Digital rectal exam may find dyssynergia in chronic constipation

Last Updated: 2015-06-16

By Larry Hand

NEW YORK (Reuters Health) - Digital rectal exams are a practical way to detect dyssynergia in patients with chronic constipation, according to Korean researchers.

"Digital rectal exam (DRE) is a useful bedside test for the screening and diagnosis of dyssynergic defecation, the specific type of constipation that can be treated with biofeedback therapy," Dr. Seung-Jae Myung, of Asan Medical Center and University of Ulsan College of Medicine, Seoul, told Reuters Health by email.

"Even in primary care, physicians without high-resolution anorectal manometry (HRAM) can diagnose the specific type of constipation by simple digital rectal examination," he said.

Dr. Myung and colleagues compared the diagnostic accuracy of DRE and HRAM in 309 patients at their center, including 268 with chronic constipation and another 41 with fecal incontinence. The median age was 64 for chronic constipation patients. About 57% were female.

The investigators excluded patients who had undergone rectoanal surgery, except hemorrhoidectomy, according to an article online June 2 in the American Journal of Gastroenterology.

Between September 2012 and September 2013, patients underwent a clinical interview and standardized DRE, HRAM, and balloon expulsion tests. A single experienced investigator for each test performed the procedures.

The investigators found moderate agreement between DRE and HRAM in diagnosing dyssynergia. Of 253 constipated patients who could be classified by coordination pattern during attempted defecation, both modalities diagnosed 76.3% with dyssynergia, and 10.7% normal. DRE diagnosed dyssynergia in 19 patients that HRAM assessed as normal. Conversely, 14 patients had normal DRE but HRAM showed dyssynergia.

The overall sensitivity and specificity of DRE for dyssynergia were 93.2% and 58.7%, respectively. The positive predictive value (PPV) was 91.0% and the negative predictive value (NPV) was 65.9%.

The overall sensitivity and specificity of DRE for assessing anal sphincter relaxation were 94.7% and 39.1%, and the PPV and NPV were 87.5% and 62.1%, respectively.

The sensitivity and specificity of DRE for failure of a balloon expulsion test came to 81.2% and 17.9%, respectively, and the PPV and NPV to 33.3% and 65.2%, respectively. But investigators found poor agreement between DRE assessment of dyssynergia and failure of a balloon expulsion test.

In patients with fecal incontinence, the sensitivity and specificity of DRE in assessing decreased anal resting tone were 48.6% and 75.0%, respectively, and the PPV and NPV were 94.7% and 13.6%, respectively, leaving poor agreement between DRE and HRAM.

"Further study is needed to compare the anal sphincter pressure and DRE in the future," Dr. Myung said. Also, "this is the study done in Asian individuals and patients. Further study to evaluate the racial differences will be valuable."

"Our present study describes, for the first time, the performance of DRE compared with HRAM in diagnosing functional anorectal disorders. DRE showed a high sensitivity and PPV in identifying dyssynergia, and a high PPV in assessing anal sphincteric pressure. These findings suggest that DRE could be a useful bedside tool for evaluating patients with functional anorectal disorders," the investigators wrote.

"Moreover," they pointed out, "DRE is usually conducted during the initial stages of an examination, making an early diagnosis possible."

The central message for clinicians from this study is, "Please do a detailed digital rectal examination in every constipated patient," Dr. Adil E. Bharucha, a specialist in anorectal and pelvic floor disorders at the Mayo Clinic, Rochester, Minnesota, told Reuters Health by email.

"A meticulous rectal exam is arguably the most important component of the physical exam in constipated patients," he continued. "If the digital rectal assessment suggests appropriate pelvic floor motion during evacuation, anal manometry and a rectal balloon expulsion test may not be required, at least initially, in patients in whom the symptoms do not strongly suggest pelvic floor dysfunction."

As for research needed now, he said, "The PPV and NPV depend on the population being studied. Only constipated patients were studied. Particularly because healthy people can have dyssynergia, further studies evaluating the utility of DRE in healthy people and constipated patients are necessary."

He explained, "The assumption is that healthy people have 'synergia' (increased rectal pressure coordinated with anal relaxation) during defecation. Hence, dyssynergia (impaired rectoanal coordination) is considered abnormal. However, it is well recognized that many asymptomatic people have dyssynergia, perhaps because it is difficult for them to replicate defecation while being examined. Hence, dyssynergia is not necessarily 'abnormal.' However, the inability to expel a rectal balloon is a more useful index of abnormal evacuation - not perfect - because some patients with disordered evacuation can expel a balloon."

The Ministry of Health & Welfare of the Republic of Korea and the National Research Foundation of Korea funded this research. The authors reported no competing interests.

SOURCE: http://bit.ly/1IFbUaU

Am J Gastroenterol 2015.