Mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury: a Finnish retrospective cohort study

Abstract Background Obstetric anal sphincter injury (OASI) is a severe complication of vaginal delivery. In previous studies, parturients with a preceding OASI are at increased risk of a recurrent OASI (rOASI) in subsequent vaginal deliveries. In Finland, the rate of OASI is low compared to other co...

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Main Authors: Elina Ristilä, Outi Palomäki, Heini Huhtala, Elli Toivonen
Format: Article
Language:English
Published: BMC 2025-07-01
Series:BMC Pregnancy and Childbirth
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Online Access:https://doi.org/10.1186/s12884-025-07882-9
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author Elina Ristilä
Outi Palomäki
Heini Huhtala
Elli Toivonen
author_facet Elina Ristilä
Outi Palomäki
Heini Huhtala
Elli Toivonen
author_sort Elina Ristilä
collection DOAJ
description Abstract Background Obstetric anal sphincter injury (OASI) is a severe complication of vaginal delivery. In previous studies, parturients with a preceding OASI are at increased risk of a recurrent OASI (rOASI) in subsequent vaginal deliveries. In Finland, the rate of OASI is low compared to other countries, at 1.4% of deliveries, and the incidence of rOASI is not well-known. This study examined recurrence and mode of delivery after an OASI. Methods This historical cohort study includes 278 women who have experienced an OASI and have delivered again in Tampere University Hospital. Deliveries complicated by an rOASI were compared to those without an rOASI, and women planning a cesarean delivery (CD) for their subsequent delivery were compared to women planning a vaginal delivery. Risk factors for OASI were explored by comparing deliveries complicated by an OASI to all deliveries. Results After an OASI, 78.1% of parturients planned a vaginal delivery and 21.9% a cesarean delivery (CD). Vaginal delivery was successful in 98.1% of cases and only 1.9% of parturients who underwent vaginal delivery experienced an rOASI. Due to the low incidence rate, no risk factors for rOASI could be identified. Parturients were most likely to have a CD in their subsequent delivery when the delivery complicated by an OASI was induced, the second stage was prolonged, episiotomy was performed, or the delivery had been assisted. The most common indication for CD was maternal request or fear of childbirth (85.9%). Assisted vaginal delivery, birthweight > 4,000 g, episiotomy, and postterm pregnancy were more common in deliveries complicated by OASI compared to all other vaginal deliveries in the study hospital during the same time period. Conclusions The recurrence rate of OASI was low and the vaginal uncomplicated delivery rate was high among women who chose it for their subsequent delivery after an OASI.
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spelling doaj-art-e35c84acb07f4f468c2a4f53c4c5f7b32025-08-20T03:46:29ZengBMCBMC Pregnancy and Childbirth1471-23932025-07-012511810.1186/s12884-025-07882-9Mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury: a Finnish retrospective cohort studyElina Ristilä0Outi Palomäki1Heini Huhtala2Elli Toivonen3Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, University of TampereCenter for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, University of TampereFaculty of Social Sciences, University of TampereCenter for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, University of TampereAbstract Background Obstetric anal sphincter injury (OASI) is a severe complication of vaginal delivery. In previous studies, parturients with a preceding OASI are at increased risk of a recurrent OASI (rOASI) in subsequent vaginal deliveries. In Finland, the rate of OASI is low compared to other countries, at 1.4% of deliveries, and the incidence of rOASI is not well-known. This study examined recurrence and mode of delivery after an OASI. Methods This historical cohort study includes 278 women who have experienced an OASI and have delivered again in Tampere University Hospital. Deliveries complicated by an rOASI were compared to those without an rOASI, and women planning a cesarean delivery (CD) for their subsequent delivery were compared to women planning a vaginal delivery. Risk factors for OASI were explored by comparing deliveries complicated by an OASI to all deliveries. Results After an OASI, 78.1% of parturients planned a vaginal delivery and 21.9% a cesarean delivery (CD). Vaginal delivery was successful in 98.1% of cases and only 1.9% of parturients who underwent vaginal delivery experienced an rOASI. Due to the low incidence rate, no risk factors for rOASI could be identified. Parturients were most likely to have a CD in their subsequent delivery when the delivery complicated by an OASI was induced, the second stage was prolonged, episiotomy was performed, or the delivery had been assisted. The most common indication for CD was maternal request or fear of childbirth (85.9%). Assisted vaginal delivery, birthweight > 4,000 g, episiotomy, and postterm pregnancy were more common in deliveries complicated by OASI compared to all other vaginal deliveries in the study hospital during the same time period. Conclusions The recurrence rate of OASI was low and the vaginal uncomplicated delivery rate was high among women who chose it for their subsequent delivery after an OASI.https://doi.org/10.1186/s12884-025-07882-9Obstetrical anal sphincter injuryThird degree tearFourth degree tearSubsequent birthVaginal deliveryCesarean section
spellingShingle Elina Ristilä
Outi Palomäki
Heini Huhtala
Elli Toivonen
Mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury: a Finnish retrospective cohort study
BMC Pregnancy and Childbirth
Obstetrical anal sphincter injury
Third degree tear
Fourth degree tear
Subsequent birth
Vaginal delivery
Cesarean section
title Mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury: a Finnish retrospective cohort study
title_full Mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury: a Finnish retrospective cohort study
title_fullStr Mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury: a Finnish retrospective cohort study
title_full_unstemmed Mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury: a Finnish retrospective cohort study
title_short Mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury: a Finnish retrospective cohort study
title_sort mode of delivery and maternal outcome in subsequent delivery after an obstetric anal sphincter injury a finnish retrospective cohort study
topic Obstetrical anal sphincter injury
Third degree tear
Fourth degree tear
Subsequent birth
Vaginal delivery
Cesarean section
url https://doi.org/10.1186/s12884-025-07882-9
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