Anal sphincter injury in vaginal deliveries complicated by shoulder dystocia.

INTRODUCTION AND HYPOTHESIS: Shoulder dystocia is an obstetric emergency that occurs in 0.2-3% of all cephalic vaginal deliveries. We hypothesized that because of the difficult nature of deliveries complicated by shoulder dystocia, the condition may be associated with anal sphincter injury. We sought to identify risk factors for obstetric anal sphincter injury in women with shoulder dystocia. METHODS: This retrospective analysis included all cases of shoulder dystocia from 2007 to 2011 at two large tertiary referral centers, in the USA and Ireland. Details of maternal demographics, intrapartum characteristics, and delivery outcomes in cases of shoulder dystocia were analyzed. Univariate and multivariate analyses were used to describe the association between shoulder dystocia and anal sphincter injury. RESULTS: There were 685 cases of shoulder dystocia, and the rate of shoulder dystocia was similar at both institutions. The incidence of anal sphincter injury was 8.8% (60 out of 685). The rate was 14% (45 out of 324) in nulliparas and 4.2% (15 out of 361) in multiparas. Women with sphincter injury were more likely to be nulliparous (75% [45 out of 60] vs 45% [279 out of 625]; p < 0.0001), have had an operative vaginal delivery (50% [30 out of 60] vs 36% [226 out of 625]; p = 0.03) and require internal maneuvers (50% [30 out of 60] vs 32% [198 out of 625], p = 0.004) than those with an intact sphincter. On multivariate regression analysis, these predictors of sphincter injury remained significant when adjusted for other risk factors. Episiotomy was negatively associated with sphincter injury on multivariate regression analysis. CONCLUSIONS: In a retrospective cohort of 685 women with shoulder dystocia, the risk of anal sphincter injury is 9%. Risk factors include nulliparity, operative vaginal delivery, and use of internal maneuvers, whereas episiotomy was found to have a protective effect against anal sphincter injury during cases of shoulder dystocia.

Obstetric anal sphincter injury, risk factors and method of delivery - an 8-year analysis across two tertiary referral centers.

OBJECTIVE: Obstetric anal sphincter injury (OASIS) represents a major cause of maternal morbidity and is a risk factor for the development of fecal incontinence. We set out to analyze the incidence of OASIS and its association with mode of delivery in two large obstetric hospitals across an 8-year study period. METHODS: This was a prospective observational study carried out at two large tertiary referral centers serving a single urban population, from 2003 to 2010. Incidence of OASIS was examined as well as the influence of parity and mode of delivery on the occurrence of OASIS. RESULTS: During the study period, there were 100 307 vaginal deliveries at the two hospitals. There was a total of 2121 cases of OASIS from 2003 to 2010, giving an incidence of 2.1% of vaginal deliveries. Patients were more likely to suffer an OASIS when having a forceps delivery than when having a normal vaginal delivery (8.6% versus 1.3%, p < 0.0001, OR: 7.1, CI: 6.4-7.9). Vacuum delivery also carried an increased risk of sphincter injury compared with normal delivery (3.7% versus 1.3%, p < 0.0001, OR: 2.9, CI: 2-2.6). About 16.7% of infants delivered were macrosomic (birthweight > 4 kg). The rate of episiotomy during the study was 19.1%. CONCLUSION: These results demonstrate that OASIS remains an important cause of maternal morbidity in contemporary obstetric practice. These results will likely be of value in risk management planning and patient debriefing in what is a highly litigious area of obstetrics.

Changes in vaginal breech delivery rates in a single large metropolitan area.

OBJECTIVE: Vaginal breech delivery rates have been accepted widely to be in decline and the Term Breech Trial (TBT) has recommended delivery of a breech-presenting infant by elective cesarean section delivery. Our aim was to examine the rate of vaginal delivery of term breech pregnancies in the 8 years before and after the publication of the TBT. STUDY DESIGN: We retrospectively examined vaginal delivery rates of breech presentations over a 16-year period in 3 large tertiary maternity hospitals that serve a single large metropolitan population. All 3 hospitals are of similar size and serve a population with similar risk profile. We also examined rates of perinatal mortality in the 3 hospitals over the study period. RESULTS: During the 16-year study period, there were 344,259 deliveries among the 3 hospitals; 11,913 of which were breech deliveries. There were 5655 breech deliveries in the 8 years before the publication of the TBT, with a cesarean delivery rate of 76.9%. There were 6258 breech deliveries in the 8 years since publication of the TBT, and the cesarean delivery rate increased to 89.7% (P < .0001). During the 8 years since publication, the rate of vaginal delivery in nulliparous women decreased from 15.3-7.2% (P < .0001). The vaginal breech delivery rate in multiparous women decreased from 32.6-14.8% (P < .0001). The rates of corrected perinatal mortality showed a significant decrease in the last 4 years of the study. CONCLUSION: Our study demonstrates that the results and recommendations of the TBT have contributed to decreasing vaginal breech delivery rates, which were already in decline before its publication.