Although perimortem delivery has been recorded in the medical literature for millennia, the procedural intent has evolved to the current fetocentric approach, predicating timing of delivery following maternal cardiopulmonary arrest to optimize neonatal outcome. We suggest a call to action to reinforce the concept that if the uterus is palpable at or above the umbilicus, preparations for delivery should be made simultaneous with initiation of maternal resuscitative efforts; if maternal condition is not rapidly reversible, hysterotomy with delivery should be performed regardless of fetal viability or elapsed time since arrest. Cognizant of the difficulty in determining precise timing of arrest in clinical practice, if fetal status is already compromised further delay while attempting to assess fetal heart rate, locating optimal surgical equipment, or transporting to an operating room will result in unnecessary worsening of both maternal and fetal condition. Even if intrauterine demise has already occurred, maternal resuscitative efforts will typically be markedly improved following delivery with uterine decompression. Consequently we suggest that perimortem cesarean delivery be renamed “resuscitative hysterotomy” to reflect the mutual optimization of resuscitation efforts that would potentially provide earlier and more substantial benefit to both mother and baby.
The Problem
Scenario no. 1: emergency medical services transports a young woman to the emergency department following high-speed frontal-impact motor vehicle accident requiring prolonged vehicular extraction. Primary survey reveals multifocal cranial and extremity trauma, and she appears to be approximately 7 months’ gestation. While lucid at the scene, she becomes unresponsive and requires airway management with endotracheal intubation. At time of arrival fetal heart tones are unable to be auscultated (suggestive of intrauterine fetal demise), and soon thereafter maternal cardiopulmonary arrest (MCPA) occurs. Scenario no. 2: in the labor and delivery suite, a 25-year-old primigravida at 39 weeks’ gestation in active labor at 9-cm dilation suddenly notes onset of dyspnea followed by loss of consciousness. No pulse is palpable. Fetal heart rate tracing previously was category 1 but now demonstrates a prolonged deceleration for 4 minutes.
Introduction
Antepartum maternal cardiac arrest is a fortuitously rare event, with an incidence of approximately 1/12,500 deliveries. The most common reported precipitating factors include hemorrhage (45%), amniotic fluid embolism (13%), heart failure (13%), sepsis (11%), anesthetic complications (8%), and trauma (3%). Maternal survival range from 17–59% and fetal survival from 61–80%, with approximately 88–100% of surviving neonates neurologically intact. The etiology, physiology, and rate of survivability of maternal cardiac arrest are categorically distinct from nonpregnant cardiac arrest. In this document, we propose a maternofetal management strategy of MCPA that is unlike the current 4-5 rule for perimortem cesarean delivery (PMCD) in both its mental model and its priority of actions.
Examining the evidence
The published literature on MCPA consists primarily of retrospective case reports and epidemiologic reviews; as Dr Vern L. Katz, MD has stated: “for obvious reasons we will never have a randomized trial for this problem….” Initial descriptions of postmortem cesarean delivery date from before recorded history, with subsequent controversial legal mandates enacted in the 13th and 14th centuries to deliver all fetuses following maternal death for independent baptism and burial. More contemporary practices focused on the possibility of fetal survival following maternal demise, particularly in instances of inpatient sudden cardiac death. Eventual accumulation of more favorable reported outcomes led to incorporation of PMCD into clinical practice, albeit based on low-quality evidence. A landmark 1986 review of all reported maternal and fetal outcomes from the turn of the century led to widespread adoption of the 4-5 rule for viable pregnancies into US residency training curriculum: if resuscitative efforts following maternal circulatory arrest are unsuccessful, cesarean delivery should be commenced at 4 minutes and completed by 5 minutes to optimize fetal outcome. A subsequent interval update in 2005 found 28/38 (74%) PMCD resulted in viable neonates (thus validating the initial premise), with the conspicuous observation that in 12/22 described cases, maternal hemodynamic status was substantially improved following delivery. A 30-year review found 32% of cases in which PMCD was considered beneficial to maternal survival and in no instances proved detrimental.
