Perimortem Cesarean Delivery

Anatomy and Physiology

Abdominal Wall

The incision of the abdominal wall is 1 of the most frequently performed surgical procedures. Prior to performing a rush PMCS, it is ideal to have a basic understanding of the layers involved. There are 9 layers of the abdominal wall 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 is in the subcutaneous tissue and supplies blood to everything above the external oblique aponeurosis and anterior rectus sheath. It consists of the superficial inferior epigastric, superficial external pudendal, and superficial circumflex artery. 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 PMCS because it takes advantage of the fact that only the terminal branches of the blood vessels and nerves are in the linea alba. This reduces the risk of major bleeds and nerve damage from the procedure and provides the most significant exposure to the abdominal organs.[4]

The Uterus  

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 uterus is supported by the uterosacral and cardinal ligament complex, round ligament, broad ligament, and the endo-pelvic fascia. 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). It 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.[5]

Physiology 

There are physiologic changes that occur during late pregnancy. During the third trimester of pregnancy, there is an increase in cardiac output and circulating blood volume by 30% to 40%. This is important because maternal signs and symptoms of shock may not manifest until the mother has lost over 40% of her blood volume. Also, an enlarged uterus can elevate the diaphragm by about 4 cm, which, in turn, can cause a 20% decrease in functional residual capacity. Finally, the gravid uterus can cause compression of the inferior vena cave (IVC), leading to hypotension.[6]

Indications

Traditional teaching expresses that resuscitative hysterotomy is performed in mothers carrying a fetus of the gestational age of 24 weeks and older who are in peri-arrest or have actively been arrested. At 24 weeks, the fetus is considered viable. There is also a 20% to 30% fetal survivability at 24 weeks onward if PMCS is performed in a scenario where appropriate neonatal critical care facilities exist. Newer theories argue the 24-week rule, as the primary goal of resuscitative hysterotomy is the resuscitation of the mother. Also, when a patient arrives in extremis, the gestational age may not be known, and ultrasound is impractical. A quick evaluation of fundal height can aid in estimating gestational age. If the uterus fundus can be seen at the umbilicus, the gestational age can be about 20 weeks. The uterine fundus grows about 1 cm every week after that.

Another critical factor in determining the need to perform PMCS is the time from arrest. Resuscitative hysterotomy should be performed 4 minutes after the patient arrests. The goal delivery time is within the first 5 minutes of arrest. Four minutes is used because this corresponds to the time after which there is a precipitous decline in neurologic recovery for the infant from anoxic injury. It is important to reiterate that PMCS can offer resuscitative benefits to the mother despite fetal survivability or neurological outcomes. The 2010 American Heart Association (AHA) guidelines for CPR and Emergency Cardiovascular Care recommend considering starting resuscitative hysterotomy after 2 cycles of CPR.[7][8]

Contraindications

Contraindications to PMCS are:

• If the patient achieves ROSC within 2 cycles of resuscitation
• If the gestational age is less than 20 weeks

Equipment

Equipment needed for a PMCS includes:

1. Definitive airway kit
2. Oxygen
3. Two large bore IVs
4. End-tidal CO₂ monitor 
5. Cesarean delivery kit, trauma laparotomy kit
6. No 10 Scalpel
7. Hemostats
8. Large scissors
9. Gauze sponges
10. Large retractors/bladder retractors
11. Infant warmer 
12. Bulb suction 
13. Pediatric airway kit

It is important to remember that the procedure also includes active simultaneous resuscitation. The first 4 types of equipment ensure adequate and effective resuscitation, and the next 6 are required for the surgical aspects of the procedure. The physician and personnel taking part in the resuscitative portion of the procedure must be different than the physician performing the surgical aspect. During resuscitation, an operating room (OR) room must be available for subsequent closure. Finally, the last 3 pieces of equipment are needed for the infant resuscitation.[3]

Personnel

An interprofessional approach should be employed. As is in the setting for trauma activation, a team of emergency medicine physicians, trauma surgeons, obstetrics and gynecology physicians, anesthesiologists, pediatric neonatologist, and emergency (ER)/intensive care unit (ICU), obstetrics (OB), and neonatal intensive care unit (NICU) trained staff should be present for these scenarios.

Preparation

If there is a concern for a peri-arrest scenario or if the patient is actively arresting, an interprofessional team must be consulted, including neonatology, obstetrics, and trauma surgery, if needed, and involved early. The physician performing the procedure should try to wear sterile attire if and when possible. The mother should remain in the supine position. A left lateral tilt can be employed but is not always necessary. Iodine solutions can be used to sterilize the skin before incision.

