An educational poster was created to summarise essential anatomical details and the aetiology of internal hernias. Congenital causes included enlargement of natural orifices and abnormalities due to intestinal malrotation, while acquired causes encompassed postoperative, post-traumatic, and iatrogenic origins.

Below are some computed tomography signs whose identification is highly illustrative and aids in the diagnosis of internal hernia:

– Whirlpool sign:The mesenteric vessels are seen twisting into a spiral configuration, indicating mesenteric torsion and an increased risk of intestinal ischaemia.

– Mushroom sign:Occurs when the mesentery and mesenteric vessels become strangulated through a hernial defect, producing a stem-like appearance surmounted by distended bowel loops, resembling a “mushroom” configuration.

– Criss-cross sign:In cases of intestinal malrotation, the superior mesenteric vein (SMV) crosses and lies to the left of the superior mesenteric artery (SMA), whereas under normal anatomical conditions it is positioned on the right.

– Grouped loops sign:A cluster of small bowel loops grouped within a focal area, surrounded by congested mesenteric fat.

– Eye of the hurricane sign:A centrally dilated bowel loop encircled by collapsed loops, creating the characteristic “eye of the hurricane” appearance.

– Hazy mesentery sign:Diffuse increased attenuation of the mesenteric fat, appearing “hazy” or “misty” on CT, secondary to mesenteric oedema or congestion.

– Peak sign:Convergence of mesenteric vessels towards a single point of entrapment, forming a triangular or “beak-like” configuration.

Illustrative CT images demonstrating these signs can be found in the gallery section.

A dedicated section is also devoted to internal hernias associated with bariatric surgery, highlighting the principal risk factors, including laparoscopic techniques that create or inadequately close mesenteric defects, as well as rapid postoperative weight loss resulting in mesenteric laxity and altered bowel motility.