fluid enters the blood stream of the mother, triggering a serious reaction which results in cardiorespiratory collapse and massive bleeding (coagulopathy). The rate at which it occurs is 1 instance per 20,000 births and it comprises 10% of all maternal deaths.
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.
An obstetric labor complication is a difficulty or abnormality that arises during the process of labor or delivery.
Placental alpha microglobulin-1 (PAMG-1) is a human protein that was first isolated in 1975 from amniotic fluid. PAMG-1 is an important biomarker for the detection of premature rupture of fetal membrane (PROM) The high concentration of PAMG-1 in amniotic fluid means it can be used to detect if this fluid is present in the cervico-vaginal discharge of pregnant women; the presence of PAMG-1 in the discharge suggests that amniotic fluid is present, and therefore suggests that PROM has occurred. PAMG-1 was originally referred to as specific alpha-1 globulin of placenta.
The fetal membranes are the four extraembryonic membranes, associated with the developing embryo, and fetus in humans and other mammals. They are the amnion, chorion, allantois, and yolk sac. The amnion and the chorion are the chorioamniotic membranes that make up the amniotic sac which surrounds and protects the embryo. The fetal membranes are four of six accessory organs developed by the conceptus that are not part of the embryo itself, the other two are the placenta, and the umbilical cord.
Circumvallate placenta is a rare condition affecting about 1-2% of pregnancies, in which the amnion and chorion fetal membranes essentially "double back" on the fetal side around the edges of the placenta. After delivery, a circumvallate placenta has a thick ring of membranes on its fetal surface. Circumvallate placenta is a placental morphological abnormality associated with increased fetal morbidity and mortality due to the restricted availability of nutrients and oxygen to the developing fetus.
Amnioinfusion is a method in which isotonic fluid is instilled into the uterine cavity.
Anhydramnios is a condition in which there is an abnormally low or complete absence of amniotic fluid surrounding the fetus in the womb. Amniotic fluid is a clear, watery substance that surrounds the fetus. It helps to maintain a constant temperature around the fetus, cushion it from injury, and allows for proper fetal movement and organ development. The cause of anhydramnios is not always clear, but several factors can contribute to its development such as fetal renal abnormalities or placental insufficiency. Untreated anhydramnios can lead to serious complications for the baby, including pulmonary hypoplasia or skeletal deformities.
