Malrotation/Volvulus

Question 1

What is malrotation?

Answer 1

= abnormal alignment of midgut after small bowel returns to abdominal cavity from the physiological hernia in the cord at 10 weeks of gestation

Question 2

When is malrotation most common?

Answer 2

1st yr

Question 3

What is the normal development of the gut (which is relevant for malrotation)?

Answer 3

• 6-10 weeks gestation: physiological hernia of cord, elongates and develops
• Gut rotates 270 degrees counterclockwise around SMA axis - caecum in RLQ and the duodenojejunal flexure in the LUQ
• Bowel returns 10 weeks
• mesentery becomes permanently adherent (by ‘zygosis’) to the posterior abdominal parietal peritoneum
• Normal mesentery has a broad, oblique attachment between ileocaecal junction and duodeno- jejunal junction, preventing volvulus

Question 4

What is the pathophysiology of malrotation?

Answer 4

• In malrotation, small bowel remains mostly on the right side of the abdomen and the caecum ends up in the mid-upper abdomen, fixed to the right lateral wall by peritoneal bands which cross the duodenum and can compress it.
  
  • Everything stays on the right - base lessens, with same bowel
• Failure of zygosis, along with abnormal placement of gut predisposes to volvulus as the small bowel has a narrow-based mesentery that is very mobile.

Question 5

When will malrotation cause ischaemic bowel, and when will it not?

Answer 5

• A 360° twist will result in venous and lymphatic engorgement and bile-stained vomiting
• A 720° twist will result in arterial ischaemia

Question 6

Why do babies with malrotation not present at birth?

Answer 6

• Before birth amniotic fluid is swallowed, but peristalsis is not very active
• After birth breast milk stimulates vastly enhanced peristalsis, which probably triggers the twist, with vigorous movement of small bowel which is not fixed by the narrow base of the mesentery
• Malrotation commonly presents a few days after birth when volvulus occurs.

Question 7

What is the classic feature of malrotation?

Answer 7

• Sudden, bile stained, grassy green vomiting

Question 8

What are some late signs of malrotation?

Answer 8

• PR bleeding - gut is starting to die
• Abdominal distension
• Abdominal tenderness - crampy

Question 9

What is the best investigation of malrotation? What will you see?

Answer 9

• Contrast study
  
  • abnormal positioning of duodenum and DJ flexure
  • Look for corkscrew
  • Gastric and proximal duodenal dilatation
  • Paucity of gas in small intestine
  • Rarely a “double bubble”

Question 10

What determines whether medical or surgical Mx in undertaken?

Answer 10

• If C-shaped duodenal loop is seen, conservative Mx

* If S-shaped duodenum seen, surgical Mx

Question 11

What is the surgical management of malrotation? What does the surgery involve?

Answer 11

Ladd’s procedure:
• Untwist the bowel
• Put all small bowel on right hand side and all large bowel on left hand side
• May lead to appendicitis presenting under the spleen
○ Therefore also take out appendix
• Wait for 10 minutes to see if reperfusion occurs (assess amount of bowel infarction)
• No need for bowel fixing as adhesions usually fix the bowel in place anyway
• Increased incidence of bowel obstruction in the future
• Widen mesentery too