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25 May 2008

Dear Editor,

AN UNUSUAL CAUSE OF BILIOUS VOMITING IN A NEONATE

Intestinal duplications represent rare congenital malformations, with the terminal ileum as the commonest site.1 Various mechanisms have been hypothesised to explain their development, including diverticulisation, failure of vacuolisation and the split notochord theory.1

Duplication cysts have been associated with intestinal atresia.2 One possible explanation of this association has been an in-utero volvulus of the intestine secondary to the duplication cysts with subsequent vascular compromise and later reabsorption of the involved segment. Volvulus in a neonate secondary to a small bowel duplication cyst has very rarely been reported with subsequent survival of the infant and appears not usually recognised prior to surgery.

Our case involved a 4.2 kg term female infant transferred to our institution with a 24 h history of bilious vomiting. She had passed meconium 8 h following an uncomplicated delivery. There was no history of abdominal distension or tenderness. An upper gastrointestinal (GI) contrast study excluded malrotation (Fig. 1). There was no relevant antenatal history, and routine screening ultrasound (US) scans were normal.

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Figure 1. Upper gastrointestinal contrast study. Note normal bowel orientation with free flow of contrast into the proximal jejunum.

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Mild abdominal distension with increasing bilious aspirates developed over the next 24 h. A repeat abdominal radiograph revealed dilated bowel loops. A contrast enema confirmed a normally located caecum. While awaiting laparotomy, dramatically increased abdominal distension developed which was associated with bloody stools.

At operation, a 3 cm diameter duplication cyst was found 30 cm from the duodenojejunal flexure. Immediately beyond this cyst was a segmental volvulus of the distal small bowel with ischaemia extending to 10 cm from the ileocaecal valve. The cyst was non-communicating and excised without resection of the adjacent intestine. The necrotic, volved small bowel was resected with stoma and mucus fistula formation. The post-operative period was uneventful although supplemental parenteral nutrition was required for 6 weeks. The stoma was reversed at 6 weeks of age without complications.

Histology revealed extensive haemorrhagic necrosis but no evidence of enterocolitis. The cyst wall contained muscularis propria with ganglion cells and submucosa but no mucosa. Much of the epithelium had sloughed into the centre of the lumen and appeared to be undergoing fibrosis.

Abdominal enteric duplications have been reported in 1 in 4500 autopsies.2 Up to 65% of those that present with symptoms do so within the first year of life and 87% by 2 years of age.1 There appears to be no gender predilection. Duplication cysts may involve any part of the GI tract, with those involving the terminal ileum most common.1 The clinical presentation depends upon the size, site and the presence of ectopic mucosa. Intestinal duplication cysts may remain asymptomatic, present as a mass or as a result of complications such as pain, haemorrhage, perforation and intestinal obstruction.1–4 These complications dictate the likely presentation, which can vary from vomiting, constipation, chronic pain or an abdominal mass. Duplication cysts may also be associated with ectopic mucosa and can therefore present with bleeding, perforation and peritonitis. Malignant change has been described in duplication cysts including adenocarcinoma developing in rectal duplication cyst in adult.5

Duplication cysts have been associated other conditions of the intestine such as intestinal atresia, stenosis, intussusception and short bowel.3 This has led to the suggestion that a vascular injury has been the common aetiology. Favara et al. described four neonates with simultaneous occurrence of intestinal atresia and duplication cyst.4 Moore et al. postulated that the intestinal atresia was a result of resorption of the necrotic bowel after mesenteric volvulus initiated by the duplication cyst.6 In addition, a post-mortem case of volvulus with gangrene of the intestine as a possible cause of sudden death in an infant has been reported in conjunction with enteric duplication cysts.7 This infant was found to have volvulus of the right-sided colon with an adjacent terminal intestinal duplication cyst at autopsy, yet the author found it difficult to explain the association. Our case suggests that an anatomical abnormality such as a duplication cyst may have acted as a fulcrum about which the volvulus occurred.

In their retrospective review of all gastrointestinal duplications, Puligandla et al. report a 13.8% incidence of volvulus (symptomatic or asymptomatic) at the time of laparotomy.8 It is unclear what proportion were diagnosed prior to surgery and at least one infant with a jejunal duplication cyst died subsequent to midgut volvulus a few days after US-guided aspiration.8

As illustrated by our patient, GI contrast studies, although useful in the diagnosis of other causes of neonatal bilious vomiting, do not assist in the diagnosis of a non-communicating duplication cyst. US has been reported in the diagnosis of duplication cysts both ante-natally and post-natally.9 It can be used to differentiate small bowel duplication from the mesenteric cysts.10 With routine use of antenatal scans, a number of intestinal duplication cysts may now be diagnosed antenatally.2 In our case, antenatal US was normal and post-natal US would have been unlikely to have been diagnostic in view of the degree of gaseous abdominal distension.

The antenatally diagnosed small duplication cysts present a management question about the timing of intervention. Even in the absence of obstructive symptoms, the potential for volvulus as a result of the duplication cyst should be kept in mind. This serious complication also supports the need for early intervention in antenatally diagnosed cases.2

Small duplication cysts can be difficult to diagnose both antenatally and post-natally. US may help in diagnosis, but clinicians should have a low threshold for early surgical intervention even in an otherwise stable infant with bilious vomiting. Once diagnosed, the potential for complications such as volvulus warrants early intervention.

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