A 24-year-old, gravida 5, para 1 woman was scheduled for repeat cesarean section at 37 weeks of gestation under spinal anesthesia. Her body weight and height before cesarean delivery were 50.3 kg and 155 cm, respectively. She had a history of prepartum severe ileus that necessitated an urgent cesarean delivery 4 years prior. Her medical history included well-controlled panic disorder, with clomipramine and bromazepam. Additionally, she had undergone an uneventful right meniscus repair surgery under general anesthesia 1 year ago. Although she had a history of hay fever, she had no recorded food or drug allergies.

Upon her arrival in the operating room, routine monitoring was initiated, and intravenous administration of 6% hydroxyethyl starch solution was started. Following intravenous administration of metoclopramide, the patient was positioned in the right lateral decubitus posture in preparation for spinal anesthesia, and infusion of cefazolin 1 g was started. After infusion of 0.8 g cefazolin in 3 min and before sterilization of the patients’ back, she reported skin itchiness. Physical examination revealed erythema across her entire body. Blood pressure dropped to 83/57 mmHg; heart rate increased to 124 bpm. Peripheral oxygen saturation remained at 98% in room air (Fig. 1).

Anesthesia record. The patient complained of itchiness and developed a systemic eruption 3 min after starting cefazolin infusion, followed by dyspnea, hypotension, and tachycardia. She was repositioned to a supine position with left uterine displacement. Intravenous adrenaline was administered repeatedly, along with procaterol aerosol for dyspnea and a continuous infusion of noradrenaline. Despite these measures, her vital signs remained unstable, and fetal bradycardia prompted an emergency cesarean section under general anesthesia. A healthy newborn was delivered 20 min after the onset of anaphylaxis. The mother’s condition stabilized significantly post-delivery, allowing for weaning off catecholamine infusions. Hydrocortisone was administered to prevent further allergic reactions. The total blood loss was 494 mL with a fluid balance of + 1360 mL. Abbreviations: SpO2, arterial oxygen saturation; NIBP, non-invasive blood pressure; HR, heart rate; Time 0, patient’s entrance into the operating theater; T, tracheal intubation; E, extubation

Promptly, supplemental oxygen was initiated, and 0.1 mg of intravenous adrenaline was administered 10 min after the onset of symptoms. The patient was repositioned to a supine position with left uterine displacement, and intravenous adrenaline 0.1 mg was repeated. The patient then complained of dyspnea, and procaterol aerosol was given for relief. Additionally, a continuous infusion of noradrenaline at 0.1 μg/kg/min was initiated. Despite these interventions, her vital signs remained unstable, with blood pressure ranging 60–80/30–40 mmHg and heart rate 140–150 bpm. Fetal bradycardia was detected through Doppler fetal heart rate monitoring, necessitating the decision for an emergency cesarean section under general anesthesia.

After rapid sequence induction using thiopental 375 mg, succinylcholine 100 mg, and tracheal intubation, cesarean section was started. A female baby was delivered 20 min after the onset of anaphylaxis symptoms, with Apgar scores of 7 at 1 min and 9 at 5 min. The umbilical artery pH was measured at 7.141, PCO2 73.2 mmHg, base excess − 4.0 mmol/L, HCO3− 25.2 mmol/L, and lactate 5.9 mmol/L. A brief period of continuous positive airway pressure was applied to assist with breathing via a face mask, which resulted in a quick recovery.

Immediately after delivery, the vital signs began to recover and stabilize. The requirement for catecholamine support gradually lessened, becoming unnecessary by the end of the surgery. Hydrocortisone 100 mg was administered to prevent the recurrence of an acute allergic reaction. Sevoflurane, midazolam, and morphine were used for maintenance of anesthesia. Total blood loss during the surgery was 494 mL, and total fluid balance was + 1360 mL.

She remained under observation in the intensive care unit overnight, and no subsequent event occurred. The baby was observed overnight in the neonatal intensive care unit, experiencing no adverse events. On the fifth day post-surgery, the mother and her baby were discharged home.

Plasma histamine levels were within the normal range 30 min after symptom onset, likely due to its rapid degradation, as indicated by the decreasing trend over time. Notably, however, the plasma tryptase level showed a significant increase at 30 min and 2 h after symptom onset (Table 1). The significant rise in tryptase levels, along with the clinical course, confirmed a definitive diagnosis of anaphylaxis.

We had intended to conduct an allergy examination to ascertain the possible trigger of the anaphylaxis (cefazolin, hydroxyethyl starch, or metoclopramide). However, scheduling difficulties have prevented her from attending our clinic up to this point.