Perimortem Cesarean Delivery

Anatomy and Physiology

Abdominal Wall

Cesarean delivery is a commonly performed surgical procedure. Before performing PMCD, a thorough understanding of the abdominal layers involved, which include the skin, subcutaneous tissue, superficial fascia, external oblique muscle, internal oblique muscle, transversus abdominis muscle, transversalis fascia, preperitoneal adipose and areolar tissue, and peritoneum. The blood supply for the abdominal wall comprises superficial and deep arteries. The superficial blood supply, consisting of the superficial inferior epigastric, superficial external pudendal, and superficial circumflex artery, dwells in the subcutaneous tissue and supplies blood to everything above the external oblique aponeurosis and anterior rectus sheath. The deep blood vessels are located in the musculofascial layers and supply blood to the muscles and fascia below the external oblique aponeurosis. A midline incision is an ideal approach in PMCD as it takes advantage of the fact that only the terminal branches of the blood vessels and nerves are in the linea alba. A midline incision reduces the risk of major hemorrhage and nerve damage from the procedure and provides the most significant exposure to the abdominal organs.[5]

The Uterus and Uterine Fundal Height

Understanding uterine anatomy is imperative for ensuring optimal exposure, maximizing hemostasis, and avoiding injury to critical abdominal structures such as viscera, blood vessels, and nerves. The uterus can be divided into 2 portions: the uterine corpus and the uterine cervix. The uterine corpus, also known as the body, has an inverted triangular shape. The superior portion of the body is called the fundus. An inferior portion that joins the cervix is known as the isthmus. The body is made up of 3 layers, which are the serosa (outer layer), myometrium (middle layer), and endometrium (inner layer). The uterosacral and cardinal ligament complex, round ligament, broad ligament, and endopelvic fascia support the uterus. The blood supply for the uterus mainly comes from the uterine artery. The uterine artery originates from the anterior division of the internal iliac arteries in the retroperitoneum. The practitioner should be aware of the importance of the course of the uterine artery. The uterine artery courses through the cardinal ligament and passes over the ureter, located 1.5 cm lateral to the uterus. The uterine artery reaches the uterus at the level of the internal cervical os. The uterine arteries give off branches, which tortuously course along the lateral aspect of the uterus, running superiorly to the corpus and inferiorly to the cervix. The corpus also receives collateral flow from anastomoses of the ovarian arteries.[6]

During maternal cardiac arrest, estimating gestational age may be necessary as resuscitative hysterotomy may be needed in patients beyond 20 weeks gestation. Symphysis-fundal height, measured from the top of the pubic bone to the uterine fundus, can roughly indicate gestational age in weeks for singleton pregnancies between 16 and 36 weeks. If a tape measure is unavailable, finger breadths or traditional landmarks may be used, eg, the uterus being palpable at the pubic symphysis at 12 weeks, the umbilicus at 20 weeks, and the xiphisternum at 36 weeks. However, factors like fetal engagement, abdominal distention, or a high body mass index can affect the accuracy of fundal height.[3]

Maternal Physiology 

Resuscitation during pregnancy is complicated by the physiological changes that occur to support both the mother and the fetus. Cardiac output increases by up to 50%, while systemic vascular resistance decreases due to vasodilators like progesterone and estrogen. Maternal signs and symptoms of shock may not manifest until the gravida has lost over 40% of her blood volume due to compensatory mechanisms.[7] Additionally, the growing uterus can compress major blood vessels, including the aorta and inferior vena cava, which may impair circulation during cardiac arrest.[8][9][2] This uterine compression, which can occur as early as 12 weeks gestation though more typically at approximately 20 weeks gestation, is especially problematic in the supine position, as it can lead to hypotension and reduced cardiac return.[3][2] Shifting to a left lateral tilt can improve maternal hemodynamics and enhance resuscitation efforts.[8][9][2]

Additionally, pregnant patients experience increased oxygen consumption and decreased functional residual capacity, making them more prone to hypoxemia. The enlarged uterus elevates the diaphragm by approximately 4 cm, reducing lung volume, while elevated progesterone levels drive increased ventilation. These factors, combined with reduced oxygen reserves, mean that pregnant patients may develop respiratory failure more rapidly during cardiac arrest. The fetus, while able to compensate for low oxygen levels to some extent, still benefits from timely maternal resuscitation to prevent complications.[8][9][2]

Consequently, due to the significant impact maternal physiological changes have on the outcomes of a pregnant patient in cardiac arrest, resuscitative interventions must be appropriately and rapidly adapted to effectuate these efforts. Moreover, clinicians must be aware that pregnant patients are likely more vulnerable to oxygen deprivation than nonpregnant patients and can have brain damage in as little as 4 minutes, which underpins the recommendation for PMCD within 5 minutes.[9][4]

