Department of Obstetrics and Gynaecology, Sheba Medical Center, Ramat-Gan, Israel.
Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
Neurourol Urodyn. 2020 Jun;39(5):1401-1409. doi: 10.1002/nau.24353. Epub 2020 Apr 7.
The levator-urethra gap (LUG), the distance between the urethral lumen center and levator insertion on the inferior pubic rami, can be used for diagnosing levator avulsion, with a previously suggested cutoff of LUG ≥2.5 cm. The aim of this study is to determine an optimal cutoff value for LUG measurements in a high-risk patient population.
Women followed prospectively after sustaining obstetric anal sphincter injury underwent an interview pelvic examination questionnaires and four-dimensional-transperineal ultrasound examination. Levator avulsion was diagnosed on contraction using tomographic ultrasound imaging. Ultrasound datasets were analyzed offline at a later time blinded to previous data. LUG was measured on each side of the three central slices, yielding six measurements and the highest available value was obtained on each side. Different cutoffs were evaluated using receiver-operating characteristics (ROC) curve analysis and Youden's test. The cutoff was validated against symptoms and signs, and sonographic findings using logistic regression analysis.
A total of 618 complete datasets were available for analysis, median age 29 years, median body mass index of 23.4 kg/m , parity 1, and 26.4% instrumental deliveries. Youden's test and ROC curve analysis gave the best area under the curve of 0.869 for a cutoff of 2.305 (95% confidence interval, 0.839-0.9). Women diagnosed with avulsion based on this cutoff were more symptomatic, whereas using larger cutoffs missed more avulsion defects.
LUG measurement is useful but should be individualized to the population studied, in our case, in a high-risk population, 2.305 cm was the optimal cutoff. Using larger cutoffs may be more specific but is likely to miss more cases.
提肌-尿道间隙（LUG），即尿道管腔中心与耻骨下支提肌附着点之间的距离，可用于诊断提肌撕裂，先前建议的截断值为 LUG≥2.5cm。本研究旨在确定高危人群中 LUG 测量的最佳截断值。
前瞻性随访分娩时发生产科肛门括约肌损伤的女性，进行访谈、盆腔检查问卷和四维经会阴超声检查。收缩时使用断层超声成像诊断提肌撕裂。稍后在不了解先前数据的情况下离线分析超声数据集。在三个中央切片的每一侧测量 LUG，得到 6 个测量值，并获得每一侧的最大可用值。使用接收者操作特征（ROC）曲线分析和 Youden 检验评估不同的截断值。使用逻辑回归分析，根据症状和体征以及超声发现对截断值进行验证。
共有 618 个完整数据集可用于分析，中位年龄 29 岁，中位体重指数为 23.4kg/m，产次 1 次，器械分娩率为 26.4%。Youden 检验和 ROC 曲线分析得出的最佳曲线下面积为 0.869，截断值为 2.305（95%置信区间，0.839-0.9）。基于该截断值诊断为撕裂的女性症状更明显，而使用较大的截断值可能会漏诊更多的撕裂缺陷。
LUG 测量是有用的，但应根据所研究的人群进行个体化，在我们的情况下，在高危人群中，2.305cm 是最佳截断值。使用较大的截断值可能更具特异性，但可能会漏诊更多病例。
