What is the procedure for a digital rectal exam (DRE) in adults, particularly in men over 50 with potential prostate cancer screening?

Digital Rectal Examination Procedure in Adult Men

Indications and Clinical Context

The digital rectal examination (DRE) should be performed in men over 50 as part of prostate cancer screening in conjunction with PSA testing, for evaluation of lower urinary tract symptoms, and when assessing for benign prostatic hyperplasia. 1, 2

• DRE is recommended by the American Cancer Society beginning at age 50 for average-risk men, at age 45 for African American men and those with first-degree relatives diagnosed before age 65, and at age 40 for men with multiple family members diagnosed before age 65 3, 1
• The examination serves to detect prostate abnormalities including nodules, induration, asymmetry, or areas of increased firmness that may suggest malignancy 1, 2
• DRE is essential to exclude locally advanced prostate cancer in patients presenting with lower urinary tract symptoms 3, 2
• Any abnormal DRE finding—including nodules, induration, asymmetry, or increased firmness—warrants prostate biopsy regardless of PSA level 2

Examination Technique

The examiner should assess prostate size, symmetry of the two lobes, consistency, and presence of nodules, induration, or asymmetry using a systematic approach. 1, 2

Patient Positioning and Preparation

• Position the patient in left lateral decubitus position (lying on left side with knees drawn up) or standing bent forward over the examination table 4
• Explain the procedure to the patient beforehand to reduce anxiety and improve cooperation 4
• Use adequate lubrication on the gloved examining finger 4

Systematic Examination Steps

• Inspect the perianal area for lesions, hemorrhoids, or fissures before digital insertion 4
• Gently insert the lubricated index finger through the anal sphincter, assessing sphincter tone 5, 4
• Palpate the posterior rectal wall first, then systematically examine the prostate gland 4
• Assess the prostate for:
  • Size: Note that DRE tends to underestimate actual prostate volume; if the prostate feels large by DRE, it is usually enlarged on ultrasound 1, 2
  • Symmetry: Compare the right and left lobes for asymmetry 1, 2
  • Consistency: Normal prostate feels rubbery; firmness or hardness suggests pathology 1, 2
  • Surface characteristics: Palpate for nodules, induration, or irregularities 1, 2
  • Tenderness: Note any pain on palpation which may suggest prostatitis 3
• Examine the lateral rectal walls and as high as the examining finger can reach 4

Critical Findings Requiring Action

Any of the following DRE findings mandate immediate prostate biopsy, even with normal PSA: 2

• Nodules or focal induration (most concerning findings) 2
• Asymmetry between lobes suggesting focal pathology 2
• Areas of increased firmness that may indicate malignancy 2
• Any change from prior examination in men on active surveillance 2

Integration with PSA Testing

DRE should not be used as a stand-alone screening test but must be performed in conjunction with serum PSA measurement. 1

• PSA testing is more sensitive than DRE alone for detecting prostate cancer 1
• However, DRE can independently identify prostate cancer even when PSA is normal, with 35% of men with normal PSA and abnormal DRE having prostate cancer on biopsy 6
• In men where DRE is an obstacle to testing, PSA alone is an acceptable alternative according to the American Cancer Society 1
• The combination of PSA and DRE provides a relatively sensitive approach to exclude prostate cancer 2

Examiner Expertise Considerations

DRE should be performed by healthcare workers skilled in detecting subtle prostate and rectal abnormalities, as examiner experience significantly affects diagnostic accuracy. 1, 5

• More experienced colorectal surgeons demonstrate significantly better agreement with objective anorectal manometry measurements (agreement index 0.7-0.96) compared to junior examiners (0.52) 5
• Interexaminer variability among urologists is only fair (kappa = 0.22), with greater variability between faculty and resident examiners 7
• Despite variability, DRE performed in primary care has demonstrated 81% sensitivity and 42% positive predictive value for detecting prostate cancer, with 76% of detected cancers being high-grade disease 6

Common Pitfalls to Avoid

• Do not dismiss an abnormal DRE based on normal PSA: Approximately 35% of men with normal PSA and abnormal DRE have prostate cancer, with substantial proportions having clinically significant disease 6
• Do not rely on single-panel office FOBT during DRE: This is not recommended for colorectal cancer screening due to very low sensitivity 3
• Do not assume DRE accurately estimates prostate size: DRE consistently underestimates actual prostate volume compared to ultrasound measurements 1, 2
• Do not perform DRE in isolation: Always combine with PSA testing and clinical history for comprehensive assessment 1, 2

Documentation Requirements

• Record prostate size (small, normal, enlarged) 2
• Document symmetry and consistency 2
• Note any nodules, induration, or areas of firmness with specific location 2
• Describe tenderness if present 3
• Compare to previous examinations when available 2