OC262: Quantification of the pelvic floor contraction using 3D/4D translabial ultrasound

Abstract

Objectives: Magnetic resonance imaging (MRI) is the gold standard for the investigation of pelvic floor anatomy and function. The objective of this study was to compare biometric measures obtained by 3D ultrasound and MRI. Methods: In this prospective study, translabial 3D ultrasound and multiplanar MRI were used to assess pelvic floor anatomy in 27 nulliparous female volunteers. 3D ultrasound was performed using a GE Kretz Voluson 730/730 Expert system; MR images were obtained using a Siemens MAGNETOM Avanto 1.5-T scanner. All subjects were imaged supine and after voiding for both modalities. Data were acquired at rest, on pelvic floor muscle contraction and on maximal Valsalva. Results: All subjects were asymptomatic for pelvic floor dysfunction. Mean age was 29.3 (21–41) years, mean body mass index was 22.4 (18–29). Measures of hiatal diameters and areas obtained on MRI and 3D ultrasound were distributed normally. Sagittal hiatal diameters correlated at r = 0.533, P = 0.005 at rest, with ranges of 3.8–6.0 cm for MRI and 3.9–5.7 cm for ultrasound. On Valsalva, these figures were r = 0.658, P < 0.001, with ranges of 2.9–8.0 cm on MRI and 3.7–7.3 cm on ultrasound. On pelvic floor muscle contraction, the correlation was r = 0.503, P = 0.01 with ranges of 3.0–5.9 cm on MRI and 3.1–4.7 cm on ultrasound. As regards area measurements, correlations were r = 0.648 at rest and r = 0.542 on Valsalva (P < 0.01). Ranges were 9.1–18.1 on MRI vs. 9.2–17.8 on ultrasound at rest and 6.53–36.5 cm2 on MRI vs. 10.7–27.9 cm2 on ultrasound on Valsalva. There was a tendency for larger MRI measurements on Valsalva (P < 0.01 for area and midsagittal diameter). Repeatability measures were good to excellent for both methods. Conclusions: In this study of 3D ultrasound and MRI of the levator hiatus, correlations between methods were moderate but highly significant. MRI seemed to yield higher measurements on Valsalva, suggesting difficulties in identifying the plane of minimal dimensions during maneuvers that led to displacement of this plane.