Sigmoid diverticulitis: value of transrectal sonography in addition to transabdominal sonography

Overlying intestinal gas often impairs transabdominal sonographic assessment of the lower sigmoid colon. The aim of this study was to investigate the usefulness of transrectal sonography in addition to transabdominal sonography for the evaluation of sigmoid diverticulitis.

Eighty-six consecutive patients with clinically suspected acute sigmoid diverticulitis were referred for transabdominal sonography as the initial imaging method. In 46 patients, transrectal sonography was performed in addition to transabdominal sonography if pain was localized to the mid lower abdomen and if a disease process could not be visualized or could be only partially visualized on transabdominal examination. An end-firing 5-9-MHz endocavitary probe was used for transrectal sonography.

Thirty-four of 50 patients with a final diagnosis of sigmoid diverticulitis underwent both transabdominal and transrectal sonography. In 20 patients, transrectal sonography showed relevant additional information: six diagnoses of diverticulitis were established on transrectal sonography alone. Transrectal sonography revealed one perforation, five abscesses, and three fistulous complications that were not shown on transabdominal sonography. In the remaining five patients, correct diagnoses were supported on transabdominal examinations, but only transrectal sonography could show an inflamed diverticulum. In 10 patients, transrectal sonography revealed signs of diverticulitis but no relevant information in addition to the results from transabdominal sonography. Four false-negative and two false-positive results were revealed with transrectal sonography.

Transrectal sonography is accurate for confirming clinically suspected acute colonic diverticulitis when the lower sigmoid colon is affected. It helps avoid false-negative results and defines the severity of disease in the lower sigmoid colon better than transabdominal sonography alone. Transrectal sonography can increase the sensitivity of sonography for diagnosing sigmoid diverticulitis.