Pelvic floor muscle contractility: digital assessment vs transperineal ultrasound

A significant reduction in hiatal area and anteroposterior diameter can be induced by pelvic floor muscle contraction, and this has been demonstrated using three-dimensional/four-dimensional (3D/4D) transperineal ultrasound (TPS) in a small group of women. Our objective was to correlate pelvic floor muscle contractility using digital assessment with the change in TPS hiatus measurements during maximum pelvic floor muscle contraction.

Nulliparous pregnant women were recruited from the antenatal clinic. Pelvic floor muscle contractility was assessed by digital palpation using the validated Modified Oxford Scale (MOS). Subsequently, women underwent 3D/4D TPS. Measurements of the hiatal area and anteroposterior diameter were taken from the rendered ultrasound images at rest and at maximum contraction, and differences in measurements were expressed as percentages. Spearman's rank (ρ) was used to assess the correlation.

Four hundred and fifty-nine assessments were performed, of which 268 were from women at around 36 weeks' gestation, and 191 were from women following delivery at 3 months postpartum. The overall correlation between MOS and TPS was found to be ρ = 0.47 for hiatal area (P < 0.001) and ρ = 0.51 for hiatal anteroposterior diameter (P < 0.001).

Digital palpation using MOS and TPS can both be used as tools to assess pelvic floor muscle contractility. Although MOS is a simple clinical tool without the need for any equipment, TPS can provide good visual biofeedback when training patients in pelvic floor muscle exercises. As TPS is non-intrusive, it may be the method of choice for some women.