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 micrograms/min, in 50 micrograms 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 less than 0.0006 and P less than 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.