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Increased bleeding time after magnesium sulfate infusion
Increased bleeding time after magnesium sulfate infusion Marketa Kynczl-Leisure, MD, and Luis A. Cibils, MD Chicago, Illinois Personal observation suggested that blood loss increased among patients with preeclampsiawho received magnesium sulfate infusions. Bleeding time (modified Ivy) was checked before infusion of magnesium and at the completion of infusion for nine patients with preeclampsia and three who did not receive magnesium. Bleeding time more than doubled among patients who needed magnesium and did not change among controls. (Am J Obstet Gyneco11996;175:1293-4.)
Key words: Bleeding, m a g n e s i u m sulfate
In a review of the charts of patients with hypertension, o n e of the authors (M.K.-L.) observed that there was markedly increased blood loss at delivery a m o n g those who received m a g n e s i u m sulfate infusion. Because there was no clear cause for this increase, we decided to study potential m e c h a n i s m s that may mediate the p h e n o m enon. After obtaining approval f r o m the institutional review board, we c o n d u c t e d a preliminary study of b l e e d i n g time before infusion of m a g n e s i u m sulfate and at discontinuation of the infusion several hours after delivery.
Technidyne, Edison, N J . ) device 1 before m a g n e s i u m was given ante partum. Bleeding time was m e a s u r e d again at the time the m a g n e s i u m infusion was discontinued (for one patient this was 5 hours after infusion was discontinued), usually between 12 and 24 hours post partum. T h e u n t r e a t e d patients (controls) had b l e e d i n g time measured in early labor and 24 hours post p a r m m . Results were c o m p a r e d by m e a n s of the Wilcoxon signed rank sum test. Results
Material and methods Twelve patients with preeclampsia scheduled to receive m a g n e s i u m sulfate participated in the study. Nine received the standard convulsion prophylaxis t r e a t m e n t with m a g n e s i u m sulfate, and three u n t r e a t e d patients served as controls. Bleeding time was m e a s u r e d by means of a m o d i f i e d Ivy m e t h o d with a Surgicatt (International
From the University of Chicago and the ChicagoLying-in Hospital. Receivedfor publication April 1, 1996; acceptedJune 10, 1996. Reprint requests: Luis A. Cibils, MD, the Chicago Lying-in Hospital, 5841 S. Maryland Ave., Chicago, IL 60637. Copyright © 1996 by Mosby-Year Book, Inc. 0002-9378/96 $5.00+ 0 6/1/75723
Tables I and II show the results. T h e b l e e d i n g time for patients before receiving medication r a n g e d f r o m 2 to 8 minutes. T h e r e was a 164% increase in b l e e d i n g time a m o n g the eight patients who u n d e r w e n t the second test at discontinuation of infusion (p < 0.01) ; there was no change in the patient who u n d e r w e n t the test 5 hours after m a g n e s i u m infusion was discontinued. T h e r e was no statistically significant change a m o n g controls. No correlation was observed between total m a g n e s i u m dose and percentage increase in b l e e d i n g time. Comment It is clear that infusion of m a g n e s i u m sulfate, as routinely used for prevention of convulsion in preeclampsia,
Table I. Bleeding time before and after m a g n e s i u m sulfate infusion in advanced gestation
Bleeding time i
CaseNo. 1 2 3 4 5 6 7 8 Mean _+SD 9
Before magnesium infusion 4 min 2 rnin 5 min 3 min 4 rain 6 min 8 rain 4 min 4 min 7 min
45 sec
15 sec 30 sec 42 sec -+ 1 min 46 sec 30 sec
After magnesium infusion 10 min 5 min 9 min 7 min 13 min 12 rain 13 min 20 min 11 min 8 min
15 sec 30 sec 45 sec 45 sec 30 sec 20 sec 30 sec -+ 4 min 7 sec
Change (%)
Duration of infusion (hr)
116 175 95 158 218 85 67 400 164 7
22 25 40 22 28 18 22 15 20
In case 9 the "after magnesium" test was conducted 5 hours after infusion was discontinued. 1293
294
Kynczl-Leisureand Cibils
November 1996 AmJ Obstet Gynecol
T a b l e II. Control subjects b l e e d i n g time during advanced gestation
Bleeding time CaseNo.
Early labor
24 hr post partum
Change (%)
10 11 12 Mean _+SD
6 min 5 rain 4 rain 45 sec 5 min 15 sec + 32 sec
7 rain 6 min 4 min 30 sec 5 min 50 sec -+ 43 sec
17 20 -6 10
increased the b l e e d i n g time of the patients in the study and explains the observation that p r o m p t e d the study. Many factors involved in spontaneous hemostasis may be i n f l u e n c e d by sustained infusion of magnesium. A study to evaluate some clotting values was started after this observation; the findings will be r e p o r t e d soon.
