To retrospectively assess the incidence and severity of perioperative protamine reactions in adult patients with documented history of fish allergy.

Retrospective observational study.

Large academic tertiary referral center.

Adults with fish allergies undergoing surgeries involving protamine, between January 1, 2008, and March 1, 2018.

Perioperative protamine administration in patients with documented fish allergy.

Perioperative protamine and anaphylactic reactions were reviewed. A diagnosis of anaphylaxis or protamine reaction was based on clinical suspicion, perioperative events, and postoperative evaluations. Among 214 patients, 2 cases (<1%) of anaphylaxis or protamine reactions occurred. Cardiac procedures were most common (67%). The median intraoperative heparin dosage was 46,000 IU, and the median protamine dosage was 310 mg. Nearly all patients (99%) were admitted to the intensive care unit postoperatively, with a median hospital stay of 6.5 days (interquartile range, 5.2-14.6 days). There were 3 deaths (1%) within 30 days, and 15 (7%) within 1 year.

The study findings suggest that in patients with a history of fish allergy, cross-reactivity with protamine is unlikely, as anaphylaxis and/or protamine reactions were rare in this patient population in the perioperative environment. Based on these findings, this study does not recommend avoiding protamine solely based on a history of fish allergy when heparin reversal is required during surgery.