The PR/DRE is one tool in the diagnostic arsenal along with percussion, palpation auscultation, etc. In the hospital patient population, many treating physicians are so adamant about the exam, some lament, “It should be considered in all patients admitted to hospital who are over the age of 40, unless the examiner has no fingers, the patient no anus, or acute illness such as myocardial infarction presents a temporary contraindication” . Indeed, current best practices require the PR/DRE exam to be performed [3, 4]. The purpose of this review paper is to challenge some of these branches in the diagnostics and treatment algorithm of the undifferentiated patient and to consider the clinical risks and benefits but also alternatives to the exam.
In conducting the diagnostic procedure, performed in the ED or on a specialty ward, as with all diagnostics, patient consent must be obtained. Further, privacy must be ensured; a chaperone is always indicated in the emergency department setting and a simple explanation to the patient about the exam, why the exam is being performed and discussion of an alternative if the patient refuses the exam. The patient is placed on their side with the knees pulled towards their chest into the left lateral position. The lubricated and gloved hand of the examiner begins the inspection of the anus and perianal area by separating the buttocks. Observation for thrombosed external hemorrhoids, skin tags, rectal prolapse, fistula-in-ano, condylomata acuminata, carcinoma of the anus, and pruritus ani are examined and noted—all without penetrating finger into anus. Of course, gross blood at the anus, acute and obvious trauma, or incontinence are also observed and ambiance appreciated at this stage.
To perform the exam intrarectally, the tip of the gloved finger is lubricated and placed over the anus, the patient can be encouraged to breathe out. The examiner introduces the finger and palpates for anal fissures, thrombosed external or internal hemorrhoids, an ischiorectal abscess, active proctitis, or anal ulceration . The finger is then rotated so that the left lateral wall, posterior wall, and right lateral wall of the rectum can be palpated in turn; then, the finger is advanced as high as possible into the rectum and slowly withdrawn along the rectal wall. A soft lesion, such as a small rectal carcinoma or polyp, is more likely to be felt with this technique on exit .
The patient can then be asked to squeeze the examiner’s finger when still in situ with the anal muscles as a further test of anal tone . This subjective phase of the exam does not account for the depth or width of the examiner’s fingers. It should be noted that among medical students and practicing consultants, no data has been collected or reported on average or maximum/minimum finger girth or length to date.
However, this exam can tell if sphincter tone is present based on the sensation of the examiner alone, if the rectal wall has been breached, if spicules of bone are palpable, if the prostate in a normal position, and subjectively if there is gross blood on the examiner’s finger . Specifically, “the rectal examination may elicit reduced tone from spinal cord injury, bleeding from lower gastrointestinal trauma, bony penetration in pelvic fracture and a high-riding prostate associated with pelvic fracture, an indicator of potential urethral injury” . The presence of rectal tone or variations in rectal tone are poorly reported. In sum, a rectal examination is performed to look for blood, lack of tone/sensation, or high-riding prostate which indicate bowel injury, spinal cord injury, or urethral injury, respectively—the rectal examination can be an important part of the examination, but stool must be tested for blood.