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Midgut Malrotation

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Overview

At around 4 weeks gestation, the gastrointestinal (GI) tract is a straight tube in the centre of the abdomen. During the next 8 weeks, the midgut rotates and fixes to the posterior abdominal wall.

Midgut malrotation (or intestinal malrotation) is a defect of this rotation, which can lead to volvulus due to twisting of the small intestine. This can cause duodenal obstruction and if the twisting obstructs blood flow in the superior mesenteric artery, this can cause bowel ischaemia and necrosis. 

People with midgut malrotation are at risk of volvulus and should be identified and managed early.

Epidemiology

  • Midgut malrotation is estimated to affect up to 1 in 2500 live births
  • Volvulus associated with malrotation occurs mostly in infants and young children
  • Around 90% of people with malrotation are diagnosed within the first year of life

Presentation

Overview

Malrotation presents differently based on age, if volvulus develops, and if bowel ischaemia occurs. Bilious vomiting is a key feature and is intestinal obstruction until proven otherwise.

Midgut volvulus without ischaemia may initially present with:

  • Acute bilious vomiting – due to obstruction of the duodenum
  • Crampy abdominal pain
  • Constipation

Midgut volvulus can lead to bowel necrosis within a few hours if untreated. Midgut volvulus with ischaemia may have the above features including:

  • Rapid acute bilious vomiting
  • Severe abdominal pain
  • Haemodynamic instability (hypotension, tachycardia, tachypnoea)
  • Peritonitis – such as rebound tenderness and guarding
  • Bloody stools
  • Metabolic acidosis
  • Increased serum lactate

Older children may present more insidiously with cyclical vomiting and recurrent abdominal pain. As bowel ischaemia develops, pain becomes more prominent.

Patients with malrotation and no volvulus may have more subtle and chronic symptoms.

Investigations

Overview

Diagnosis and management should not be delayed to obtain lab results. Key investigations include:

  • Ultrasound scanning:
    • To screen for intussusception
  • Upper gastrointestinal contrast studies:
    • The diagnostic test for malrotation

Other investigations may include:

  • Full blood count:
    • May show leukocytosis if bowel ischaemia develops
    • May show anaemia if significant blood loss occurs
    • Loss of fluid in the intravascular space may lead to a falsely elevated haemoglobin concentration
  • Blood gases:
    • May show metabolic acidosis and increased lactate if bowel ischaemia is present

Management

Overview

Due to the potentially life-threatening nature of volvulus, patients with volvulus or those deemed at high risk for its development undergo a surgical technique known as Ladd’s procedure.

The patient is resuscitated, the volvulus is corrected, the Ladd’s bands over the duodenum are cut, and the base of the mesentery is made wider.

Complications

  • Volvulus, bowel obstruction, and ischaemia:
    • If untreated, this can lead to bowel necrosis, perforation, peritonitis, sepsis, and death
  • Short-gut syndrome may develop after surgery:
    • This depends on how much bowel is lost and may cause problems with the absorption of nutrients with enteral nutrition. These patients may require long-term parenteral nutrition.
  • Small bowel adhesions:

Prognosis

  • The mortality of midgut volvulus can be as high as 10%
  • Bowel obstruction, ischaemia, and necrosis can be fatal

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