Non-traumatic abdominal pain of small bowel origin includes a spectrum of medical and surgical aetiologies ranging from minor to life-threatening conditions. Diagnosis of the aetiology has been a dilemma due to many factors related to the unique anatomy of the small bowel and its continuous motion [2].
In this study, a retrospective data analysis was done for 47 patients complaining of non-traumatic abdominal pain for whom MDCT enterography has been done in attempt to reach the aetiological diagnosis. The MDCTE diagnosis was correlated with the histopathological findings in all cases.
Inflammatory bowel disease was the most common cause of non-traumatic bowel-related abdominal pain in our study. This is consistent with Paulsen et al. who stated that inflammatory bowel disease and intestinal ischemia are the two most common causes of bowel-related non-traumatic abdominal pain [6]. Twenty-seven cases (57%) were diagnosed as having inflammatory bowel disease by CT enterography. Twenty-five cases (93%) of them were proven pathologically to have IBD. Tochetto et al. stated that the estimated sensitivity of MDCT enterography for detecting ileal inflammation is about 75–90% using mucosal inspection and biopsy as a reference standard. This percentage improves to 90–95% if associated with clinical and follow-up data [7].
In our study, the terminal ileum was involved in most patients showing characteristic skip lesions. Karlinger et al. and ElSayes et al. stated that Crohn’s disease may affect any segment of the gastrointestinal tract with a special predilection for the terminal ileum [8, 9]. According to Macari et al., there is significant correlation between the presence of homogeneous mural hyper enhancement and the active Crohn’s disease histopathological findings which was confirmed in our study. Another finding that correlates well with the degree of activity of Crohn’s disease is the presence of peri-enteric inflammation in the form of increased fat density and vascular engorgement of the vasa recta [10]. Eleven patients were found to have the aforementioned findings, and they were clinically suggested to have active acute exacerbation.
In our study, one patient with ulcerative colitis was found to have a rectal inflammatory polyp as an associated finding. Other extra-enteric finding such as sacroiliitis was found separately in one patient with active Crohn’s disease.
In our study, four cases were diagnosed as fibrotic stricture. The main points to differentiate fibrotic stricture from active inflammatory process are the absence of vasa recta engorgement or reactive lymphadenopathy in case of fibrotic stricture and the pattern of bowel wall enhancement which is seen restricted to the mucosa compared to wall stratification in active cases. Sakurai et al. and Minordi et al. stated that bowel stenosis due to fibrotic structure is the thickening of the bowel wall with subsequent narrowing of its lumen. According to the degree of luminal narrowing, proximal bowel dilatation may be present [11, 12].
Two cases were diagnosed as having intussusception with the characteristic target like mass. Kim et al. stated that the main advantage of CT is to clearly identify the entering bowel wall, the returning bowel wall, the mesenteric fat, and intra-luminal space. An added value of the MDCTE is detection and proper characterization of a lead point mass as aetiology [13].
Another cause of non-traumatic bowel-related pain is bowel ischemia. In our study, only two cases were diagnosed as having bowel ischemia. Both of them showed superior mesenteric venous thrombosis associated with portal venous thrombosis as well in one patient. As per Furukawa et al., the diagnosis is based on the identification of more than two of the following signs: circumferential mural thickening, decreased enhancement of the bowel wall, intramural gas, mesenteric edema, mesenteric vascular engorgement, and an intravascular filling defect [14]. In our study, the combination of these five signs or at least four of them resulted in accurate diagnosis of all cases of intestinal ischemia. The diagnosis was confirmed by obtaining operative data in 2 cases (100%). In contrast to Gangadhar et al., who stated that intestinal ischemia is the second most common cause of bowel-related non-traumatic abdominal pain coming in order of frequency after IBD [15]. In our study, only 2 cases (4%) of the total population were diagnosed as having bowel ischemia. This can be explained by emergency surgical interventions that were done for other patients that were suspected clinically to have mesenteric ischemia.
In our study, four patients were diagnosed as having other pathologies or having non-specific findings. Two of them were found to be presenting clinically at time of examination with picture of subacute intestinal obstruction for which they were surgically operated upon. By MDCTE, one patient was diagnosed as adhesive bowel obstruction with a beak transition between proximally dilated bowel loops and collapsed distal bowel loops. No evidence of extrinsic mass compression or mural wall thickening was detected. The other one was diagnosed as left para-duodenal internal hernia. The operative records of both patients confirmed the diagnosis.
One case of SMA syndrome was diagnosed showing the characteristic pattern of compression of the third part of the duodenum between the descending aorta and the superior mesenteric artery (SMA). Proximal dilatation involving the stomach and the second part of the duodenum is noted. This is agreeing with Gangadhar et al. who stated that acute aorto-mesenteric angle of less than 25° and attenuated aorto-mesenteric distance of less than 10 mm at the level of the third part of the duodenum are the main diagnostic criteria of SMA syndrome along with proximal bowel dilatation [15].
One case of rectal AVM was also diagnosed showing a polypoidal highly vascular mass.
The diagnosis was not sure in five patients out of 47 cases. Non-specific findings were detected like diffuse bowel dilatation. No specific enhancement pattern was retrieved. Revision of their histopathological records revealed one IBD, one FMF, one celiac disease, and two neoplastic lesions confirmed to be GIST. This is compared to a study by Misra et al. who reported a sensitivity and specificity of MDCTE to be 95.83% and 100% respectively with accuracy of 96.66% in diagnosis of small bowel diseases [16].