ABPS Family Medicine Obstetrics cheat sheet

Preeclampsia with severe features: BP ≥160/110 mmHg, platelets <100,000, AST/ALT >2x ULN, creatinine >1.1 mg/dL or doubling, pulmonary edema, new visual/cerebral symptoms.

Gestational hypertension: BP ≥140/90 after 20 weeks without proteinuria or severe features; preeclampsia: hypertension plus proteinuria (≥300 mg/24h or P/C ratio ≥0.3) or severe features.

Fetal growth restriction: estimated fetal weight <10th percentile for gestational age; subclassified as early (<32 weeks) or late (≥32 weeks).

Twin-twin transfusion syndrome (TTTS): monochorionic diamniotic twins with polyhydramnios/oligohydramnios sequence; Quintero staging I–V.

Preterm birth prevention: vaginal progesterone 200 mg nightly for singleton with short cervix (<25 mm) at 16–24 weeks.

Magnesium sulfate for fetal neuroprotection: given for anticipated preterm birth <32 weeks, typically 4 g IV load then 1 g/h until delivery.

RhD alloimmunization prophylaxis: 300 mcg anti-D at 28 weeks and within 72 hours postpartum if infant RhD-positive; dose adjusted by rosette test if large fetomaternal hemorrhage.

Placenta accreta spectrum: risk increased with prior cesarean and placenta previa; diagnosis by ultrasound (loss of clear zone, lacunae, bladder invasion).

First-trimester combined screening: nuchal translucency, free β-hCG, PAPP-A at 11–14 weeks; detection rate for trisomy 21 ~85–90% at 5% false-positive rate.

Cell-free DNA screening: can be offered from 10 weeks; highest sensitivity for trisomy 21 (>99%), lower for trisomy 18 and 13; not diagnostic.

Quad screen (15–22 weeks): AFP, hCG, unconjugated estriol, inhibin A; detects ~80% of trisomy 21 at 5% false-positive rate.

Gestational diabetes screening: 50-g glucose challenge at 24–28 weeks; abnormal if ≥130–140 mg/dL, followed by 100-g 3-hour OGTT (Carpenter-Coustan or NDDG criteria).

Group B Streptococcus screening: vaginal-rectal swab at 36 0/7–37 6/7 weeks; intrapartum prophylaxis for positive, unknown, or risk factors.

Routine prenatal labs: CBC, blood type/Rh/antibody screen, rubella immunity, varicella immunity, syphilis, HIV, hepatitis B, urinalysis, and chlamydia/gonorrhea as indicated.

Dating ultrasound: crown-rump length 7–13 weeks is most accurate (±5–7 days); later ultrasound less accurate for dating.

Folic acid supplementation: 400 mcg daily for average risk; 4 mg daily starting ≥1 month before conception for prior neural tube defect.

Active phase of first stage: cervical dilation ≥6 cm with regular contractions; arrest defined as ≥6 cm dilation with ruptured membranes and no cervical change ≥4 hours of adequate contractions or ≥6 hours with inadequate contractions.

Second stage: nulliparous arrest if ≥3 hours without epidural or ≥4 hours with epidural; multiparous ≥2 hours without or ≥3 hours with epidural (plus one hour for fetal malposition or other extenuating factors).

Fetal heart rate categories: Category I (baseline 110–160, moderate variability, no late/variable decelerations); Category III (absent variability with recurrent late/variable decelerations, bradycardia, or sinusoidal pattern).

Tachysystole: >5 contractions in 10 minutes averaged over 30 minutes; manage by reducing oxytocin, maternal repositioning, IV fluids, and tocolysis if needed.

Shoulder dystocia maneuvers: McRoberts, suprapubic pressure, internal rotation (Rubin II/Woods), delivery of posterior arm, episiotomy only if needed for access.

Postpartum hemorrhage: cumulative blood loss ≥1000 mL or bleeding with signs of hypovolemia within 24 hours after birth; uterine atony most common cause.

Active management of third stage: uterotonic (oxytocin 10 IU IM/IV), controlled cord traction, uterine massage reduces PPH risk.

Operative vaginal delivery prerequisites: fully dilated, engaged head, known position, adequate pelvis, ruptured membranes, anesthesia, and willingness to abandon if unsuccessful.

Postpartum endometritis: fever ≥38°C on at least two of the first 10 days postpartum, with uterine tenderness and foul lochia; treat with clindamycin plus gentamicin.

Lactogenesis stage II (copious milk production) occurs around 2–5 days postpartum; triggered by drop in progesterone and rise in prolactin.

Breastfeeding jaundice: inadequate intake and dehydration in first week; breastfeeding-associated jaundice: later onset, associated with insufficient milk transfer.

Contraindications to breastfeeding: infant galactosemia, maternal HIV (in resource-rich settings), active untreated TB, certain drugs (e.g., chemotherapy), and active herpes lesions on breast.

Postpartum depression screening: Edinburgh Postnatal Depression Scale at 4–6 weeks; score ≥10 suggests possible depression.

Lochia: rubra (1–4 days), serosa (4–10 days), alba (after 10 days); foul odor or return to rubra suggests infection or retained products.

Ovulation can occur before first postpartum menses; exclusive breastfeeding provides contraception only if amenorrhea, fully breastfeeding, and <6 months postpartum (LAM).

Rh immunoglobulin: 300 mcg anti-D within 72 hours postpartum if infant Rh-positive and mother Rh-negative unsensitized.

Cesarean delivery indications: absolute (placenta previa, vasa previa, transverse lie, cord prolapse, prior classical cesarean, active genital herpes) and relative (dystocia, nonreassuring fetal status, malpresentation).

VBAC criteria: one prior low-transverse cesarean, no contraindication, available anesthesia and staff for emergency cesarean; success rate ~60–80%.

External cephalic version: attempted at ≥36 weeks for breech; contraindications include placenta previa, multiple gestation, ruptured membranes, and nonreassuring fetal status.

Operative vaginal delivery: vacuum or forceps; risks include scalp trauma, intracranial hemorrhage, shoulder dystocia, and maternal perineal injury.

Episiotomy: midline or mediolateral; not routine, indicated for shoulder dystocia, operative delivery, or imminent tear.

Amniotomy: artificial rupture of membranes to augment labor; risks include cord prolapse, infection, and fetal heart rate decelerations.

Cervical ripening: prostaglandins (misoprostol, dinoprostone) or mechanical (Foley balloon); avoid misoprostol with prior cesarean due to uterine rupture risk.

Postpartum sterilization: tubal ligation can be performed postpartum; consider long-acting reversible contraception for reversible option.

Pregestational diabetes: target HbA1c <6.5% before conception; risk of congenital malformations (cardiac, neural tube) increases with poor glycemic control.

Gestational diabetes: A1GDM (diet-controlled) vs A2GDM (medication); insulin is preferred if pharmacotherapy needed.

Chronic hypertension: BP ≥140/90 before 20 weeks or persisting postpartum; risk of superimposed preeclampsia.

Thyroid disease: hypothyroidism treated with levothyroxine; dose often increased 20–30% in pregnancy; hyperthyroidism due to Graves disease, risk of fetal thyrotoxicosis.

Epilepsy: most antiepileptic drugs increase major malformation risk (valproate highest); continue therapy to prevent seizures, use lowest effective dose.

Asthma: exacerbations common; continue controller medications; uncontrolled asthma worse for fetus than medications.

Cardiac disease: most common acquired is mitral stenosis; congenital most common is bicuspid aortic valve; risk of heart failure in third trimester and postpartum.

Venous thromboembolism: pregnancy is hypercoagulable; low-molecular-weight heparin is preferred anticoagulant; warfarin contraindicated (teratogenic).

Postpartum hemorrhage management: uterine massage, uterotonics (oxytocin, methylergonovine, carboprost, misoprostol), tranexamic acid, balloon tamponade, surgical interventions (B-Lynch, hysterectomy).

