Effect Of Rectal Examination Research Articles

Effect of Digital Rectal Examination and Needle Biopsy on Serum Total and Percentage of Free Prostate Specific Antigen Levels

We determined the effect of digital rectal examination and prostatic biopsy on serum total and free prostate specific antigen (PSA) concentrations in men undergoing screening for prostate cancer. In 93 men recruited from our PSA screening program we measured the serum concentrations of total and free PSA on 3 occasions during a 30-day interval before performing digital rectal examination. Total and free PSA measurements were repeated 1 and 24 hours after the rectal examination. Serum total and free PSA also was measured immediately before, and 1 hour, 24 hours and 1 week after prostatic biopsy in 30 men. Biological variation for total and free PSA was 14.7 and 14.0%, respectively. At 1 hour after rectal examination total and free PSA increased by more than the biological variation in 31 and 48% of the men, respectively. Increases were significantly greater in men whose initial PSA concentrations were less than 4.0 ng./ml. There was a dramatic increase in total and percentage of free PSA in all men 1 hour after prostatic biopsy. Increases in percentage of free PSA were greater in men whose biopsies revealed cancer. Total PSA remained elevated for at least 1 week in most men, while percentage of free PSA returned to within or less than the biological variation of the baseline level in 90% of the men by 24 hours. Digital rectal examination causes a modest increase in total and percentage of free PSA. Prostate needle biopsy causes more dramatic increases in both forms of PSA. Free PSA is preferentially released into the serum after prostatic manipulation and appears to be cleared more rapidly than complexed PSA. The differential return of the different PSA forms to baseline levels after biopsy could affect the use of measurements of the percentage of free PSA in clinical practice.

The effect of rectal examination on serum acid phosphatase levels in benign and malignant prostatic disease.

Summary Serum acid phosphatase was measured in patients with enlarged benign and malignant prostate before and after rectal examination. Amongst the patients with benign glands, rectal examination did not produce any significant false elevation of the enzyme. Rectal examination, however, caused a rise in the enzyme level in a few untreated cancer patients and in cancer patients who had become refractory to hormonal therapy. This rise would help rather than mislead in the diagnosis of malignant prostate and also in identifying treated patients who had become refractory to treatment. Thus, when serum acid phosphatase is properly determined, elevated levels should always arouse suspicion of malignant prostate or other lesions associated with high enzyme level even if such determination was preceded by rectal examination. There appears to be no merit in the teaching that the determination of serum acid phosphatase should be delayed after rectal examination.