Chapter 37: Trauma in Pregnancy

The incidence of trauma related injuries during pregnancy has increased dramatically over the past 25 years¹ and is now the leading cause of nonobstetrical maternal death in the United States.² Adverse fetal outcomes include preterm delivery, low birthweight, and fetal demise.³

The severity of trauma does not always predict the severity of injury to mother and fetus, but major trauma is associated with a 40–50% risk of fetal death.⁴ Minor trauma, encompassing lower energy mechanisms, occurs much more frequently but still carries significant risk to the fetus. A Tennessee study identified 5352 expectant mothers and classified their injuries as major if hospital admission was required or minor if only emergency room evaluation occurred.⁴ They found that women in their first or second trimester with minor injury were 1.19 times more likely to have a child with prematurity or low birth weight.

Trauma complicates an estimated 1 in 12 pregnancies,¹ and 0.4% of pregnant women require hospitalization for their injuries.⁵ Motor vehicle crashes account for 50% of all traumatic injuries during pregnancy and 82% of trauma-related fetal deaths.⁶ A major risk factor is improper use of a seatbelt.⁷ Correct placement has the lap belt underneath the abdominal dome, decreasing the pressure transmitted across the uterus in a motor vehicle crash. The shoulder harness should overly the clavicle and run between the breasts. Sadly, this information is often overlooked during prenatal counseling.

Pregnancy makes women more prone to falls due to inherent changes such as increased joint laxity, weight gain, and dynamic postural stability.⁸ It is estimated that 1 in 4 will fall at least once during their pregnancy.⁹ Schiff found that 79% of pregnant women hospitalized after a fall were in their third trimester, and the most common injury was fracture in a lower extremity.¹⁰ The study also showed an 8-fold increase in placental abruption, a 4.4-fold increase in preterm labor, a 2.1-fold increase in fetal distress, and a 2.9-fold increase in fetal hypoxia.

Literature on thermal injuries and pregnancy is limited to case reports and series. Extensive burns cause significant physiologic stress, putting both the mother and fetus at risk. It is estimated that once the total body surface area of a burn exceeds 40%, the risk of mortality for the mother and fetus approaches 100%.¹¹

Intentional trauma is divided into two categories including assault by another person and self-inflicted injuries. Intimate partner violence (IPV) is the most common form of intentional trauma and carries significant risk to both the mother and fetus. The risk of preterm birth nearly triples and low birth weight increases 5.3-fold with such trauma.¹² The prevalence of domestic violence involving pregnant women that results in serious injury has been estimated between 10 and 30%.¹³ Risk factors associated with IPV include maternal or intimate partner substance abuse, low socioeconomic status, low maternal education level, unintended pregnancy, history of domestic violence prior to pregnancy, history of witnessed violence as a child, and unmarried status.¹⁴ The abdomen is the most common target associated with assault,¹⁵ increasing the likelihood of an intra-abdominal injury and fetal morbidity and mortality. The American College of Obstetricians and Gynecologists (ACOG) recommends universal screening of all pregnant women regarding IPV, and any pregnant woman who presents with a vague or suspicious history of trauma should raise the concern of battery.¹⁵ Warning signs include frequent office or emergency room visits, depression, substance abuse, discrepancy between injuries and given history, and a partner’s insistence on being present for the interview and examination.¹⁶ Questions regarding Intimate Partner Screening from ACOG are provided in Table 37-1.¹⁷

Suicide accounts for approximately 20% of all postpartum maternal deaths.¹⁸ Major risk factors include depression, substance abuse, history of domestic violence, and fetal or child death. Substance abuse is the best identifier for detecting women at risk,¹⁹ and a history of domestic violence or IPV has been associated in up to 54% of suicide cases among pregnant women.^20,21 Unsuccessful suicide attempts put the pregnant mother at risk for premature labor, cesarean delivery, need for transfusion, the respiratory distress syndrome, and low birthweight infants.^14,19

Understanding the many anatomic and physiologic changes that occur with pregnancy (Table 37-2) will help the treating physician better manage the mother and the fetus. The most obvious change seen in pregnancy is uterine growth. Figure 37-1 illustrates the uterine position throughout pregnancy. At 12 weeks of gestation, the uterus becomes an intra-abdominal organ as it rises above the pelvic brim. At 20 weeks, the top of the uterus is at the level of the umbilicus and, at 36 weeks, it reaches the costal margin. Toward the end of pregnancy, the fetal head drops back into the pelvis, lowering the fundal height. This descent makes the fetal head more susceptible to injury, particularly if the mother suffers a pelvic fracture.¹⁶ Uterine growth also shifts the maternal organs within the abdominal cavity, altering the typical findings on a physical examination and x-rays.

Cardiovascular System

The growing fetus requires a marked increase in oxygen delivery from the mother, and increased oxygen carrying capacity, cardiac output and minute ventilation augment this. The maternal plasma volume begins to increase at 10 weeks gestation and expands by 45% at full-term, while the red blood cell volume only increases by 18–30%.²² The disproportionate increase in plasma compared to red blood cells is protective as the mother will lose a large amount of blood during delivery. A higher plasma volume relative to red blood cell volume results in fewer lost red cells during hemorrhage. This physiologic anemia of pregnancy, with hematocrit falling to 32–34% at its nadir, occurs between the 30th and 34th week of gestation. Importantly, the extra blood volume may give a false sense of security for the treating physician because approximately 35% of maternal blood volume may be lost before any clinical signs of shock are observed.

During pregnancy, the normal blood pressure drops by 5–15 mm Hg, and the resting heart rate increases by 10–15 beats/min to increase cardiac output.²³ It is important not to attribute tachycardia or hypotension after trauma to physiologic changes associated with pregnancy without adequately evaluating for sources of hemorrhage. The uterine arteries supply the majority of blood to the fetus and are maximally dilated during pregnancy. Hypovolemia may cause vasoconstriction to divert blood to the mother’s vital organs, and this will significantly decrease the placental blood flow. Shunting of blood away from the placenta may manifest as fetal distress before systemic signs of hemorrhage are seen in the mother.

As the growing uterus displaces the diaphragm, it pushes the heart to the left and upward along its long axis, producing an enlarged cardiac silhouette on chest radiographs. Most pregnant women will have some degree of benign pericardial effusion, while an electrocardiogram will show only a slight left-axis deviation from the altered position of the heart.²⁴

During the middle of the second trimester, maternal position greatly affects cardiovascular physiology. While supine, the gravid uterus compresses the inferior vena cava leading to a decrease in venous return to the heart and a drop in the cardiac output by as much as 25%. The “supine hypotensive syndrome” leads to dizziness, pallor, tachycardia, diaphoresis, nausea, and hypotension. The uterus also compresses the aorta causing decreased blood flow to the uterus. With the uterine arteries maximally dilated during pregnancy, autonomic regulation is lost and blood flow is entirely dependent on maternal mean arterial pressure.²⁵ Placing the mother in the left lateral decubitus position restores venous flow and improves cardiac output.

Respiratory System

Both hormonal and mechanical changes in pregnancy contribute to increased minute ventilation. As the gravid uterus enlarges, it displaces the diaphragm approximately 4 cm, decreasing functional residual capacity. Elevated progesterone levels cause increased tidal volume and hyperventilation which augments minute ventilation, and it is common for a woman in her third trimester to have hypocapnia (PaCO₂ of 30 mm Hg) and a compensated respiratory alkalosis. It is important to recognize that a pregnant patient with a PaCO₂ of 35–40 mm Hg may be exhibiting signs of impending respiratory failure. The baseline hyperventilation of pregnancy also reduces the mother’s ability to compensate for metabolic acidosis.

