Risk Factors For Sphincter Injury Research Articles

Anal Sphincter Injury Associated with Vaginal Twin Delivery

Obstetric anal sphincter injury remains the most common cause of fecal incontinence in women, and research in twin pregnancies is sparse. This study aimed to examine risk factors for sphincter injury in twin deliveries over a 10-year period. This was a retrospective study of twin vaginal deliveries in a tertiary-level hospital over 10 years. We examined the demographics of women who had a vaginal delivery of at least one twin. Logistic regression analysis was used to examine risk factors. There were 1,783 (2.1%) twin pregnancies, of which 556 (31%) had a vaginal delivery of at least one twin. Sphincter injury occurred in 1.1% (6/556) women with twins compared with 2.9% (1720/59,944) singleton vaginal deliveries. Women with sphincter injury had more instrumental deliveries (83.3 vs. 27.6%; p = 0.008). On univariate analysis, only instrumental delivery was a significant risk factor (odds ratio: 2.93; p = 0.019). Sphincter injury occurs at a lower rate in vaginal twin pregnancies than in singletons. No twin-specific risk factors were identified. Discussion of the risk of sphincter injury should form part of patient counseling with regard to the mode of delivery.

Anal sphincter injury associated with shoulder dystocia

Objective: Shoulder dystocia is an obstetric emergency, occurring in 0.2–3% of vaginal deliveries. Research has mainly focused on the neonatal morbidity arising from shoulder dystocia, such as brachial plexus injury and hypoxic-ischemic encephalopathy. Maternal morbidity is thought to be increased with shoulder dystocia though is much less commonly reported. Obstetric anal sphincter injury remains the leading cause of fecal incontinence in women and shares several antenatal and intrapartum risk factors with shoulder dystocia. The aim of this study was to identify risk factors for sphincter injury associated with shoulder dystocia.Methods: This retrospective analysis included all cases of shoulder dystocia from 2008 to 2017 in a single unit in North-East Ireland. Maternal characteristics and delivery outcomes were analyzed. Two groups were compared, those with and without anal sphincter injury in our shoulder dystocia cohort and those with and without shoulder dystocia, regardless of sphincter injury. Univariate and multivariate logistic regression models were used to examine risk factors for sphincter injury.Results: There were 24,159 singleton cephalic vaginal deliveries over the study period, with 495 cases of shoulder dystocia, giving an incidence of 2.1% (495/24 159). The rate of anal sphincter injury in those with shoulder dystocia was 4.4% (22/495), with 7.6% (12/158) in nulliparas, and 3.0% (10/337) among multiparas. Women with sphincter damage were more likely to be nulliparous than those with an intact sphincter (54.5% [12/22] vs. 30.9% [146/473]; p = .036) and have an operative vaginal delivery (72.7% [16/22] vs. 39.1% [185/473]; p = .004). Episiotomy was more common in those with a sphincter injury (68.2% [15/22] vs. 37.0% [175/473]; p = .007). On univariate regression analysis, nulliparity (OR 2.69) and operative vaginal delivery (OR 4.15) were associated with sphincter injury. No risk factors were identified on multivariate regression analysis.Discussion: In our population, the risk of anal sphincter injury with shoulder dystocia is 4.4%. Risk factors include nulliparity and operative vaginal delivery. After controlling for other factors, these associations became nonsignificant. Further research into sphincter injury at shoulder dystocia is warranted.

Single prior caesarean section and risk of anal sphincter injury.

