Persistent descending mesocolon – An under-recognized entity!

A 35-year-old female patient presented to the outpatient department with complaints of abdominal discomfort in the right iliac fossa for one year. Ultrasound was inconclusive.

A contrast-enhanced computed tomography was done to rule out causes of abdominal pain as per the local protocol. NCCT abdomen revealed an empty left paracolic gutter with medialization of the descending colon with small bowel loops placed lateral to the descending colon. The left iliac fossa was empty. The sigmoid colon was seen in the right iliac fossa. No bowel obstruction was seen. CECT abdomen revealed no abnormal vascular course or bowel wall pathology.

Persistent descending mesocolon (PDM) is defined as “failure of fusion of the mesentery of the descending colon with the lateral and posterior parietal peritoneum” [1]. It gives the descending colon unusual motility. Most of the patients are asymptomatic. However, some patients can present with chronic pain in the abdomen. The diagnosis of this entity holds clinical significance as the unusual motility of the mesocolon can lead to intestinal obstruction secondary to volvulus, intussusception, and internal hernias [2]. Persistent descending mesocolon increases the risk of haemorrhage and operative timings in laparoscopic resection of colorectal carcinomas [3]. Another alarming PDM-related abnormality is colonic varices as a result of local hypertension due to abnormal bowel course [4]. Post-operative anastomotic stenosis due to impaired arterial supply to the reconstructed colon is also a well-known complication [5].

The investigation of choice is Computed tomography and Barium studies. Computed tomography gives additional information regarding the length of the mesocolon, intestinal obstruction, and abnormal vascular supply. Multiplanar imaging and Minimum intensity projection help in preoperative mapping of inferior mesenteric artery and mesenteric variation in PDM [6].