Three- and Four-Dimensional Pelvic Floor Ultrasound in Chronic Pelvic Pain: Evidence, Technical Considerations, and a Proposed Framework

Chronic pelvic pain (CPP) is a heterogeneous condition in which visceral, musculoskeletal, neuropathic, and pain-processing contributors often overlap. Pelvic floor ultrasound can depict morphology and movement, but its CPP-specific evidence base remains limited. This targeted narrative review summarizes direct CPP evidence; evidence from endometriosis, dyspareunia, myofascial pain, and methodological pelvic floor cohorts; and the technical distinctions among transperineal/translabial and transvaginal routes, static three-dimensional (3D) volumes, real-time four-dimensional (4D) assessment, multiplanar reconstruction, and tomographic ultrasound imaging (TUI). Direct evidence includes one reliability study in 49 women with CPP, one small uncontrolled treatment cohort, and a recent cross-sectional study of 747 women; none establishes a diagnostic threshold or validates an imaging phenotype. We therefore propose, rather than validate, a structured acquisition and reporting framework that specifies patient preparation, probe pressure, rest-contraction-Valsalva maneuvers, quality control, pain-limited modifications, measurements, and uncertainty language. Reduced hiatal excursion, asymmetry, or discontinuity should be reported as observations, not as proof of increased tone or a pain mechanism. Clinical interpretation requires symptom reproduction, pelvic floor examination, and, when indicated, manometry, electromyography, magnetic resonance imaging, or disease-specific imaging. Prospective CPP-specific validation and reliability studies are required before routine diagnostic use.