Risk factors for operative vaginal delivery after a previous instrumental delivery

The aim of the present study was to assess factors associated with a repeat operative vaginal delivery (OVD) in women with a previous history of OVD.

A single-centre retrospective observational study was performed in the maternity ward of the Angers University Hospital between 20/09/2010 and 01/04/2021. All the patients who underwent an OVD between 01/09/2010 and 31/10/2013 (delivery n°1, n = 1215) and who subsequently delivered up to the 01/04/2021 (delivery n°2, n = 652) were included. Multivariate logistic regression was used to assess the risk of subsequent recurrent OVD, adjusted for clinical potential confounder based on univariate analysis.

Among the 520/652 (79.7%) patients who delivered vaginally during delivery n°2, 51/520 (9.8%) had undergone a repeated OVD. Gestational age, parity, history of uterine scars, percentage of labour's induction and the duration of labor were similar between patients who delivered spontaneously and those who required an OVD during delivery n°2. There were 7/51 (13.7%) patients who underwent an OVD during delivery n°2 with a newborn in cephalic posterior presentation compared to 20/469(4.3%) in cases of spontaneous vaginal delivery n°2 (p < 0.01). A posterior cephalic presentation increased the risk of subsequent OVD by 3.7 [Confidence Interval 95% (1.4-9.6), p < 0.01] CONCLUSION: In the case of a history of OVD, a low proportion of women required a repeated OVD (9.8%). The only factor associated with the need for repeated OVD was a persistent fetal cephalic posterior presentation at the time of delivery.