Factors Influencing the Likelihood of Instrumental Delivery Success

Article, Refereed Journal
Aiken, C.E.M., Aiken, A.R.A., Brockelsby, J.C., Scott, J.G. (2014). Factors Influencing the Likelihood of Instrumental Delivery Success. Obstetrics Gynecology, 123(4): 796-803. PMC4009507

pOBJECTIVE: To evaluate risk factors for unsuccessfulnbsp;instrumental delivery when variability between individualnbsp;obstetricians is taken into account.br /
METHODS: We conducted a retrospective cohort studynbsp;of attempted instrumental deliveries over a 5-year periodnbsp;(2008ndash;2012 inclusive) in a tertiary United Kingdom center.nbsp;To account for interobstetrician variability, we matchednbsp;unsuccessful deliveries (case group) with successful deliveriesnbsp;(control group) by the same operators.nbsp;Multivariatenbsp;logistic regression was used to compare successful andnbsp;unsuccessful instrumental deliveries.br /
RESULTS: Three thousand seven hundred ninety-eightnbsp;instrumental deliveries of vertex-presenting, single, termnbsp;newborns were attempted, of which 246 were unsuccessfulbr /
(6.5%). Increased birth weight (odds ratio [OR]nbsp;1.11; P,.001), second-stage labor duration (OR 1.01;nbsp;P,.001), rotational delivery (OR 1.52; P,.05), and usenbsp;of ventouse compared with forceps (OR 1.33; P,.05)nbsp;were associated with unsuccessful outcome. When interobstetriciannbsp;variability was controlled for, instrumentnbsp;selection and decision to rotate were no longer associatednbsp;with instrumental delivery success. More seniornbsp;obstetricians had higher rates of unsuccessful deliveriesnbsp;(12% compared with 5%; P,.05) but were used to undertakenbsp;more complicated cases. Cesarean delivery duringnbsp;the second stage of labor without previous attempt atnbsp;instrumental delivery was associated with higher birthnbsp;weight (OR 1.07; P,.001), increased maternal age (ORnbsp;1.03; P,.01), and epidural analgesia (OR 1.46; P,.001).br /
CONCLUSION: Results suggest that birth weight andnbsp;head position are the most important factors in successfulnbsp;instrumental delivery, whereas the influence ofnbsp;instrument selection and rotational delivery appear tonbsp;be operator-dependent. Risk factors for lack of instrumentalnbsp;delivery success are distinct from risk factors fornbsp;requiring instrumental delivery, and these should not benbsp;conflated in clinical practice./p

Research Topic
Health Care and Health Policy