OP14.05: How good is SmartPelvic software at measuring the levator hiatus?

One of the most important measures obtained on pelvic floor ultrasound is the area of the levator hiatus on Valsalva. Manual measurement involves substantial user effort, suggesting an opportunity for automation. Several manufacturers now offer AI-based automatic measurement of hiatal dimensions. This was an observational study in women attending a tertiary urogynecological unit in 2023. All had a 4D pelvic floor ultrasound with a Mindray Nuewa 9 system. The software includes single button detection and measurement of hiatal dimensions. Manual measurements were performed first, the automated method second to guarantee blinding. The figure shows a comparison of manual (left) and automated (right) measurements of the hiatus on Valsalva. Outliers (patients in whom measurements differed by 20% or more) were reviewed separately by the authors. 104 women were seen. Three automatic measurements were unavailable, leaving 101 for comparison. Means were 25.9 (SD 8.4) and 28.9 (8.6)cm2 for manual and automated measurements respectively. Correlations were high (Pearson's r = 0.842, P < 0.001) but the difference is significant (P < 0.001), with Bland Altman analysis showing a systematic error. In 22 cases the discrepancy between automatic and manual measurement was >=20%. These were reviewed separately. In most instances the discrepancy was due to excessively cranial placement of the region of interest (n = 16); in three cases the ROI was not centred, leading to mis- identification of the plane of minimal dimensions. Sub-optimal boundary conditions seemed responsible for a systematic over-estimate. The SmartPelvic software produces measurements that are strongly correlated with manually obtained data. It produces a systematic error however, partly due to sub- optimal boundary conditions, partly due to excessively cranial placement of the region of interest. Inexperienced users are advised to check measurements manually, especially in women with large rectocele or recto-enterocele. Development of this software is ongoing, suggesting that improvement is to be expected.