Indications

PMCD is indicated during maternal cardiac arrest in the latter half of pregnancy to relieve aortocaval compression, which can enhance the chances of successful maternal resuscitation even if the fetus is nonviable. The AHA also recommends PMCD as soon as possible in cases where the mother is unable to be resuscitated (eg, nonsurvivable trauma) for the survival of a viable fetus. PMCD should be considered if maternal resuscitation is not achieved within 4 minutes of arrest and the uterus is large enough to cause hemodynamic compromise, typically at or above the umbilicus, to improve maternal and neonatal survival.[3] The previous AHA guidelines recommended considering starting resuscitative hysterotomy after 2 cycles of cardiopulmonary resuscitation (CPR).[10]

While the optimal timing varies based on clinician skill and resources, delivering the fetus within 5 minutes of cardiac arrest is ideal, as this is linked to better outcomes. Though studies have not shown improved outcomes, specifically with delivery at 4 to 5 minutes, this goal is used as this corresponds to the time after which a steep decline in neurologic recovery from anoxic brain injury is observed and maternal and fetal survival rates decrease.[3][7] In cases where left uterine displacement fails to relieve compression, PMCD becomes necessary as the procedure helps both by aiding resuscitation and reducing the risk of hypoxic fetal brain damage.[11][4][8][3]

Contraindications

PMCD is not recommended in the following settings:

• Manual left uterine displacement and advanced cardiac life support (ACLS) has successfully resuscitated the patient within 5 minutes
• Gestational age is less than 20 weeks (ie, fundal height under maternal umbilicus or patient gestational age known by prior imaging)
• A physician trained to perform PMCD is not present [12][11][8]

Equipment

In institutions that provide care for pregnant patient, a protocol for maternal cardiac arrest should be established, including preprepared equipment necessary to perform a PMCD if needed, either placed in the crash cart or as an emergency cesarean delivery pack that assigned personnel can quickly bring to the resuscitation site.[8][7] Equipment required for a PMCD includes:

• Scalpel with 10-blade
• Balfour retractor
• Gauze sponges
• Kelly clamps
• Russian forceps
• Suture scissors
• Suture
• Needle driver
• Umbilical cord clamps [8][7]

The procedure also involves active simultaneous resuscitation. Therefore, equipment required for effective resuscitation, including oxygen, a laryngoscope, large bore intravascular catheters, end-tidal CO₂ monitor, suction device, as well as neonatal resuscitation equipment, is also essential.[8][7]

Personnel

An interprofessional approach is essential to enable maternal resuscitation and PMCD to be performed simultaneously. As in the setting for trauma activation, a team of emergency medicine physicians, trauma surgeons, obstetrics and gynecology physicians, anesthesiologists, pediatric neonatologists, intensive care unit personnel, and neonatal intensive care unit clinicians should be present.[8]

Preparation

Preparing for PMCD requires specific steps to ensure emergency readiness, especially in areas where cesarean delivery is not routinely performed. Healthcare teams should be trained in managing cardiac arrest in pregnant patients to facilitate an effective response. Furthermore, a clear protocol should be established for PMCD, including activation of the maternal cardiac arrest response team and ensuring that all necessary equipment for both cesarean delivery and neonatal resuscitation is readily available. In settings where PMCD consent may be required (eg, unstable pregnant patient), it should be obtained in advance.[7][8]

Additionally, the AHA recommends that units be equipped with essential medications, eg, oxytocin and prostaglandin F2α, and for critically ill patients, decisions about neonatal resuscitation and viability should be made and documented in collaboration with the obstetrician, neonatologist, and family. Early identification of patients at high risk for cardiac arrest, such as the modified early warning systems used in Great Britain, may also help healthcare teams to make preparations in case a patient's condition deteriorates.[7][8]

Technique or Treatment

Advanced Cardiac Life Support in Pregnant Women

Before the decision to perform a PMCD is made, maternal resuscitation with ACLS protocol is performed with lateral uterine displacement. Immediately after maternal cardiac arrest or decompensation that will soon lead to cardiac arrest is identified, the maternal resuscitation team should be called so that the clinicians necessary to perform a PMCD are already assembled. Due to the need for a rapid response in these settings and to prevent any foreseeable delays, the AHA recommends institutions have maternal resuscitation response teams and protocols already in place.[3] 

ACLS in pregnant individuals should be carried out using the same algorithm followed in nonpregnant individuals with a few technique modifications. These modifications primarily include lateral uterine displacement to reduce aortocaval compression and preparation for PMCD if resuscitation is unsuccessful. Clinicians should be aware that lateral uterine displacement should be achieved by manually pulling or pushing the uterus upwards and to the left instead of maternal leftward tilt, as this allows the patient to remain in the supine position, ensuring that chest compressions are effective.[2][3][4] Additionally, fetal monitors should be removed so that resuscitative measures are not impeded.[3] ACLS protocol, including airway management, cardiopulmonary resuscitation, and defibrillation, should be conducted in the same manner in nonpregnant and pregnant patients.[3]

Perimortem Cesarean Delivery

The technique for PMCD centers around the critical 5-minute window to assess whether cardiac arrest can be reversed using ACLS protocols. In some cases, such as with severe maternal injury or prolonged pulselessness, PMCD may be initiated sooner, especially if the fetus is viable. Although the 5-minute goal is rarely met in practice, maternal survival has been documented even when PMCD occurred up to 15 minutes after arrest. Fetal survival rates are highest when delivered within 5 minutes postarrest, particularly at gestational ages beyond 24 to 25 weeks. Though infants have survived even when PMCD occurred beyond this timeframe, studies show that shorter arrest-to-delivery times are linked to better maternal-fetal outcomes.[2][8][7]

