Management of Perforated Necrotizing Enterocolitis
INTRODUCTION
Necrotizing enterocolitis (NEC) continues to be associated with extreme prematurity, resulting in increased morbidity and mortality. Various studies have reported an incidence of NEC of 14% in infants with a birth weight of 501–750 g and an odds ratio for death of 14 for nonsurgical NEC and 25 for surgical NEC. There remains some controversy regarding the diagnosis of perforated NEC vs spontaneous intestinal perforation, and an ongoing multicenter, randomized, controlled trial is attempting to better define the 2 conditions. Regardless of the etiology, severe inflammation and subsequent necrosis, ischemia, perforation, and peritonitis may result in not only death but also severe neurodevelopmental impairment and intestinal failure (IF).
The 2 common surgical interventions for intestinal perforation are exploratory laparotomy and peritoneal drainage. Several case series and observational studies examined the utility and outcome of both operations. To date, only 2 randomized studies compared the 2 operations, with conflicting results concerning mortality. There is a paucity of data regarding the long-term outcomes of either operation.
This chapter focuses on the dilemma of surgical intervention for intestinal perforation/NEC. This discussion includes preoperative, operative, and postoperative management. In addition, the chapter reviews novel therapies designed to prevent the complications associated with surgical NEC.
PREOPERATIVE MANAGEMENT
It is essential first to determine if a patient actually has perforated NEC. Whenever possible, it is strongly recommended to obtain a pediatric surgical consultation when concerned about perforation. Several clinical scenarios of perforation can present to the caregivers. The first is the presence of free abdominal gas within the peritoneal cavity. A patient may demonstrate a large pneumoperitoneum that is easily appreciated on supine abdominal imaging. Radiographic findings include a large gas bubble or gas surrounding the liver, as well as the so-called football sign by which free abdominal gas highlights the falciform ligament. It can be more difficult to detect when there is less free abdominal gas. In these cases, it is imperative to obtain both supine and left lateral decubitus radiographs. The left lateral decubitus image is preferred to a “cross-table” supine study as the former allows free abdominal gas to migrate between the body wall and the liver and not be confused with a gas-filled loop of intestine. In the absence of free abdominal gas, the determination of intestinal perforation is more challenging.
To date, there are no studies designed to confirm perforation by either radiographic or biomarker methods. There are case reports of clinicians utilizing abdominal paracentesis to detect perforation. This technique is associated with significant complications and should be reserved for patients who require therapeutic paracentesis for severe abdominal distension that is having an impact on ventilation. Often, patients with a “gasless” abdomen or with presumed NEC totalis (extensive NEC involving the entire intestinal tract) may require surgical intervention even with no clinical evidence of perforation.
Once the diagnosis of proven or presumed intestinal perforation is made, the patient needs to be quickly moved to a center where pediatric surgical evaluation can be obtained. Regardless of the location, the ABCs of resuscitation need to be applied. Most patients require tracheal intubation and mechanical ventilation. Establishing arterial catheter monitoring of both ventilation and hemodynamics is desirable. The clinician needs to correct any acid-base imbalance and maintain normal age-appropriate arterial blood pressure. Commonly, there is marked fluid loss into the peritoneal spaces, and patients with NEC and sepsis may become markedly edematous. Resuscitation with large amounts of volume may be necessary to support blood pressure and perfusion of the bowel and kidneys. Maintaining adequate urine output has been associated with improved outcome. It is important to remember that patients with perforated NEC will often deteriorate after their operation, so establishing secure vascular access before the surgery will avoid the potential need for subsequent surgically obtained venous catheters.
Although only 25% of patients with NEC have culture-proven bacteremia, broad-spectrum antibiotics need to be administered. Common initial choices are vancomycin, gram-negative coverage such as an aminoglycoside or piperacillin/tazobactam, and metronidazole as an aerobic bacterial antibiotic. As mentioned, many of these patients have extensive abdominal distention, so placing a large-diameter sump-type orogastric tube with adequate continuous suction will assist in decompression and improve mesenteric perfusion and diaphragmatic excursion.
By developing a long-standing and collegial relationship with pediatric surgeons, the preoperative period can be streamlined. Two major impediments to timely surgical intervention are the availability of an operating room/team and blood products for operation. Many institutions have developed protocols permitting both peritoneal drainage and exploratory laparotomy at the bedside in the neonatal intensive care unit (NICU), thus eliminating the need for an operating room and the time and risk involved in moving the patient. It is important for the nonsurgical clinician to remember that performing a laparotomy requires an entire surgical team and often a pediatric anesthesiologist. Thus, consulting a surgeon early will avoid delays. Last, regardless of surgical procedure choice, cross-matched blood products need to be available prior to any operation.
OPERATIVE MANAGEMENT
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