To optimize small-bowel distention and visualization of the mucosa, patients ingest a large volume (1,000 to 2,000 cc) of neutral contrast material (such as low w/v barium solutions, water, polyethylene glycol, or methylcellulose suspensions) prior to the examination. IV contrast enhances the small-bowel wall such that it is well seen adjacent to the neutral intraluminal contrast. Single- or dual-phase (arterial and portal venous, respectively) acquisitions may be obtained. Using CT findings of inflammation (wall thickening, mucosal hyperenhancement, mural stratification, peripouch stranding, peripouch hyperemia, and peripouch abscess, fistula, or sinus tract), Liszewski et al [48] showed that IV Anorectal Disease contrast-enhanced CT enterography had a 90% sensitivity, 67% specificity, 90% PPV, 67% NPV, and 85% accuracy for diagnosis of pouchitis when more than 2 signs of inflammation were present. CT Pelvis The appropriate CT protocol for imaging a patient with an anorectal complaint depends upon the presentation and differential diagnosis. IV contrast is preferred to a noncontrast examination to help visualize and characterize fluid collections, abscesses, and fistulous tracts. CT without contrast is not useful in this clinical scenario. CT with and without IV contrast would only be useful when there is benefit from dual-phase imaging, but it is not typically performed in this scenario. Water-soluble rectal contrast is generally not necessary to diagnose a rectal abscess and may be challenging to administer, depending on symptom severity. However, rectal contrast may help delineate perforation or leak in a patient with a history of trauma or recent surgery. Water-soluble rectal contrast is preferred over barium to avoid the possibility of barium spilling into the peritoneal cavity or spaces of the extraperitoneal pelvis. Water-soluble rectal contrast is also preferred in patients who could potentially be undergoing surgery.
Anorectal Disease. To optimize small-bowel distention and visualization of the mucosa, patients ingest a large volume (1,000 to 2,000 cc) of neutral contrast material (such as low w/v barium solutions, water, polyethylene glycol, or methylcellulose suspensions) prior to the examination. IV contrast enhances the small-bowel wall such that it is well seen adjacent to the neutral intraluminal contrast. Single- or dual-phase (arterial and portal venous, respectively) acquisitions may be obtained. Using CT findings of inflammation (wall thickening, mucosal hyperenhancement, mural stratification, peripouch stranding, peripouch hyperemia, and peripouch abscess, fistula, or sinus tract), Liszewski et al [48] showed that IV Anorectal Disease contrast-enhanced CT enterography had a 90% sensitivity, 67% specificity, 90% PPV, 67% NPV, and 85% accuracy for diagnosis of pouchitis when more than 2 signs of inflammation were present. CT Pelvis The appropriate CT protocol for imaging a patient with an anorectal complaint depends upon the presentation and differential diagnosis. IV contrast is preferred to a noncontrast examination to help visualize and characterize fluid collections, abscesses, and fistulous tracts. CT without contrast is not useful in this clinical scenario. CT with and without IV contrast would only be useful when there is benefit from dual-phase imaging, but it is not typically performed in this scenario. Water-soluble rectal contrast is generally not necessary to diagnose a rectal abscess and may be challenging to administer, depending on symptom severity. However, rectal contrast may help delineate perforation or leak in a patient with a history of trauma or recent surgery. Water-soluble rectal contrast is preferred over barium to avoid the possibility of barium spilling into the peritoneal cavity or spaces of the extraperitoneal pelvis. Water-soluble rectal contrast is also preferred in patients who could potentially be undergoing surgery.