Efficacy of PSA in the detection of carcinoma of the prostate in patients presenting with acute urinary retention

Objectives: A temporary elevation in serum-prostate specific antigen (PSA) levels has been reported in association with acute urinary retention. In sp ite of this, it is not uncommon for clinicians to assay PSA at the time a p atient presents with acute urinary retention, We sought to evaluate whether this practice can be justified. Patients and method: Fifty-four patients, aged between 55 and 89 years, who presented to a single institution with ac ute urinary retention were studied, A PSA assay was performed on admission and a record made of the prostatic size as assessed by digital rectal exami nation. All patients underwent a trial without catheter, those that failed to void underwent prostatic surgery whilst all others were followed up as o utpatients, Results: Five patients were found to have prostatic carcinoma, three following transurethral resection of the prostate (TURP) and two foll owing needle biopsy, performed because of persistent elevation of the PSA, A significant elevation in the PSA was associated with acute urinary retent ion, with only 15 (28%) patients having a PSA of 4.0 ng/ml or less, This el evation reduced the sensitivity of PSA in detecting carcinoma of the prosta te; even with a cut-off of 20ng/ml, the positive predictive value of the te st was only 21%. Conclusions: A PSA assay should not be performed at the ti me of presentation with acute urinary retention as it may lead to unnecessa ry investigations and anxiety for the patient, For those in whom a PSA assa y is desirable a delay of 2 weeks should be allowed prior to sampling, as t he half-life of PSA is known to be 2-3 days.