Shoulder dystocia: call for help, McRoberts maneuver, suprapubic pressure, internal rotation, posterior arm delivery, Gaskin maneuver; avoid fundal pressure.

Umbilical cord prolapse: call for help, elevate presenting part, knee-chest or Trendelenburg position, fill bladder, immediate delivery.

Preeclampsia with severe features: magnesium sulfate for seizure prophylaxis (4–6 g IV load, 1–2 g/h maintenance), antihypertensives (labetalol, hydralazine, nifedipine) for BP ≥160/110.

Amniotic fluid embolism: sudden hypoxia, hypotension, coagulopathy; supportive care, CPR, massive transfusion protocol.

Uterine rupture: sudden fetal bradycardia, loss of station, abdominal pain; immediate laparotomy and delivery.

Placental abruption: painful vaginal bleeding, uterine tenderness, fetal distress; manage with maternal stabilization and delivery.

Sepsis in pregnancy: antibiotics within 1 hour, fluid resuscitation, source control; common sources: chorioamnionitis, endometritis, pyelonephritis.

Influenza vaccine: recommended for all pregnant women during any trimester; reduces maternal and infant influenza risk.

Tdap vaccine: recommended during each pregnancy at 27–36 weeks, preferably 27–36 weeks, to maximize maternal antibody transfer.

Group B Streptococcus: intrapartum prophylaxis with penicillin G or ampicillin for positive screen, unknown status with risk factors, or prior GBS-affected infant.

HIV: universal screening; antiretroviral therapy reduces vertical transmission to <1%; avoid breastfeeding if safe alternatives exist.

Syphilis: screen at first prenatal visit and again in third trimester if high risk; treat with penicillin; desensitize if penicillin allergy.

Hepatitis B: screen all pregnant women; vaccinate newborns of HBsAg-positive mothers within 12 hours with HBIG and vaccine.

Rubella: screen for immunity; vaccinate postpartum if nonimmune; live vaccine contraindicated during pregnancy.

Varicella: nonimmune women should be vaccinated before pregnancy; if exposed, varicella-zoster immune globulin (VZIG) may be given.

FDA pregnancy categories replaced by Pregnancy and Lactation Labeling Rule (PLLR) in 2015; labels now include risk summary, clinical considerations, and data.

Known teratogens: isotretinoin (retinoic acid), warfarin, valproate, carbamazepine, methotrexate, ACE inhibitors, angiotensin receptor blockers, tetracyclines, thalidomide.

Folate antagonist methotrexate: causes neural tube defects, skeletal anomalies; avoid in pregnancy.

ACE inhibitors/ARBs: fetal renal failure, oligohydramnios, skull hypoplasia; discontinue in pregnancy.

Warfarin embryopathy: nasal hypoplasia, stippled epiphyses; risk highest 6–9 weeks; use heparin in pregnancy.

Valproate: increased risk of neural tube defects (1–2%) and neurodevelopmental disorders; avoid if possible.

Genetic counseling: offer to women with advanced maternal age (≥35), family history, consanguinity, or abnormal screening.

Aneuploidy risk: trisomy 21 risk increases with maternal age; 1 in 1500 at age 20, 1 in 100 at age 40.

Informed consent: patient must be informed of risks, benefits, alternatives, and have capacity; documented.

Patient autonomy: right to refuse treatment, including cesarean delivery, even if fetal harm may result; court orders rarely justified.

Maternal-fetal conflict: prioritize maternal autonomy; offer counseling and support; ethics consultation if needed.

Confidentiality: adolescent pregnancy confidentiality varies by state; encourage parental involvement but respect minor's rights.

Mandatory reporting: child abuse, domestic violence (with state-specific requirements), and certain communicable diseases.

Professionalism: maintain boundaries, avoid discrimination, and provide culturally competent care.

Health systems: ensure access to prenatal care, postpartum visits, and contraception; address social determinants of health.

Documentation: accurate and timely records are essential for quality care and medico-legal protection.