Congenital duodenal webs/diaphrams are a rare cause of duodenal obstruction. The incidence is estimated at anywhere from 1 in 10 000 to 1 in 40 000 patients. Congenital diaphragms are believed to be secondary to incomplete recanalization of the duodenal epithelium during the fourth and fifth weeks of gestation. The most common location of web formation is in the second portion of the duodenum near the ampulla. Patients with congenital webs often present with vomiting, abdominal distension, and failure to thrive. The mainstay of therapy has been surgical intervention with bypass or excision. Modern endoscopic techniques have revolutionized the management of duodenal diaphragms.

Successful endoscopic treatment has been reported and involves two approaches. First, it must be remembered that the pancreaticobiliary tree exit is embryologically inherent in such a congenital defect. Second, this defect may exist undiagnosed for months and sometimes years as soft food, macerated by the stomach, can pass through even the smallest pinhole defect. In terms of treatment endoscopically, a number of options have been reported and fortunately a major laparotomy can now be avoided in most cases with this approach.

Either membranectomy via balloon dilation (Figure 39.1) or division using a ceramic‐tip endo‐knife may be successful, but the preferred and more successful (anecdotal) technique involves utilization of a double channel “operating endoscope.” This ideal technique involves insertion of a guidewire through the defect (Figure 39.2) which can be very small, then anchoring the web which is of a ‘wind‐sock’ type towards the scope by passing the balloon beyond the web and inflating it, then retracting the web (Figure 39.3). A ceramic‐tip needle‐knife can then be used to incise the web in a direction corresponding to 3–8 o’clock, thereby avoiding the pancreaticobiliary radicles (Figure 39.4); endo‐ultrasound can help in identifying these structures if necessary and a preceding MRCP is also useful in doing so. The ceramic tip prevents bursting of the balloon.

Not uncommonly, there may be a second web distal to the first and this one does not usually contain any ampulla‐type structures. Full division of the membrane is not usually necessary to allow resolution of obstructive symptoms (Figure 39.5). On‐table radiological contrast and imaging can occur at the end of the procedure in order to identify any perforation and an amylase the next day would be ideal to ensure the absence of pancreatitis.