Postpartum evaluation with 3D transperineal ultrasound of primiparous women who sustained a perineal injury

Abstract

Purpose: Local data on Obstetric Anal Sphincter Injuries (OASIS) in primiparous women is lacking. This study evaluated the incidence rate of recognized and occult OASIS, investigated the frequency and symptoms in OASIS and investigated the relationship of confounding factors with OASIS. Since OASIS have a drastic effect on the quality of life of patients, their diagnosis and eventual optimal repair and follow up of these patients is paramount to minimize long term sequalae. Objectives: To assess the incidence of recognized and occult OASIS in primiparous women in Malta and evaluate the frequency and type of symptoms they suffer. Methodology: 59 primiparous women delivering between 2017 and 2019 were recruited and categorized in 3 groups (1st - no tears/1st degree tear, 2nd – 2nd degree tears, 3rd – OASIS). Maternal characteristics and data regarding delivery were collected retrospectively. The participants’ incontinence symptoms were recorded using St Marks’ Incontinence Score (SMIS) while a 3D Transperineal Ultrasound (TPUS) was performed to assess anal sphincter muscle integrity and evaluate the incidence of clinically diagnosed and TPUS diagnosed OASIS. The study reviewed the healing of such injuries and symptomatology in the post-partum period and compared both clinically diagnosed and ultrasound diagnosed OASIS with covariables, such as: maternal age, height, weight, body mass index (BMI), gestation age, baby birth weight at delivery, duration of 2nd stage of labour, type of labour (spontaneous/induced), mode of delivery (normal vaginal delivery or instrumental), and use of episiotomy and epidural. Results: Malta’s incidence of clinically diagnosed OASIS was 1.65% (CI 1.38-1.92%); 2.573% (CI 2.11-3.04%) in primiparous and 0.64% (CI 0.40-0.90%) in multiparous women. There were 47.62% (CI 26.27-68.98%) of missed significant US diagnosed tears and 60.71% (CI 42.62-78.80%) of all US diagnosed tears missed. Most of the confounding factors were not significantly different between groups except maternal age between Group 2 and 3, 31.85 years vs 28.65 years; birth weight between Group 1 and 2, 3.04kg vs 3.35kg; and maternal weight and BMI in the most severe OASIS (Internal anal sphincter defects), BMI 21.67 vs 25.99. Symptoms after OASIS repair was present in up 21% of patients and although most are asymptomatic, up to 80% of women had persistent significant EAS tears after repair of OASIS. Conclusions: The incidence of clinically diagnosed OASIS is low however the rate of clinically undiagnosed OASIS and rate of inadequate repair of OASIS was high.