Obstetrics

Obstetrics

Obstetrics (from the Latin obstare, "to stand by") is the medical specialty dealing with the care of all women's reproductive tracts and their children during pregnancy (prenatal period), childbirth and the postnatal period. Veterinary obstetrics is the same concept for veterinary medicine although theriogenology is more commonly used term that includes obstetrics, gynecology, and andrology. Almost all modern obstetricians are also gynaecologists.

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 reagent (RPR) which screens for syphilis
  • Rubella antibody screen
  • Hepatitis B surface antigen
  • Gonorrhea and Chlamydia culture
  • PPD for tuberculosis
  • Pap smear
  • Urinalysis and culture
  • HIV screen
  • Group B Streptococcus screen – will receive IV penicillin or ampicillin (it is much cheaper and has a wider coverage)if positive (if mother is allergic, alternative therapies include IV clindamycin or IV vancomycin)
genetic screening for downs syndrome (trisomy 21) and trisomy 18 the national standard in the United States is rapidly evolving away from the AFP-Quad screen for downs 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 (thick skin is bad) and two chemicals (analytes) Papp-a and bhcg (pregnancy hormone level itself). It gives an accurate risk profile very early. There is a second blood screen at 15 to 20 weeks which 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 alpha-fetoprotein; inhibin; estriol; bhcg or free bhcg) - 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 trannsvaginal 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 by family history or prior birth history.
Third trimester
 
Hematocrit (if low, mother will receive iron supplementation)
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
 
Antenatal record
 
On the first visit to her obstetrician or midwife, the pregnant woman is asked to carry out the antenatal record, which constitutes a medical history and physical examination. On subsequent visits, the gestational age (GA) is rechecked with each visit.
 
Symphysis-fundal height (SFH; in cm) should equal gestational age after 20 weeks of gestation, and the fetal growth should be plotted on a curve during the antenatal visits. The fetus is palpated by the midwife or obstetrician using Leopold maneuver to determine the position of the baby. Blood pressure should also be monitored, and may be up to 140/90 in normal pregnancies. High blood pressure indicates hypertension and possibly pre-eclampsia, if severe swelling (edema) and spilled protein in the urine are also present.
 
Fetal screening is also used to help assess the viability of the fetus, as well as congenital problems. Genetic counseling is often offered for families who may be at an increased risk to have a child with a genetic condition. Amniocentesis at around the 20th week is sometimes done for women 35 or older to check for Down's Syndrome and other chromosome abnormalities in the fetus.
 
Even earlier than amniocentesis is performed, the mother may undergo the triple test, nuchal screening, nasal bone, alpha-fetoprotein screening and Chorionic villus sampling, also to check for disorders such as Down Syndrome. Amniocentesis is a prenatal genetic screening of the fetus, which involves inserting a needle through the mother's abdominal wall and uterine wall, to extract fetal DNA from the amniotic fluid. There is a risk of miscarriage and fetal injury with amniocentesis because it involves penetrating the uterus with the baby still in utero.
 
Imaging
 
Imaging is another important way to monitor a pregnancy. The mother and fetus are also usually imaged in the first trimester of pregnancy. This is done to predict problems with the mother; confirm that a pregnancy is present inside the uterus; estimate the gestational age; determine the number of fetuses and placentae; evaluate for an ectopic pregnancy and first trimester bleeding; and assess for early signs of anomalies.
 
 
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 fetus. No effects of magnetic resonance imaging (MRI) on the fetus have been demonstrated, but this technique is too expensive for routine observation. Instead, ultrasound 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.
 
Ultrasound imaging may be done at any time throughout the pregnancy, but usually happens at the 12th week (dating scan) and the 20th week (detailed scan).
 
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.
 
