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Difficulty: HardObstetric Complications

Match each clinical presentation of an obstetric complication to its most likely etiology.

  • A 30-year-old G3P2 at 38 weeks gestation with a history of classical myomectomy. Vitals: BP 100/60 mm Hg, HR 110/min. She experiences sudden tearing abdominal pain, loss of fetal station, and abrupt cessation of uterine contractions. Fetal tracing shows sudden bradycardia.Uterine rupture
  • A 34-year-old G2P1 at 36 weeks gestation. Vitals: BP 165/110 mm Hg, HR 98/min. She develops a rigid, exquisitely tender uterus, frequent low-amplitude contractions, and dark vaginal bleeding. Fetal tracing shows recurrent late decelerations.Placental abruption
  • A 28-year-old G1P0 at 39 weeks gestation with known velamentous cord insertion. Vitals: BP 115/75 mm Hg, HR 85/min. She experiences painless vaginal bleeding immediately after amniotomy. Fetal tracing shows an acute drop in fetal heart rate to 75/min with loss of variability.Vasa previa
  • A 32-year-old G4P3 at 37 weeks gestation with three prior cesarean deliveries. Vitals: BP 120/80 mm Hg, HR 88/min. She presents with new-onset, painless, bright red vaginal bleeding. Fetal tracing is reactive with a baseline of 140/min and moderate variability.Placenta previa

Answer

The presentations match as follows: classical myomectomy history with loss of station is uterine rupture; severe hypertension with rigid uterus is placental abruption; bleeding after amniotomy with fetal bradycardia is vasa previa; and painless bleeding with prior cesareans is placenta previa.
Each scenario maps to distinct pathophysiologic processes: Uterine rupture presents with anatomical disruption (loss of station); abruption involves retroplacental bleeding causing uterine tetany; vasa previa involves torn fetal vessels causing rapid fetal exsanguination; and placenta previa involves exposed maternal vessels bleeding painlessly.

Step-by-Step Solution

1
Evaluate the first vignette for key diagnostic signs.
Identified prior classical incision, sudden pain, loss of station, and cessation of contractions as diagnostic for uterine rupture.
Classical incisions carry the highest risk for rupture, and loss of station occurs when the fetus extrudes into the abdominal cavity.
2
Evaluate the second vignette, focusing on maternal vitals and uterine tone.
Matched severe hypertension, rigid/tender uterus, and dark bleeding to placental abruption.
Hypertensive disorders cause abnormal decidual vasculature, leading to premature placental separation and retroplacental hematoma (hypertonic uterus).
3
Analyze the third vignette's sequence of events and fetal heart rate.
Linked velamentous cord insertion, amniotomy, and immediate fetal bradycardia to vasa previa.
Fetal vessels crossing the membranes are torn during amniotomy, leading to rapid fetal exsanguination and profound bradycardia.
4
Assess the fourth vignette's bleeding characteristics and risk factors.
Correlated painless, bright red bleeding and prior cesarean deliveries with placenta previa.
Prior cesareans predispose to low placental implantation, which bleeds painlessly as the lower uterine segment develops.

Key Concept

Differentiating third-trimester bleeding requires analyzing pain (present in abruption/rupture, absent in previa/vasa previa), uterine tone (rigid in abruption), fetal station changes (rupture), and timing of bleeding relative to membrane rupture (vasa previa).
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Topics

Obstetric Complications

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