Magnesium sulfate tocolysis in selected patients with symptomatic placenta previa.

Tocolysis can be used to arrest contractions in selected patients with placenta previa if the maternal condition is stable. Over a 5-year period, 41 patients with symptomatic placenta previa were treated, of whom 18 were given magnesium sulfate therapy for tocolysis. The mean prolongation of gestation was 18.5 days, and tocolysis was successful in 17 of 18 cases. Since betamimetic drugs used for tocolysis may mask or blunt maternal cardiovascular responses to volume depletion, magnesium sulfate is a better choice to inhibit contractions in patients with symptomatic placenta previa whose bleeding is mild or moderate.