Rosen Hadar, Barrett Jon, Okby Rania, Nevo Ori, Melamed Nir
Maternal-Fetal Medicine Division, Department of Obstetrics and Gynaecology, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada.
Int Urogynecol J. 2016 May;27(5):757-62. doi: 10.1007/s00192-015-2842-2. Epub 2015 Sep 30.
Risk factors for obstetric anal sphincter injuries (OASIS) have been well-established in singleton pregnancies. Considering the unique characteristics of twin deliveries, our aim was to identify risk factors for OASIS that are specific to twins.
A retrospective study of all vaginal twin deliveries in a tertiary center between 2000 and 2014. Women who experienced OASIS (the OASIS group) were compared with those whose anal sphincter was intact (controls).
Overall 717 women were eligible for the study, of whom 20 (2.8 %) experienced OASIS. Women in the OASIS group were more likely to be nulliparous (95.0 % vs 53.7 %, p < 0.001) and were characterized by a higher gestational age at delivery (36.1 ± 2.5 vs 34.6 ± 3.3, p = 0.04), a higher birth weight for both twin A and twin B (2,507 ± 540 g vs 2,254 ± 525 g, p = 0.03, and 25,49 ± 420 g vs 2,232 ± 606 g, p = 0.004 respectively), and a higher rate of episiotomy (40.0 % vs 14.2 %, p = 0.001), instrumental delivery for twin A (80.0 % vs 13.5 %, p < 0.001) or twin B (80.0 % vs 18.7 %, p < 0.001), and inter-twin delivery interval of over 30 min (20.0 % vs 7.5 %, p = 0.04). The only factor that remained significant on multivariate analysis was instrumental delivery: forceps delivery of twin A (OR = 8.8, 95 % CI 2.6-30.1), vacuum extraction of twin A (OR = 9.2, 95 % CI 2.6-34.6), and forceps delivery of twin B (OR = 15.4, 95 % CI 4.9-48.6). In women with certain combinations of risk factors the risk of OASIS was as high as 30 %.
The overall rate of OASIS in twins is low and instrumental delivery, especially by forceps, is a risk factor.
单胎妊娠中产科肛门括约肌损伤（OASIS）的危险因素已得到充分证实。考虑到双胎分娩的独特特征，我们的目的是确定双胎特有的OASIS危险因素。
对2000年至2014年在一家三级中心进行的所有阴道双胎分娩进行回顾性研究。将发生OASIS的女性（OASIS组）与肛门括约肌完整的女性（对照组）进行比较。
共有717名女性符合研究条件，其中20名（2.8%）发生了OASIS。OASIS组的女性更可能为初产妇（95.0%对53.7%，p<0.001），其特点是分娩时孕周较大（36.1±2.5对34.6±3.3，p=0.04），双胞胎A和双胞胎B的出生体重均较高（分别为2507±540g对2254±525g，p=0.03，以及2549±420g对2232±606g，p=0.004），会阴切开率较高（40.0%对14.2%，p=0.001），双胞胎A器械助产率较高（80.0%对13.5%，p<0.001）或双胞胎B器械助产率较高（80.0%对18.7%，p<0.001），以及双胎分娩间隔超过30分钟（20.0%对7.5%，p=0.04）。多因素分析中唯一仍具有显著性的因素是器械助产：双胞胎A产钳助产（OR=8.8，95%CI 2.6-30.1）、双胞胎A真空吸引助产（OR=9.2，95%CI 2.6-34.6）以及双胞胎B产钳助产（OR=15.4，95%CI 4.9-48.6）。在具有某些危险因素组合的女性中，OASIS风险高达30%。
双胎中OASIS的总体发生率较低，器械助产尤其是产钳助产是一个危险因素。
