Objective    To assess the response of uterine myometrium to oxytocin.     Methods    Thirty patients (mean age 39.77±4.34 years) with uterine fibroids and 15 patients (mean age 36.27±4.54 years) with focal adenomyosis underwent Doppler ultrasound to observe the nutrient artery waveform for 30 min before and after intravenous injection of oxytocin (0.04 U/min).     Results    After applying oxytocin

abnormal waveforms were seen in 24 patients with uterine fibroids (80%)

as well as in 10 patients with focal adenomyosis (66.7%)

including monophasic-wedged

monophasic-domed

biphasic-wedged

or tropical fish-like. Waveform changes could be categorized into two types

i.e.

bizarre waveforms such as persistent change (19/30

6/15) and alternative change (5/30

4/15); and normal waveforms like velocity change (6/30

5/15). Different formwave changes appeared in the periphery and internal artery of all different types of uterine fibroids. We did not observe any waveform changes in uterine arcuate artery and bilateral uterine artery.     Conclusion    Doppler ultrasound waveform changes of nutrient artery are useful for evaluating the response to oxytocin in uterine myometrium. Abnormal waveforms may be caused by myometrial contraction that leads to nutrient artery stenosis or spasm.