Pregnancy and Perimortem Cesarean Section

Pregnancy changes the way trauma and cardiac arrest are reasoned about because two patients are involved and maternal physiology is profoundly altered. This topic also covers perimortem cesarean section, now often called resuscitative hysterotomy, an intervention considered during maternal cardiac arrest both to improve maternal resuscitation and to address fetal viability.

Definition

Pregnancy and perimortem cesarean section is the trauma and resuscitation topic addressing how pregnancy alters injury patterns and the response to cardiac arrest, and the role of perimortem cesarean section (resuscitative hysterotomy) as an intervention considered during maternal cardiac arrest.

Scope

The entry covers the altered maternal physiology relevant to injury and resuscitation, the concept of aortocaval compression by the gravid uterus, the maternal-fetal relationship in trauma, and the rationale and historical framing of perimortem cesarean section as a resuscitative measure. It is a reference topic on how these scenarios are understood; it gives no dosing, timing-as-instruction, or individualized care.

Core questions

• How does altered maternal physiology change the response to injury and resuscitation?
• What is aortocaval compression and why does it matter in the supine pregnant patient?
• What is the rationale for perimortem cesarean section during maternal cardiac arrest?

Key concepts

• Altered maternal cardiovascular and respiratory physiology
• Aortocaval compression by the gravid uterus
• Two patients: maternal and fetal
• Increased plasma volume and physiologic anemia
• Perimortem cesarean section / resuscitative hysterotomy
• Relief of caval compression to aid maternal resuscitation
• Gestational age and fetal viability considerations

Mechanisms

Pregnancy raises blood volume, heart rate, and cardiac output and lowers systemic vascular resistance, so a pregnant patient may lose substantial blood before vital signs change, and physiologic dilutional anemia complicates interpretation of blood counts. In the later stages, the gravid uterus can compress the inferior vena cava and aorta when the patient is supine (aortocaval compression), reducing venous return and undermining the effectiveness of chest compressions during cardiac arrest. Perimortem cesarean section addresses this by emptying the uterus, which relieves caval compression and can improve maternal hemodynamics during resuscitation, while also delivering the fetus; the intervention is therefore framed primarily as a maternal resuscitative measure as well as a means of addressing fetal viability (Jeejeebhoy et al., 2015; Katz et al., 2005). Decision-making is shaped by gestational age, the cause of arrest, and substantial human-factors challenges in a rare, high-pressure event (Capstick et al., 2024).

Clinical relevance

This topic explains why resuscitation guidance for pregnant patients differs from the standard adult approach and why perimortem cesarean section is included in maternal cardiac arrest algorithms. The content is educational, describing the physiologic rationale and how the evidence and guidelines are framed; it is not a basis for individual diagnostic or treatment decisions and contains no procedural timing instructions.

Epidemiology

Trauma is a leading non-obstetric cause of maternal injury and death, with motor-vehicle collisions, falls, and violence among the common mechanisms (Norton & Kobusingye, 2013). Maternal cardiac arrest is rare, and perimortem cesarean section is correspondingly uncommon; reviews of reported cases have informed how the intervention is understood (Katz et al., 2005).

History

Perimortem cesarean section has historical roots stretching back centuries, but its modern framing as a resuscitative intervention emerged in the late twentieth century. Katz and colleagues critically re-examined long-standing assumptions about its timing and outcomes (Katz et al., 2005), and subsequent guidance, including the American Heart Association scientific statement on cardiac arrest in pregnancy, incorporated it into structured maternal resuscitation, increasingly under the term resuscitative hysterotomy (Jeejeebhoy et al., 2015).

Debates

How rigid is the classic time threshold for perimortem cesarean section?

A long-cited interval for performing the procedure after arrest has been re-examined, with reviews and case reports suggesting maternal and fetal benefit can occur outside the traditional window and emphasizing context over a fixed clock.

Seminal works

• katz-2005
• jeejeebhoy-2015

Frequently asked questions

Why is resuscitation of a pregnant patient different?

Pregnancy alters cardiovascular and respiratory physiology, two patients are at risk, and the gravid uterus can compress the major abdominal vessels when the patient is supine, which reduces venous return and can blunt the effect of chest compressions.

Why is perimortem cesarean section considered a resuscitative measure?

Emptying the uterus relieves compression of the inferior vena cava and aorta, which can improve maternal blood return and circulation during cardiac arrest. This entry describes the physiologic rationale; it is not procedural instruction.