Bilious vomiting and intestinal obstruction — branching viva

Opening — framing the problem

The examiner begins: a 4-day-old term baby, previously feeding well, suddenly vomits bright green fluid and looks comfortable with a soft abdomen. What is your first thought? [1]

My first thought is that this is malrotation with midgut volvulus until proven otherwise, because green vomit means the obstruction is beyond the ampulla and a volvulus can strangle the whole midgut within hours. I am not reassured by the soft abdomen, because tenderness, distension and shock are late signs, so I would treat this as a surgical emergency from the outset. [1] [2]

Branch A — the anatomy behind the danger

Why is the malrotated bowel so prone to a catastrophic twist? [2]

Because incomplete rotation leaves the mesentery fixed on a short, narrow base instead of the broad diagonal base of normal rotation. The whole midgut then hangs from a narrow pedicle carrying the superior mesenteric artery and vein, so when it twists clockwise it both obstructs the duodenum and occludes those vessels. Obstructing peritoneal Ladd bands add a second, non-vascular cause of duodenal obstruction. [2] [12]

Branch B — resuscitation and imaging

The baby is now with you. What do you do, and how do you confirm the diagnosis? [6]

I resuscitate and confirm in parallel. I keep the baby nil by mouth, gain intravenous access, give a fluid bolus and correct electrolytes, and pass a wide-bore nasogastric tube to decompress the stomach. If the baby is stable I arrange an urgent upper gastrointestinal contrast study looking for an abnormally low and right-sided duodenojejunal flexure and a corkscrew of volvulus, but if the baby is peritonitic or shocked I go straight to theatre without waiting for imaging. [6] [2]

Branch C — the operation

The contrast study confirms volvulus. What operation is done and what are its steps? [12]

The Ladd procedure. The surgeon untwists the volvulus counter-clockwise to restore perfusion, divides the Ladd bands crossing the duodenum, widens the narrow mesenteric base to prevent re-twisting, removes the appendix, and leaves the bowel in a non-rotated position with the small bowel on the right and colon on the left. Frankly necrotic bowel is resected and a second look may be planned if viability is borderline. [12] [2]

Branch D — the distended newborn

Now a different baby: 2 days old, abdomen distended, no meconium passed, now vomiting bile. How does your thinking change? [7]

This pattern of distension with delayed meconium and later bilious vomiting points to a low obstruction rather than a high one. My differential is ileal atresia, meconium ileus and Hirschsprung disease, with an anorectal malformation excluded by inspecting the perineum. I would resuscitate and decompress as before, then arrange a contrast enema, which can show a microcolon or a transition zone and, in meconium ileus, may be therapeutic. [7] [8]

Closing — the safety rule

Give me the single rule you want every junior to hold about bilious vomiting. [1]

Bilious vomiting in a neonate is malrotation with midgut volvulus until proven otherwise, so resuscitate, decompress with a nasogastric tube, call the surgeon and image urgently, and never send such a baby home on the strength of looking well. [1] [2]