Renal System

To compensate for the increased blood volume in pregnancy, the renal plasma flow and glomerular filtration rate (GFR) both increase. Paired with hemodilution from a 50% increase in plasma volume, the serum creatinine concentration decreases by an average of 0.4 mg/dL. In pregnancy, a normal creatinine ranges from 0.4 to 0.8 mg/dL.²⁶ The increased GFR leads to excretion of other metabolic products that may exceed the tubular reabsorption capability and result in proteinuria and glucosuria, also. As the uterus grows, it can cause partial ureteral obstruction and physiologic hydronephrosis, particularly in the late stages of gestation. The right side is more affected than the left, due to the cushioning of the left ureter by the sigmoid colon.²⁴

Coagulation System

Thrombosis in pregnancy is related to two components of Virchow’s triad—stasis and hypercoagulability. Stasis occurs as the uterus grows and compresses venous outflow; however, the risk of venous thromboembolic events is the same throughout all stages of pregnancy, suggesting that hypercoagulability is the more significant factor. Increased concentrations of clotting factors cause hypercoagulability in pregnancy and may protect the mother from hemorrhage at childbirth or miscarriage. Pregnant women are at higher risk of thromboembolic events, with a three- to fourfold increase in arterial thromboembolism and four- to fivefold increase in venous thromboembolism.²⁷ Of interest, deep venous thrombosis represents 80% and pulmonary embolus 20% of venous events. In pregnancy, deep venous thrombosis is more likely to be proximal, massive and on the left.²⁷

Gastrointestinal System

Nausea and vomiting are common in pregnancy. Gastric emptying is unchanged, but pregnant women are more susceptible to aspiration with anesthetics. Alterations in liver function tests include a mild generalized decrease of aspartate transaminase, alanine transaminase, gamma-glutamyl transpeptidase, and bilirubin.²⁸ Alkaline phosphatase activity increases, particularly in the third trimester, while serum albumin concentration decreases throughout pregnancy and can be as low as 3.0 g/dL in the third trimester. Total body albumin, however, is elevated because of hemodilution.²⁴ As the fetus grows, maternal nutrition needs to increase, so a pregnant patient who is to remain nil per os (NPO) for an extended period of time should receive total parenteral nutrition (TPN) with a goal of 36 kcal/kg/d.²⁹

The first priority in treating an injured pregnant patient is the mother as early and aggressive maternal resuscitation directly correlates with improved fetal outcomes.³⁰ Fetal mortality increases with the severity of maternal injuries and is more likely after direct fetoplacental injury, maternal shock, pelvic fracture, maternal injury to the brain, or hypoxia.²⁴ Preterm delivery is a significant risk, and a fetus delivered before 23 weeks is considered not viable.

Prehospital Care

The initial assessment of the mother in the field should be the same as with any injured patient. The National Center for Injury Prevention and Control recommends that pregnant women over 20 weeks gestation be transported to a center capable of timely and thorough evaluation and initial management of potentially serious injuries.³¹ Supplemental oxygen is given to prevent fetal hypoxia as small improvements in maternal oxygen saturation have a greater effect on the fetus due to fetal hemoglobin’s higher affinity for oxygen. Fluids should be given liberally to compensate for blood loss and, during transport, the mother should have a wedge placed to alleviate aortocaval compression from the gravid uterus. If injuries to the spine are suspected, the mother can be placed on a backboard with a bolster to raise her right side up 4–6 in.

Primary Survey

The primary survey is performed as for all trauma patients. Lower doses of succinylcholine are required during rapid sequence intubation due to the lower concentration of pseudocholinesterase during pregnancy.³² Once the patient’s breathing has been addressed, two large bore intravenous catheters are placed. If central venous access is necessary, the femoral vessels should be avoided due to compression of the inferior vena cava by the uterus which can alter the distribution of fluids and medications.³³ The relative hypervolemia of the mother may mask the clinical signs of shock as previously noted. Resuscitation should be started once intravenous access is secured. It is important to avoid hypotension and give supplemental oxygen when treating the pregnant patient due to the significant fetal vulnerability to hypoxia.

