Transperineal ultrasound to estimate the appropriate ring pessary size for women with pelvic organ prolapse

This was a prospective case–control study. Women with symptomatic POP choosing pessary treatment were included. Women who were already using a pessary at intake assessment and those who started the pessary fitting process more than 4 weeks after intake ultrasound assessment were excluded. All women underwent an interview, clinical examination, and 3D/4D TPUS. POP was assessed using the Pelvic Organ Prolapse Quantification system (POPQ) [6].

Pessary fitting was performed according to our standard clinical practice, similar to that described in the literature [7‐12], in which the appropriate pessary size is estimated based on clinical examination (i.e., POPQ and digital assessment of fornix posterior width and LAM support). “Fitting trial” was defined as the event of a woman being fitted with a specific ring pessary size, leaving the clinic with the pessary in place, and attending the 2- to 4-week follow-up, in which the success of the fitting trial was assessed. Only fitting trials of ring pessaries (with or without support) were assessed, because the ring pessary is the type most commonly used in our clinic (CooperSurgical®, Milex® pessaries). A fitting trial was considered successful if the specific ring pessary size the woman was fitted with was still in situ at follow-up, if she was satisfied with it, and if she decided to continue using it. On the contrary, if she decided not to continue using the specific ring pessary size she was fitted with, it was considered unsuccessful. In this case, the woman was asked which one of the following was the reason for failure: dislodgment (defined as a pessary that did not stay in place because it fell down or was expelled), failure to relieve POP symptoms, pain/discomfort, increased/de novo urinary incontinence, or other reasons [7]. In the case of unsuccessful fitting, the woman was offered an additional fitting trial with an adjusted ring pessary size. If she agreed, a new pessary was inserted and a 2- to 4-week follow-up was scheduled. One patient could thus have more than one fitting trial, each one with a different ring pessary size. This process continued until an appropriate ring pessary size was found or until pessary treatment was considered not suitable for the woman and a different treatment was chosen. For every fitting trial, the size of the pessary diameter was recorded in centimeters.

At intake, TPUS was performed in supine position after bladder emptying. Women were instructed to perform maximal pelvic floor contraction and maximal Valsalva maneuver according to the method described by Dietz [13]. We used a Philips Epiq 7G machine with a X6–1 transducer covered with a gel pad 2 cm thick, and a glove. The gel pad was used to create more distance between the transducer and the woman, so that the LAM could be fully visible within the opening angle on the coronal plane. TPUS volumes analyzed in the current study were acquired without pessary in situ.

An in-house tool was developed in MeVisLab 3.0.2. [14] for TPUS volume assessment, which was done by one observer (CM) blinded to all clinical data. As described in the literature [15], hiatal area at rest (HArest), maximal pelvic floor contraction (HActx), and maximal Valsalva maneuver (HAval) were manually segmented at the plane of minimal hiatal dimensions. In addition, the presence of LAM avulsion was assessed on volumes obtained at maximum contraction. Complete avulsion was defined as a levator–urethra gap of ≥25 mm on the three central slices and could be unilateral or bilateral [15].

The levator hiatal area to pessary size (HARP) ratio was calculated as levator HA (cm²) divided by ring pessary size (cm). The HARP ratio at rest (rest HARP ratio), maximum contraction (contraction HARP ratio), and maximum Valsalva (Valsalva HARP ratio) were calculated for each fitting trial. To the best of our knowledge, no studies have been published in which the HARP ratio is used. Therefore, no formal sample size could be calculated, and this work should be considered an exploratory study.

Rest HARP ratio, contraction HARP ratio, and Valsalva HARP ratio of successful trials and unsuccessful trials, which were separately analyzed based on the reason for failure, were compared. A Welch’s ANOVA and a Games–Howell post hoc test were used if the data were normally distributed and if there were no outliers, but the assumption of homogeneity of variances for a one-way ANOVA was violated. A Kruskal–Wallis test was run if the data were not normally distributed or if there were outliers in the data. Receiver operating characteristic (ROC) curves of the HARP ratios were constructed in the prediction of successful trials. As the dimension of levator HA can be influenced by the presence of complete avulsion [16], ROC curves were also constructed for trials of women with and without complete avulsion. In addition, the cut-off that optimized sensitivity and specificity was identified. Based on this cut-off two groups were defined (i.e., HARP ratio ≤ cut-off and HARP ratio > cut-off) and their association with fitting trial success was tested with a Chi-squared test. Last, the relative risk (RR) of an unsuccessful/successful trial based on the HARP ratio ≤ cut-off or > cut-off was calculated. The statistical analysis was conducted using IBM v 27 SPSS software.