INCREASED FETAL ACTIVITY AND HEART-RATE DURING AND IMMEDIATELY AFTER PULSED DOPPLER-ECHOCARDIOGRAPHY

Introduction: Previous reports have suggested that the use of continuo us-wave Doppler for non-imaging heart rate monitoring or in utero Dopp ler imaging increased fetal activity. In this study, 11 fetuses (EGA 2 0-28 weeks) underwent a cardiac 2-D ultrasound and pulsed Doppler exam ination (since pulsed Doppler is more often used for fetal cardiac dia gnosis) with 2-D and Doppler performed in a randomized order and with 10-minute ultrasound observation periods with as little transducer mov ement as possible before, during, and after 2-D only, and Doppler eval uation. Methods: All studies were performed with informed consent at t he lowest available Doppler power < 90 mW/cm2 spatial peak temporal av erage. Fetal heart rate, the number of fetal gross movements/min, and the percent time occupied by fetal movements were evaluated by two bli nded observers from video taped records. Patients had been referred to rule out fetal heart disorders but all echoes showed normal cardiac a natomy. Results: Fetal heart rate after pulsed Doppler study was stati stically higher by analysis of variance (mean 127 beats/min) than in t he pre-Doppler evaluation period (mean 120) and was highest during the Doppler exam period (mean 136; P < 0.05) in 10 of 11 fetuses. The per cent time of fetal movements was highest during the Doppler exam perio d and in 9 of 11 fetuses movement increased. The raw number of gross m ovements/min, however, was highest after the Doppler. No such changes occurred during or after 2-D alone. Conclusion: Whether associated wit h slightly higher energy output, minimal thermal changes, or audible s witching or electronic output sounds transmitted from the instrumentat ion through the uterus, fetal heart rate and activity increased in our study both during and after pulsed Doppler examination.