*Necrotizing Enterocolitis DOI: http://dx.doi.org/10.5772/intechopen.85784*

*Pediatric Surgery, Flowcharts and Clinical Algorithms*

*Modified Bell's staging criteria for necrotizing enterocolitis in neonates [33].*

inflammatory response and poor response to correction of metabolic and hematological derangements, such as severe metabolic acidosis, hyponatremia, hyperglycemia, thrombocytopenia, DIC, anemia, and neutropenia, eventually progressing

Age of onset varies in an inverse relationship with GA at birth, and the average post menstrual gestational age of NEC is estimated to be 31–32 weeks. In a cohort of preterm infants under 33 weeks gestational age, NEC presented at a mean of 7 days in more mature infants, while it was delayed to 32 days in lower birth weight and gestational age neonates [1]. The average age of onset has been reported to be 20.2 days for babies born at less than 30 weeks' estimated gestational age, 13.8 days for babies born at 31–33 weeks, and 5.4 days for babies born after 34 weeks of gestation. Term infants develop necrotizing enterocolitis much earlier, with the average

To classify the severity of NEC based on clinical findings, a staging criterion was proposed by Bell in 1978 which was later modified (**Table 3**) [37]. In about one third of cases, NEC is suspected but not confirmed (stage I), and symptoms resolve gradually with treatment. In 25–40% of cases, the progression of NEC is fulminant with signs of peritonitis and sepsis and the rapid development of DIC and shock (stage III). About 30% of the cases may develop intestinal perforation, peritonitis, and other complications necessitating surgical intervention. Mean LOS is 62 days in surgical and 36 days

age of onset within the first week or within the first 1–2 days of life [36].

in medical NEC cases [15]. Surgical NEC cases incur higher hospital costs.

In all cases of NEC, CBC with diff, blood culture, C-reactive protein, serum electrolytes, pH, lactate, acid-base indicators, arterial blood gases,

**7. Laboratory and radiological investigations**

**32**

**Table 3.**

to death.

and pertinent radiography should be done. The characteristic anomalies are metabolic or mixed acidosis, high C-reactive protein (CRP), hyponatremia, hyperglycemia, thrombocytopenia, neutropenia, or leukocytosis with high I/T ratio. CSF studies are suggested, and peritoneal fluid analysis for bacteria and fecal material should be done if paracentesis abdominis is performed for therapeutic or diagnostic purposes. Presentation of NEC is similar to, or may be associated with sepsis, and the differentiation is confirmed by the presence of pneumatosis intestinalis (PI) on radiography (**Figure 5**). Apart from PI other radiological features of NEC are ileus, bowel wall thickness, and bowel perforation with peritoneal air. Bowel wall thickening, with or without echogenicity, indicates increasing inflammation, swelling, and perfusion of the area. Bowel loops may be separated by the presence of peritoneal fluid and give an impression of thickening. Thin bowel wall with a central echogenic focus and a hypoechoic rim, called pseudo-kidney sign, if present, may indicate necrotic bowel and imminent perforation. Ultrasound detection of small air bubbles in the bowel wall as in pneumatosis intestinalis can be spatially differentiated from air bubbles in stool that can sometimes be misdiagnosed as pneumatosis on radiographs. Ultrasonography also can detect intermittent gas bubbles in the liver parenchyma and portal venous system that are not detected on radiography. Ultrasound is more sensitive in detecting peritoneal fluid collections. Doppler ultrasound is dynamic and permits real-time visualization of bowel wall thickness, peristalsis, and perfusion. It is more sensitive than abdominal radiography in detecting bowel necrosis [15]. Evidence of free peritoneal air and ascites indicate intestinal perforation. Contrast enemas are not recommended if NEC is suspected, as it may result in bowel perforation with extravasation of contrast material into the peritoneum. Near-infrared spectroscopy (NIRS) is a new, noninvasive method of estimating local tissue hemoglobin oxygen saturation by measuring the difference between oxyhemoglobin and deoxyhemoglobin and may have utility in diagnosing intestinal ischemia in NEC. Fortune et al. demonstrated cerebro-splanchnic oxygenation ratio < 0.75 to have a positive predictive value of 0.75 for intestinal ischemia, whereas, if above 0.75, intestinal ischemia is excluded with a negative predictive value of 0.96 [38].

#### **Figure 5.**

*On left: massive pneumoperitoneum with visualization of falciform ligament, massive lucency involving the entire abdomen, visualization of the liver margin. On right: left lateral decubitus radiograph demonstrating massive lucency with visualization of the liver margin and bowel. [Courtesy of Dr. Renu Aggarwal, Attending Neonatologist, NYU Winthrop Hospital, Mineola, NY, USA].*
