[Uncommon case of incomplete left paraduodenal hernia].

Internal hernias are very rare. The hernial orifice, sac and content are situated inside the abdomen. Paraduodenal hernias are relatively rare congenital malformations and account about 50 per cent of all internal hernias. The cause of this malformation is the incomplete rotation of the mid-gut. Right and left paraduodenal hernias are different, varying in anatomic structure and embryological origin. In right paraduodenal hernia the small bowel is partially or completely localised behind the mesocolon of the ascending colon, in left paraduodenal hernia behind the mesocolon of the descending colon. That is why the widely used name "mesocolic" hernia is more convenient, because it refers on the pathogenesis of the disorder. The complaints can vary from recurrent atypical abdominal pains to the complete small bowel obstruction, but often there are no complaints. Abdominal CT scan and the barium meal provide the best diagnostic approach for paraduodenal hernias, but it will be recognised very often only at an emergency operation. A case of small bowel obstruction caused by incomplete left paraduodenal hernia discovered after swallowing a foreign body is described with pathogenesis, diagnosis and possible treatments for the disease.