From the Guidelines

Small-bowel obstruction (SBO) should be diagnosed in a patient with ileus.

The diagnosis of SBO can be challenging, especially in the perioperative period, where it may be difficult to differentiate SBO from a postoperative ileus based on a single examination 1.
CT abdomen and pelvis is the preferred imaging modality for diagnosing SBO, with a diagnostic accuracy of more than 90% 1.
CT provides more information than abdominal radiographs, including the site and cause of the obstruction and complications of SBO, such as ischemia and strangulation 1.
Abdominal radiography may be useful in some cases, but its accuracy is variable, and it may not be definitive in many patients with suspected SBO 1.

In patients with a known or suspected SBO, CT with IV contrast is preferable for routine imaging to demonstrate whether the bowel is perfusing normally or is potentially ischemic 1.
Multiplanar reconstruction capabilities on multidetector CT scanners can increase accuracy and confidence in locating the transition zone in SBO, which can be useful if an operative intervention is planned 1.
Oral contrast medium is not required in patients with a suspected high-grade SBO, as it can delay diagnosis, increase patient discomfort, and increase the risk of complications 1.

From the Research

In a patient with ileus, several factors should be diagnosed, including:

The type of ileus, whether it is mechanical or functional 2
The site of blockage, as the manifestations of ileus and its degree of severity generally depend on this 2
The presence of peritoneal involvement with cancer, as this can pose a challenge in distinguishing between mechanical and functional causation 2
The need for surgical intervention, as some patients with mechanical obstruction or ileus may still require surgery despite initial conservative treatment 3

Various diagnostic tools can be used to evaluate a patient with ileus, including:

Computed tomography (CT) scan, which can help diagnose mechanical obstruction or ileus and guide further management 3
Ultrasound examination, which can provide additional information on the location of the obstruction, the presence of dilated intestinal loops, and other sonographical findings 4
Plain films, which can show characteristic findings such as erected dilated intestinal loops with fluid levels 4

Ileus can have systemic consequences, including:

Increased intra-abdominal pressure (IAP), which can lead to multiple organ dysfunction 5
Abdominal fluid sequestration, intestinal bacterial overgrowth, and systemic invasive infections 5
Release of cytokines and the development of the systemic inflammatory response syndrome 5

Therapeutic considerations for a patient with ileus include:

Maintenance of adequate hydration status 5
Avoidance of drugs known to impair intestinal perfusion 5
Stimulation of gastric and intestinal motility 5
Various nutritional aspects 5
Minimization of opioids, early patient mobilization, pharmacologic intervention, and multidisciplinary care in orthopaedic patients 6