Systemic mastocytosis complicating pregnancy.

Background: Systemic mastocytosis is a rare medical disorder in which an increased number of mast cells can precipitate immediate hypersensitivity reactions, leading to hypotension, shock, and death. It is characterized by persistent elevated serum tryptase levels. The few published reports on pregnancy complicated by systemic mastocytosis indicate favorable maternal and fetal outcomes in gravidas known to have systemic mastocytosis.

Case: A pregnant woman treated with terbutaline at 31 weeks of gestation developed severe hypotension which resulted in fetal demise; this was initially diagnosed to be an anaphylactic reaction. The finding of persistently high maternal tryptase levels led to the diagnosis of systemic mastocytosis. In her subsequent pregnancy she was treated with an H1 blocker. Hypotension during her cesarean delivery was managed with steroid and epinephrine therapy.

Conclusion: Exacerbations of systemic mastocytosis during pregnancy can lead to significant maternal and fetal complications. Treatment with H1 blockers, and when indicated, steroids and epinephrine, can reduce these complications.