Secondary Survey and Maternal Assessment

The secondary survey should begin with a thorough history and physical, including a complete obstetric and prenatal history. A prior history of preterm labor, placental abruption, or placental previa are important historical points. Urgent obstetric consultation provides assistance with the evaluation of the fetus, particularly in the second and third trimester. Measuring fundal height allows estimation of gestational age, particularly when the mother is unresponsive. A discrepancy between the fundal height and known gestational age can also be a sign of uterine trauma, specifically uterine rupture or hemorrhage. The pelvic examination should include a speculum exam, especially if a pelvic fracture is suspected and vaginal bleeding or hematuria is present.³⁰

X-rays should be ordered as in any trauma evaluation. The uterus is shielded when not being directly evaluated. The Focused Assessment with Sonography for Trauma (FAST) examination is a safe and efficient modality to evaluate for intra-abdominal fluid. In a retrospective cohort of more than 2300 FAST exams, the sensitivity and specificity for the detection of free fluid or intra-abdominal injury in pregnant and nonpregnant trauma patients were similar.³⁴ In addition, fetal ultrasound assesses activity, gestational age, fetal position, and placental location. Figure 37-2 provides a useful algorithm summarizing the initial evaluation and management of the pregnant trauma patient.

Evaluation of the Fetal-Placental Unit

Fetal death after maternal trauma results from direct fetal injury, hypotension, placental abruption, and preterm delivery. Placental abruption occurs when the relatively inelastic placenta separates from the elastic uterine myometrium. Major separation typically results in fetal death, but minor abruption can often go unnoticed. Clinical examination is unreliable as vaginal bleeding is only present in 35% of patients with abruption.³⁵ As the placenta separates from the uterus, it compromises oxygen transfer to the fetus, leading to fetal distress or death.³⁰

Clinical assessment identifies if injury has occurred to the uterus or fetus. Concerning findings include the following: vaginal bleeding, ruptured membranes, a bulging perineum, presence of contractions, and an abnormal fetal heart rate or rhythm. Vaginal bleeding is abnormal before labor and can indicate placental abruption, early labor, premature cervical dilation, or placenta previa (placenta moving to cover a portion of the cervical os). Rupture of the amniotic sac should be suspected when there is cloudy, white or green discharge which increases the risk of infection. A ruptured amniotic sac can also lead to prolapse of the umbilical cord which is an obstetric emergency requiring immediate cesarean section.

Routine laboratory tests should be sent after major trauma and, if indicated, the Kleihauer-Betke (KB) test which identifies if fetal blood has entered the maternal circulation. The practice management guideline of the Eastern Association for the Surgery of Trauma supports giving an initial dose of immune globulin for all unsensitized, Rh-negative, pregnant patients suspected of having a blunt uterine injury.³⁶ The KB test can be used to quantify subclinical levels of bleeding and identify those patients at risk of receiving inadequate dosing of the Rh immune globulin. At many institutions, a KB test is ordered routinely for all pregnant trauma patients, but its clinical application has become more controversial. Studies have shown that a positive KB test correlates with placental abruption as well as being a predictor of preterm labor.^3,37 Dhanraj and Lambers showed that routine KB testing on women with low-risk pregnancies, however, had a 5.1% positive KB test, while only 2.6% of trauma patients had a positive test.³⁸ These authors suggest that the KB test does not contribute to clinical decision making.

Fetal heart tones can be detected as early as 12 weeks of gestation and are normally between 110 and 160 beats per minute (bpm). Initially, fetal hypoxia manifests as tachycardia, but, as the arterial oxygen content decreases, the fetus becomes bradycardic and any rate less than 120 bpm should be recognized as fetal distress. Monitoring of fetal heart rate should be started on any woman greater than 24 weeks gestation and is typically recommended for 4–6 hours after the initial presentation. Placental abruption has been documented at up to 24 hours after injury, but not without the presence of at least one contraction every 10 minutes within a 4-hour period.^3,15 Monitoring should continue for 24 hours if frequent contractions, vaginal bleeding, ruptured amniotic membranes, maternal abdominal pain, or non-reassuring fetal heart rate patterns are present.

