Gut malrotation

Definition

• Rotational anomalies and failure of fixation caused by:
  • Abnormal rotation of the embryonic gut

Incidence

• Midgut volvulus usually present in first month of life
• But can present into adulthood
• Other forms of malrotations may present later:
  • Caecal volvulus
  • Internal hernia
  • Incidental finding of non-rotation

Pathophysiology

• Process of normal rotation and fixation of occurs between 6-10th weeks gestation
  • Gut herniates - Gastrointestinal embryology
    • Revolves 270° anticlockwise around axis of SMA and vitellointestinal duct
    • Returns to abdominal cavity and fixates
• Non-rotation
  • No rotation occurs, mesentery wide based, no correction required
• Malrotation
  • Rotation process interrupted - typically 90 degrees has occurred
  • Caecum and duodenojejunal junction close together
    • This leads to the caecum fusing to the peritoneum of the right lateral abdominal wall via Ladd bands.
  • Narrow based mesentery
  • Midgut volvulus may occur around SMA
    • Leading to intestinal ischaemia
  • Complications
    • Volvulus, e.g. Caecal
    • Paraduodenal hernia
    • Internal hernia (under Ladd’s band)
    • Ectopic appendicitis

Diagnosis

• AXR
  • Absence of right-sided jejunal markings
  • Absence of stool-filled colon in the RLQ
• Barium swallow
  • Abnormal DJ junction
    • Fails to cross midline to the left of the left-sided vertebral body pedicle
    • DJ lies inferior to the duodenal bulb
  • Z-shaped course of distal duodenum and proximal jejunum
  • Proximal jejunum on the RIGHT of the abdomen
    • Does not cross midline
• USS
  • May show Whirlpool Sign
  • Clockwise wrapping of SMV and mesentery around the SMA
  • Switched position of SMA & SMV (i.e. rotation shows SMA on the right and SMV on the left)
• CT-AP
  • Absence of retro-mesenteric D3
  • Abnormal SMA-SMV relationship
  • LB mostly on the left and SB mostly on the right

Management

• Laparotomy + Reduction of volvulus It has 6 key steps:   1)  Division of LADD’S bands   2)   Detorsion of the small bowel   3)  Widening of the mesentery via peritoneal incisions   4)  Assess luminal patency   5) Place bowel back in non-rotated position
  • Small bowel to the right, colon to the left   6) Appendicectomy