TRANSPERINEAL ULTRASOUND: Pessary treatment and image analysis advancements

Abstract

In this thesis we assess the added value of transperineal ultrasound (TPUS) in pessary treatment for pelvic organ prolapse (POP) and set out to improve the anatomical and functional assessment of the levator ani muscle (LAM).

In Chapter 1, we report prevalence, risk factors and clinical manifestations of POP. In addition, we describe how POP is assessed and treated with focus on pessary treatment. Furthermore, LAM anatomy and the technique for LAM avulsion and levator hiatal area (HA) assessment with TPUS are described.

In Chapter 2, we present a meta-analysis of the predictive parameters for unsuccessful pessary fitting for POP up to three months follow-up. We observe that younger age, higher BMI, pre-menopausal status, de novo stress urinary incontinence, prior surgery, solitary predominant posterior compartment POP, presence of colorectal symptoms, shorter total vaginal length, wide introitus, LAM avulsion and larger HA on maximum Valsalva are associated with unsuccessful pessary fitting. Furthermore, we conclude that more research is needed to investigate the added value of TPUS in pessary fitting process and the association of anatomical parameters with specific reasons for unsuccessful pessary fitting.

In Chapter 3, we assess the association of clinical, demographical and TPUS parameters with specific reasons for unsuccessful pessary fitting. We observe that complete LAM avulsion and a small ring pessary with respect to the levator HA in Valsalva are predictors of pessary dislodgment, while solitary predominant posterior compartment POP is a predictor of failure to relieve POP symptoms.

In Chapter 4, TPUS is used to predict the right ring pessary size based on the levator HA. We conclude that a ring pessary size that produces a Valsalva HARP-ratio (i.e., levator HA in Valsalva divided by the ring pessary size) > 5.00 has a higher risk of dislodgment/failure to relieve POP symptoms.

In Chapter 5, we assess the functional changes of the puborectalis muscle (PRM) three months after successful pessary fitting. In the entire sample the relative difference between levator HA at rest and in contraction (i.e., displacement in contraction) increases by 2.1%. In women without complete LAM avulsion levator HA at rest increases by 4.1% and displacement in contraction increases by 2.7%. We conclude that PRM function changes three months after successful pessary fitting, especially in women without complete avulsion.

In Chapter 6, we use deep learning to automatically identify the plane of minimal hiatal dimensions and automatically segment levator HA and levator diameters with interclass correlation coefficients (ICC) of 0.94 (0.87-0.97), 0.92 (0.78-0.97), and 0.82 (0.66-0.91) for levator HA, anteroposterior diameter and coronal diameter, respectively.

In Chapter 7, we identify and describe the appearance of the LAM subdivisions on TPUS, which has not been reported in literature before. This work is the first step in the direction of static analyses of the LAM in 3D and of in vivo 3D biomechanical analyses of LAM function.

In Chapter 8, we discuss our main results and their clinical implication. Lastly, we report strength and limitations of our original studies and delineate future applications of TPUS to pessary treatment.