title: The effect of magnesium sulfate on bleeding time in pregnancy.
abstract: OBJECTIVE
  The bleeding time is one of the most commonly used diagnostic tests to evaluate platelet-related hemorrhagic disorders. Magnesium has been shown in vitro to be a platelet antiaggregant. This study was conducted to evaluate the hypothesis that magnesium sulfate has no effect on the template bleeding time.
  
  
  METHODS
  The study group consisted of 24 women who required magnesium sulfate in pregnancy. A blood cell count, platelet count, magnesium level, bleeding time, and mean arterial pressure were obtained before and 2 hours after magnesium sulfate infusion. Magnesium sulfate was infused beginning with a 6 gm intravenous bolus followed by 2 gm/hr. A template bleeding time was performed with a Simplate-II (Organon Teknika, Durham, N.C.) device. Two of the authors performed all the bleeding times. Data were analyzed with a paired t test and Wilcoxon rank test.
  
  
  RESULTS
  Fifteen (63%) patients received magnesium sulfate for tocolysis or before external cephalic version and nine (37%) for preeclampsia prophylaxis. No differences were found between the normotensive and hypertensive groups regarding maternal age, gestational age, initial bleeding time, or platelet count. Analysis of the entire study group revealed a prolongation of the bleeding time after magnesium sulfate (5.7 +/- 1.8 vs 6.6 +/- 1.9 minutes, p < 0.05); a lowering of the mean arterial pressure (p < 0.05), and a rise in the magnesium level (p < 0.05). Four patients (16.7%) had a postmagnesium bleeding time > 9 minutes.
  
  
  CONCLUSIONS
  Magnesium sulfate appears to prolong the bleeding time in pregnancy. The clinical significance remains to be determined.
mesh_terms: D000328:Adult; D001760:Bleeding Time; D001777:Blood Coagulation / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D001946:Breech Presentation; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D008278:Magnesium Sulfate / Q000627:therapeutic use*; D007752:Obstetric Labor, Premature / Q000097:blood / Q000188:drug therapy; D011247:Pregnancy; D015149:Tocolytic Agents / Q000627:therapeutic use*; D014710:Version, Fetal
chemical_list: D015149:Tocolytic Agents; D008278:Magnesium Sulfate