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Bowel Obstruction

Summary

  • delay in carrying out surgery may result in the loss of large amounts of bowel
  • not all infants with bowel obstruction require transfer by the NETS team. Infants diagnosed early and without fluid or electrolyte problems may be safely transferred with local ambulance services. However, it is advisable to discuss such infants with the receiving hospital or the NETS team

Introduction

Signs of bowel obstruction can include

  • vomiting with or without bile stained material, therefore never ignore bile-stained vomiting in the newborn
  • gastric residuals before feedings
  • failure to pass meconium in the first 24 hours of life
  • abdominal distension (particularly with low level obstruction)

Differential Diagnosis

Intestinal obstruction without bilious vomiting

  • duodenal atresia (if obstruction proximal to Ampulla of Vater – 20% of cases)
  • duodenal stenosis
  • annular pancreas
  • pyloric stenosis (usually presents at 4-6 weeks of life but may present as early as the first week)

Intestinal obstruction with bilious vomiting

  • malrotation and volvulus
  • duodenal atresia (if obstruction distal to Ampulla of Vater – 80% of cases)
  • jejunoileal atresia
  • meconium ileus
  • necrotising enterocolitis (see NecrotisingEnterocolitis)

Intestinal obstruction with marked abdominal distension

  • ileal atresia
  • Hirschsprung disease
  • meconium ileus
  • meconium plug
  • imperforate anus

Duodenal Atresia

Duodenal atresia may take the form of either a membranous or interrupted-type lesion at the level of the papilla of Vater. In 80% the papilla of Vater opens into the proximal duodenum causing the vomiting to be bilious

  • obstruction due to failure of recanalisation of the 2nd part of the duodenum during foetal development
  • occurs in 1:5,000-10,000 live births
  • commoner in males
  • associated with Down syndrome in 25%
  • polyhydramnios is seen antenatally
  • X-ray usually shows a characteristic 'double-bubble' appearance

Midgut Malrotation and Volvulus

  • most patients with midgut malrotation develop volvulus within the first week of life
  • bilious vomiting is the initial symptom and abdominal distention minimal until at a late stage
  • bowel can be involved in strangulation at any time and age. Once midgut ischaemia occurs, unstable haemodynamics, intractable metabolic acidosis and necrosis with perforation develop
  • malposition of the superior mesenteric vessels demonstrated by ultrasound examination is diagnostic
  • upper gastrointestinal contrast studies should be performed by experienced practitioners only. Features include
    • obstruction at the second portion of the duodenum
    • spiral configuration of the jejunum or a duodenojejunum that occupies the right hemi-abdomen
  • symptomatic infants require immediate surgery

Jejunoileal Atresia

  • caused by a mesenteric vascular accident during fetal life
  • abdominal distention with bilious vomiting is observed within the first 24 hours after birth. The more proximal the lesion, the earlier the bile-stained vomiting
  • X-ray shows air-fluid levels proximal to the lesion. Calcification due to meconium peritonitis may be present

Meconium Ileus

  • thick tenacious meconium in the bowel (ileum, jejunum or colon) causes obstruction
  • 50% have associated
    • volvulus
    • jejunoileal atresia
    • bowel perforation and/or meconium peritonitis
  • meconium ileus occurs in 15% of newborns with cystic fibrosis, and at least 90% of patients with meconium ileus have cystic fibrosis
  • presentation includes
    • early marked bowel distension
    • bilious vomiting
    • remarkable abdominal distention, tenderness and/or erythema of the abdominal skin may indicate perforation
    • on rectal examination mucus plugs may be evacuated after withdrawal of the examination finger (fifth finger)
  • X-ray shows
    • distended loops of intestine with thickened bowel walls
    • a large amount of meconium mixed with swallowed air produces the so-called 'ground-glass' sign typical of meconium ileus, a characteristic feature but often absent
    • calcification, free air or very large air-fluid levels suggest bowel perforation

Patients with uncomplicated meconium ileus may be successfully treated with hypertonic enemas performed while adequate intravenous fluid is maintained. Immediate surgery is indicated for infants with complicated meconium ileus or where conservative treatment fails.

Hirschsprung Disease

  • causes 15-20% of newborn intestinal obstructions
  • 80% of cases present in the first 6 weeks of life
  • 4:1 male:female ratio
  • presents with failure to pass meconium in the first 24 hours plus gradual onset of abdominal distension and vomiting. Distal short segment disease can present later in life with persistent and progressive constipation
  • the most serious complication is enterocolitis. This occurs as a result of progressive colonic dilation with decreased ileal and colonic fluid resorption, stasis with bacterial overgrowth and mucosal ischaemia which may lead to massive acute fluid loss into the bowel with diarrhoea, shock and dehydration. Enemas should be avoided during episodes of enterocolitis because of the possibility of perforating the colon
  • definitive diagnosis is made by a full thickness rectal biopsy showing a lack of ganglion cells in the myenteric plexus of the colon

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Investigation of Bowel Obstruction

  • thorough physical examination including digital rectal examination and assessment of the circulation with documentation of findings
  • bowel obstruction may be a part of multiple anomalies, therefore look for associated abnormalities eg Vertebral Anal Cardiac Tracheo–Esopageal atresia Renal Limb (VACTERL) sequence with imperforate anus, trisomy 21 with duodenal atresia
  • plain abdominal X-rays
  • contrast studies and ultrasound examinations are best undertaken in centres with paediatric surgical services

Management

  • place infant in an incubator for close observation and temperature control
  • nurse supine or on the right side with the head elevated
  • place an orogastric tube (8 - 10FG) on low pressure suction (or aspirate with a syringe every 60 minutes and leave on free drainage). The amount and type (eg bile-stained, faeculent) of fluid aspirated should be recorded
  • place nil by mouth
  • commence IV fluids. Give maintenance fluids plus ml for ml replacement of NG aspirate with normal saline
  • obtain abdominal x-rays (include supine and erect or decubitus view). Note that a relatively gasless abdomen is compatible with mid-gut volvulus
  • consult with a paediatric surgeon or NETS to arrange transfer to an appropriate surgical centre
  • it may be appropriate to commence antibiotics preferably after blood culture taken(discuss with the receiving unit or NETS)
  • obtain blood for FBE, electrolytes, blood grouping and hold for X match (and blood cultures if commencing antibiotics)
  • frequently, these infants have associated problems of acidosis and  shock

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