Incidence and risk factors of obstetric anal sphincter injuries: a retrospective study

BACKGROUND:
Obstetric anal sphincter injuries (OASIS) are severe complications of vaginal deliveries with long-term physical and psychological sequelae. Data on the prevalence and risk factors of OASIS are limited in Saudi Arabia. This study aimed to assess the incidence of OASIS annually from 2017 to 2020, identify associated maternal and delivery factors, and investigate patients' characteristics related to OASIS Grades.


OBJECTIVE:
To evaluate the annual incidence of OASIS from 2017 to 2020, identify maternal and delivery-related risk factors, and assess characteristics associated with different OASIS grades.


DESIGN:
Single-center, retrospective observational study


SETTING:
King Abdulaziz University Hospital, Jeddah, Saudi Arabia


METHODS:
Medical records of all vaginal deliveries from 2017 to 2020 were reviewed. The study included 112 patients with singleton vaginal deliveries complicated by OASIS, out of a total of 12 081 deliveries. Exclusion criteria included preterm births and incomplete records. Data on maternal demographics, obstetric history, labor type, mode of delivery, episiotomy use, and neonatal outcomes were collected. The Royal College of Obstetricians and Gynaecologists (RCOG) classification was used to grade OASIS severity. Chi-square and t-tests were used for analysis.


MAIN OUTCOME MEASURES:
Annual incidence of OASIS, distribution of OASIS grades, and associations between clinical variables and injury severity.


SAMPLE SIZE:
112 cases of OASIS among 12081 vaginal deliveries


RESULTS:
The incidence of OASIS was 0.93%, showing a decreasing trend from 2017 to 2020. Most patients were Saudis (78.6%), primigravidae (58%), and nulliparous (67%). Spontaneous vaginal delivery occurred in 73.2% of cases, with episiotomies performed in 62%. Grade III tears were observed in 79.5% of cases, whereas 8.0% were classified as Grade IV. No significant differences were observed between Grades III and IV in terms of maternal and delivery characteristics, except for higher estimated blood loss in Grade IV cases. Incomplete documentation was noted in repair techniques and episiotomy details.


CONCLUSION:
Incidence of OASIS shows a decreasing trend in both the number of cases and the incidence rate over the four years between 2017 and 2020. Further research is necessary to address documentation gaps and refine regional prevention and management practices.


LIMITATION:
Retrospective design and missing values limited the ability to analyze some variables thoroughly.