Radiographic Evaluation

The choice of imaging in the pregnant trauma patient should be similar to the nonpregnant patient if life-threatening injuries are suspected. The risk of a missed injury or delayed diagnosis in the fetus is much greater than the risk of radiation. As noted, FAST is a useful tool in the early evaluation of the mother and fetus, but has limitations. Computed tomography remains the mainstay for evaluation of trauma patients and should be used if clinically indicated in the pregnant patient. Effort should be taken to decrease unnecessary scans, reduce the overlap of body sections, and avoid multiple passes when possible.³⁹ Low-dose protocols often give little diagnostic information and should be avoided.

Fetal risks from ionizing radiation include developmental delay, small head size, organ malformations, cancer and death.⁴⁰ The average background radiation that a fetus is exposed to over 9 months of gestation is approximately 1 mGy (0.1 rad). Table 37-3 shows the estimated radiation exposure to the fetus during many common radiographic procedures used to assess injured patients. As expected, radiation exposure increases substantially when the fetus is in the field of view. Radiation dose and gestational age are the two main variables in the risk assessment of the fetus. Data from survivors of the atomic bombs indicate that the risk is greatest between 8 and 15 weeks gestation, the period of fetal organogenesis and neuronal development.⁴¹ There is no proven risk less than 8 weeks or greater than 25 weeks gestation. ACOG guidelines for imaging in pregnancy emphasize that exposure to less than 5 rad (50 mGy) has not been associated with fetal abnormalities or pregnancy loss. The complete guidelines are shown in Table 37-4.

Thoracic Trauma

Injuries to the thorax are treated the same in pregnant and nonpregnant patients. It is important to remember that the gravid uterus elevates the diaphragm approximately 4 cm when performing procedures such as a tube thoracostomy. The insertion point for a chest tube should be 1–2 rib spaces above the usual fifth intercostal space.³⁰

Blunt Abdominal Trauma

Similar to thoracic injuries, blunt abdominal injuries are treated the same in pregnant patients as in nonpregnant patients. Primary focus should be on the evaluation and rapid treatment of the mother as maternal shock is associated with an 80% fetal mortality.⁵ Injury to a solid organ can be safely observed if the mother remains hemodynamically stable; however, if signs of shock or infection develop, early operative intervention is indicated as a delay in treatment leads to worse fetal outcomes.

The most devastating fetal injuries following blunt trauma include placental abruption and uterine rupture. Abruption is thought to complicate 1–6% of minor injuries and up to 50% of major injuries.^3,24 Uterine rupture is rare, occurring in less than 1% of pregnant trauma patients, and is usually associated with direct impact with substantial force.²⁴ A previously scarred uterus is more likely to rupture, and the risk increases with gestational age as the uterus grows and becomes an abdominal organ. The increased blood flow that accompanies advanced pregnancy makes rupture a severe complication which can lead to extensive hemorrhage.³⁰ The extent of uterine damage is typically not apparent clinically and must be evaluated with operative exploration. Injuries to the skull and brain of the fetus are uncommon, but are more likely to occur if there is a maternal pelvic fracture and when the fetal head is engaged within the pelvis. Maternal orthopedic injuries are common, and one study from Parkland Memorial Hospital in Dallas, Texas, found that 6% of 1067 pregnant women had an orthopedic injury and this led to an increased risk of preterm birth, placental abruption, and fetal mortality.⁴²

There are no data on the use of tranexamic acid (TXA) for traumatic hemorrhage in pregnant patients, but one of the early uses of TXA was in obstetric patients for postpartum hemorrhage.⁴³ A relative contraindication to TXA is a prothrombotic state which is common in pregnancy, but Lindoff showed there was no increase in thrombotic complications when TXA was used in pregnant women to treat bleeding disorders.⁴⁴

