Obstetrics: Antepartum, Intrapartum, and Postpartum Essentials
Core concepts
Obstetrics questions reward a structured approach: establish gestational age and dating, then classify the problem as maternal, fetal, or placental. Know normal labor curves (cervical change, descent), the stages of labor, and the definitions of abnormal progress (protraction vs. arrest). Understand hypertensive disorders by timing and end-organ involvement: chronic hypertension, gestational hypertension, preeclampsia with and without severe features, and eclampsia. Be solid on antepartum hemorrhage (placenta previa vs. abruption), preterm labor and PPROM management principles, and fetal surveillance (NST, BPP, contraction stress testing). Postpartum: hemorrhage causes (tone, trauma, tissue, thrombin), and the sequence of uterotonics.
Traps
- Painless bleeding in late pregnancy points to previa; painful, tense bleeding to abruption. Do not perform a digital exam when previa is suspected.
- Preeclampsia without severe features can be managed expectantly near term; severe features mandate delivery regardless of gestational age after stabilization.
- Magnesium sulfate prevents and treats seizures; it is not an antihypertensive.
- Arrest of dilation requires adequate contractions and documented cervical change over time; do not diagnose arrest too early.
- Late decelerations reflect uteroplacental insufficiency; variable decelerations reflect cord compression.
Worked example / rule of thumb
A patient at 34 weeks has BP 158/108 with platelets 90,000 and AST elevated. These are severe features: give magnesium sulfate for seizure prophylaxis, treat BP, and plan delivery after maternal stabilization. Rule of thumb: severe features trump gestational age.
Focus study on definitions and thresholds; most missed items are definitional, not conceptual.