Factores de riesgo para desgarro perineal en partos sin episiotomía atendidos por personal en entrenamiento en un hospital universitario de Bogotá (Colombia) 2007

objective: identifying the risk factors associated with second degree or higher perineal tearing during vaginal delivery in patients attended by medical students at a teaching hospital having a selective episiotomy policy. methodology: this was a prospective analytic cohort study, including women who delivered vaginally at the hospital de engativa (medium complexity hospital) between november 2006 and may 2007. those who had suffered second or higher degree of perineal tears were identified. women who had undergone episiotomy, surgically-assisted vaginal delivery or caesarean section were excluded. results: 149 patients were included. 81 (54,4%) presented perineal tears requiring surgical correction. the significant risk factors identified for perineal tearing during vaginal delivery without episiotomy were: labour lasting more than 420 minutes (rr=1,45; 95%ci 1,10-1,91), neonatal weight greater than 3.100 g (rr=1,43; 95%ci 1,05-1,94) and induced labour (rr=1,38; 95%ic 1,03-1,86). the medical personnel's educational level/experience, parity, cephalic perimeter and second period duration were not statistically significant. logistic regression analysis showed that only fetal weight (rr=2,6; 95%ic 1,25-5,49) and duration of labour (rr=3,0; 95%ci 1,33-6,48) were significant risk factors. conclusions: the main risk factors for perineal lacerations requiring repair were the duration of labour and neonatal weight. on the contrary, induced labour, the medical personnel's degree of experience or prolonged second period were not statistically significant risk factors.