From the Guidelines
A normal prostate on physical examination (PE) should feel smooth, firm, and rubbery with a distinct median sulcus (groove) dividing it into two lateral lobes. The size should be approximately 2-3 cm in diameter, often described as "walnut-sized," and should not extend beyond the examining finger's reach. The prostate should have well-defined borders and should not be tender when palpated. The consistency should be uniform throughout without any nodules, induration, or asymmetry. During a digital rectal examination (DRE), the examiner inserts a lubricated, gloved finger into the rectum to feel the posterior surface of the prostate through the rectal wall. This examination is typically performed with the patient either bending forward at the waist, lying on their side with knees drawn up, or in the lithotomy position. Changes from normal findings such as nodularity, asymmetry, induration, or significant enlargement may indicate conditions like prostatitis, benign prostatic hyperplasia (BPH), or prostate cancer, warranting further evaluation, as suggested by the American Urological Association guidelines 1. Some key points to consider during the examination include:
- The presence of locally advanced prostate cancer should be excluded by DRE, as it can produce lower urinary tract symptoms (LUTS) similar to BPH 1.
- A focused neurologic examination should assess the patient’s general mental status, ambulatory status, lower extremity neuromuscular function, and anal sphincter tone 1.
- The digital rectal exam tends to underestimate the true prostate size, so if the prostate feels large by DRE, it usually also is found to be enlarged by ultrasound or other measurement techniques 1. It is essential to note that a normal DRE should be sufficient to exclude locally advanced cancer as a cause of voiding dysfunction, but prostate-specific antigen (PSA) testing may be considered in patients with a life expectancy of more than 10 years or when the presence of prostate cancer would change management 1.
From the Research
Definition of a Normal Prostate in Physical Examination
A normal prostate in a physical examination (PE) is typically defined as a prostate that is symmetric, without any palpable nodules or induration, and has a smooth surface [ 2 ].
Characteristics of a Normal Prostate
The characteristics of a normal prostate include:
- Symmetry of the lateral lobes
- No palpable nodules or induration
- Smooth surface
- Normal size and consistency [ 3 ]
Digital Rectal Examination (DRE) Findings
Digital rectal examination (DRE) is a valuable tool in the detection of prostate cancer [ 3 ]. A normal DRE finding is characterized by:
- No abnormality in prostate size, shape, or consistency
- No palpable nodules or induration
- Smooth surface [ 4 ]
Prostate-Specific Antigen (PSA) Levels
Prostate-specific antigen (PSA) levels are also an important factor in determining the normality of a prostate [ 5 ]. A normal PSA level is typically considered to be less than 4.0 ng/mL [ 5 ].
Diagnostic Value of DRE and PSA
The diagnostic value of DRE and PSA in detecting prostate cancer has been extensively studied [ 6 ]. While DRE can detect some cases of prostate cancer, PSA is a more sensitive and specific marker for detecting prostate cancer [ 6 ].
Key Findings
Key findings from the studies include: