The digital rectal exam is used to examine the palpable prostate, rectum, anus, and to assess for spinal cord injury, foreign bodies, and bloody stool.
Performing the Test
For a right-handed examiner, ask the patient to lie on their left side, buttocks close to edge of table, with hips and knees flexed
Lubricate gloved, right index finger
Ask patient to strain down, place pad of index finger over anus
Warn the patient that you are about to touch them and it's likely to feel cold from the lubricant
Once sphincter relaxes, insert index fingertip into anal canal in direction facing umbilicus. Ensure that the remainder of your fingers are flexed into your palm. Assess:
Tone of sphincter and anus
Tightness may indicated anxiety, inflammation, scarring
Laxity is associated with some neurologic diseases
Nodules, irregularities, induration, tenderness
After inserting finger into rectum as far as possible:
Palpate posterior wall of rectum
Rotate hand clockwise to palpate right side of rectum
Rotate hand counterclockwise to palpate left side of rectum
To bring suspected lesion into reach, take finger off rectal surface, ask patient to strain down, palpate again
Rotate hand counterclockwise so that finger examines posterior surface of prostate gland and note:
Identify lateral lobes and median sulcus
Size, shape, consistency
A normal prostate is rubbery, nontender, ~2.5 cm long
Extend finger beyond prostate to region of seminal vesicles/peritoneal cavity
Palpate rectal shelf for peritoneal metastases (Blumer's shelf) or tenderness (peritoneal inflammation)
Withdraw finger
Note colour fo fecal matter on glove finger
Test for occult blood
Give the patient a tissue to clean up with
Interpretation
For assessing spinal cord injuries in patients who underwent blunt trauma, the DRE is insensitive (only 50%) but reasonably specific (93%). It's positive predictive value is only 27%.
References
Bickley, S. L. The Anus, Rectum, and Prostate. In: Bates’ Guide to Physical Examination. 10th ed. Philadelphia PA: Lippincott Williams & Wilkins; 2009: 555-564.
Guldner, GT. The sensitivity and specificity of the digital rectal examination for detecting spinal cord injury in adult patients with blunt trauma. Am J Emerg Med. 2006. Jan;24(1):113-7.