Radiologic Evaluation of Suspected Intestinal Obstruction in Bedridden Patients

Introduction to Radiologic Projections

The American College of Radiology recommends abdominal radiography as the initial imaging evaluation for suspected intestinal obstruction, with a sensitivity of 74-84% and specificity of 50-72% 1, 3.
In patients who cannot stand, a left lateral decubitus radiograph should be performed in addition to the supine radiograph to adequately evaluate for pneumoperitoneum and hydroair levels 2.

Classic radiographic findings in intestinal obstruction include dilated intestinal loops and air-fluid levels, with the presence of dilated loops and air-fluid levels in the same intestinal segment being highly predictive of high-grade obstruction 3.
The presence of dilated intestinal loops with air-fluid levels and relative or complete absence of gas in the colon favors the diagnosis of intestinal obstruction over paralytic ileus 1.

Despite the relatively high accuracy of abdominal radiographs in detecting intestinal obstruction, computed tomography (CT) provides more information, including the site and cause of obstruction and complications, with a sensitivity of 93%, specificity of 100%, and accuracy of 94% 1, 3.
CT should be considered as the next diagnostic step when radiography is inconclusive, especially to determine the level and cause of obstruction 4.
Abdominal ultrasound may be an alternative with a sensitivity of 91% and specificity of 84% for the diagnosis of intestinal obstruction, particularly useful in pediatric patients or when CT is not available 1, 5.

In patients with suspected intestinal perforation, a left lateral decubitus radiograph is essential to detect pneumoperitoneum, which appears as free air between the abdominal wall and the liver 2, 4.
Radiologic evaluation should be complemented with clinical evaluation, including vital signs and abdominal examination, as severe intestinal obstruction can cause hypovolemic shock and, in case of perforation, septic shock 3.

Initial evaluation with supine abdominal radiograph to identify dilated intestinal loops 1, 3.
Left lateral decubitus radiograph is essential in patients who cannot stand to detect air-fluid levels and pneumoperitoneum 2.
If findings are equivocal or more information is required, consider abdominal CT with IV contrast as the method of choice to determine the site, cause, and complications of obstruction 4.
In selected cases (pediatric patients, pregnant women, or when CT is not available), consider abdominal ultrasound or studies with hydro-soluble contrast 1, 5.