Causes of Congenital Malrotation
Congenital intestinal malrotation is primarily caused by abnormal or incomplete rotation of the fetal intestine around the superior mesenteric artery axis during embryonic development. 1 This developmental anomaly results in abnormal bowel fixation or complete lack of fixation of portions of the bowel.
Primary Embryological Causes
- Disrupted midgut rotation: The normal 270-degree counterclockwise rotation of the intestine fails to occur properly during weeks 5-10 of fetal development
- Abnormal intestinal fixation: Results in:
- Abnormal mesenteric bands (Ladd's bands)
- Narrow mesenteric base
- Improper positioning of the duodenojejunal junction and cecum
Associated Genetic and Syndromic Causes
- 22q11.2 Deletion Syndrome: Intestinal malrotation is one of several gastrointestinal abnormalities associated with this genetic condition 2
- Other congenital GI anomalies that may occur alongside malrotation include:
- Esophageal atresia
- Tracheoesophageal fistula
- Intestinal atresia
- Anal atresia/stenosis
- Imperforate anus
- Hirschsprung disease 2
Anatomical Variations and Consequences
- Abnormal position of duodenojejunal junction: In normal anatomy, this junction should be lateral to the left-sided pedicles of the vertebral body and posterior (retroperitoneal) on lateral views 3
- Abnormal cecal position: Often found in the midline or left hemiabdomen rather than right lower quadrant 4
- Narrow mesenteric pedicle: Creates risk for volvulus (twisting of intestine around mesenteric axis)
Associated Anomalies
- Situs problems: Abnormal positioning of abdominal organs
- Anomalies of the inferior vena cava
- Polysplenia
- Preduodenal portal vein 1
Clinical Implications
The abnormal intestinal fixation or lack of fixation significantly increases the risk of:
- Midgut volvulus: Potentially life-threatening twisting of intestine
- Intestinal obstruction: Due to Ladd's bands or volvulus
- Intestinal ischemia and necrosis: When blood supply is compromised 1, 3
Diagnostic Considerations
- Upper GI Series (UGI) remains the gold standard for diagnosis with 96% sensitivity 1, 5
- Ultrasonography can evaluate the position of superior mesenteric vein (SMV) in relation to superior mesenteric artery (SMA) and detect the "whirlpool sign" specific for volvulus 1
- Jejunal position can lead to inaccurate UGI interpretation and should be carefully evaluated 5
Malrotation can present at any age, though it most commonly presents in newborns and can occur at any time during life with decreasing frequency with age 2. In adults, it's often discovered incidentally during imaging or surgery for unrelated conditions 6, 7, 4.
Early recognition and surgical correction are critical to prevent life-threatening complications, especially in patients with associated congenital anomalies 1.