Complications and emergencies
 
The main emergencies include:
 
  • Ectopic pregnancy is when an embryo implants in the Fallopian tube or (rarely) on the ovary or inside the peritoneal cavity. This may cause massive internal bleeding.
  • Pre-eclampsia is a disease which is 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 a convulsions occur, which can be fatal. Preeclamptic patients with the HELLP syndrome show liver failure and Disseminated intravascular coagulation (DIC).
  • Placental abruption where the patient can bleed to death if not managed appropriately.
  • Fetal distress where the fetus is getting compromised in the uterine environment.
  • Shoulder dystocia where one of the fetus' shoulders becomes stuck during vaginal birth, especially in macrosomic babies of diabetic mothers.
  • Uterine rupture can occur during obstructed labor and endangered fetal and maternal life.
  • Prolapsed cord refers to the prolapse of the fetal cord during labor with the risk of fetal suffocation.
  • Obstetrical hemorrhage may be due to a number of factors such as placenta previa, uterine rupture of tears, uterine atony, retained placenta or placental fragments, or bleeding disorders.
  • Puerperal sepsis is a progressed infection of the uterus during or after labor.
Fetal assessments
 
Ultrasound is routinely used for dating the gestational age of a pregnancy from the size of the fetus, the most accurate dating being in first trimester before the growth of the fetus has been significantly influenced by other factors. Ultrasound is also used for detecting congenital anomalies (or other fetal anomalies) and determining the biophysical profiles (BPP), which are generally easier to detect in the second trimester when the fetal 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.
 
Other tools used for assessment include:
 
  • Fetal karyotype can be used for the screening of genetic diseases. This can be obtained via amniocentesis or chorionic villus sampling (CVS)
  • Fetal hematocrit for the assessment of fetal 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

Childbirth

Induction
 
Induction is a method of artificially or prematurely stimulating labour in a woman. Reasons to induce can include pre-eclampsia, placental malfunction, intrauterine growth retardation, and other various general medical conditions, such as renal disease. Induction may occur any time after 34 weeks of gestation if the risk to the fetus or mother is greater than the risk of delivering a premature fetus regardless of lung maturity.
 
Induction may be achieved via several methods:
 
  • 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)
Labor
 
During labor itself, the obstetrician/doctor/intern/medical student under supervision may be called on to do a number of tasks. These tasks can include:
 
  • Monitor the progress of labor, by reviewing the nursing chart, performing vaginal examination, and assessing the trace produced by a fetal monitoring device (the cardiotocograph)
  • Accelerate the progress of labor by infusion of the hormone oxytocin
  • Provide pain relief, either by nitrous oxide, opiates, or by epidural anesthesia done by anaesthestists, an anesthesiologist, or a nurse anesthetist.
  • Surgically assisting labor, by forceps or the Ventouse (a suction cap applied to the fetus' head)
  • Caesarean section, if there is an associated risk with vaginal delivery, as such fetal or maternal compromise supported by evidence and literature. Caesarean section can either be elective, that is, arranged before labor, or decided during labor as an alternative to hours of waiting. True "emergency" Cesarean sections include abruptio placenta, and are more common in multigravid patients, or patients attempting a Vaginal Birth After Caeserean section (VBAC).
Postnatal
 
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.
 
Post-Natal Care
 
Care provided to the mother following parturition. Certain things must be kept in mind as the physician proceeds with the post-natal care.
  1. General Condition of the patient.
  2. Check for Vital Signs (Pulse, Blood Pressure, Temperature, Respiratory Rate, (Pain) at times)
  3. Palor?
  4. Edema?
  5. Dehydration?
  6. Fundus (height following parturition, and the feel of the fundus) (Per Abdominal Examination)
  7. If an Episiotomy or a C-Section was performed, check for the dressing. Intact, pus, oozing, haematomas?
  8. Lochia (colour, amount, odour)?
  9. Bladder (keep the patient catheterized for 12 hours following local anaesthesia and 24–48 hours after general anaesthesia) ? (check for bladder function)
  10. Bowel Movements?
  11. Follow up with the neonate to check if they’re healthy.
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