How reliable is digital examination for the evaluation of anal sphincter tone?

This study investigates whether digital examination of the anal canal can differentiate reliably between competent and incompetent sphincters. Digital examinations were performed by an experienced proctologist who was blinded with regard to the patient's history as well as manometric and endoscopic findings. There was poor correlation between manometric findings and digital assessment of anal sphincter tone. The sensitivity of digital examination for diagnosing incompetent sphincters ranged from 63% to 84%, whereas specificity was calculated as only 57%. It is concluded that even the experienced examiner needs to use more sophisticated methods than digital examination for the evaluation of anal sphincter competence.