1241. Intestinal Malrotation in Adults: Prevalence and Findings Based on CT Colonography
Authors * Denotes Presenting Author
  1. Alberto Perez *; University of Wisconsin School of Medicine and Public Health
  2. Perry Pickhardt; University of Wisconsin School of Medicine and Public Health
Intestinal malrotation, or nonrotation, is largely a pediatric diagnosis, but initial detection can be made in adulthood. CT colonography (CTC) provides an ideal means for adult diagnosis, given its bowel focus, and for estimating prevalence. The purpose of this study was to evaluate the prevalence and imaging findings of intestinal malrotation in asymptomatic adults at CTC screening, as well as incomplete optical colonoscopy (OC) referral.

Materials and Methods:
The CTC database of a single academic institution was searched for cases of intestinal malrotation (developmental nonrotation). Prevalence was estimated from 11,176 individuals, including 9,844 adults (mean age, 57 years; 4532M/5312F) undergoing initial CTC screening and 1,332 (mean age, 63 years; 493M/839F) referred for incomplete OC. After secondary confirmation of all cases, the demographic, clinical, imaging (CTC and other abdominal exams), and surgical data were reviewed in the EHR and PACS.

27 cases of malrotation were confirmed (mean age, 62±9 years; 15M/12F), including 17 from the CTC screening cohort (0.17% prevalence) and 10 from incomplete OC (0.75% prevalence; p<0.001). Most cases (56%; 15/27) were initially diagnosed at CTC. In 67% (12/18), the presence of malrotation was missed on at least one relevant abdominal imaging examination (CT, MR, or GI fluoroscopy) other than CTC. At least 22% (6/27) had a history of unexplained, chronic intermittent abdominal pain. At CTC, the SMA-SMV relationship was normal in only 11% (3/27), reversed in 56% (15/27), and vertical in 33% (9/27). The cecum and ileocecal valve were located in the RLQ in only 22% (6/27). Two patients (7%) had associated findings of heterotaxy (polysplenia). Diagnosis of malrotation was either not apparent or equivocal on the CTC scout view in 56% (15/27).

The prevalence of intestinal malrotation was over four times greater for patients referred from incomplete OC compared with primary screening CTC, likely related to anatomic challenges at physical endoscopy. Malrotation was frequently missed at other abdominal imaging examinations, even when performed for unexplained abdominal pain. CTC can uncover unexpected cases of malrotation in adults, which may be relevant in terms of unexplained abdominal pain and the potential for future complications.