A 27-year-old G2P2002 is recovering in the hospital on postpartum day 3 after a low transverse C-section. During morning rounds, she reports a “pus-like” discharge and shaking chills overnight. She also endorses increased uterine cramping compared to the day before, but her postpartum course has otherwise been uneventful with a well-healing incision and normal vaginal bleeding. The patient’s prenatal care was complicated by HIV with a recent viral load of 400 copies/mL, type I diabetes well controlled on insulin, and a history of herpes simplex virus encephalitis in her first child. She did not have any genital lesions during the most recent pregnancy. Four days ago, she presented to the obstetric triage unit after spontaneous rupture of membranes and onset of labor. She made slow cervical change and reached full dilation after 16 hours, but there was limited fetal descent. Cephalopelvic disproportion was felt to be the reason for arrest of descent, so prophylactic ampillicin was administered and C-section was performed. A vaginal hand was required to dislodge the fetus’s head from the pelvis, and a healthy baby boy was delivered. On postpartum day 3, her temperature is 101.5°F (38.6°C), blood pressure is 119/82 mmHg, pulse is 100/min, and respirations are 14/min. Her incision looks clean and dry, there is mild suprapubic tenderness, and a foul yellow discharge tinged with blood is seen on her pad. Which of the following is the most significant risk factor for this patient’s presentation?

History of herpes simplex virus in previous pregnancy

A 25-year-old woman comes to the emergency department one hour after the sudden onset of diffuse abdominal pain and nausea. She has no history of serious illness. Menses occur at regular 27-day intervals and last 4 to 6 days with moderate flow. Her last menstrual period was 6 weeks ago. She is sexually active with two sexual partners and uses oral contraceptive pills inconsistently. She appears pale and diaphoretic. Her temperature is 37.7°C (99.9°F), pulse is 120/min, respirations are 20/min, and blood pressure is 85/70 mm Hg. Abdominal examination shows diffuse abdominal tenderness. Pelvic examination shows a normal appearing vagina, cervix, and uterus, with right adnexal tenderness. Her hemoglobin concentration is 13 g/dL, leukocyte count is 10,000/mm3, and platelet count is 350,000/mm3. Results of a pregnancy test are pending. Which of the following is the most appropriate next step in management?

Administer intravenous normal saline fluids

Perform exploratory laparoscopy

Perform CT scan of the abdomen and pelvis with contrast

Transfuse O negative packed red blood cells

A 36-year-old woman, gravida 3, para 2, at 37 weeks' gestation comes to the emergency department because of sparse vaginal bleeding for 3 hours. She also noticed the bleeding 3 days ago. She has had no prenatal care. Both of her previous children were delivered by lower segment transverse cesarean section. Her temperature is 37.1°C (98.8°F), pulse is 90/min, respirations are 16/min, and blood pressure is 110/80 mm Hg. The abdomen is nontender, and no contractions are felt. Examination shows that the fetus is in a vertex presentation. The fetal heart rate is 160/min and shows no abnormalities. Which of the following is the most appropriate next step in management?

Perform transvaginal sonography

Conduct contraction stress test

A 30-year-old woman, gravida 2 para 1, at 39 weeks gestation presents to the hospital with painful contractions and a rupture of membranes. She reports that the contractions started a couple hours ago and are now occurring every 4 minutes. She is accompanied by her husband who states, “her water broke an hour ago before we left for the hospital." The patient denies vaginal bleeding, and fetal movements are normal. The patient has attended all her pre-natal visits without pregnancy complications. She has no chronic medical conditions and takes only pre-natal vitamins. Her blood pressure is 110/75 mm Hg and pulse is 82/min. A fetal heart rate tracing shows a pulse of 140/min with moderate variability and no decelerations. Cervical examination reveals a cervix that is 7 cm dilated and 100% effaced with the fetal head at -1 station. The patient forgoes epidural anesthesia. During which of the following scenarios should a cesarean delivery be considered for this patient?