Pelvic Fractures

A pelvic fracture is the most common maternal injury that results in fetal death. Leggon et al reviewed 101 pregnant women with pelvic fractures, and the fetal mortality rate was 35%.⁴⁵ Causes of death included direct fetal injury (20%), placental abruption (32%), and maternal shock (36%). Dilated retroperitoneal vessels place the mother at high risk of bleeding after sustaining a pelvic fracture and maternal mortality was reported by Leggon et al as 9%. Angiography and embolization of these bleeding vessels often delivers a higher dose of radiation than is usually considered safe, and these women should be counseled on the risk. Operative fixation of both pelvic and acetabular fractures is generally considered safe during pregnancy. Most women can safely attempt vaginal delivery after a pelvic fracture, even in the third trimester. Relative indications for a cesarean delivery include fractures of the pubic rami adjacent to the urethra or bladder, severe lateral compression fractures, and acute fractures of the pelvis with marked displacement.⁴⁵

Penetrating Injuries

In contrast to blunt trauma, maternal mortality is more favorable after penetrating injury as the gravid uterus protects the mother’s vital organs from injury.⁴⁶ Conversely, fetal mortality is increased and has been reported as high as 73%.⁴⁷ The thick uterus provides protection to the mother and fetus, particularly from low-velocity stab injuries. Gunshot wounds to the uterus are much more likely to cause fetal injury. Alternatively, visceral injuries are less likely when the entry site is anterior and below the uterine fundus.¹⁴ Potential abdominal injuries from thoracoabdominal wounds should be suspected at a higher level than normal given displacement by the uterus. Exploration should be considered for any gunshot wound or any stab wound to the upper abdomen, particularly because peritoneal irritation is blunted during pregnancy.²⁴ Diagnostic laparoscopy is reasonable in the hemodynamically stable patient.

Neurologic Injuries

A moderate or severe traumatic brain injury is associated with an adverse fetal outcome. Ikossi et al found that a Glasgow Coma Scale (GCS) score less than or equal to 8 was a significant risk factor for death of the fetus.⁴⁸ The range of hyperventilation used for traumatic brain injury should be decreased in a pregnant patient as this causes a mechanical reduction in venous return and, therefore, cardiac output, which can have negative effects on the fetus. Hypothermia and mannitol should also be avoided, as well, but the use of hypertonic saline has no known deleterious effects.⁴⁹

Thermal Injuries

Burn injury in the pregnant patient presents a unique management challenge as it causes increased capillary permeability and can lead to rapid fluid loss and hypovolemia. Fetal survival is dependent on fetal age and the extent of maternal injury, so, if the fetus is in the third trimester and the mother has extensive burns, early delivery is recommended.⁵⁰ Wound care in the pregnant patient should limit the use of silver sulfadiazine (Silvadene) as it can potentially cause kernicterus in the newborn; however, one author has shown successful use without any adverse effects.⁵¹

Preparing for the Operating Room

If operative intervention is indicated, it is crucial to operate immediately, as a delay in treatment puts the fetus further at risk. Fetal viability should be documented using fetal heart tones or ultrasound pre- and postoperatively, and on-site obstetric consultation is recommended. Intubation can be difficult in the pregnant patient due to physiologic oropharyngeal edema, and inhalation anesthesia has a more rapid onset in pregnant patients, requiring an adjustment in dose.

