## Contraindications to Trial of Labor After Cesarean (TOLAC) **Key Point:** Maternal HIV infection on antiretroviral therapy (ART) with undetectable viral load (viral load <50 copies/mL) is NOT a contraindication to TOLAC. Vaginal delivery is safe and recommended in this scenario. ### Absolute Contraindications to TOLAC | Contraindication | Reason | |---|---| | **Recurrent indication (e.g., CPD)** | If cephalopelvic disproportion caused prior cesarean, it will recur; vaginal delivery will fail | | **≥2 prior cesarean sections** | Uterine rupture risk increases with multiple scars; TOLAC not recommended | | **Placenta previa or abruption** | Absolute contraindication regardless of prior surgery | | **Transverse lie** | Absolute contraindication regardless of prior surgery | | **Active genital herpes lesions** | Risk of neonatal infection | ### Maternal HIV: NOT a Contraindication to TOLAC **High-Yield:** Maternal HIV on ART with undetectable viral load (<50 copies/mL) has: - **Vertical transmission risk <2%** with vaginal delivery - **Equal safety to cesarean delivery** when viral load is undetectable - **ACOG recommendation:** Vaginal delivery preferred to reduce maternal morbidity [cite:ACOG Committee Opinion 752] - **Zidovudine (AZT) intrapartum** further reduces transmission risk **Clinical Pearl:** The key is undetectable viral load; detectable viral load (>1000 copies/mL) is a relative contraindication favoring planned cesarean. ### Why Other Options ARE Contraindications 1. **Recurrent CPD:** If maternal pelvis was inadequate before, it remains inadequate → failed labor → emergency cesarean with higher morbidity 2. **Two prior cesareans:** Cumulative uterine scar weakness increases rupture risk beyond acceptable threshold 3. **Fetal macrosomia (4200 g):** Estimated weight >4500 g is relative contraindication; 4200 g is borderline but not absolute contraindication, though labor risk is elevated **Mnemonic:** **TOLAC-NO** = Transverse lie, Placenta previa, Abruption, CPD recurrent, ≥2 prior cesareans, Obstetric contraindication (active herpes), Nonreassuring fetal status
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