For a 42-year-old pregnant woman (G1) at 40 2/7 weeks gestation, found unresponsive in the supine position and receiving chest compressions after a motor vehicle collision (MVC), how many minutes after initiation of cardiopulmonary resuscitation (CPR) should a perimortem cesarean delivery be undertaken if there is no return of spontaneous circulation?

Perimortem Cesarean Delivery Timing in Maternal Cardiac Arrest

Perimortem cesarean delivery should be STARTED at 4 minutes after the onset of maternal cardiac arrest if there is no return of spontaneous circulation. 1

The Critical 4-Minute Decision Point

The answer is b. 4 minutes.

• The procedure must be STARTED at 4 minutes to achieve delivery by 5 minutes, which is the critical window for optimal maternal and fetal outcomes 1
• This timing applies to any pregnant patient with a fundus at or above the umbilicus (approximately ≥20 weeks gestation), as aortocaval compression significantly impairs resuscitation efforts 1
• The American Heart Association 2020 Guidelines explicitly state: "PMCD should be considered at 4 minutes after onset of maternal cardiac arrest or resuscitative efforts if there is no ROSC" 1

Why This Timing Matters for Maternal Survival

The primary goal is maternal resuscitation, not just fetal salvage 1, 2:

• In a case series of 38 perimortem cesarean deliveries, 12 of 20 women achieved return of spontaneous circulation immediately after delivery 1
• Emptying the uterus relieves aortocaval compression, dramatically improving cardiac output and coronary perfusion pressure 1, 2
• In 31.7% of cases, perimortem cesarean delivery was determined to have been beneficial to maternal survival, with no cases showing maternal harm from the procedure 1, 3
• Multiple case reports document return of maternal pulse and blood pressure only after the uterus was emptied 1, 4

The Evidence Behind the 4-Minute Rule

Recent systematic reviews support the 4-minute initiation time 1, 3:

• Maternal survival is significantly improved when perimortem cesarean delivery occurs within 10 minutes of arrest (OR 7.42, p<0.05) 3
• The median time from collapse to delivery was 3 minutes in women who survived compared with 12 minutes in those who did not 1
• Neurological damage begins after 4-6 minutes of anoxic cardiac arrest without return of spontaneous circulation 1

Fetal Outcomes Support Early Intervention

• Best fetal survival occurs when delivery happens within 5 minutes after maternal cardiac arrest, particularly at gestational ages >24-25 weeks 1, 5
• At gestational ages >30 weeks, infant survival has been documented even when delivery occurred >5 minutes from onset of maternal cardiac arrest 1
• In surviving neonates, the median time to delivery was 10 minutes versus 20 minutes in non-survivors 1

Critical Action Steps at the 4-Minute Mark

Do not wait—activate the protocol immediately 1:

• Designate a timekeeper to call out times at 1-minute intervals 1
• Prepare for bedside cesarean delivery while CPR continues 1, 2
• Moving to an operating room should only be considered if it can be accomplished in 1-2 minutes 1
• Continue all maternal resuscitative efforts during and after the procedure 2

Common Pitfalls to Avoid

The most dangerous error is delay 5, 2:

• Do not wait for an operating room—perform the procedure at bedside in the emergency department 1, 2
• Do not delay in cases of obvious nonsurvivable maternal injury (such as this severe MVC)—proceed immediately to perimortem cesarean delivery 1, 5
• Do not assume the procedure is only for fetal benefit—maternal hemodynamic improvement is the primary goal 1
• Recognize that both mother and infant may die if blood flow to the mother's heart cannot be restored 1, 5

Special Considerations for This Case

This 40 2/7 week pregnant patient after MVC requires immediate preparation 1:

• At term gestation with fundus well above the umbilicus, aortocaval compression is maximal 1
• Trauma is a leading cause of maternal cardiac arrest 1
• If the maternal injury is nonsurvivable, there is no reason to delay performing perimortem cesarean delivery 1
• The patient should already be supine on a firm surface with manual left uterine displacement during chest compressions 1, 2