Predictors of Failed Operative Vaginal Delivery in a Contemporary Obstetric Cohort

Abstract

Risk factors identified before an operative vaginal delivery attempt cannot be used to accurately predict whether an operative vaginal delivery attempt will fail.

Prolonged Second Stage of Labor and Anal Sphincter Injury in a Contemporary Cohort of Term Nulliparas

“…As actual birth weight is not readily available to the provider making clinical decisions, we created an estimated fetal weight (EFW) variable by first randomly varying the actual birth weight along a normal distribution within 20% of the actual birth weight, and then randomly selecting a value from this distribution. 15 This estimate is consistent with the error margins of measurements used in clinical practice to estimate fetal weight based on ultrasound or physical examination. 16 Cases were defined as women with a third-or fourthdegree laceration at the time of delivery.…”

Randomised Italian Sonography for occiput POSition Trial Ante vacuum (R.I.S.POS.T.A.)

“…An additional factor that further reduced the clinical validity of our results is the low incidence of failed vacuum delivery in our study population. Within our cohort, the vacuum delivery failure rate was considerably lower than formerly reported and expected (1% vs 5%). A possible explanation for this is that physicians involved in patient recruitment opted to randomize only women for whom fetal extraction was considered to be easy, whereas ultrasound assessment was performed systematically in the case of potentially challenging instrumental delivery.…”

“…Instrumental vaginal delivery by vacuum extraction is a widely performed obstetric procedure used to expedite delivery when there is substantial risk for the mother or fetus during the second stage of labor. Although successful in most cases, a 4–6% failure rate has been reported following attempted vacuum delivery. Cesarean section and sequential instrumental delivery with forceps are the available options to achieve delivery of the fetus after failure of vacuum extraction, but increased risk of maternal and fetal complications has been reported in such cases.…”

“…Although successful in most cases, a 4–6% failure rate has been reported following attempted vacuum delivery. Cesarean section and sequential instrumental delivery with forceps are the available options to achieve delivery of the fetus after failure of vacuum extraction, but increased risk of maternal and fetal complications has been reported in such cases.…”

Predictors of shoulder dystocia at the time of operative vaginal delivery

“…Therefore, we did not use this variable but instead, using a previously described methodology, created a variable for estimated fetal weight (EFW) that incorporates the reported inaccuracy of birth weight estimation. [18][19][20]21 Specifically, we generated an EFW for each patient by randomly varying the true birth weight assuming a normal distribution and utilizing the actual birth weight as the mean and 20% of the true birth weight as the standard deviation.…”