Malrotation and Volvulus

Epidemiology

Malrotation is present in around 1 in 500 live births², however not all of these will become symptomatic. Symptomatic presentation is most common in the neonatal and infant period with 60% of cases presenting by one year of age³.

Pathophysiology

By around week 4 of embryological development the primitive gut tube develops (divided into foregut, midgut and hindgut). From the midgut comes the distal duodenum along to the proximal two thirds of the transverse colon.

By 10 weeks’ gestation the midgut has herniated out of the abdominal cavity, rotated 270 degrees counterclockwise around the SMA/V axis and returned to the abdominal cavity. Then there is bowel fixation to the abdominal wall via the mesentery⁴.

Under normal circumstances the mesentery provides a wide base to the small bowel, however, in malrotation this base is often narrow which predisposes it to twisting (midgut volvulus). This can cause bowel obstruction, SMA obstruction and subsequent ischaemia and small bowel necrosis.

In infants with malrotated gut, peritoneal bands (Ladd’s bands) can contribute to obstructive symptoms with formation across various parts of the small bowel (often the second part of the duodenum).

Carmine Grassi, Luigi Conti, Gerardo Palmieri, Filippo Banchini, Maria Diletta Dacco, Gaetano Maria Cattaneo, Patrizio Capellia, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Figure 1
an image depicting Ladd’s bands hindering midgut rotation

Risk Factors

Malrotation is associated with several congenital abnormalities:

• Abdominal wall defects
• Congenital diaphragmatic hernia
• Heterotaxy syndrome

Clinical Features

Malrotation cannot be detected antenatally so presentation is usually with an unwell infant with volvulus.

Can be tricky to diagnose clinically, needs to be actively excluded.

• Bilious vomiting – a surgical problem until proven otherwise
• Abdominal pain – can manifest as an inconsolable state in infants
  • Can be intermittent colicky pain in older children with intermittent obstruction – can also present with vomiting and failure to thrive due to malabsorption
• In the early stages à well baby, soft abdomen, haemodynamically stable
• In the later stages:
  • Shocked infant
  • Tachycardic
  • Tender and distended abdomen
  • Blood-stained NG aspirates
  • Bloody stool

Differential Diagnoses

Given the most common presentation of malrotation volvulus is bilious vomiting in an infant, there are a wide range of differentials⁵:

• Atresias (e.g. duodenal, biliary)
• Sepsis
• Metabolic abnormalities
• Necrotising enterocolitis

Investigations

The gold standard investigation for malrotation (+/- volvulus) is an upper GI contrast study to assess positioning of various parts of the bowel.

A lower GI contrast study can also have value in assessing caecal positioning if upper GI series was inconclusive.

CT or Ultrasound – can see the classical Whirlpool sign

Other more basic investigations such as plain film abdominal x-rays or routine bloods do not tend to add any value or diagnostic insight⁶.

Management

Definitive management is surgical correction via a Ladd’s procedure (see box below)

• Time critical due to risk of volvulus and associated morbidity/mortality

Initial management of the sick/shocked child (should not delay emergency surgery):

• Fluid resuscitation
• NG tube decompression
• Gram-negative antibiotic coverage
• Involve surgical team early – there is often a decision to go straight to theatre without radiological diagnosis

In the older child with chronic symptoms where malrotation is picked up on investigation, surgery is required on a timely but not urgent basis.

Complications

Complications include⁸:

• Bleeding
• Wound infection
• Post-operative ileus (due to bowel handling during surgery)
• Recurrent volvulus – incidence reported to be around 2-7%⁹ although likely higher
  • Risk is higher with laparoscopic approach due to less adhesions formed during surgery which aid in the process of intestinal fixation
• Adhesional bowel obstruction
• Short gut syndrome – if there has been vascular compromise with the need for extensive bowel resection
• Death from complications such as bowel necrosis and sepsis can occur (mortality ~10%)

References