Perinatal and maternal morbidity and mortality after attempted operative vaginal delivery at midpelvic station

Abstract

When there is an arrest in the descent of the fetal head at midpelvic station during the second stage of labour, mode of delivery and perinatal and maternal outcomes are largely dependent on the urgency to expedite delivery and operator skill with midpelvic operative vaginal delivery.1,2 Operative vaginal delivery provides a temporal advantage over cesarean delivery, although midpelvic forceps or vacuum application requires skill and experience. Although cesarean delivery generally decreases the risk of birth trauma compared with instrument use, engagement of the fetal head in the pelvis means the risk of trauma is not eliminated by an emergency cesarean delivery.3,4 Assessments of the balance of risks and benefits between midpelvic operative vaginal delivery and cesarean delivery have tended to favour the latter option in recent decades, and this has contributed to a rising rate of cesarean delivery worldwide.1 In 2014, a consensus statement by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine 5 recommended operative vaginal delivery as a strategy to reduce the rate of cesarean delivery. In Canada, midpelvic operative vaginal delivery accounts for over 20% of all operative vaginal deliveries and about 2%-3% of term singleton deliveries. 6 The literature on perinatal and maternal mortality and morbidity after operative vaginal delivery compared with cesarean delivery is inconsistent. [7][8][9][10][11][12][13][14][15][16] In addition, studies on the risks and benefits of these Increased use of operative vaginal delivery (i.e., forceps or vacuum application), of which 20% occurs at midpelvic station, has been advocated to reduce the rate of cesarean delivery. We aimed to quantify severe perinatal and maternal morbidity and mortality associated with attempted midpelvic operative vaginal delivery.

Ecological association between operative vaginal delivery and obstetric and birth trauma

“…However, an ecological design is appropriate for assessing associations at the population level, 22,23 and individual-level studies also show that operative vaginal deliveries cause obstetric and birth trauma. [6][7][8][9] Measurement of pelvic Note: ARR = adjusted rate ratio, CI = confidence interval, OVD = operative vaginal delivery. *ARRs and 95% CIs expressing the change in obstetric trauma and severe birth trauma rates per 1% absolute increase in OVD rates and associated number of excess cases per year, term singleton deliveries, Canada, 2004-2014; includes data from Alberta, Manitoba, Ontario, and Saskatchewan.…”

“…5 Such recommendations for addressing increases in cesarean delivery are premised on the assumption that operative vaginal delivery has greater relative safety compared with cesarean delivery. However, recent studies [6][7][8][9] have shown higher rates of severe perinatal and maternal adverse outcomes after operative vaginal delivery. In particular, our previous work 6,7 showed substantially higher rates of obstetric trauma among midpelvic forceps and vacuum deliveries, compared with cesarean deliveries (adjusted rate ratio [ARR] 8.48, 95% confidence interval [CI] 7.22-9.96 and 6.90, 95% CI 5.86-8.13, respectively).…”

“…However, recent studies [6][7][8][9] have shown higher rates of severe perinatal and maternal adverse outcomes after operative vaginal delivery. In particular, our previous work 6,7 showed substantially higher rates of obstetric trauma among midpelvic forceps and vacuum deliveries, compared with cesarean deliveries (adjusted rate ratio [ARR] 8.48, 95% confidence interval [CI] 7.22-9.96 and 6.90, 95% CI 5.86-8.13, respectively). The ARRs for severe birth trauma were 4.33, 95% CI 2.31-8.11 for forceps and 3.16, 95% CI 1.65-6.05 for vacuum versus cesarean delivery.…”

Re: Perinatal and maternal morbidity and mortality among term singletons following midcavity operative vaginal delivery versus caesarean delivery

“…Equally importantly, pregnant women have little understanding of the issues relating to expertise in midcavity operative vaginal delivery, and our study findings reflect the experience and skills of contemporary practitioners. Also, in a previous study based on pan-Canadian data, 4 we showed that the effect of operative vaginal delivery on perinatal and maternal severe morbidity/mortality was not modified by institutional delivery volume. Finally, if the caesarean delivery group benefited from more skilled operators and less complicated fetal positions (as postulated by Mohan et al 1 ), then the effect of midcavity operative vaginal delivery on perinatal and maternal severe morbidity/mortality documented in our study represent underestimates of the true effect.…”

Authors/ reply re: Perinatal and maternal morbidity and mortality among term singletons following mid cavity operative vaginal delivery versus caesarean delivery

“…Lastly, given the results of our studies comparing perinatal and maternal morbidity and mortality following OVD versus caesarean delivery, we would be cautious in interpreting a decreased rate of caesarean delivery per se as evidence of more discriminating assessments in the absence of a formal assessment of corresponding outcome rates.…”