[Undiagnosed hereditary angioedema in a patient undergoing emergency caesarean section]

Hereditary angioedema (HAE) is characterized by acute, recurrent attacks of localized edema. Surgical procedures, trauma, and infections have been considered as potential triggers of HAE. Although HAE is a rare genetic disorder, approximately 50-60% of all HAE patients are involved with at least one occurrence of upper airway obstruction. The airway trouble is the most life-threating complication in HAE patients because HAE-related edema does not respond to typical treatment, such as administration of epinephrine, antihistamines, or glucocorticoids. Indeed, mortality rates of laryngeal attack are estimated around 25% to 40%. Here we describe a case of undiagnosed HAE patient undergoing emergency caesarean section under neuraxial blockade. A 31-year-old woman showed multiple regions at her lip margin during surgery and rapidly developed lip swelling after admission to the ward. Neither respiratory nor hemodynamic instability was found during and after surgery. Immediately, in order to assess whether HAE caused these dermatological manifestations, we measured values of both complement component 4 (C4) and functional activity of C1-esterase inhibitor (C1-inh), a protein of the complement system. These laboratory data showed low levels, which were compatible with HAE definition. After commencement of C1-inhibitor replacement therapy, her lip swelling and erythema gradually disappeared without adverse drug reactions. The patient was finally discharged from our institution 10 days after surgery.