Grade III and IV perineal tears: risk factors and clinical progress

Objective: To study the prevalence of risk factors associated with obstetric anal sphincter injury and its development in the short term. Material and methods: Observational retrospective study of grade III and IV tears over a period of 3 years. We evaluated maternal risk factors and factors related to childbirth. We also followed patients during the first year after delivery. Results: The incidence of anal sphincter tears was 2.03% (62.6% type IIIA). The principal modifiable risk factors were instrumental delivery (61%), with a relative risk of laceration of 9.1% for forceps, 4.4% for vacuum extraction, and 3.6% for spatulas, compared with 0.86% for normal deliveries. Prolonged labor (more than 3 hours) was recorded in nearly 50% of patients. The main nonmodifiable risk factor was primiparity (85.1% of cases). At the first check-up, 63.9% of patients were asymptomatic; at the second, 92.7% were asymptomatic, and perineal tone had improved. Conclusion: Health professionals must be trained to assess risk factors for perineal tears, as well as to make a correct diagnosis and provide appropriate treatment. Patients should be followed up and receive instructions on pelvic floor muscle exercises.