Flashcards in Malrotation/Volvulus Deck (11):
What is malrotation?
= abnormal alignment of midgut after small bowel returns to abdominal cavity from the physiological hernia in the cord at 10 weeks of gestation
When is malrotation most common?
What is the normal development of the gut (which is relevant for malrotation)?
• 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
What is the pathophysiology of malrotation?
• 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.
When will malrotation cause ischaemic bowel, and when will it not?
• A 360° twist will result in venous and lymphatic engorgement and bile-stained vomiting
• A 720° twist will result in arterial ischaemia
Why do babies with malrotation not present at birth?
• 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.
What is the classic feature of malrotation?
• Sudden, bile stained, grassy green vomiting
What are some late signs of malrotation?
• PR bleeding - gut is starting to die
• Abdominal distension
• Abdominal tenderness - crampy
What is the best investigation of malrotation? What will you see?
• 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”
What determines whether medical or surgical Mx in undertaken?
• If C-shaped duodenal loop is seen, conservative Mx
• If S-shaped duodenum seen, surgical Mx