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418 Necrotising Enterocolitis

Table 70.1: Specific and nonspecific signs of NEC. for surgery in its own right as it may be a transient phenomenon);
Gastrointestinal signs Nonspecific physiologic signs • constant (“fixed”) small bowel loop present on serial x-rays, which
Feeding intolerance Hypotension indicates necrotic loop of bowel;
Abdominal distention Temperature instability • ascites;
Blood per rectum Apnoeic spells (with bradycardia) • thickening of the abdominal wall due to cellulitis;
Bilious emesis Lethargy
• outline of falciform ligament highlighted by intraperitoneal air
Haematemesis Glucose instability (“football sign”); and
• outlining of the intestinal wall between two gas lucencies (“Rigler’s
Laboratory Testing and Imaging sign”).
A complete blood count often demonstrates thrombocytopaenia and Bell Staging System
31
may show leukocytosis or, more commonly, leukopaenia. Blood gas
Based on this initial work-up, patients with a presumed diagnosis of
analysis (arterial, venous, or capillary) may demonstrate a significant
NEC can be classified into one of three clinical stages, as described by
base deficit due to metabolic acidosis associated with hypoperfusion, 37
Bell et al. (Table 70.2).
but is not necessarily indicative of intestinal necrosis. Because the
initial history, physical exam, and laboratory findings in patients with Table 70.2: Simplified Bell staging system for NEC..
NEC are often nonspecific, sepsis from a source other than the GIT
Stage NEC involvement Manifestations Radiographic signs
is the most common diagnosis that needs to be excluded in cases of
I Infants with mild Gastrointestinal, Abdominal
suspected NEC. Other diagnoses that may be included are malrotation features suggestive, includes feeding radiograph with
of the intestines with midgut volvulus, gastroenteritis, Hirschsprung’s but not diagnostic, intolerance, nonspecific ileus
disease, intestinal atresia, intussusception, and, less commonly, gastro- of NEC abdominal pattern
distention, blood
oesophageal reflux disease.
per rectum, etc.;
Plain radiography remains the imaging modality of choice in
the diagnosis of NEC. In 70% of cases, the diagnosis is established systemic
by the presence of pneumatosis intestinalis on plain abdominal includes
radiograph. Other radiographic findings in infants with NEC include temperature
instability,
air in the portal vein, a ground-glass appearance suggestive of ascites, lethargy,
pneumoperitoneum (Figure 70.4), and the “fixed-loop” sign, which is bradycardia, etc.
the defined as one or several loops of dilated small intestine that remain II Infants with definitive Persistent Abdominal
unchanged in position on x-ray over 24 to 36 hours. The fixed loop sign NEC but without or marked radiograph with
is suggestive of a nonperistalsing segment of intestine due to necrosis. indication for surgical gastrointestinal pneumatosis
intervention
or systemic
intestinalis
Whereas contrast studies of the GIT, such as computed tomography manifestations
(CT) and magnetic resonance imaging (MRI) scans, have not been III Infants with more Above Above radiographic
proven to be clinically useful in the evaluation of patients with NEC, 32– advanced NEC, signs with signs with
35 a recent study has suggested a possible role for sonography due to its defined by intestinal deteriorating pneumoperitoneum
necrosis, signs of vital signs, or other signs
increased ability to detect intraabdominal fluid, bowel wall thickness, clinical deterioration evidence of suggestive of
36
and bowel wall perfusion. The resources available in developing or intestinal septic shock intestinal necrosis
countries may limit the applicability of ultrasound in such regions. perforation or marked
gastrointestinal
Radiologic features commonly associated with NEC include:
haemorrhage
• thickened, distended bowel loops;
• pneumatosis intestinalis, or gas in the bowel wall; Source: Kliegman RM, Fanaroff AA. Necrotizing enterocolitis. N Engl J Med 1984; 310:1093–1103.
• pneumoperitoneum, which indicates intestinal perforation;
Differentiation of NEC from Spontaneous
• portal venous air (a severe infection that is not an absolute indication Intestinal Perforation
Spontaneous intestinal perforation (SIP) or focal intestinal perforation
(FIP) have been reported as disease entities different from NEC. The
aetiology, pathophysiology, and best treatment of spontaneous intesti-
nal perforation remain subjects of ongoing research, but the principles
for the management of NEC mostly apply. Similar to NEC, FIP presents
with the sudden onset of a pneumoperitoneum. However, unlike NEC,
FIP often represents a small isolated perforation, which may spontane-
ously seal without surgery in the very low weight infant (<1,000 g).
Management
Initial management of acute NEC consists primarily of supportive care.
If patients are receiving enteral alimentation, the feedings should be
discontinued and an orogastric tube should be placed to decompress
the stomach. Aggressive intravenous fluid resuscitation is critical in the
early phase of NEC to prevent exacerbation of intestinal hypoperfu-
sion, and a catheter may be inserted into the bladder to help monitor
urine output and adequacy of resuscitation. Blood and urine cultures
Figure 70.4: Decubitis abdominal radiograph demonstrating pneumoperitoneum should be obtained, and broad-spectrum antibiotics should be adminis-
(arrow); Rigler’s sign is also seen.