Cervix is 7 cm dilated and fetal head is at 0 station after 4 hours, with contractions every 2 minutes

Cervix is 7 cm dilated and fetal head is at -1 station after 2 hours with contractions every 7 minutes

Cervix is 9 cm dilated and fetal head is at -1 station after 3 hours, with contractions every 3 minutes

Cervix is 10 cm dilated and fetal head is at +1 station after 2 hours, with contractions every 2 minutes

Cervix is 7 cm dilated and fetal head is at 0 station after 1 hour, with contractions every 5 minutes

A 30-year-old woman, gravida 2, para 1, at 38 weeks' gestation comes to the hospital for regular, painful contractions that have been increasing in frequency. Her pregnancy has been complicated by gestational diabetes treated with insulin. Pelvic examination shows the cervix is 50% effaced and 4 cm dilated; the vertex is at -1 station. Ultrasonography shows no abnormalities. A tocometer and Doppler fetal heart monitor are placed on the patient's abdomen. The fetal heart rate monitoring strip shows a baseline heart rate of 145/min with a variability of ≥ 15/min. Within a 20-minute recording, there are 7 uterine contractions, 4 accelerations, and 3 decelerations that have a nadir occurring within half a minute. The decelerations occur at differing intervals relative to the contractions. Which of the following is the most appropriate next step in the management of this patient?

Placement of fetal scalp electrode

Trial of labor after cesarean for USMLE Step 3: High-Yield OB/GYN Lessons

TOLAC Candidates - The Green Light

Primary Prerequisite: 1-2 prior low-transverse cesarean deliveries (LTCDs).
Pelvic Assessment: Clinically adequate pelvis (e.g., gynecoid).
Uterine Integrity: No other uterine scars (e.g., myomectomy entering the cavity) or prior uterine rupture.
Fetal Factors: Singleton, vertex presentation.
Institutional Readiness:
- Immediate availability of surgeon & anesthesia for emergency C-section.
- Continuous fetal monitoring capability.

⭐ High-Yield Fact: Successful VBAC (Vaginal Birth After Cesarean) occurs in 60-80% of appropriate TOLAC candidates.

Uterine incisions: low-transverse vs. classical

Risks vs. Benefits - The Balancing Act

Benefits of Successful TOLAC (i.e., VBAC):
- Avoids major abdominal surgery, leading to shorter recovery.
- ↓ Overall maternal morbidity compared to elective repeat cesarean section (ERCS).
  - Lower rates of hemorrhage, infection, and thromboembolism.
- ↓ Risks for future pregnancies, such as placenta previa and accreta spectrum.
Risks Associated with TOLAC:
- Uterine Rupture: The most feared complication.
  - Can cause catastrophic hemorrhage, fetal hypoxia/demise, and need for hysterectomy.
- Failed TOLAC: Necessitates an intrapartum C-section.
  - A failed TOLAC carries higher maternal/fetal morbidity than a successful TOLAC or an ERCS.

⭐ The absolute risk of uterine rupture after one prior low-transverse cesarean section (LTCS) is 0.5-0.9%. This risk significantly increases with classical incisions or prostaglandin use.

Intrapartum Care - The Watchful Wait

Continuous Monitoring: Mandatory continuous electronic fetal monitoring (EFM) and tocometry to detect non-reassuring fetal status or abnormal uterine activity (e.g., tachysystole).
Resource Readiness: Immediate availability of anesthesia, obstetric staff, and operating room facilities is crucial for emergency C-section.
Labor Management:
- Augmentation: Oxytocin may be used cautiously.
- ⚠️ Contraindication: Prostaglandin cervical ripening agents (e.g., Misoprostol) are contraindicated due to a significantly ↑ risk of uterine rupture.
Analgesia: Epidural analgesia is safe and does not mask key signs of uterine rupture.

⭐ The most common sign of uterine rupture is a non-reassuring fetal heart rate pattern, such as fetal bradycardia or recurrent, deep variable decelerations.

Uterine Rupture - The Red Alert

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High-Yield Points - ⚡ Biggest Takeaways

Trial of labor after cesarean (TOLAC) offers a chance for vaginal birth (VBAC), avoiding repeat surgery.

The most feared complication is uterine rupture (≈0.5-1% risk with prior low transverse scars).

Prior classical (vertical) uterine incision or extensive transmural myomectomy are absolute contraindications.

Continuous intrapartum fetal monitoring is mandatory to detect complications early.

Fetal bradycardia is the most common and reliable sign of uterine rupture.

Success rates for VBAC are high (60-80%) in appropriately selected candidates.

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