Introduction: Transperineal mapping biopsy (TPMB) is becoming increasingly popular in the diagnose of prostate cancer because of its low infection rate compared to transrectal biopsy. This approach is also being favored by several fusion biopsy technologies. However, controversy exists as to the optimal number of specimens (cores) to take with the bias to retrieve fewer to limit morbidity. There are multiple reports of an increase in urinary side effects and erectile dysfunction when a comprehensive biopsy is done. We sought to identify which of these complications occur by analyzing a prospective database which utilized standardized reporting instruments.
Methods: 242 men with suspicion of prostate cancer had TPMB which was performed under anesthesia using a template with biopsies taken at 5 mm intervals. Prior to biopsy patients had residual urine (Ures) determined by pelvic ultrasound and completed IPSS and SHIM questionnaires. After TPMB the urinary catheter was removed in the recovery room or the following day if the prostate volume (PV) was greater than 50 cc. Post-TPMB IPSS and Vres were measured at 1 week while SHIM at 1 month. Differences in these variables were determined by 2-tailed t-test and associations of continuous and categorical variables to urinary retention (Uret, reinsertion of catheter) were calculated by ANOVA and chi-square tests.
Results: Mean (range) age, BMI, PV and number of biopsies were 67.1 years (47-87), 27.7 (18-38.1), 48.6 cc (14-137) and 48.5 (23-86). 19 (7.8%) developed urinary retention which resolved in 1, 2 and 3 days in 12 (63.2%), 6 (31.6%) and 1 (5.2%). Older age and higher BMI were not associated with retention while larger PV (71.8 vs, 46.6 cc, p<0.001) and increased number of biopsies 57.4 vs 47.7 (p < 0.001) were. Limiting the number of biopsies to 40 or less reduced retention risk from 10.7 to 1.4% (p=0.014, OR 8.6). Two (0.8%) men developed infection (1 epididymitis and 1 sepsis) both of which required hospitalization. While perineal bruising was common (206-85.1%), gross hematuria was not (6-2.5%). Mean change in Vres, IPSS and SHIM were 4.2 cc, 1.7 and -0.8 (p < 0.001). 86.3% of men with a SHIM > 17 prior to biopsy maintained a SHIM > 17 afterwards (p < 0.001).
Conclusions: TPMB is a safe procedure with low infection and hospitalization rates. The main complication is urinary retention which occurred in 7.8%. Keeping the number of biopsies to 40 or less reduced this rate to 1.4%. Most men do not experience a decline in erectile function. Urologist should consider the transperineal biopsy approach when evaluating a patient for prostate cancer.
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