['To determine if transrectal ultrasound-guided (TRUS) prostate biopsy causes dissemination of prostate cells into the circulation as assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) targeted against prostate-specific antigen (PSA) mRNA.', 'RT-PCR PSA analysis was performed before and after prostatic invasive manipulations in 50 men. The cases consisted of 47 patients with TRUS and 3 with transurethral resection of the prostate (TURP). Peripheral venous blood (8 mL) was drawn before and within 60 minutes after the procedure. Total RNA was extracted from fractionated blood, and RNA/cDNA quality was assured and normalized with beta-actin RT-PCR analysis. The PSA primers hybridize exons 3 and 5, yielding a 254-basepair PCR product. The assay detects one LNCaP cell in a background of 100 million lymphoid cells and a single copy of PSA cDNA on an ethidium bromide gel.', 'Among the 47 TRUS cases, 43 specimens were evaluable. Forty-two cases were negative before biopsy; among these patients, 4 cases (9.5%) converted to a positive RT-PCR PSA result. Both benign and malignant TRUS biopsies were capable of producing a positive RT-PCR PSA signal implicating iatrogenic dissemination of cells. All three TURP cases converted from a negative to a highly intense positive signal.'] Does transrectal ultrasound-guided biopsy cause hematogenous dissemination of prostate cells as determined by RT-PCR?