PMCD should be performed at the site of maternal resuscitation rather than moving the patient to an operating room, as transportation can delay the procedure.[2][8] Resuscitative efforts, including manual left uterine displacement, should continue during the procedure. Although sterile skin preparation is not essential for PMCD, some experts recommend that skin preparation be completed within the first few minutes after the cardiac arrest and may act as a visual cue signaling that PMCD is imminent.[4] The choice of incision, whether vertical or Pfannenstiel, is left to the performing physician's discretion; vertical incisions offer better access, but either method is acceptable.[2][8][7] For the most part, the remainder of the cesarean delivery should follow standardized cesarean techniques. Please see StatPearls' companion resource, "Cesarean Delivery," for more information on the cesarean delivery procedure.

After delivery, the placenta is removed, and the uterus is quickly closed with absorbable sutures. Postprocedure, if maternal resuscitation is successful, antibiotics and oxytocin may be administered, though caution is advised with oxytocin to avoid triggering re-arrest. Institutions with limited staff or resources should prioritize rapid response to maternal cardiac arrest, as the timely performance of PMCD can significantly improve survival outcomes.[2][8][7]

Complications

Complications that are associated with PMCD are similar to those related to a standard cesarean section. However, complications can be further exacerbated by complications caused by maternal cardiac arrest. Complications of PMCD include hemorrhage, infection, thromboembolism, bladder and bowel injury, and anesthetic complications.[13] Bladder and bowel injury can be avoided by using retractors to displace the bladder or bowel. If bladder distention is noted, the bladder can be decompressed with needle aspiration or with the use of a Foley catheter before initiation of the procedure.[14] A midline abdominal incision can help to avoid major arterial bleeding from the uterine blood vessels that run laterally along the uterine border.[2][8][7] 

The risk of fetal trauma during cesarean is approximately 1%, including skin laceration, fracture of the clavicle or skull, facial or brachial plexus nerve damage, and cephalohematoma.[15] In addition to short-term surgical risks, cesarean delivery also confers long-term risks, both to the patient and to her subsequent pregnancies, including adhesion formation and abnormal placentation (eg, placenta accreta).[16] 

Clinical Significance

The outcomes for both mother and baby can vary, but performing a PMCD at 20 weeks or later in pregnancy may enhance survival when resuscitation efforts are unsuccessful. In cases where left uterine displacement fails to relieve compression, PMCD becomes necessary as the procedure helps both by aiding resuscitation and reducing the risk of hypoxic fetal brain damage. The decision to proceed with PMCD is complex and influenced by factors, including the underlying cause of cardiac arrest, the stage of pregnancy, and available medical resources. As a result, standardized guidelines for PMCD are limited, though the recommendations issued by the AHA on cardiopulmonary resuscitation for pregnant patients, including guidelines for PMCD, have been widely recognized.[3][4][1]

The primary effects of PMCD are facilitating maternal resuscitation by relieving pressure on the large blood vessels, thereby improving venous return and reducing the risk of neurological damage from oxygen deprivation for the mother and infant. Studies have shown that performing PMCD within 5 minutes of cardiac arrest leads to better outcomes. Ideally, healthcare institutions providing obstetric care should have dedicated teams and protocols in place to manage maternal cardiac arrest and perform PMCD when necessary to ensure PMCD is performed as rapidly as possible when needed.[3][4][1]

Enhancing Healthcare Team Outcomes

In the management of an arrested pregnant patient, a collaborative, interprofessional approach is critical to improving outcomes for both the mother and the baby. Early involvement of an interprofessional team significantly increases the chances of survival. Similar to trauma activations, the team should include emergency medicine physicians, trauma surgeons, obstetricians, anesthesiologists, pediatric neonatologists, and nurses trained in critical care, such as those from the emergency room or intensive care unit. Effective hospital policies are essential in facilitating the early activation of these specialized groups, ensuring that all necessary team members are quickly mobilized during such high-stakes situations. The physician with the most surgical experience in the room takes the lead in performing the PMCD to minimize complications.

Interprofessional communication and care coordination are essential for ensuring seamless teamwork during these emergencies. This includes clear, real-time communication between physicians, nurses, pharmacists, and other health professionals to coordinate care quickly and safely. Each team member must understand their role and responsibilities, prioritizing patient-centered care and safety. For example, anesthesiologists manage the airway, neonatologists focus on neonatal resuscitation, and nurses ensure that the equipment and medications are readily available. Collaboration between the obstetrics, neonatal, emergency, anesthesiology, and intensive care teams, as recommended by the AHA, is vital for planning and executing effective responses to maternal cardiac arrest. Proper training and easy access to necessary equipment in areas where such situations are likely to occur, like the emergency department, intensive care unit, or labor and delivery, are also critical for enhancing team performance and improving outcomes.