A mechanistic, imaging-based classification of complete retrograde ejaculation: insights from dynamic transrectal...

Complete retrograde ejaculation (CRE), defined by total semen reflux into the bladder, currently lacks a standardized classification based on underlying pathophysiological mechanisms. Conventional diagnostic approaches are indirect and unable to visualize the dynamic, real-time dysfunction of the bladder neck (BN) and external urethral sphincter (EUS) during ejaculation.

To directly characterize the ejaculatory process in CRE using dynamic transrectal ultrasound (TRUS) and establish an etiology-specific, mechanism-driven classification system.

In this single-center study, consecutive eligible patients with CRE (n = 20) underwent real-time TRUS during stimulated ejaculation to assess BN and EUS function. The cohort comprised two etiological subgroups: diabetes mellitus (n = 10) and urethral stricture (n = 10). Observations were complemented by a literature-based characterization of the spinal cord injury (SCI) subtype. Detailed dynamic video analysis was performed on selected representative cases from each subgroup for illustration, while quantitative analysis and statistical comparison were conducted across the entire cohort.

Systematic TRUS imaging revealed three distinct functional phenotypes of CRE, each linked to a specific etiology: Coordination dysfunction type (SCI-associated): Characterized by delayed BN closure coupled with failure of EUS relaxation, leading to post-ejaculatory reflux. Incomplete closure type (stricture-associated): Marked by partial BN incompetence under conditions of high outflow resistance, resulting in significantly delayed reflux concurrent with ejaculation. Complete bladder neck failure type (diabetes-associated): Defined by an absent BN contraction from the onset, causing immediate and total semen reflux into the bladder.

Dynamic TRUS provides direct, real-time visualization of the ejaculatory mechanism in CRE, enabling quantification of dysfunction and revealing distinct pathophysiology across etiologies. This study proposes a novel three-type classification system-Coordination Dysfunction, Incomplete Closure, and Complete Bladder Neck Failure-which is grounded in both dynamic imaging and objective quantitative differences. This classification enhances diagnostic precision and lays the groundwork for personalized therapeutic strategies. However, this framework is derived from a single-center study with a limited cohort and incorporates a literature-based subtype (spinal cord injury); therefore, it requires validation in larger, prospective, and multicenter studies. Nevertheless, TRUS emerges as a valuable minimally invasive diagnostic tool for characterizing ejaculatory dysfunction.