Geller E J, Robinson B L, Matthews C A, Celauro K P, Dunivan G C, Crane A K, Ivins A R, Woodham P C, Fielding J R
Division of Female Pelvic Medicine and Reconstructive Surgery, Department of Ob/Gyn, University of North Carolina at Chapel Hill, Chapel Hill, USA,
Int Urogynecol J. 2014 May;25(5):631-6. doi: 10.1007/s00192-013-2273-x. Epub 2013 Dec 12.
Shortened perineal body (PB) is associated with an increased risk of ultrasound-detected obstetric anal sphincter tear. The objective was to determine if shortened perineal body length (<3 cm) is a risk factor for ultrasound-detected anal sphincter tear at first delivery.
Pregnant nulliparous women were recruited over 18 months. At 35-37 weeks' gestation and 6 weeks' postpartum perineal body length (PB) was measured and subjects completed quality of life questionnaires. Primary outcome was ultrasound-diagnosed anal sphincter tear at 6 weeks postpartum. Secondary outcomes were also assessed. A priori power analysis determined that 70 subjects were needed to detect a difference in anal sphincter tear based on a PB cut-off of 3 cm.
Seventy-three subjects completed the study. Mode of delivery was 69.9% spontaneous vaginal, 15.1% operative vaginal, and 15.1% labored cesarean. There were 25 anal sphincter abnormalities (34.2%) seen on ultrasound: 11 (15.1%) internal or external sphincter tears, 3 (4.1%) internal sphincter atrophy, 6 (8.2%) external sphincter thinning, and 7 (9.6%) external sphincter scarring. Only the 11 sphincter tears qualified as abnormal for the primary outcome. In the vaginal delivery group 16.4% (10 out of 61) had a sphincter tear, compared with 8.3% (1 out of 12) in the labored cesarean group (p = 0.68). Women with PB < 3 had a significantly higher rate of ultrasound-diagnosed anal sphincter tear (40.0% vs 11.1%, p = 0.038). When comparing women with and without sphincter tear, there was a significant difference in mean antepartum PB (3.1 vs 3.7 cm, p = 0.043).
A shortened perineal body length in primiparous women is associated with an increased risk of anal sphincter tear at the time of first delivery.
会阴体（PB）缩短与超声检测到的产科肛门括约肌撕裂风险增加相关。目的是确定会阴体长度缩短（<3 cm）是否是首次分娩时超声检测到肛门括约肌撕裂的危险因素。
在18个月内招募未生育的孕妇。在妊娠35 - 37周和产后6周测量会阴体长度（PB），并让受试者完成生活质量问卷。主要结局是产后6周超声诊断的肛门括约肌撕裂。还评估了次要结局。预先的功效分析确定需要70名受试者来检测基于3 cm的PB临界值的肛门括约肌撕裂差异。
73名受试者完成了研究。分娩方式为自然阴道分娩69.9%，手术阴道分娩15.1%，剖宫产15.1%。超声检查发现25例肛门括约肌异常（34.2%）：11例（15.1%）内外括约肌撕裂，3例（4.1%）内括约肌萎缩，6例（8.2%）外括约肌变薄，7例（9.6%）外括约肌瘢痕形成。只有11例括约肌撕裂符合主要结局的异常标准。阴道分娩组中16.4%（61例中的10例）有括约肌撕裂，相比之下，剖宫产组为8.3%（12例中的1例）（p = 0.68）。PB < 3的女性超声诊断的肛门括约肌撕裂率显著更高（40.0%对11.1%，p = 0.038）。比较有和没有括约肌撕裂的女性时，产前平均PB有显著差异（3.1对3.7 cm，p = 0.043）。
初产妇会阴体长度缩短与首次分娩时肛门括约肌撕裂风险增加相关。
