obstetrics obstetrics obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. as a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (ob/gyn), which is a surgical field. this article is about the medical specialty. for the health profession, see midwifery. look up obstetrics in wiktionary, the free dictionary. obstetricianoccupationnames physician surgeon occupation typespecialtyactivity sectorsmedicine, surgerydescriptioneducation required doctor of medicine (m.d.) doctor of osteopathic medicine (d.o.) bachelor of medicine, bachelor of surgery (m.b.b.s.) bachelor of medicine, bachelor of surgery (mbchb) fields ofemploymenthospitals, clinics 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 along with telehealth care for women with low-risk pregnancies: 3d ultrasound of 3-inch (76 mm) fetus (about 14 weeks gestational age) fetus at 17 weeks fetus at 20 weeks first trimester routine tests in the first trimester of pregnancy generally include: complete blood count blood type rh-negative antenatal patients should receive rhogam at 28 weeks to prevent rh disease. indirect coombs test (agt) to assess risk of hemolytic disease of the newborn rapid plasma reagin test to screen for syphilis rubella antibody screen hbsag test to screen for hepatitis b testing for chlamydia (and gonorrhea when indicated mantoux test for tuberculosis urinalysis and culture hiv screen genetic screening for down syndrome (trisomy 21) and edwards syndrome (trisomy 18), the national standard in the united states, is rapidly evolving away from the afp-quad screen, 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), pregnancy-associated plasma protein a and human chorionic gonadotropin (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. down syndrome karyotype second trimester msafp/quad. screen (four simultaneous blood tests) (maternal serum afp, inhibin a, estriol, and 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. the result of an ultrasonography: a black and white image that shows a clear view of the interior abdomen fetal assessments a dating scan at 12 weeks 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, 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 been 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 diseases in pregnancy further information: pre-existing disease in pregnancy a pregnant woman may have a pre-existing disease, that may become worse or become a risk to the pregnancy, or to postnatal development of the offspring 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, foetal obesity (macrosomia), polyhydramnios and birth defects. lupus 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. hyperemesis gravidarum in pregnancy occurs due to extreme, persistent nausea and vomiting during pregnancy. if untreated, can lead to dehydration, weight loss, and electrolyte imbalances. most women develop nausea and vomiting during the first trimester. the cause of hyperemesis gravidarum is not known. however, it is believed to be caused by a rapidly rising blood level of a hormone, human chorionic gonadotropin (hcg), which is released by the placenta. preeclampsia is a condition that causes high blood pressure during pregnancy. if left untreated, it can be life-threatening. in pregnant women, preeclampsia may occur after 20 weeks of pregnancy, often in women who have no history of high blood pressure. symptoms of preeclampsia may include severe headache, vision changes and pain under the ribs. however, in some women, symptoms may not occur, until they go for a routine prenatal visit. induction and labour main articles: induction (birth) and childbirth further information: pain management during childbirth 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 membranes pessary of prostin cream, prostaglandin e2 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 foetal or maternal compromise. complications and emergencies main article: complications of pregnancy 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) foetus, 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. postpartum period further information: postpartum period the world health organization makes a distinction between the use of postpartum care when it concerns the care of the mother after giving birth, and postnatal care when the care of the newborn is concerned. postpartum care is provided to the mother following childbirth. a woman in the western world who gives birth 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 later, but usually averages a stay of one or two days; the average postnatal stay following delivery by caesarean section is three to four days. during this time the mother is monitored for bleeding, bowel and bladder function, and baby care. the infant's health is also monitored. history two midwives assisting a woman in labour on a birthing chair in the 16th century, from a work by eucharius rößlin prior to the 18th century, caring for pregnant women in europe was confined exclusively to women, and rigorously excluded men. the expectant