Necrotizing enterocolitis (NEC)

Premature
newborn with feeding intolerance. Supine AXR shows diffusely dilated loops of bowel throughout the abdomen. There is no evidence of pneumatosis intestinalis, portal venous gas, or free air.The diagnosis was necrotizing enterocolitis.
pediatricimaging.org • CC-by-nc-sa 4.0
Pneumatosis
intestinalis und hepatis bei nekrotisierender Enterokolitis
Wikipedia • CC BY-SA 4.0
Infant with
feeding intolerance after recovering from a documented episode of necrotizing enterocolitis. AXR (left) shows dilated loops of bowel throughout the abdomen. AP image from an enema (above right) shows narrowing of the colon at the rectosigmoid colon, splenic flexure and cecum. AP image from later in the exam (below right) shows dilated loops of small bowel filled with contrast above the level of the narrowing in the cecum.The diagnosis was multiple colonic strictures after necrotizing enterocolitis.
pediatricimaging.org • CC-by-nc-sa 4.0
Premature
newborn with abdominal distension 2 weeks after recovery from a documented episode of necrotizing enterocolitis. AXR AP (left) shows multiple dilated loops of bowel throughout the abdomen. AP image from early in a barium enema (above right) shows a fixed narrowing in the sigmoid colon while AP image from later in the enema (below right) shows additional areas of fixed narrowing beneath the splenic flexure, at the splenic flexure and beneath the hepatic flexure.The diagnosis was multiple colonic strictures after necrotizing enterocolitis.
pediatricimaging.org • CC-by-nc-sa 4.0
Infant status
post surgery for bowel perforation. AP image from an UGI exam (left) shows contrast opacifying the proximal jejunum. An image obtained a minute later (right) shows contrast entering the surgical drain in the left lower quadrant of the abdomen.The diagnosis was enterocutaneous fistula after bowel perforation in a patient with necrotizing enterocolitis.
pediatricimaging.org • CC-by-nc-sa 4.0
necrotizing
enterocolitis
Wikipedia • CC BY-SA 3.0
Premature
newborn with past history of necrotizing colitis who is having difficulty stooling. AP image from an enema (left) shows a transition zone in the lower right of the image from a narrow sigmoid colon to a more dilated descending colon above it. Spot image from the enema (right) shows the narrowed colonic lumen filled with contrast connecting those two parts of the colon.The diagnosis was a stricture of the descending colon after necrotizing enterocolitis.
pediatricimaging.org • CC-by-nc-sa 4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Necrotizing enterocolitis (NEC) is the most common gastrointestinal condition in premature neonates. It is characterized by inflammation, ischemia, and permeability of the neonatal bowel wall to bacteria. It is potentially life-threatening with significant associated morbidity .

Epidemiology

NEC usually develops 2-3 days following birth, with 90% developing within the first 10 days of life . The incidence is inversely proportional to gestational age, with 90% occurring in premature infants. Its overall incidence is ~1 in 1000 births but is as high as 20% in low birth weight infants (<1500 grams) .

Clinical presentation

The presentation is often non-specific and includes:

  • poor feeding 
  • bile stained vomitus
  • abdominal distension
  • blood-stained stools +/- explosive diarrhea
  • respiratory distress with acidosis
  • sepsis
Risk factors

Pathology

NEC is usually idiopathic and multi-factorial. A combination of ischemic and infective etiology with added contributive factors such as immature immunity have been proposed .  Although a partially infective etiology has been hypothesized, no causative organism has been isolated. Translocation of intestinal flora through immature mucosa has been postulated .

Inflammation starts from the mucosal surface and progresses to hemorrhagic and coagulative necrosis. There is ensuing loss of mucosal integrity, transmural necrosis, and perforation.

Although NEC can affect any part of the large or small bowel, the most common location is the terminal ileum. The right colon (including cecum) is occasionally involved. Involvement of the stomach is less common.

Radiographic features

Plain radiograph

Supine abdominal x-rays are the mainstay of diagnosis. If NEC is suspected clinically, or there is a concern on supine films, an additional cross-table lateral or left-lateral decubitus view provides increased sensitivity . Findings include:

For follow-up, supine and lateral projections have been recommended for the first 48 hours as this is when most perforation occurs. After 48 hours, vertical beam supine projections may be sufficient if there no concern for perforation .

Ultrasound
  • bowel wall thickening  
  • alteration of the vascular state
    • hypervascular (viable but engorged in early stage)
    • hypovascular (infarcted in a later stage)
  • intramural gas manifesting as hyperechoic foci within the bowel wall
  • free fluid, especially with echogenic debris, suggests perforation

Treatment and prognosis

NEC can be managed both medically and surgically and appropriate patient selection is essential in optimizing outcome. A clinical staging system has been developed (see necrotizing enterocolitis staging), with stage I and II receiving medical therapy and stage III undergoing surgery .

Medical management consists of supportive measures and cessation of oral feeding, along with broad-spectrum antibiotics and gastric aspiration .

Surgery is usually reserved for patients with evidence of perforation and entails resection of clearly necrotic bowel and the creation of a proximal enterostomy . Other relative indications for surgery include portal venous gas, a fixed dilated loop on serial x-rays and abdominal wall erythema . Re-anastomosis is usually delayed until the infant has completely recovered.

Despite therapy, mortality remains significant, ranging between 9 and 28% . Furthermore ~20% of surviving patients will go on to develop stricture. These are more common in the large bowel (80%) and may result in bowel obstruction weeks to months later .

Differential diagnosis

In the correct clinical scenario, the presence of gas within bowel wall has a little differential.
Conditions worth keeping in mind include :

Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu Nekrotisierende Enterokolitis:
Fokale
Intestinale Perforation (FIP)
Wikipedia • CC BY-SA 4.0
Pneumatosis
intestinalis
Wikipedia • CC BY-SA 4.0
Mekoniumileus
 
pediatricimaging.org • CC-by-nc-sa 4.0
Pneumatosis
coli
Wikipedia • CC BY-SA 3.0
Morbus
Hirschsprung
pediatricimaging.org • CC-by-nc-sa 4.0
intramurale
Gaseinschlüsse
Wikipedia • CC BY-SA 3.0
Pneumoperitoneum
beim Neugeborenen
Wikipedia • CC BY-SA 4.0