Shuichiro YOSHIMURA , Hideaki MASUZAKI, Kiyonori MIURA , Hideo GOTOH , Tadayuki ISHIMARU

Department of Obstetrics and Gynecology, Nagasaki University School of Medicine

キーワード : Doppler ultrasound , Preterm labor , Ritodrine hydrochloride, Transthoracic echocardiography, Ultrasound

Objective: To determine the effect of ritodrine hydrochloride on fetal arteries (the umbilical artery, descending aorta, middle cerebral artery, and renal artery) and uterine artery wave forms in patients with premature labor.
Method: Velocimetry of four fetal arteries and the uterine artery was performed using pulsed Doppler ultrasonography in 216 uncomplicated control pregnancies and 83 pregnancies treated for premature labor. To investigate the effect of fetal and maternal heart rates on pulsatility index (PI) ratios, we examined the relationships between PI ratios of fetal artery wave forms and fetal heart rate, and between PI ratios of uterine artery wave forms and maternal heart rate in control pregnancies. We compared the effect of oral (n=28) and intravenous administration (n=55) of ritodrine on PI ratios in each group after correction of blood flow waveforms.
Results: Treatment with oral ritodrine did not influence PI ratios in patients with preterm labor, although intravenous ritodrine significantly decreased PI ratios of umbilical and uterine artery wave forms. PI ratios of umbilical and uterine artery wave forms were significantly higher in patients with preterm labor than in those with term labor.
Conclusion: Doppler studies of patients with premature labor may be clinically helpful in identifying patients at high risk for preterm birth.