Uterine Atony
Uterine atony is the most common cause of postpartum hemorrhage,
and it is caused by ineffective uterine muscle contraction in the postpartum period.
Risk factors include prolonged labor, an overdistended uterus (macrosomia or multiple
births), infection, grand multiparity, and administration of drugs that relax the
uterus (halogenated anesthetics, β-sympathomimetic agonists, and magnesium sulfate).
Treatment includes oxytocin; however, boluses of this drug may precipitate hypotension,
so continuous infusions are preferable.[271]
Carboprost
tromethamine (Hemabate), a 15-methyl analog of prostaglandin-F2α
,
is also a potent uterotonic that can be used. Side effects include nausea, vomiting,
and bronchoconstriction. This drug is given intramuscularly either by the anesthesiologist
or directly into the uterus by the obstetrician.[272]
In addition, the ergot derivatives (ergonovine and methylergonovine) are also potent
uterotonic agents that are given intramuscularly. Because profound hypertension
may occur, this drug should be avoided in patients with hypertensive disease.
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