What are normal findings on a digital rectal exam (DRE) of the prostate?

From the Guidelines

Normal findings on a digital rectal examination (DRE) of the prostate include a smooth, firm, and elastic gland with a palpable median sulcus dividing the prostate into two lateral lobes, as described in the highest quality and most recent study available 1. The normal prostate is approximately walnut-sized, measuring about 2-3 cm in length and 3-4 cm in width, with a volume of 20-30 cc. It should have well-defined borders and be non-tender when palpated. The consistency should be uniform throughout, similar to the firmness of the contracted thenar eminence of the thumb. The rectal mucosa should move freely over the prostate, indicating no adherence to surrounding tissues. The seminal vesicles are not normally palpable. During the examination, the patient may experience a sensation of pressure or a mild urge to urinate, which is normal. Some key points to consider when performing a DRE include:

• The prostate should be smooth and firm, with no nodularity or induration
• The median sulcus should be palpable, dividing the prostate into two lateral lobes
• The prostate should be non-tender and have well-defined borders
• The rectal mucosa should move freely over the prostate Any findings that deviate from these characteristics, such as nodularity, induration, asymmetry, tenderness, or significant enlargement, would warrant further evaluation as they could indicate pathological conditions like prostatitis, benign prostatic hyperplasia, or prostate cancer, as noted in 1. It's also important to note that an abnormal DRE is an indication for biopsy, but as an independent variable, PSA is a better predictor of cancer than either DRE or transrectal ultrasound (TRUS), as stated in 1.

From the Research

Normal Findings on Digital Rectal Exam (DRE) of the Prostate

Normal findings on a digital rectal exam (DRE) of the prostate are not explicitly defined in the provided studies, as they primarily focus on the detection of prostate cancer. However, the studies imply that a normal DRE finding is the absence of any suspicious areas, such as nodules, induration, or irregularities.

Digital Rectal Examination (DRE) Findings

• A suspicious DRE finding is associated with a higher risk of prostate cancer, particularly in patients with elevated prostate-specific antigen (PSA) levels 2, 3, 4.
• The sensitivity and specificity of DRE in detecting prostate cancer vary, with reported values ranging from 27% to 63% 3, 4.
• DRE has limited accuracy in identifying and localizing prostate cancer, with many cancers not being palpable or sonographically visible 5.

Prostate Cancer Detection

• The combination of DRE, PSA, and transrectal ultrasonography (TRUS) biopsy is useful in detecting prostate cancer, with a cancer-detection rate of 52% reported in one study 6.
• The positive predictive values (PPVs) for prostate cancer detection based on DRE and PSA levels are:
  • Normal DRE and PSA < 4 ng/mL: 9% 6
  • Normal DRE and PSA 4-10 ng/mL: 31% 6
  • Normal DRE and PSA > 10 ng/mL: 48% 6
  • Abnormal DRE and PSA < 4 ng/mL: 27% 6
  • Abnormal DRE and PSA 4-10 ng/mL: 67% 6
  • Abnormal DRE and PSA > 10 ng/mL: 85% 6

Clinical Implications

• DRE should still be used as part of active surveillance for prostate cancer, as it can predict the presence of clinically significant prostate cancer, even with low PSA values 4.
• A suspicious nodule on DRE represents a higher risk of upgrading and should prompt further assessment 4.