Ritodrine treatment for uterine hyperactivity during the active phase of labor

Forty consecutive patients with uterine hyperactivity, defined as either tachysystole and/or hypertonus during the active phase of vertex delivery, were treated with intravenous ritodrine (50 up to 300 μg/min, in 50 μg increments/5 min). Thirty-four patients (85%) responded within 20 min with termination of the uterine dysfunction and all (21, 52%) concomitant fetal heart rate distress signs disappeared. The treatment did not prolong labor, as this was significantly correlated to parity and cervical dilation when treatment was initiated (P < 0.0006 and P < 0.008, respectively). Fifteen patients were delivered by cesarean section (37.5%) mainly for cephalopelvic disproportion. Multiparas were older and had shorter ritodrine initiation-delivery intervals, but these were the only significant differences when compared to primiparas. Ritodrine is therefore suggested as an effective treatment of uterine hypercontractility dysfunction.