The repeatability of measurements of male pelvic floor anatomy and function made from transperineal ultrasound images of healthy men and those before and after prostatectomy

Abstract

Aims: To investigate the inter-and intratester repeatability of measurement of the location and displacement of five pelvic landmarks related to pelvic floor muscles with transperineal ultrasound (TPUS) imaging recorded from healthy men and men before and after prostatectomy.Methods: TPUS images were selected from four different participant groups: healthy men, men awaiting prostatectomy, men 2 weeks after prostatectomy, and men 12 months after prostatectomy. On two separate occasions, two assessors with different levels of experience performed analysis of location and displacement of five pelvic landmarks in images made at rest and during voluntary contraction. A two-way mixed effects, single measurement, absolute agreement intraclass correlation coefficient (ICC) was used to investigate the repeatability. Results: Intertester reliability of all locations at rest for all groups was excellent (ICCs > 0.8) except for the craniocaudal coordinate of the ventral urethrovesical junction for men 2 weeks postprostatectomy and the anorectal junction for men with a cancerous prostate. Intertester reliability of the measurement of landmark displacement was acceptable (>0.5) for the dorsoventral axis of motion but not for the craniocaudal axis of motion for all landmarks across all groups. The more experienced assessor was consistently more repeatable. More deeply placed landmarks were more often excluded from analysis and had poorer reliability. Conclusions: Analysis of TPUS images across clinical groups is repeatable for both location and displacement of pelvic landmarks related to pelvic floor muscles when measures are made twice. Analysis experience, landmark depth and optimization of ultrasound settings appear to be important factors in reliability.

The influence of prostatectomy and body position on location and displacement of pelvic landmarks with pelvic floor muscle contraction

“…Landmark locations were identified in the rest frame of the first repetition in each position. Measures were made of the x ‐coordinates of MU and BP, and the x ‐ and y ‐coordinates and vector length relative to the origin of ARJ and UVJ as these have the greatest repeatability 17 and are meaningful for interpretation of PFM anatomy and function. Displacement was measured as a change in landmark location between rest and contract frames ( x ‐ [dorsal/ventral] and y ‐ [cranial/caudal] component, vector length) and averaged across the three repetitions.…”

“…Data were recorded in video format onto the US device (Aixplorer; Supersonic Imagine) and then exported for analysis. Measurement of pelvic landmark location and displacement with contraction provides a valid 16 and repeatable measure of PFM anatomy and function 17 …”

“…Image frames of each repetition were exported from the video data at two time points; (i) at rest before contraction (rest), and (ii) at the maximum displacement of landmarks during the 3‐s sustained contraction (contraction). The location of pelvic landmarks was defined in each image relative to a coordinate system with its origin at the dorsal pole of the pubic symphysis using previously described methods 18 according to the following definitions 17 (Figure 1): Mid‐urethra (MU): A point on the ventral border of the membranous urethra that undergoes the greatest dorsal movement during contraction. The dorsal motion of the MU correlates with SUS muscle activity 16 …”

“…Measurement of pelvic landmark location and displacement with contraction provides a valid 16 and repeatable measure of PFM anatomy and function. 17…”

The relationship between pre‐ and postprostatectomy measures of pelvic floor muscle function and development of early incontinence after surgery

“… 7 , 8 , 9 These striated muscles include the striated urethral sphincter (SUS), puborectalis (PR) (part of levator ani), and bulbocavernosus (BC) muscles. 9 , 10 Activity of these muscles can be assessed reliably 11 with transperineal ultrasound imaging (TPUS) 10 and recent investigations in healthy men 12 provide new insight into their contribution to continence during voluntary and automatic (e.g., cough) tasks. Prostatectomy removes much of the smooth muscle of the proximal urethra with the prostate 13 and surrounding connective tissues are cut.…”