What is the purpose and procedure of a digital rectal exam (DRE)?

Digital Rectal Examination (DRE): Purpose and Procedure

The digital rectal examination (DRE) is a clinical examination procedure primarily used to assess the prostate gland in men, evaluate rectal abnormalities, and screen for potential cancers, though its value as a standalone screening test for prostate cancer is limited due to poor diagnostic performance.

Purpose of Digital Rectal Examination

• DRE serves as a physical examination technique to assess the prostate gland, rectum, and surrounding structures 1
• When evaluating the prostate, DRE helps detect subtle abnormalities including changes in symmetry, consistency, induration, or nodules that may suggest prostate cancer 1
• For benign prostatic hyperplasia (BPH), DRE helps estimate prostate size, though it tends to underestimate the true prostate size compared to ultrasound measurements 1
• In rectal cancer evaluation, DRE is an important diagnostic tool for patients with rectal bleeding or positive fecal immunochemical tests (FIT) 2

Role in Prostate Cancer Screening

• DRE alone has poor performance as a standalone screening test for prostate cancer, with significantly lower cancer detection rates (0.01,95% CI: 0.01-0.02) compared to PSA testing (0.03,95% CI: 0.02-0.03) 3
• Recent evidence shows that combining DRE with PSA testing does not significantly improve cancer detection rates compared to PSA testing alone 3
• A 2023 study found that DRE had a true-positive detection rate of only 0.22 (95% CI: 0.07-0.72) relative to PSA screening, with 86% of PSA-detected cancers having unsuspicious DRE findings 4
• The positive predictive value of DRE ranges from 4-11% in men with PSA levels of 0-2.9 ng/mL and 33-83% in men with PSA levels of 3.0-9.9 ng/mL 5

Procedure of Digital Rectal Examination

• The patient is typically positioned in one of three ways:

  • Lateral decubitus position (lying on side with knees drawn up toward chest)
  • Lithotomy position (lying on back with feet in stirrups)
  • Standing and bending forward at the waist 1

• The examiner:

  1. Wears gloves and applies lubricant to the index finger
  2. Gently inserts the lubricated index finger into the rectum
  3. Systematically palpates the rectal walls and prostate gland (in men)
  4. Assesses for any abnormalities including masses, tenderness, or irregularities 1

• For prostate examination specifically, the examiner evaluates:

  • Size (normal prostate is approximately walnut-sized)
  • Symmetry of the two lobes
  • Consistency (normally rubbery)
  • Presence of nodules, induration, or asymmetry 1

Current Guideline Recommendations

• The American Cancer Society recommends DRE as part of prostate cancer screening beginning at age 50 for average-risk men, and at a younger age for high-risk groups including African Americans and those with strong family history 1
• The American College of Physicians (ACP) includes DRE in their guidance statement on prostate cancer screening but notes its limitations 1
• The National Comprehensive Cancer Network (NCCN) recommends baseline DRE for men aged 50-70 years as part of early detection evaluation 1
• The American Urological Association (AUA) recommends DRE as part of the physical examination for patients with suspected benign prostatic hyperplasia 1

Limitations and Controversies

• DRE has poor sensitivity (14%) for detecting prostate cancers that are identified through PSA screening 4
• A significant proportion (46.2%) of patients with rectal symptoms or positive FIT tests do not recall having a DRE performed by their primary care provider 2
• Some evidence suggests that DRE may not be essential for patients with PSA levels of 2.5-10 ng/mL if patients are appropriately counseled before PSA testing 6
• Women are less likely to undergo DRE than men (28.6% vs. 44.3%) when presenting with rectal symptoms 2

Best Practice Recommendations

• DRE should be performed by healthcare workers skilled in detecting subtle abnormalities of the prostate and rectum 1
• For prostate cancer screening, DRE should not be used as a stand-alone test but should be performed in conjunction with serum PSA measurement 1
• DRE remains valuable for assessing patients with urological and rectal symptoms despite its limitations as a screening tool 6
• Clinicians should be aware that DRE tends to underestimate prostate size; if the prostate feels large by DRE, it is usually found to be enlarged by ultrasound or other measurement techniques 1