Midgut volvulus and intestinal malrotation

Volvulus is defined as the twisting of a loop of bowel on its mesentery and is one of the most common causes of intestinal obstruction. Volvulus in a neonate or infant almost always presents as a midgut volvulus secondary to intestinal malrotation. Patients typically show features of bowel obstruction (abdominal pain, distension, bilious vomiting) or of bowel ischemia and gangrene (tachycardia, hypotension, hematochezia, peritonitis) in severe cases. Upper GI series is the investigation of choice in infants with suspected midgut volvulus, which is seen as a cork-screw duodenum. The Ladd procedure (laparotomy and detorsion of the volvulus) is indicated in all patients with intestinal malrotation since it is impossible to predict if volvulus of the midgut will occur in an asymptomatic patient or not.

See “Sigmoid volvulus and cecal volvulus” for more details of volvulus occurring in adults.

• Incidence: symptomatic malrotation (midgut volvulus) in 1:6000 live births in the United States
• Age: neonates and infants ^[1][2]

SigmOid volvulus is more common in Older individuals while Midgut volvulus and Malrotation are more common in Minors.

Epidemiological data refers to the US, unless otherwise specified.

• Normal intestinal rotation: the midgut starts to elongate in utero (4^th week) → herniation of the midgut out of the umbilicus (6^th week) → 90° counter-clockwise rotation of the midgut → re-entry of the midgut into the abdominal cavity(10^th week) → 180° rotation inside the abdominal cavity (a total of 270°) → fixation of the duodenojejunal flexure and cecum to the posterior abdominal wall
• Intestinal malrotation: arrest in the normal rotation of the gut in utero, resulting in an abnormal orientation of the bowel and mesentery within the abdominal cavity

• Midgut volvulus: torsion of a malrotated midgut causing mechanical bowel obstruction, mostly in neonates and infants
  • Torsion of bowel on its axis ^[6]
    • Closed-loop mechanical bowel obstruction → accumulation of gas and feces within the loop → increased intraluminal pressure → impaired capillary perfusion of bowel → bowel strangulation, ischemia, and gangrene
    • Torsion of the mesenteric vascular pedicle → occlusion/thrombosis of mesenteric vessels → bowel strangulation, ischemia, and gangrene
• Gastric volvulus: an abnormal rotation of the stomach of more than 180° → closed-loop obstruction → possible incarceration and strangulation → intestinal ischemia and perforation

• Intestinal bands/adhesions
• Intestinal malrotation: abnormal rotation of the bowel with abnormal fixation of mesentery to the posterior abdominal wall
• Megacolon (Hirschsprung disease, Chagas disease)
• Anatomic disorder (e.g., paraesophageal hernia is commonly associated with gastric volvulus)

• Malrotation: mostly asymptomatic
• Midgut volvulus
  • Bilious vomiting with abdominal distension in a neonate/infant
  • Signs of bowel ischemia: hematochezia, hematemesis, hypotension, and tachycardia
• Features of gastric volvulus: severe abdominal pain, retching, and inability to pass a nasogastric tube
• Features of duodenal obstruction: bilious vomiting without abdominal distension
• Variable presentation in older children/adults ; ^[5][7]
  • Recurrent episodes of abdominal pain and vomiting
  • Failure to gain weight
  • Malabsorption
• Abdominal examination is unreliable in neonates/infants because abdominal tenderness/rebound tenderness is difficult to assess in this population.
• Features of associated congenital anomalies
  • Commonly associated anomalies: congenital diaphragmatic hernia (∼ 100%), congenital heart defects (up to 90%), omphalocele (up to 45%)
  • Less commonly associated anomalies: gastroschisis, Meckel diverticulum, esophageal atresia, biliary atresia

Intestinal malrotation and midgut volvulus

• Work-up follows the same protocol as that for bowel obstruction. Only the specific findings seen in intestinal malrotation and midgut volvulus are mentioned here.
• See “Sigmoid volvulus and cecal volvulus” for more details of volvulus occurring in adults.
• Laboratory studies: complete blood count; electrolyte levels; arterial blood gas analysis ^[8][9]

References:^{[5][8][9][10][11][12][13][14][15]}

• In neonates/infants with recurrent vomiting: duodenal atresia and stenosis; , hypertrophic pyloric stenosis
• In neonates with features of bowel ischemia/gangrene: necrotizing enterocolitis (NEC)
• In older children with abdominal pain and vomiting: intussusception
• In older children/adults with nonspecific symptoms: GERD; chronic mesenteric ischemia; food allergy
• See “Differential diagnosis of lower gastrointestinal bleeding in children.”

References:^[16][17]

The differential diagnoses listed here are not exhaustive.

• Midgut volvulus with/without peritonitis
  • Initial resuscitation: NPO; nasogastric tube insertion; IV fluids; correction of electrolyte imbalance; broad-spectrum IV antibiotics
  • Emergency surgery (Ladd procedure) ^[4]
    • The volvulus is reduced/untwisted and the Ladd bands removed.
    • Gangrenous/necrotic bowel, if present, is resected and either anastomosed or created into a stoma.
    • Appendix is removed (to prevent future diagnostic/operative difficulties)
    • Development of postoperative adhesions decreases the chance of recurrent volvulus.
• Incidentally detected/asymptomatic intestinal malrotation: elective surgery (Ladd procedure) ^[18]