Injury to the anal sphincter at vaginal delivery remains the leading cause of faecal incontinence in women. Previous studies reported an increased incidence of obstetric anal sphincter injury (OASI) in women attempting vaginal birth after caesarean section (VBAC). The aim of the paper was to establish whether women in their second pregnancy, with one previous uterine scar, are at a higher risk of OASI compared with nulliparous women. All primiparous and secundiparous women with a previous caesarean section who delivered from 2008 to 2017 were analysed in a single-centre retrospective study. The primary endpoint was OASI. Labour characteristics in both groups were compared, and a multiple regression model was created. There were 8573 vaginal deliveries of nulliparous women and 3453 deliveries of women in their second pregnancy with a previous caesarean section, of whom 550 had a successful VBAC. There was no significant difference in the rate of OASI between primiparous women and those who had a successful VBAC: 3.5% (297/8573) versus 3.1% (17/550), P = 0.730). Foetal macrosomia (>4kg) and forceps delivery were risk factors for sphincter injury, while episiotomy and epidural anaesthesia were protective. VBAC does not confer an increased risk of OASI after a first delivery by caesarean section when compared with nulliparous women. The rate of successful VBAC may be contributory and suggests that the risk conferred by VBAC may be unit-specific. Unit and national-level audit is necessary to investigate this risk further.

Quels sont les facteurs de risque de l’incontinence anale du post-partum ?

Fecal incontinence is one of the most feared complications of vaginal delivery. It may be the consequence of sphincter tears, of pudendal neuropathy, or of a combination of the two. Fecal incontinence occurs immediately following 13-54% of vaginal deliveries but its persistence in the mid and long term is poorly known. The incidence of perineal tear with anal sphincteric defect varies from 1-9% and the incidence of unrecognized sphincter injury may be as high as 18-35%. Half the women who undergo primary anal sphincter repair have short or long term continence problems. Pudendal neuropathy is caused by nerve stretch during pushing in the second stage of labor and descent of the fetal head ; it may occur even with the first delivery. Risk factors for sphincter injury and pudendal neuropathy include forceps delivery, large neonatal size, and prolonged second stage of labor. The risk of fecal incontinence must be considered even during the first pregnancy. Routine episiotomy does not prevent sphincter injury and may even predispose to it. Pudendal neuropathy following delivery may lead to delayed fecal incontinence abetted by postmenopausal hormonal deficiency and tissue senescence. The possible benefit of early episiotomy for women at high risk of sphincter injury must be evaluated by prospective studies.

Risk Factors for Obstetric Anal Sphincter Injury: A Prospective Study

Anal incontinence is an embarrassing condition that is largely underreported. Obstetric anal sphincter injuries are the major etiological factor. Recognition of risk factors may minimize the development of sphincter injuries. The objective of this study was to identify risk factors for sphincter injuries and measure dimensions of mediolateral episiotomies. Women expecting their first vaginal delivery were invited to participate, and an experienced research fellow performed a perineal and rectal examination and classified tears according to the new international classification. Dimensions of episiotomies were measured and obstetric variables recorded prospectively. Of the 241 women recruited, 59 (25%) sustained sphincter injuries. Univariate analysis revealed that forceps delivery OR 4.03 (1.63-9.92), vacuum extraction OR 2.64 (1.25-5.54), gestation > 40 weeks OR 3.18 (2.35-4.29), and mediolateral episiotomy OR 5.0 (2.64-9.44) were associated with these injuries. In addition, compared with women who had no injuries, sphincter injuries were more common with higher birthweight (3.51 vs 3.17 kg, p < 0.01), larger head circumference (34.3 vs 33.3 cm, p < 0.01), and longer second stage of labor (76 vs 51 min, p < 0.01). Multiple logistic regression revealed higher birthweight and mediolateral episiotomy OR 4.04 (1.71-9.56) as independent risk factors. Episiotomies angled closer to the midline were significantly associated with such injuries (26 vs 37 degrees, p = 0.01). No midwife and only 13 (22%) doctors performed truly mediolateral episiotomies. Mediolateral episiotomy is an independent risk factor for anal sphincter injuries. Although a liberal policy of mediolateral episiotomy does not appear to reduce the risk of such injuries, it may be related to inappropriate technique. A concerted approach to educate trainees in appropriate episiotomy technique and identification of sphincter injuries is imperative to enable reexamination of the true merits or disadvantages of mediolateral episiotomy.