Risk factors for third- and fourth-degree perineal tears during vaginal delivery

Objective. To identify risk factors for thirdand fourth-degree perineal tears, so as to anticipate and intervene in order to prevent this complication that can severely affect a woman’s quality of life. The study design was a retrospective case control study. Method. Ninety-three cases of third- and fourth-degree perineal tears were identified from the birth register of a tertiary referral hospital (Tygerberg Hospital). One hundred and nine patients with normal vaginal deliveries in the same time period were used as control group. Results. An analysis of the results revealed that there were no significant differences between cases and controls with regards to age, body mass index (BMI), gestation at delivery, duration of second stage, episiotomy and birth weight. However, there were significantly more primigravidas, assisted deliveries (forceps and vacuum), occipitoposterior positions, HIV negative patients and shoulder dystocia in the study group. Conclusions. Antenatal risk factors for thirdand fourth-degree tears are difficult to identify. However, intrapartum occipitoposterior and assisted deliveries, especially in the primigravid patient, should warn the obstetrician/ midwife about the risk of a severe tear. A restrictive episiotomy policy should be practiced. Shoulder dystocia was invariably associated with third- and fourth-degree tears in this study. The higher incidence of HIV negative patients in the study group requires further research.