Tachysystole

Tachysystole is an obstetric term describing excessively frequent uterine contractions during labor. It is commonly defined as more than five contractions in 10 minutes, averaged over a 30-minute window, though definitions can vary by guideline. Contractions are typically monitored with external fetal monitoring or internal devices that measure uterine activity.

Causes and contributing factors include augmentation or induction of labor with oxytocin, cervical ripening agents such as prostaglandins, uterine overdistension from multiple gestation or polyhydramnios, and high parity or uterine infection. In some cases tachysystole occurs even with minimal pharmacologic stimulation.

Clinical significance centers on the potential for reduced placental perfusion, which can lead to nonreassuring fetal heart rate patterns, decreased fetal reserve, and potential acidosis if the condition is prolonged. The impact depends on the fetal status, duration of contractions, and the interval between contractions.

Diagnosis relies on fetal heart rate tracings in combination with contraction frequency, with tachysystole noted when there are more than five contractions in 10 minutes over a 30-minute window.

Management begins with assessing fetal status. If there are nonreassuring fetal tracings or persistent tachysystole, the priority is to discontinue oxytocin and other uterotonics, reposition the patient, and ensure adequate IV fluids. If contractions persist, a tocolytic such as terbutaline may be administered to reduce uterine activity, and the situation should be monitored closely. If fetal distress continues or delivery is indicated, expedite delivery by vaginal assistance or cesarean section as appropriate.

Prevention focuses on careful titration of uterotonics, adherence to monitoring guidelines, and prompt recognition to minimize risk. With timely management, outcomes are typically favorable, though sustained tachysystole with fetal compromise increases risk.