Digital rectal examination had a highly positive predictive value for diagnosing dyssynergia in patients with chronic functional constipation, wrote Dr. Satish S.C. Rao and colleagues in the November issue of Clinical Gastroenterology and Hepatology.

In what they called the first study to examine the use of digital rectal exam (DRE) in identifying dyssynergia, the authors looked at 209 patients (191 men) referred to a specialized defecation disorders clinic who fulfilled Rome III criteria for functional constipation (Clin. Gastroenterol. Hepatol. 2010 November [doi:10.1016/j.cgh.2010.06.031]).

The Rome III criteria, developed in 2006, define functional constipation as involving at least two of the following symptoms occurring with 25% of defecations: straining, lumpy or hard stools, feeling of incomplete defecation, feeling of blockage, or use of manual maneuvers. Having fewer than three defecations per week is also a symptom.

The criteria also stipulate that for functional constipation to be present, loose stools must be rare without laxative use, and irritable bowel syndrome must be ruled out.

Patients who met these criteria underwent both a DRE and anorectal manometry, with the latter considered the gold standard for the diagnosis of dyssynergia. The same experienced examiner performed all of the digital exams in the study.

Overall, 183 of the patients received a diagnosis of dyssynergia based on manometry. Of these, 134 (73%) also had “features of dyssynergia” according to digital exam. Four patients who had no dyssynergia on manometry were misidentified as dyssynergic on digital exam.

That translated to an overall sensitivity of DRE for dyssynergia diagnosis of 75% and a specificity of 87%, with a positive predictive value of 97%.

Dr. Rao, of the University of Iowa, Iowa City, and his colleagues, also found “good” agreement for normal resting anal sphincter tone between DRE and manometry (87 and 101, respectively, or 86%) and “fair” agreement for increased resting sphincter tone (12 and 28, or 43%). There was low agreement between the two modalities for decreased resting sphincter tone (12 and 80, or 15%).

Despite the value of DRE shown in this study – including its low cost and ease of use – the authors commented that previous studies have shown that medical students are not being trained to use the technique.

“It is imperative that serious efforts are made by faculty mentors during medical school and residency training to improve and facilitate the acquisition of this clinical skill,” wrote the authors. “This is particularly relevant as sophisticated tests such as anorectal manometry and balloon expulsion test, although useful and diagnostic, are not widely available.”

The authors pointed out several limitations, including the fact that anorectal manometry “may be falsely positive for dyssynergia in 15% of asymptomatic subjects,” according to one study cited by the authors.

In addition, “even when performed meticulously, several subjects had low resting and low squeeze sphincter pressure on [anorectal manometry], but were felt to have normal resting sphincter tone and normal squeeze tone during digital rectal examination,” they wrote. “This may be due to an apprehension or fear of DRE on the part of a subject that may have temporarily and falsely increased resting tone.”

The authors reported having no conflicts of interest related to this study. Dr. Rao disclosed support from the U.S. National Institutes of Health. Another researcher was supported by Chulalongkorn University, Bangkok.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

一项研究表明，在慢性功能性便秘患者中应用直肠指检(DRE)诊断肌协同失调阳性预测值极高。

 

本研究共纳入209例患者(男性191例)，入组患者均符合罗马Ⅲ标准对功能性便秘的定义(Clin. Gastroenterol. Hepatol. 2010 November [doi:10.1016/j.cgh.2010.06.031])。研究者对这些患者进行了DRE和肛管直肠压力测定(肌协同失调诊断金标准)，所有患者的DRE检查均由同一个经验丰富的医师进行。

 

经测压法检查后，183例被确诊患有肌协同失调，在直肠指检时，上述患者中有134例(73%)存在肌协同失调特征，有4例被误诊为肌协同失调。DRE诊断肌协同失调的灵敏度和特异度分别为75%和87%，阳性预测值高达97%。此外，DRE和测压法在测定正常肛门括约肌静息压力时具备较高一致性(分别检出87例和101例，一致率86%)，在检测肛门括约肌静息压力增高时也有相当的一致性(分别检出12例和28例，一致率43%)。两种诊断方法在检测肛门括约肌静息压力下降时一致性较低(分别检出12 例和 80例，一致率15%)。

 

研究的局限性在于，在对无症状受试者进行肛管直肠压力测定时，其肌协同失调诊断假阳性率可达15%。此外，即便以非常仔细的态度实施DRE，有数位肛门括约肌静息及收缩压力均较低的受试者(测压法测定)在行DRE时仍被诊断为静息及收缩压力正常。

 

本研究表明，DRE具备很高价值，且成本低廉，使用方便，鉴于肛管直肠压力测定和气囊排出试验这类复杂检测虽然具备很高诊断价值但普及率不高，医学教师和临床指导者们应该在医学院校和住院医师培训中大力宣传并传授这一临床技能，这非常必要。

 

作者表示无研究相关利益冲突。

 

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