A few of the patients require PMCS secondary to a traumatic cause. It is essential to keep in mind basic management principles in the setting of trauma. When faced with a pregnant trauma patient, it is crucial to understand that the focus of care should initially be on resuscitating the mother. Special considerations should also be given to the primary survey, airway, breathing, and circulation (ABCs). First, when managing the airway, it is important to realize that during the third trimester, there is a physiologic narrowing of the airway. Therefore, it is preferential to use an endotracheal tube that is 1 size smaller. Also, rapid sequence intubation is the recommended method of intubation, given an increased risk for aspiration.

Regarding breathing, pregnant patients have a higher disposition of rapid decline in their PaO₂ during apneic episodes. It is important to place all pregnant patients on supplemental oxygen (O₂), regardless of their peripheral capillary oxygen saturation (SpO₂). Given the sizeable circulating blood volume, hypovolemia must be considered in pregnant patients before the presentation of clinical signs and symptoms of hypovolemia and shock. Aggressive fluid resuscitation should be initiated despite normal blood pressure readings.

In addition, while chest compressions are being performed, maneuvers must be employed to displace the gravid uterus from the inferior vena cava. Older teachings have recommended placing a board behind the back, with a 30-degree tilt to the left; however, this may make CPR more difficult and less effective. Newer models propose that the uterus be manually displaced with 2 hands to the left of the patient while CPR is actively being performed.[9]

Technique or Treatment

The physician performing the perimortem cesarean section should ideally be 1 with the most surgical experience in the room. During normal Cesarean deliveries, the most common incision types include the Joel-Cohen incision, Pfannenstiel incision, and midline vertical incision. However, in a PMCS, a midline vertical incision is the preferred initial approach. The initial incision should begin from the level of the uterine fundus to the pubic symphysis. Other authors have quoted a more optimal approach with an incision from the xiphoid to the pubis. Ideally, a No. 10 blade scalpel should be used for the incision. One should cut through the subcutaneous tissues to get to the peritoneal wall, and blunt dissection can be used to achieve this method as well. Once the peritoneal wall is reached, an incision can be made inferiorly with a scalpel or scissors (ideally). Subsequently, the peritoneum can be cut vertically with scissors. Once the uterus is delivered, a midline vertical incision should be made on the lower portion of the uterine corpus to avoid the placenta while avoiding the bowel and the bladder. Once the uterine cavity is initially entered, the index and middle fingers should be used to separate the uterine wall away from the fetus, and then the incision can be extended with scissors. The incision should be extended upward until the baby is exposed. Once exposed, the cord should be clamped and cut. Once delivered, the infant should be promptly resuscitated. The open uterus and the abdomen should be packed to prevent further bleeding. Further closure of the incision depends on the maternal response to resuscitative efforts. ACLS/ATLS should be continued on the mother until ROSC is achieved, and if achieved, further closure should be continued in the OR. Also, if maternal survivability is considered likely, the patient should receive antibiotic prophylaxis with any broad-spectrum penicillin or cephalosporin in a single dose.[10][11]

Complications

Bladder Injury

• It can be avoided by using retractors to displace the bladder inferiorly.
• If distended, the bladder can be decompressed with needle aspiration or with the use of a Foley catheter before initiation of the procedure.[12]

Injury to the Fetus

• It can be avoided by creating a lower midline uterine incision to avoid placental injury.
• Also, by using scissors instead of a scalpel, to extend the incision superiorly.

Arterial Injury

• A midline abdominal incision avoids major arterial bleeding.
• Avoid transverse lateral uterine incisions, as the uterine blood vessels run laterally along the uterine border.

Clinical Significance

The goal of resuscitative hysterotomy should be primarily aimed at saving the life of the mother. PMCS improves maternal survivability by decreasing compression of the IVC by the gravid uterus, which improves venous return. PMCS also improves diaphragmatic displacement, which in turn improves respiratory dynamics.[13][14][15]

Enhancing Healthcare Team Outcomes

In the setting of a peri-arresting or arrested pregnant patient, the highest likelihood for survival for the mother and the infant is when an interprofessional approach is employed early in the course of the arrest. As is in the setting for trauma activation, a team of emergency medicine physicians, trauma surgeons, obstetrics and gynecology physicians, anesthesiologists, pediatric neonatologists, and ER- or ICU-trained staff should be present for these scenarios. Hospital policies should be set in place for a peri-arrest or arresting pregnant patient. This allows for easy and early activation of the groups mentioned above. As mentioned earlier, the procedure should be performed by the physician with the most surgical experience in the room to reduce complications. Areas where this situation can occur (ie, ED, ICU, labor and delivery) should also have easy access to all equipment required to perform the procedure. Per AHA 2010 guidelines, "Team planning should be done in collaboration with the obstetric, neonatal, emergency, anesthesiology, intensive care, and cardiac arrest services (Class I, LOE C)."[7]