A duodenal web, diaphragm or intraluminal duodenal diverticulum (IDD) 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 center differentiating this from duodenal atresia.
Although they are frequently congenital and occur in the pediatric population, some can present in adults 3-4 and may also be acquired 3. The presentation is variable, depending on the size of the aperture.
Pathology
They have a tendency to occur at the 2nd part of the duodenum 1. There are many types of duodenal webs 6:
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.
Duodenal dimple sign: pressure exerted by a nasogastric tube on the obstructive web can cause dimpling of duodenal wall nearby. 5
2. Berrocal T, Torres I, Gutiérrez J et-al. Congenital anomalies of the upper gastrointestinal tract. Radiographics. 19 (4): 855-72. Radiographics (full text) - Pubmed citation
3. Rha SE, Lee JH, Lee SY et-al. Duodenal diaphragm associated with long-term use of nonsteriodal antiinflammatory drugs: a rare cause of duodenal obstruction in an adult. AJR Am J Roentgenol. 2000;175 (3): 920-1. AJR Am J Roentgenol (full text) - Pubmed citation
5. Lee Alexander Grant, Grant, Nyree Griffin. Grainger and Allison's Diagnostic Radiology Essentials. (2019) ISBN: 9780702034480
6. Lee N, Kim S, Jeon T et al. Complications of Congenital and Developmental Abnormalities of the Gastrointestinal Tract in Adolescents and Adults: Evaluation with Multimodality Imaging. Radiographics. 2010;30(6):1489-507. doi:10.1148/rg.306105504 - Pubmed