Comparing second-line tests to assess fetal wellbeing in Labor: a feasibility study and pilot randomized controlled trial

Objective: To explore the feasibility of conducting a randomized controlled trial (RCT) designed to compare the performance of digital fetal scalp stimulation (dFSS) and fetal blood sampling (FBS) as second-line tests of fetal wellbeing in Labor. Design: A feasibility study included 66 women who consented to both dFSS and FBS performed contemporaneously. A pilot randomized controlled trial included 50 women who were randomized to either dFSS or FBS. Setting: University-affiliated maternity hospital. Population: Women in Labor who required second-line testing of fetal well-being following abnormal fetal heart rate monitoring. Outcome measures: The primary outcome of interest was delivery by emergency cesarean section. Secondary outcomes included maternal and perinatal morbidity outcomes and procedural factors. Results: Of the 66 women recruited to the feasibility study 50 (76%) received the two interventions as per protocol. The demographic data indicated that future RCT should be limited to nulliparous women. After initial training and reminders, the dFSS procedure appeared to be acceptable to patients and clinicians and was interpreted appropriately. Recruitment of eligible women to the pilot RCT was successful (88%) with 50 of 63 eligible women randomized (79%) and no drop-outs. The cesarean section rate was high in both arms as expected with a cohort of women requiring second-line tests for abnormal fetal heart rate monitoring in Labor (5/25; 20% dFSS versus 13/25; 52% FBS, p = .018). Conservative estimates suggest that a sample size of 2500 randomized women would be required for a definitive RCT. Conclusions: This study suggests that dFSS, which has the potential to be a reliable alternative to FBS, could be evaluated in a well-designed randomized controlled trial.

Automated summary

This study explores the feasibility of using digital fetal scalp stimulation (dFSS) as an alternative to fetal blood sampling (FBS) for second-line tests of fetal wellbeing in Labor, and concludes that dFSS shows potential as a reliable alternative to FBS.