title: Risk factors for anal sphincter tear in multiparas.
abstract: OBJECTIVE
  To assess maternal, newborn, and obstetric risk factors associated with anal sphincter tear in multiparous women.
  
  
  METHODS
  This case-control study identified 18,779 multiparous vaginal deliveries from 1992 to 2004 from an obstetric automated record database at the University of Alabama at Birmingham. Two hundred eighty-four patients were selected, 145 cases and 139 controls. Variables from the index pregnancy and prior pregnancies were analyzed, and multivariable logistic regression models were constructed to determine significant predictor variables for anal sphincter tear in multiparous women.
  
  
  RESULTS
  One hundred forty-five multiparous women with no history of cesarean delivery sustained a sphincter tear. Multivariable logistic regression showed a significant association with episiotomy (odds ratio [OR] 16.3, 95% confidence interval [CI] 7.7-34.4), shoulder dystocia (OR 7.9, CI 1.6-38), forceps delivery (OR 4.7, CI 2.0-11.2), and being married (OR 2.2, CI 1.1-4.6). A second exploratory model that included variables from previous pregnancies, showed that in addition to episiotomy (OR 34.6, CI 8.8-136), shoulder dystocia (OR 11.1, CI 1.3-95.2), forceps delivery (OR 6.1, CI 1.6-23.5), previous sphincter tear (OR 7.7, CI 1.2-48.7), and second stage of labor greater than 1 hour (OR 6.7, CI 1.1-42.5) were associated with tear.
  
  
  CONCLUSIONS
  The strongest clinical risk factors for anal sphincter tear in multiparous women are episiotomy, shoulder dystocia, previous sphincter tear, prolonged second stage of labor, and forceps delivery.
  
  
  METHODS
  II-2.
authors.affiliation: Department of Obstetrics and Gynecology, University of Alabama at Birmingham, 35249, USA.
authors.forename: DeAnn
authors.initials: D
authors.lastname: DiPiazza
authors.forename: Holly E
authors.initials: HE
authors.lastname: Richter
authors.forename: Victoria
authors.initials: V
authors.lastname: Chapman
authors.forename: Suzanne P
authors.initials: SP
authors.lastname: Cliver
authors.forename: Cherry
authors.initials: C
authors.lastname: Neely
authors.forename: Chi Chiung
authors.initials: CC
authors.lastname: Chen
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Burgio
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000293:injuries*; D016022:Case-Control Studies; D036861:Delivery, Obstetric / Q000009:adverse effects; D004841:Episiotomy / Q000706:statistics & numerical data; D005113:Extraction, Obstetrical / Q000009:adverse effects; D005260:Female; D006801:Humans; D007748:Labor Stage, Second; D010298:Parity; D011247:Pregnancy; D012307:Risk Factors; D013997:Time Factors