Younger Age and Anal Sphincter Tone Linked to Biopsy Vasovagal Reactions

Younger age and elevated anal sphincter tone measured during digital rectal examination are significantly associated with vasovagal reactions in patients undergoing transrectal ultrasound-guided prostate biopsy, according to findings from a retrospective cohort study published in BMC Urology. Investigating clinical characteristics linked to procedural susceptibility, researchers identified these two clinical factors as key variables connected to the onset of peri-procedural vasovagal events.

The single-center retrospective study evaluated records from 663 consecutive patients who underwent transrectal ultrasound-guided prostate biopsies between May 2022 and May 2024. Overall, vasovagal reactions were documented in 30 of the 663 individuals, representing an incidence rate of 4.52 percent within the investigated patient population. Across the entire cohort, factors linked to susceptibility were analyzed to better clarify peri-procedural complications that remain insufficiently understood.

All 663 consecutive patients followed a standardized pre-procedural analgesic regimen before undergoing biopsy. Specifically, each participant received 100 mg (2 mL) of tramadol administered via intramuscular injection approximately 30 minutes prior to the procedure. Physical assessment of anal sphincter tone was standardized through digital rectal examination performed and graded by the same senior urologist, who evaluated resistance during gentle finger insertion while patients were explicitly not instructed to voluntarily contract.

Using conventional multivariable logistic regression with patient age analyzed as a continuous variable, the researchers found that each 5-year decrease in age was associated with higher odds of experiencing a vasovagal reaction, yielding an adjusted odds ratio of 1.379 with a 95 percent confidence interval ranging from 1.139 to 1.668 (P = 0.001). Concurrently, high anal sphincter tone assessed via digital rectal examination demonstrated a pronounced association with vasovagal reactions, producing an adjusted odds ratio of 16.315 with a 95 percent confidence interval between 4.867 and 54.685 (P < 0.001).

To evaluate potential estimation bias, the investigators applied Firth bias-reduced penalized logistic regression as a sensitivity analysis. This model confirmed consistent estimates, showing an odds ratio of 1.367 per 5-year decrease in age (95 percent confidence interval: 1.142 to 1.667) and an odds ratio of 14.141 for high digital rectal examination-assessed sphincter tone (95 percent confidence interval: 5.182 to 53.126). In assessing model discrimination, the apparent area under the receiver operating characteristic curve reached 0.8393, while internal validation via 2,000 bootstrap resamples generated a bootstrap-corrected value of 0.8383.

The study authors highlighted several key methodological boundaries, emphasizing that the retrospective investigation was restricted to a single clinical center and lacked external validation in outside cohorts. Given these constraints, the investigators concluded that their findings require confirmation through prospective, multicenter studies that utilize standardized criteria for vasovagal reaction assessment along with more objective or reproducible techniques for evaluating anal sphincter tone.

Subject of Research: Clinical factors associated with vasovagal reactions during transrectal ultrasound-guided prostate biopsy

Article Title: Age and DRE-assessed anal sphincter tone are associated with vasovagal reactions during transrectal ultrasound-guided prostate biopsy

Article References: Peng, P., Zheng, L., Cheng, B., Zheng, Z., Xu, Y., Peng, H., & Qiu, Q. (2026). Age and DRE-assessed anal sphincter tone are associated with vasovagal reactions during transrectal ultrasound-guided prostate biopsy. BMC Urology. https://doi.org/10.1186/s12894-026-02384-y

Image Credits: AI Generated

DOI: 10.1186/s12894-026-02384-y

Keywords: prostate biopsy, transrectal ultrasound, vasovagal reactions, anal sphincter tone, digital rectal examination, urology, tramadol, retrospective cohort study, DRE-assessed, anal, sphincter, tone