Failed vacuum extraction. Maternal risk factors and pregnancy outcome.

OBJECTIVE: To evaluate obstetric risk factors associated with a failed trial of vacuum extraction and to assess its pregnancy outcome. STUDY
DESIGN: All attempted vacuum extractions between the years 1990 and 1998 were identified, and a comparison of successful and failed trials of vacuum extraction in singleton, vertex deliveries was performed.
RESULTS: Of 2,111 trials of vacuum extraction, 113 (5.4%) cases were complicated by failed extraction and underwent cesarean section. Those neonates were significantly more likely to be large for gestational age, specifically to weigh > 4,000 g as compared to the controls. Patients lacking prenatal care had significantly higher rates of failed vacuum extraction trials. While cervical and uterine tears were rather rare, parturients who had failed trials of vacuum extraction had significantly higher rates of cervical and uterine tears as compared to those with successful vacuum extractions. This association remained significant after controlling for a previous cesarean section using the Mantel-Hanszel technique. Women from the failed vacuum extraction group had significantly higher rates of postpartum anemia. Pregnancies complicated by failed vacuum extraction had significantly higher rates of intrapartum and postpartum fetal death. Those neonates had significantly higher rates of Apgar scores < 7 at one and five minutes.
CONCLUSION: Failed trial of vacuum extraction is associated with adverse maternal and fetal outcomes. Risk factors associated with such failures are fetal weight and lack of prenatal care. Thus, careful estimation of fetal weight should be performed before the procedure, and estimated fetal weight > 4,000 g might be considered a relative contraindication to vacuum extraction, especially among patients who did not have prenatal care.