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Intestinal malrotation is a spectrum of congenital anomalies resulting from abnormal rotation and fixation of the midgut during embryonic development.

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It predisposes to midgut volvulus, which is a surgical emergency.

Midgut volvulus and intestinal malrotation // AMBOSS

Etiopathology

Embryology: Normal midgut rotation:

• At 6 weeks gestation → midgut herniates into umbilical cord.

• Rotates 270° counter-clockwise around the superior mesenteric artery (SMA).

• By 10–12 weeks → returns to abdomen and becomes fixed with duodenojejunal (DJ) flexure to the left of spine, cecum in right lower quadrant.

  ![Normal intestinal rotation: a, b Primary intestinal loop before rotation (lateral view). The superior mesenteric artery forms the axis of the loop and of subsequent rotation. c–e Counter-clockwise rotation of the gut occurs through 270° concomitantly with herniation of the small intestinal loops followed by return of the gut to the abdominal cavity during the third month of gestation.

  Filston HC, Kirks DR (1981) Malrotation—the ubiquitous anomaly. J Pediatr Surg 4(Suppl 1):614–620](attachment:096a342d-1d6e-4ea5-822d-e2578d769ae0:image.png)

  Normal intestinal rotation: a, b Primary intestinal loop before rotation (lateral view). The superior mesenteric artery forms the axis of the loop and of subsequent rotation. c–e Counter-clockwise rotation of the gut occurs through 270° concomitantly with herniation of the small intestinal loops followed by return of the gut to the abdominal cavity during the third month of gestation.

  Filston HC, Kirks DR (1981) Malrotation—the ubiquitous anomaly. J Pediatr Surg 4(Suppl 1):614–620

Etiopathology

Malrotation: failure or incomplete counterclockwise rotation.

Schematic drawings of normal rotation and malrotation: A, Drawing shows that normal 270° rotation and fixation of midgut results in familiar positioning of bowel with broad mesenteric attachment (dotted line).B, Drawing shows that malrotation results in malpositioned bowel and narrow base of mesenteric fixation (dotted line), which is prone to midgut volvulus. Abnormal fibrous peritoneal bands of Ladd (curved lines)that attach to right colon predispose to internal herniation older patients.

Types (spectrum)

1. Non-rotation: midgut does not rotate → small bowel on right, colon on left.
2. Incomplete rotation (classic malrotation): DJ flexure lies to right of midline, cecum displaced.
3. Reverse rotation: rare; colon posterior to SMA, may cause obstruction.

![Stringer classification of malrotation: type 1: nonrotation, type 2: incomplete rotation, and type 3: reverse rotation

Harvitkar RU, Joshi A. Congenital Midgut Malrotation Presenting as Acute Duodenal Obstruction in an Adult— Laparoscopic Management. World J Lap Surg 2021; 14(1):61–64.](attachment:ecbcfb26-cacf-47e1-bfa3-b1118fb55dfd:image.png)

Stringer classification of malrotation: type 1: nonrotation, type 2: incomplete rotation, and type 3: reverse rotation

Harvitkar RU, Joshi A. Congenital Midgut Malrotation Presenting as Acute Duodenal Obstruction in an Adult— Laparoscopic Management. World J Lap Surg 2021; 14(1):61–64.

Associated abnormalities:

• Ladd’s bands: peritoneal fibrous bands crossing duodenum → extrinsic obstruction.