What is intestinal malrotation?

Intestinal Malrotation

Intestinal malrotation is a congenital anomaly resulting from incomplete rotation or fixation of the fetal intestine around the superior mesenteric artery axis, which increases the risk of life-threatening complications including midgut volvulus, intestinal obstruction, and bowel necrosis. 1

Embryology and Anatomy

Intestinal malrotation represents a spectrum of rotational abnormalities that occur during fetal development:

• Normal intestinal development involves a 270-degree counterclockwise rotation of the midgut around the superior mesenteric artery (SMA)
• In malrotation, this rotation is either incomplete or absent, resulting in abnormal positioning of intestinal segments 2
• The abnormal bowel fixation (by mesenteric bands) or absence of fixation increases the risk of complications 2

Clinical Presentation

The presentation varies by age:

• Neonates and infants (first month of life):

  • Bilious vomiting (most common and concerning symptom) 3, 4
  • Signs of intestinal obstruction
  • Failure to thrive

• Children (1 month to 5 years):

  • Vomiting remains the predominant symptom 5
  • Intermittent abdominal pain
  • Malabsorption

• Older children (6-15 years) and adults:

  • Abdominal pain becomes the predominant symptom 5
  • Chronic, vague abdominal complaints
  • May remain asymptomatic and be discovered incidentally 6, 7

Complications

• Midgut volvulus: Twisting of the intestine around the SMA axis, which can lead to:

  • Intestinal ischemia
  • Bowel necrosis
  • Sepsis
  • Death if not promptly treated 4

• Duodenal obstruction: Due to Ladd's bands (peritoneal bands running from the cecum to the right lateral abdominal wall) 6

• Chronic symptoms: Intermittent vomiting, abdominal pain, failure to thrive 2

Diagnosis

The diagnosis is heavily reliant on imaging:

• Upper GI Series (UGI):

  • Gold standard with 96% sensitivity 3, 1
  • Key finding: Abnormal position of the duodenojejunal junction (should normally be lateral to the left-sided pedicles of the vertebral body) 2
  • False positives (10-15%) and false negatives (3-4%) can occur 1
  • Potential mimics include improper technique, gastric overdistension, splenomegaly, and scoliosis 2

• Ultrasonography:

  • Evaluates two key anatomical landmarks:
    1. Position of the superior mesenteric vein (SMV) in relation to the SMA
    2. Position of the third portion of the duodenum behind the SMA
  • The "whirlpool sign" (clockwise wrapping of the SMV and mesentery around the SMA) is specific for volvulus 3, 1
  • Limited by bowel gas obscuration in up to 17% of cases 3

• Contrast Enema:

  • Less direct than UGI series for diagnosing malrotation
  • False negative rate of approximately 20%
  • False positive rate of up to 15% due to normal mobile cecum 3

Treatment

• Surgical intervention is the standard of care for symptomatic intestinal malrotation 1

• Ladd procedure is the preferred treatment, which includes: 1, 4

  • Evisceration and inspection of the mesenteric root
  • Counterclockwise derotation of midgut volvulus (if present)
  • Lysis of Ladd's bands with straightening of the duodenum
  • Appendectomy (due to abnormal position of appendix)
  • Placement of the cecum into the left lower quadrant

Outcomes and Prognosis

• Postoperative complications occur in approximately 20% of patients 5
• Higher risk of complications in:
  • Extremely preterm infants
  • Patients with severely affected intestinal circulation due to volvulus 5
• Long-term complications include:
  • Adhesive bowel obstruction (11%)
  • Recurrent midgut volvulus (rare)
  • Intestinal failure due to midgut loss 5

Key Points for Clinicians

• Maintain a high index of suspicion for malrotation in patients with bilious vomiting, especially in neonates
• Consider malrotation in patients with situs problems, anomalies of the inferior vena cava, polysplenia, or preduodenal portal vein 1
• Prompt diagnosis and appropriate surgical therapy are essential for favorable outcomes
• Adult cases are rare but can present with either acute obstruction or chronic abdominal pain 6