Comparison of end-fire and side-fire probes in transrectal ultrasound-guided transperineal prostate biopsy: a retrospective study

This study aimed to compare the diagnostic efficacy and clinical safety of commercially available end-fire probes with conventional side-fire probes for transrectal ultrasound-guided transperineal prostate biopsy (TR-TPPB). Additionally, differences in imaging features and intraoperative manipulation between the two probe types were systematically analyzed. These findings may provide a clinical foundation for improving the accessibility and equity of prostate cancer (PCa) diagnosis and treatment in resource-limited settings. This retrospective study included 256 patients who underwent TR-TPPB between 2016 and 2025, including 62 patients in the end-fire probe group and 194 patients in the side-fire probe group. Overall detection rates of PCa and clinically significant prostate cancer (csPCa) were compared between the two groups. PCa and csPCa detection rates were further analyzed according to prostate-specific antigen (PSA) strata. Per-core positive rates and postoperative complication rates were also compared. Multivariable logistic regression analysis was performed to evaluate the association between probe type and PCa detection. Sensitivity analyses were conducted to assess the robustness of the main findings. Differences in probe manipulation and ultrasound imaging characteristics between the two probe types were summarized descriptively. There were no significant differences between the end-fire and side-fire groups in overall PCa detection rate (41.94% vs 49.48%, p = 0.311) or csPCa detection rate (30.65% vs 40.72%, p = 0.178). In the PSA-stratified analyses, PCa and csPCa detection rates were not significantly different between groups across all PSA subgroups (all p > 0.05). Per-core positive rates did not differ significantly between groups at individual biopsy sites (all p > 0.05). However, the cumulative per-core positive rate was significantly lower in the end-fire group than in the side-fire group (22.66% vs. 28.49%, p = 0.0023). On multivariable analysis, probe type was not an independent predictor of PCa detection. Postoperative complication rates also did not differ significantly between the two groups (all p > 0.05). The results of the sensitivity analyses were consistent with the primary analysis, further supporting the robustness of these findings. End-fire probes showed no statistically significant differences in diagnostic performance or postoperative safety outcomes compared with conventional side-fire probes for TR-TPPB, and probe type did not emerge as an independent predictor for PCa detection. Although end-fire probes may require greater spatial orientation and operational coordination, no significant differences in biopsy outcomes were observed, suggesting that end-fire probes may represent a feasible alternative for TR-TPPB. Adoption of end-fire probes may help improve equitable access to PCa diagnosis and treatment in resource-limited healthcare settings.