236: When to deliver monochorionic-monoamniotic twins undergoing inpatient continuous fetal monitoring -- A decision analysis

Abstract

To determine the optimal gestational age of delivery for women undergoing inpatient management for monochorionic-monoamniotic (MCMA) twin gestations. We developed a decision-analytic model to determine the optimal timing of delivery for MCMA pregnancies undergoing continuous inpatient fetal monitoring beginning at 26 weeks. Gestational age at time of induction of labor ranged from 28 weeks to 34 weeks. Strategies involving expectant management accounted for the probabilities of intrauterine fetal demise (IUFD) and spontaneous delivery at each successive week. Outcomes examined included quality adjusted life years (QALYs), IUFD, cerebral palsy and neonatal death. All probabilities, utilities, and costs were derived from the literature. Univariate and multivariate analyses were used to investigate the robustness of the model results. In a theoretical cohort of 250 MCMA twin pregnancies, the lowest rates of neonatal death (2) and cerebral palsy (8) were associated with delivery at 34 weeks of gestation, whereas the rate of intrauterine fetal demise (6 total IUFD) was lowest at 28 weeks. The optimal strategy was delivery at 31 weeks of gestation, which led to the greatest QALYs (21,146). Delivery at 31 weeks would prevent 5 neonatal deaths and 15 cases of cerebral palsy compared to delivery at 28 weeks gestation, and would prevent 5 gestations affected by at least one stillbirth compared to delivery at 34 weeks. Sensitivity analysis demonstrated that 31 weeks of gestation remained the optimal strategy until risk of neonatal death in an inpatient setting was increased 2.5-fold or the risk of IUFD decreased by 35 percent. Delivering at 31 weeks gestation optimizes perinatal outcomes and total QALYs in MCMA twin gestations undergoing continuous inpatient management. A better understanding of the factors affecting the risk of IUFD would help guide the timing of delivery. The economic consequences of this strategy should be examined in future analyses.View Large Image Figure ViewerDownload Hi-res image Download (PPT)