Risk Factors Scoring System as Predictor Model in Obstetric Anal Sphincter Injury
IUGA Academy. Mochtar A. Jun 30, 2018; 212916; 414 Topic: Anal Incont - Fecal Urgency
Mr. Arufiadi Anityo Mochtar
Mr. Arufiadi Anityo Mochtar

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Risk factors scoring system as predictor model in obstetric anal sphincter injury

Mochtar, AA1; Hakim, S1; Priyatini, T1; Erwinanto, E1


Introduction: Anal sphincter injury is one of the most common complications found after vaginal birth. About 85% women had perineal tear after vaginal birth and 0.6-36% women had anal sphincter injury caused by labor. Various risks of anal sphincter injury has been identified, such as parity, maternal body mass index (BMI), length of perineum body, estimated fetal weight, fetal head circumference, shoulder dystocia, prolonged expulsive phase, posterior occiput persistent, and assisted delivery using instruments. All of those factors can be rated in antepartum or during labor period. Antepartum risk factors must be known to establish a prediction for anal sphincter injury. Such risk factors are parity, maternal BMI, length of perineum body, estimated fetal weight and fetal head circumference (by ultrasound sonography). However, until now, there is no scoring system using combination of maternal and antenatal fetal biometry to predict obstetric anal sphincter injury.

Objective: To obtain a scoring system from several antenatal risk factors that can be used to predict obstetric anal sphincter injury based on risk factors analysis, such as parity, maternal BMI, length of perineum body, estimated fetal weight and estimated fetal head circumference with obstetric anal sphincter injury cases.

Method: This is a prospective cohort study, analyzing risk factors, such as parity, maternal BMI, length of perineum body, estimated fetal weight, and fetal head circumference as a predictor model of obstetric anal sphincter injury cases.

Result: A total of 284 patients consistent with the inclusion and exclusion criteria were recruited from February until June 2016. From the population, 53 subjects did not have laceration and 231 subjects had perineum laceration. From all of the subjects whom had perineum laceration, 200 subjects had first and second-degree perineal lacerations, 31 subjects (10.9%) had third and fourth-degree perineal lacerations (obstetric anal sphincter injuries). From 31 subjects who had obstetric anal sphincter injuries, 28 subjects (9.9%) had third-degree perineal lacerations and 3 subjects (1.1%) had fourth-degree perineal lacerations. All risk factors of obstetric anal sphincter injuries were analyzed using multivariate logistic regression analysis. In this study, risk factors which contributed to third and fourth-degree perineal lacerations are nulliparous women (OR 2.60, 95% CI 1.18-5.75), fetal weight ≥ 3500 grams (27.5%), length of perineum body ≤ 2.5 cm (OR 7.83), and fetal head circumference ≥ 33,5 cm (OR 5.00). Maternal BMI did not showed any significance differences with third and fourth-degree perineal lacerations (p = 0.85). Then, multivariate analysis results were made into the scoring system and its probability number, thus each score obtained for each variable was 1. Score 1 showed that probability of anal sphincter injury to be occurred is 7.6%, score 2 is 31.3%, score 3 is 71.5%, and score 4 is 93.2%.

Conclusions: In this study, risk factors variables can be used as a prognostic predictor of obstetric anal sphincter injury, using four variables: parity, length of perineum body, estimated fetal weight, and estimated fetal head circumference.


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