title: The incidence, risk factors and obstetric outcome in primigravid women sustaining anal sphincter tears.
abstract: BACKGROUND
  The incidence of anal sphincter tears is highest among nulliparous women. The aim of this study was to ascertain if there were other factors that increased their risk.
  
  
  METHODS
  This was a retrospective study of all primigravid vaginal deliveries that had sustained an anal sphincter tear (n = 122), compared with deliveries that did not have this complication (n = 16,050). The study sample was drawn from a computerized maternity information database, comprising 52 916 deliveries in the South Glamorgan region during 1990-99. SPSS version 10 was used for statistical analysis.
  
  
  RESULTS
  The incidence of anal sphincter tears in this study population was 0.8% (122/16172). Postdates (OR = 1.8, 95% CI = 1.3-2.6) and fetal macrosomia (OR = 3.8, 2.4-6) together with induction of labor (OR = 1.5, 1.01-2.2), use of spinal analgesia at delivery (OR = 3.1, 1.1-8.4), assisted vaginal delivery (OR = 1.9, 1.3-2.7; especially the use of forceps, OR = 2.2, 1.3-3.9) and doctor-conducted deliveries (OR = 2.2, 1.6-3.2) were found to be associated with a significantly higher incidence of anal sphincter tears. Logistic regression revealed fetal macrosomia and doctor-conducted deliveries to be independent risk factors that, when occurring together, were associated with a fourfold increase in the risk of occurrence of anal sphincter tears.
  
  
  CONCLUSIONS
  This study suggests that careful assessment and counseling of women, particularly > 40 weeks gestation or those potentially having macrosomic fetuses, especially if forceps are to be used for prolonged second stage in primigravid women, may help to identify those at significant risk of anal sphincter tears.
authors.affiliation: Department of Obstetrics and Gynecology, University of Wales College of Medicine, Cardiff, UK.
authors.forename: Nandini
authors.initials: N
authors.lastname: Gupta
authors.forename: Talakere Usha
authors.initials: TU
authors.lastname: Kiran
authors.forename: Varsha
authors.initials: V
authors.lastname: Mulik
authors.forename: Jackie
authors.initials: J
authors.lastname: Bethel
authors.forename: Kiron
authors.initials: K
authors.lastname: Bhal
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000293:injuries*; D036861:Delivery, Obstetric / Q000009:adverse effects*; D005260:Female; D005320:Fetal Macrosomia / Q000150:complications*; D005865:Gestational Age; D020073:Gravidity; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007233:Infant, Postmature; D017063:Outcome Assessment, Health Care; D011183:Postoperative Complications; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D012307:Risk Factors