Translabial Ultrasound Combined With Magnetic Resonance Imaging Assessing the Distensibility of Levator Ani Muscle With Unilateral High-Grade Tears.

Abstract

It is hypothesized that unilateral high-grade tears damage levator ani muscle (LAM) integrity and increase LAM distensibility. This study aimed to investigate how a unilateral high-grade tear caused overdistension of LAM and whether tear positions affect the degree of distension. A total of 209 women were screened by translabial ultrasonography. Then, 18 nulliparous women with an intact LAM and 26 postpartum women with unilateral levator ani defects were recruited. The anteroposterior diameter (AP), coronal diameter (LR), and hiatal area (HA) of the minimum levator hiatus were recorded and compared for assessing the distensibility. All 44 subjects underwent magnetic resonance imaging for the diagnosis of levator ani defect and detection of tear positions. Within the software, 3-dimensional pelvic models were developed from magnetic resonance imaging scans for the direct visualization and measurements. Of the 26 postpartum women, 15 were diagnosed with unilateral high-grade tear (caudad in 9, cephalad in 6). The △AP, △LR, and △HA (Valsalva-rest) values of women with a unilateral high-grade tear were significantly larger than those of women with an intact LAM (P < 0.05). The △AP, △LR, and △HA (Valsalva-rest) values of cephalad tears were larger than those of women with caudad tears (P < 0.05). A unilateral high-grade tear caused the overdistension of LAM. It was validated that cephalad tears caused higher degree of LAM distension than caudad tears.