Risk Factors for Severe Perineal Tear: Can We Do Better?

Abstract

Our aim was to investigate the risk factors associated with severe perineal tears defined as either third- or forth-degree tears and, ultimately, find strategies for prevention. We carried a retrospective analysis of a computerized perinatal database, collected prospectively, from a single county hospital between January 1, 1993 and June 30, 1998. Singleton vaginal vertex deliveries were analyzed for potential risk factors using univariate and multiple logistic regression analysis including all two-way interactions. Severe perineal tear occurred in 1905 (8.2%) of 23,244 vaginal deliveries. In the multiple logistic regression analysis, the following factors carried a significantly higher risk for severe laceration: midline episiotomy, primary vaginal delivery, use of pudendal block, forceps deliveries, and birth weight more than 4000 g. The study of interactions demonstrated that mediolateral episiotomy was associated with an increased risk for severe tear only during the first vaginal delivery, but not during a repeat vaginal delivery. Our data suggest that primary vaginal delivery, fetal weight above 4000 g, and the use of pudendal analgesia can help identify in advance patients at highest risk for severe perineal tear. During the delivery of these patients usage of vacuum (instead of forceps) and restricting the use of midline episiotomy might reduce the incidence of severe perineal tear. In cases where episiotomy seems crucial, the use of a mediolateral episiotomy may reduce the likelihood of severe perineal tear.

Anal sphincter lacerations and upright delivery postures—a risk analysis from a randomized controlled trial

“…In the present trial, a sitting position was associated with more frequent episiotomies and consequently less subjects had an intact perineum. Compared to midline episiotomy, a mediolateral incision has been associated with a decreased risk of sphincter lacerations [24]; however, there is evidence suggesting that mediolateral episiotomies also substantially increase the risk of sphincter laceration during delivery [25]. In the present study, a mediolateral episiotomy was associated with grade III-IV obstetrical tears at logistic regression analysis; however, the number of sphincter tears were insufficient to allow for reliable data.…”

Determinants of the length of episiotomy or spontaneous posterior perineal lacerations during vaginal birth

“…Larger cohort studies of perineal measurements during vaginal birth are needed to further clarify these findings. There is also considerable genetic and ethnic variation in the topography, structural morphology, and functional elasticity of the female perineum [1,2,8,11,[19][20][21]25]. Significant ethnic differences in perineal measurements were not, however, observed in our study population most likely because of the small sample size in each ethnic subgroup.…”

“…However, the value of this procedure is increasingly questioned because of the associated postoperative morbidity in the absence of clearly defined evidence for efficacy [13][14][15][16][17][18]. Paradoxically, episiotomy, particularly if median, is associated with occurrence of posterior perineal tears involving the anal sphincter in most [1,3,5,[12][13][14][15][16][17][19][20][21][22] but not all [2,[6][7][8]23] studies. Episiotomy also decreases perineal muscle strength and performance during the postpartum period more than does spontaneous posterior perineal laceration because of greater tissue disruption [4,9,16,24].…”

“…Hence, a ''short'' or ''long'' perineum is often cited in the literature as a risk factor for severe perineal injury without a clear description of the normal measurements of the perineum [3,20,21,25]. The optimum length of episiotomy or its relationship to perineal length is also rarely, if ever, described in obstetric or operative texts [10].…”

Episiotomy and the Development of Postpartum Dyspareunia and Anal Incontinence in Nulliparous Females

“…Previous studies have reported that episiotomies cause 3 rd and 4 th degree perineal lacerations. This situation occurs less frequently with medial lateral episiotomies [9,10]. In 9-26% of patients with median episiotomies, 3 rd and 4 th degree lacerations have been observed.…”