RISK FACTORS FOR RECURRENT OBSTETRICANAL SPHINCTER INJURY: A SYSTEMATIC REVIEW AND META-ANALYSIS
S. JHA, V. PARKER;
Urogynaecology, Sheffield Teaching Hosp., Sheffield, UnitedKingdom.
Introduction: The incidence ofObstetric anal sphincter injury (OASI) appears to be rising withrates reported between 0.6% in Finland to 19.3% in a primiparouspopulation in the US. A recent UK survey showed rates ranging from0-8 % with a median of 2.85 %, which is an increase from theprevious reported rates of 1%. Furthermore, another UK surveyreported a trebling in the incidence of OASI from 2000 to 2012.Similar increasing rates of OASI have been reported from Australia,Scandinavia and the US. Aside from the usual concerns with OASIrelated to faecal incontinence, perineal pain, dyspareunia,psychological problems including depression and overall impact onquality of life, concerns about recurrence can deter women fromhaving another vaginal delivery or avoiding childbirth altogether.Reported rates of recurrent OASI (rOASI) are variable ranging from 2%to 13.4 % and risk factors are poorly reported. A betterunderstanding of the overall risk of recurrence and factors thatcontribute would enable women and caregivers to make more informeddecisions with regards to future childbearing options and mode ofdelivery.
Objective: The objective of this study was toestimate the risk of recurrent OASI (rOASI) in women who havesuffered anal sphincter injury in their previous pregnancy andanalyse the risk factors for recurrence through a systematic reviewand meta-analysis.
Methods: A review was performedaccording to PRISMA guidelines. Searches were made in Ovid Medline(1996 to present), Pubmed, EMBASE and Google scholar includingbibliographies and conference proceedings. Observational studies(cohort/ case control) evaluating rOASI and risk factors wereselected. Two reviewers selected studies and analysed theirmethodological quality. Pooled ORs for rOASI and individualrisk factors were calculated using Revman 5.3.
Results:Eight studies were included in the Meta-analysis. The overall risk ofrOASI was 6.3% compared to a 5.7% risk of OASI in the firstpregnancy. The risk of OASI in parous women with no previous OASI was1.5%. Factors which increased the risk of rOASI in a future pregnancyinclude instrumental delivery with forceps (OR 3.12, 95% CI2.42-4.01) or ventouse (OR 2.44, 95% CI 1.83-3.25), previous 4thdegree tear (OR 1.7, 95% CI 1.24-2.36) and birthweight ≥4kg (OR2.29, 95% CI 2.06-2.54). Maternal age ≥35years marginally increasesrisk (OR 1.16, 95% CI 1-1.35).
Conclusions: The overallrate of rOASI and the associated risk factors for recurrence aresimilar to the rate and risk factors of primary OASI. Antenataldecisions could be based on assessment of fetal weight andintrapartum decisions based upon the requirement for an instrumentaldelivery.
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