From a practical perspective, multiple authors stress the difficulties of accomplishing delivery within 5 minutes in either actual or simulated scenarios. This is likely because transitioning from the mind-set of maternal resuscitation to performing a laparotomy seems barbaric and teleologically indicative of forfeiture of further attempts at maternal salvage. The term “perimortem cesarean delivery” implies eventual mortality of the mother (and therefore, a last ditch or even futile attempt to save her) and prioritization of fetal status at potential maternal expense, a fetocentric perspective per se, without considering the intraresuscitative benefits of PMCD. A term for the procedure that communicates both maternal and therefore fetal benefits could assist providers in optimizing maternal resuscitation through uterine evacuation.
Hemodynamic effects during resuscitation
Data on the hemodynamic effects of resuscitation in pregnancy are lacking and often extrapolated from varied sources; effects of differing maneuvers/positions are simulated in mannequins or pregnant women not currently under cardiac arrest conditions. During cardiopulmonary resuscitation in nonpregnant patients, chest compressions at best can produce 30% of normal cardiac output, and this value may be closer to 10% in pregnant patients. Current recommendations for the management of MCPA strongly encourage either manual displacement of the gravid uterus or maternal torso tilt of ∼30 degrees to decrease compression of the inferior vena cava (IVC) and provide maximal cardiac preload. There is no robust evidence, however, showing improvement of hemodynamics with either maneuver, and moreover tilting of the torso may decrease the quality of cardiac compressions. An ultrasound study in pregnant noncardiac arrest patients showed the largest diameter of the IVC in the supine position is approximately 25% of that achieved with ≥30 degree of either the right or left lateral tilt.
Multiple reports highlight the dramatic return of spontaneous circulation following PMCD, particularly when external relief of IVC compression has been ineffective. Early evidence for improvement in maternal circulatory parameters following delivery was suggested in a 1986 report describing a 60% increase in maternal cardiac output following delivery due to relief of aortocaval compression by the gravid uterus. A similar 1998 report suggested cesarean delivery of twins after maternal arrest resulted in immediate recovery of cardiac rhythm, a finding corroborated in a 2010 report from The Netherlands of 12 patients undergoing PMCD describing restoration of cardiac output in 8 patients (67%) postdelivery. Furthermore, among 18 case reports of PMCD that had recorded hemodynamic parameters throughout the code, 12 cases (67%) described a cesarean delivery immediately preceding return of maternal pulse and blood pressure, which often returned, as the authors of this review of published reports describe it, “in a dramatic fashion.”
Current guidelines
The American Heart Association, Society for Obstetric Anesthesia and Perinatology, and European Resuscitation Council provide similar recommendations for management of cardiopulmonary arrest during pregnancy, incorporating the general principles of :
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Rapid assessment of gestational age based on fundal height (umbilicus or above).
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Displacement of the gravid uterus through either manual uterine displacement or table tilt to reduce aortocaval compression.
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Immediate initiation of basic resuscitative efforts (airway and circulatory support) with transition to advanced cardiac life support (ACLS) once skilled providers and resources are available.
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Evaluation for primary etiology to direct therapy.
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Cesarean delivery within 5 minutes if initial maternal resuscitation attempts are unsuccessful.
The American Heart Association guideline is summarized in the Table . It is important to highlight that despite a common end result, the shockable rhythms (ventricular tachycardia and ventricular fibrillation) carry a better prognosis as these often occur in patients with previous structural cardiac pathology but somewhat intact prearrest physiology; this may occur suddenly in the community or as inpatients with no pre-event deterioration. Regarding nonshockable rhythms (pulseless electrical activity and asystole), these represent terminal rhythms with a grim prognosis, and typically present as a result of critically compromised physiology, such as in cases of trauma in the outpatient setting and sepsis or bleeding in the inpatient arena.
