Obstetrics
Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is - in some jurisdictions - combined with gynecology under the discipline known as obstetrics and gynecology, which is a surgical field.
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: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 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 Edwards syndrome, 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 can be done at 10 plus weeks to 13 plus weeks with an ultrasound of the fetal neck and two chemicals, pregnancy-associated plasma protein A and human chorionic gonadotropin. 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 – 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 for women over 35 or who reach 35 by mid pregnancy or who are at increased risk due to family history or prior birth history.
Third trimester
- Hematocrit
- 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 – screens for gestational diabetes; if > 140 mg/dL, a glucose tolerance test is administered; a fasting glucose > 105 mg/dL suggests gestational diabetes.
Fetal assessments
is routinely used for dating the gestational age of a pregnancy from the size of the fetus, determining the number of fetuses and placentae, evaluating for an ectopic pregnancy and first trimester bleeding, with the most accurate dating being in the first trimester before the growth of the fetus has been significantly influenced by other factors. Ultrasound is also used for detecting congenital anomalies and determining the biophysical profiles, which are generally easier to detect in the second trimester when the foetal structures are larger and more developed.X-rays and computerized tomography 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 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 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
- Foetal haematocrit for the assessment of foetal anemia, Rh isoimmunization, or hydrops can be determined by percutaneous umbilical blood sampling, 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 for fetal heart rate
- Oxytocin challenge test
Diseases in pregnancy
- Diabetes mellitus and pregnancy deals with the interactions of diabetes mellitus and pregnancy. Risks for the child include miscarriage, growth restriction, growth acceleration, foetal obesity, polyhydramnios and birth defects.
- Lupus and pregnancy confers an increased rate of foetal death in utero and spontaneous abortion, 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. Pregnancy itself is a factor of 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, 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
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
- Monitor the progress of labour, by reviewing the nursing chart, performing vaginal examination, and assessing the trace produced by a foetal monitoring device
- 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
- Ectopic pregnancy is when an embryo implants in the uterine tube or 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. 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 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, and abdominal pain, offensive lochia increased lochia, clots, diarrhea and vomiting.