Perimortem Cesarean Section (PMCS) / Resuscitative Hysterotomy

Terminology

• Roberts and Hedges' Clinical Procedures in Emergency Medicine, p. 3991
• Tintinalli's Emergency Medicine, p. 2032

Definition

1. Improving maternal resuscitation - by relieving aortocaval compression, increasing venous return and cardiac output by 25-30%
2. Saving a viable fetus - by delivering before irreversible hypoxic-ischemic injury occurs

Physiology: Why PMCS Helps the Mother

• Reduces venous return to the right heart
• Reduces maternal cardiac output
• Makes CPR generate only 30-40% of normal cardiac output
• Severely compromises placental perfusion

"PCS in itself may represent the most important variable for successful maternal resuscitation." - Roberts and Hedges', p. 4002

Indications

• If exact gestational age is unknown, estimate by fundal height: at 28 weeks the fundus lies ~28 cm above the symphysis pubis (fundal height in cm ≈ weeks gestation between 18-30 weeks).
• PMCS before ~24 weeks is not generally indicated as the fetus is unlikely to be viable.
• Aortocaval occlusion can begin as early as 20 weeks, which is why left uterine displacement should be used during CPR from that point.

Timing - The "4-Minute Rule"

Technique (Step-by-Step)

• Use a large scalpel (No. 10 blade)
• Midline vertical incision from symphysis pubis to umbilicus
• Follow the "linea nigra" (hyperpigmented midline) as a guide
• Carry the incision through all abdominal layers into the peritoneal cavity
• Do NOT waste time on sterile prep or draping

• Place retractors if available; retract laterally
• Reflect the bladder inferiorly
• If bladder is full, aspirate it for better uterine access

• Make a small (~5 cm) vertical incision through the lower uterine segment until amniotic fluid is obtained or the uterine cavity is entered
• Insert index and middle fingers into the incision to lift the uterine wall away from the fetus

• Use bandage scissors (not the scalpel) to extend the uterine incision vertically toward the fundus to obtain wide exposure
• This two-fingered technique protects the fetus from blade injury

• Gently deliver the infant
• Clamp and cut the umbilical cord
• Because the vertical incision is high in the uterus, the head may not be easily accessible - in this case, grasp the feet and deliver as a breech
• Hand infant to neonatal resuscitation team immediately

Key Practical Points

• No sterile prep, no OR transfer, no fetal monitoring - time is everything
• Do not delay for arrival of an obstetrician. If no obstetric backup is immediately available, the emergency physician should proceed
• Do not search for fetal heart tones or perform US to assess viability - this wastes critical minutes
• Continue CPR throughout the procedure
• IV access should be placed above the diaphragm (antecubital or central venous) to ensure medications reach the heart despite IVC compression
• Discontinue magnesium sulfate if it was running (cardiac depression)
• Consider difficult airway management - pregnant patients have increased aspiration risk and reduced FRC

Factors Affecting Prognosis

• Earlier gestational age at time of delivery (more mature fetus)
• Sudden death of a previously healthy mother (vs. chronic illness)
• Rapid, high-quality CPR from time of arrest
• PMCS performed within the 4-5 minute window

• Time from arrest to delivery
• Quality of CPR during the interval
• Fetal maturity
• Pre-arrest maternal health

Causes of Maternal Cardiac Arrest Requiring PMCS

• Pulmonary embolism / amniotic fluid embolism
• Eclampsia / magnesium toxicity
• Hemorrhage (abruption, uterine rupture)
• Anesthetic complications (high spinal, local anesthetic toxicity)
• Sepsis
• Trauma

Recent Evidence (2021-2026)

Summary Box