OBJECTIVES: Saline infusion sonohysterography has been reported to suppress the color signal within the endometrium at color or power Doppler evaluation. The aim of this study was to evaluate if gel instillation sonography (GIS) affects the power Doppler signal in patients with endometrial polyps. MATERIAL AND METHODS: Ultrasound volumes of the uterus obtained by three-dimensional ultrasound imaging from 25 women with histologically confirmed endometrial polyps were assessed "off-line" by six gynecologists with special interest in gynecological ultrasound. Each woman contributed four volumes: one gray scale volume and one power Doppler volume before GIS and one gray scale volume and one power Doppler volume at GIS. The power Doppler features before and after gel infusion were compared. RESULTS: At unenhanced ultrasound a pedicle artery was seen in 27 to 46 46% of cases, whereas, after gel infusion the examiners reported a pedicle artery in 30 to 46% of cases (Exact McNemar's test p-values ranging from 0.50 to 1.00). The level of agreement between unenhanced ultrasound and GIS ranged from 59% to 91% (Cohen's kappa values ranging from 0.17 to 0.79) There was no tendency for a pedicle artery to be identified less often at GIS than before gel instillation. CONCLUSION: Gel infusion does not affect the power Doppler signal in patients with endometrial polyps. Gel may therefore become the distension medium of choice in further studies on endometrial vascularity e.g. aiming to differentiate between benign and malignant polyps or between asymptomatic polyps and polyps likely to cause bleeding.