Comparative analysis of obstetric anal sphincter injuries in forceps-assisted and vacuum-assisted term delivery

Introduction: Obstetric anal sphincter injuries are significant complications of vaginal delivery, particularly instrumental deliveries such as forceps and vacuum-assisted deliveries. These injuries may lead to fecal incontinence and pelvic pain, along with long-term morbidity. Objective: To determine and compare the incidence of anal sphincter injuries with forceps-assisted and vacuum-assisted delivery in term pregnancy at Bahawal Victoria Hospital Bahawalpur, Punjab Pakistan. Materials and Methods: An analytical cross-sectional study was conducted from 30th June 2020 to 29th December 2020. A total of 237 pregnant females with singleton term pregnancy, undergoing vaginal delivery were selected and divided into 2 groups based on the mode of assisted vaginal delivery as per protocol. Group A (n=64) women underwent vacuum-assisted delivery while group B (n=173) participants had forceps-assisted delivery. All procedures were performed by the consultant gynecologist. The frequency of anal sphincter injuries in both groups were determined. Results: The study population had a mean age of 30±5 years with an average gestational age of 39±1 weeks. Perineal tear developed in 12.5% of patients with vacuum-assisted delivery and 23.6% of patients in the forceps-assisted delivery group. Frequency of OASIs was significantly associated with advanced maternal age (p=0.0001), 37-39 weeks of gestational age (p=0.0001), and fetal weight >3kg (p=0.009). Conclusion: Frequency of anal sphincter injuries in term pregnancy are far greater with forceps-assisted delivery as compared to vacuum-assisted delivery in this study.