During a laparotomy for trauma, the goals should be the same as in a nonpregnant patient—hemorrhage and contamination control. The uterus should be retracted inferiorly while exploring the other abdominal organs. Once completed, the uterus is thoroughly inspected for any injuries, particularly in the setting of penetrating trauma. Small lacerations to the uterus can be repaired with chromic sutures. If the laceration extends into the uterus and the fetus is at a survivable age, then a cesarean delivery should be performed. A cesarean delivery can also be performed if the gravid uterus prevents adequate exploration of the mother. After significant blunt trauma, a uterine rupture may occur. Attempts should be made to repair the uterus primarily if possible, but, if there is extensive uterine damage or hemorrhage cannot be controlled, hysterectomy should be performed; however, fetal survival after extensive uterine damage is rare.³⁰ An injury to the gastrointestinal tract increases the risk of loss of the pregnancy, and the abdomen should be irrigated extensively in addition to the administration of perioperative antibiotics.³⁰

Cesarean Section Following Injury

Indications for cesarean delivery after trauma are vague and must be made on an individual basis. The three possible goals when a cesarean section is indicated include save the mother, save both the mother and baby, and save only the child. Cesarean section prior to 23 weeks usually results in fetal death and should only be done to allow successful resuscitation of the mother.¹⁵ After 23 weeks, cesarean section should be performed if fetal distress outweighs the risk of prematurity or if the uterus prevents repair of maternal injuries during laparotomy.⁵² A cesarean delivery is not indicated with exploratory laparotomy for trauma, but it is important to have the obstetrical team available for any unforeseen problems.

Cardiopulmonary Resuscitation in Pregnancy

The America Heart Association (AHA) recommends four key interventions to prevent a possible cardiopulmonary arrest in the critically injured pregnant patient as follows: (1) place the patient in full left lateral position to relieve aortocaval compression; (2) give 100% oxygen; (3) establish intravenous catheter access above the diaphragm; and (4) assess for hypotension defined as systolic blood pressure less than 100 mm Hg which reduces placental perfusion.⁵³ If cardiopulmonary resuscitation (CPR) is required, the mother should be taken out of a left lateral tilt as this reduces the efficacy of chest compressions.³⁰ To relieve aortocaval compression, manual left lateral and upward displacement of the uterus can be done by a member of the treating team. Chest compressions should be performed slightly higher than normal due to the upward displacement of the thoracic structures by the uterus.⁵⁴ The rate of compressions and the use of defibrillation and cardiac medications remain unchanged from the recommendations in a nonpregnant patient.

The AHA and ACOG both recommend cesarean delivery be considered within 4 minutes of maternal cardiopulmonary collapse if there is no return of spontaneous circulation.^53,55,56 Delivery within 5 minutes in women beyond 20 weeks is encouraged in order to facilitate maternal resuscitation. This recommendation is based on the assumption that the compression of the vena cava and aorta by the gravid uterus may interfere with maternal hemodynamics. Katz et al reviewed the literature and found case reports in which 12 out of 18 patients had sudden and often profound improvement in hemodynamic status with return of blood pressure and pulse immediately after a cesarean delivery,⁵⁷ changing the concept of delivery from a postmortem cesarean to perimortem cesarean. The four minute time frame advocated for postmortem cesarean delivery is often unmet, yet neonatal survival is still likely if delivery occurs within 10 or even 15 minutes of arrest.⁵⁶ Earlier cesarean delivery theoretically benefits both mother and neonate by minimizing ischemic neurological damage.

Emergency cesarean delivery should be performed at the location of arrest. Time should not be taken to check for fetal viability or to move to an operating room. CPR should continue during the procedure in case maternal circulation is restored. Gestational age can quickly be estimated as the uterine fundus should be two finger breadths above the umbilicus at 24 weeks.⁵⁸ To perform delivery, a large midline skin incision from xiphoid to pubis is made and the uterus is opened with a vertical incision through the upper portion. The surgeon should then place their hand between the fetal head and pubic symphysis to deliver the baby and placenta.²⁴ The uterus should be closed with a single layer, running chromic suture followed by quick closure of the fascia. CPR should continue well after the procedure and, if successful, the mother should be transported to the intensive care unit for recovery. A summary of the guidelines for perimortem cesarean section is provided in Table 37-5.