Postoperative Ileus Workup

Updated: Nov 01, 2021
  • Author: Burt Cagir, MD, FACS; Chief Editor: Vinay K Kapoor, MBBS, MS, FRCSEd, FICS, FAMS  more...
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Laboratory Studies

Laboratory studies and blood work should focus on evaluations for infectious, electrolytic, and metabolic derangements. Inflammatory markers such as interleukins 1 and 6 (IL-1, IL-6) and tumor necrosis factor alpha (TNF-a) could help identify early the presence of protracted postoperative ileus. [25]

Preoperative low serum albumin [26] , postoperative deep venous thrombosis, and electrolyte levels are associated with postoperative ileus. Age, previous abdominal surgery, and chronic preoperative use of narcotics were independently correlated with postoperative ileus. [27]


Imaging Studies

Computed tomography (CT) scanning

Findings from a systematic review indicate that CT scanning with Gastrografin may have the best specificity and sensitivity for differentiating between postoperative ileus and other conditions, whereas clinical findings and x-ray studies were of limited value in the differential diagnosis. [25]

The German Society of Gastroenterology, Digestive and Metabolic Diseases (DGVS) recommends obtaining CT scanning before considering endoscopic intervention to differentiate between mechanical obstruction and paralytic ileus/intestinal pseudo-obstruction. [28] It is also crucial to identify the presence of tumors and their site; localization guides selection of the decompression procedure. [28]

Multidetector CT (MDCT) scanning has the potential to be an effective and reliable tool in the early identification of chronic gallstone perforation and ileus. In one study, this imaging modality was able to differentiate and locate 88.5% of ectopic biliary stones compared with 50% with abdominal radiography, as well as reveal the presence of cholecystitis, edema, discontinuous walls of the gallbladder and intestine, and bilioenteral fistula. [29] In the same study, MDCT scanning and magnetic resonance imaging (MRI) provided precise visualization of the bilioenteral fistula and the ruptured bile duct.


On plain abdominal radiographs, ileus appears as copious gas dilatation of the small intestine and colon with air fluid levels; however there is no transition point as is seen in mechanical obstruction. With enteroclysis, the contrast medium in patients with paralytic ileus should reach the cecum within 4 hours; if the contrast medium remains stationary for longer than 4 hours, mechanical obstruction is suggested. [30]  The oral contrast is hyperosmolar; it draws water from the bowel wall in to the lumen – this reduces the bowel wall edema and may help in resolution of the ileus.