REFERENCE
1. Mielke CH, Kaneshiro MM, Maher Ilk, et al. The standardized normal Ivy bleeding time and its prolongation by aspirin. Blood 1969;34:204-15.
Key words: Bleeding, m a g n e s i u m sulfate
In a review of the charts of patients with hypertension, o n e of the authors (M.K.-L.) observed that there was markedly increased blood loss at delivery a m o n g those who received m a g n e s i u m sulfate infusion. Because there was no clear cause for this increase, we decided to study potential m e c h a n i s m s that may mediate the p h e n o m enon. After obtaining approval f r o m the institutional review board, we c o n d u c t e d a preliminary study of b l e e d i n g time before infusion of m a g n e s i u m sulfate and at discontinuation of the infusion several hours after delivery.
Technidyne, Edison, N J . ) device 1 before m a g n e s i u m was given ante partum. Bleeding time was m e a s u r e d again at the time the m a g n e s i u m infusion was discontinued (for one patient this was 5 hours after infusion was discontinued), usually between 12 and 24 hours post partum. T h e u n t r e a t e d patients (controls) had b l e e d i n g time measured in early labor and 24 hours post p a r m m . Results were c o m p a r e d by m e a n s of the Wilcoxon signed rank sum test. Results
Material and methods Twelve patients with preeclampsia scheduled to receive m a g n e s i u m sulfate participated in the study. Nine received the standard convulsion prophylaxis t r e a t m e n t with m a g n e s i u m sulfate, and three u n t r e a t e d patients served as controls. Bleeding time was m e a s u r e d by means of a m o d i f i e d Ivy m e t h o d with a Surgicatt (International
From the University of Chicago and the ChicagoLying-in Hospital. Receivedfor publication April 1, 1996; acceptedJune 10, 1996. Reprint requests: Luis A. Cibils, MD, the Chicago Lying-in Hospital, 5841 S. Maryland Ave., Chicago, IL 60637. Copyright © 1996 by Mosby-Year Book, Inc. 0002-9378/96 $5.00+ 0 6/1/75723
Tables I and II show the results. T h e b l e e d i n g time for patients before receiving medication r a n g e d f r o m 2 to 8 minutes. T h e r e was a 164% increase in b l e e d i n g time a m o n g the eight patients who u n d e r w e n t the second test at discontinuation of infusion (p < 0.01) ; there was no change in the patient who u n d e r w e n t the test 5 hours after m a g n e s i u m infusion was discontinued. T h e r e was no statistically significant change a m o n g controls. No correlation was observed between total m a g n e s i u m dose and percentage increase in b l e e d i n g time. Comment It is clear that infusion of m a g n e s i u m sulfate, as routinely used for prevention of convulsion in preeclampsia,
Table I. Bleeding time before and after m a g n e s i u m sulfate infusion in advanced gestation
Bleeding time i
CaseNo. 1 2 3 4 5 6 7 8 Mean _+SD 9
Before magnesium infusion 4 min 2 rnin 5 min 3 min 4 rain 6 min 8 rain 4 min 4 min 7 min
45 sec
15 sec 30 sec 42 sec -+ 1 min 46 sec 30 sec
After magnesium infusion 10 min 5 min 9 min 7 min 13 min 12 rain 13 min 20 min 11 min 8 min
15 sec 30 sec 45 sec 45 sec 30 sec 20 sec 30 sec -+ 4 min 7 sec
Change (%)
Duration of infusion (hr)
116 175 95 158 218 85 67 400 164 7
22 25 40 22 28 18 22 15 20
In case 9 the "after magnesium" test was conducted 5 hours after infusion was discontinued. 1293
294
Kynczl-Leisureand Cibils
November 1996 AmJ Obstet Gynecol
T a b l e II. Control subjects b l e e d i n g time during advanced gestation
Bleeding time CaseNo.
Early labor
24 hr post partum
Change (%)
10 11 12 Mean _+SD
6 min 5 rain 4 rain 45 sec 5 min 15 sec + 32 sec
7 rain 6 min 4 min 30 sec 5 min 50 sec -+ 43 sec
17 20 -6 10
increased the b l e e d i n g time of the patients in the study and explains the observation that p r o m p t e d the study. Many factors involved in spontaneous hemostasis may be i n f l u e n c e d by sustained infusion of magnesium. A study to evaluate some clotting values was started after this observation; the findings will be r e p o r t e d soon.
REFERENCE
1. Mielke CH, Kaneshiro MM, Maher Ilk, et al. The standardized normal Ivy bleeding time and its prolongation by aspirin. Blood 1969;34:204-15.