Beta-2 Agonists May be Superior to Epinephrine to Relieve Severe Anaphylactic Uterine Contractions.

Background: Uterine contractions are recognized as a potential manifestation of anaphylaxis, but literature on their proper management is limited. It is widely recognized that anaphylactic reactions can cause uterine contractions, but little is known about their optimal management.

Objective: Review potential treatments for painful uterine contractions associated with anaphylaxis or mast cell activation.

Methods: This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines. PubMed, Embase, and Cochrane were searched in English, French, and Spanish for reports of uterine anaphylaxis published up until July 2020. The search strategy used a combination of Boolean operators and included the following Medical Subject Heading terms and keywords: hypersensitivity; anaphylaxis; mastocytosis; uterus; uterine contraction; pelvic pain; labor, obstetric; labor, premature; and endometriosis.

Results: This systematic review identified 19 studies reporting on 31 cases of painful uterine contractions occurring during anaphylaxis or other events associated with mast cell activation. Nine patients were pregnant. We present 2 additional cases in nonpregnant women, one associated with an oral food challenge and the other associated with oral food desensitization. The most frequent triggers were subcutaneous immunotherapy (14 cases), food (6 cases), and drugs (4 cases). Uterine cramps were associated with systemic symptoms in 24 cases and lasted on average for 2.4 hours. Pretreatment with antihistamines and montelukast generally failed to prevent recurrence, but nonsteroidal anti-inflammatory drugs were used successfully in some reports. Response to intramuscular epinephrine was inconsistent. Data from ex vivo models indicate that epinephrine may paradoxically contribute to uterine contractions through alpha-receptor activity. A small number of cases showed good response to beta-2 agonists.

Conclusions: There is a lack of quality data on painful uterine contractions occurring in the context of anaphylactic reactions and on their optimal management. In the absence of counterindication, use of a beta-2 agonist and premedication with nonsteroidal anti-inflammatory drugs could be the preferred options.