Fetal heart rate baselines in twins - Interobserver agreement in antepartum estimation

OBJECTIVE: To assess interobserver agreement in antepartum estimation of fe tal heart rate (FHR) baselines in twins. STUDY DESIGN: Two residents and one specialist in obstetrics and gynecology , all with special interest in FHR monitoring, independently estimated base lines in 162 consecutive antepartum FHR tracings recorded in 24 twins. Trac ings were obtained with a dual-channel fetal monitor for the simultaneous r ecording of both twins' heart rates. Baselines were estimated, as single va lues corresponding to the mean of the lowest stable FHR segment, in the abs ence of fetal movements and uterine contractions, within physiologic limits (110-150 bents per minute [bpm]). If these criteria were not met, the poss ibility of persistent bradycardia or tachycardia was considered, and if thi s was confirmed in a tracing with at least 40 minutes, a baseline < 110 or > 150 bpm was chosen. Interobserver agreement was assessed by the proportio ns of agreement (PA), kappa statistic (K) and intraclass correlation coeffi cient (ICCC), with 95% confidence intervals (CIs). RESULTS: Interobserver agreement was excellent, with a PA of 0.90 (95% CI: 0.89-0.91), K of 0.88 (95% CI: 0.84-0.92) and ICCC of 0.91 (95% CI: 0.88-0. 94). CONCLUSION: Interobserver agreement in antepartum estimation of fetal heart rate baselines in twins was excellent with the baseline concept used in th is study.