Duodenal web

A duodenal web, diaphragm or intraluminal diverticulum refers to a complete or incomplete obstruction at the duodenum due to a membranous web or intraluminal diverticulum. There is usually a small aperture at the centre differentiating this from a duodenal atresia. 

Although they are frequently congenital and occur in the paediatric population, some can present in adults ^3-4  and may also be acquired ³. The presentation can be variable depending on the size of the aperture. 

Pathology

They have a tendency to occur at the 2^nd part of the duodenum ¹ .

Associations

• Down syndrome
• intestinal malrotation
• annular pancreas

Radiographic features 

Plain radiograph

If severely obstructive may show a double bubble sign.

Fluoroscopy

Can typically give a "windsock sign" (gradual ballooning of the duodenal diaphragm) or "halo sign" due to the web projecting caudally into the duodenal lumen.

Ultrasound 

• may show a dilated stomach and proximal duodenum. 
• may how a hypoechoic intraluminal diverticulum

Differential diagnosis

Imaging differential considerations include:

• duodenal stenosis
• duodenal atresia