The present case describes anaphylaxis in a pregnant woman who underwent combined spinal and epidural anesthesia for cesarean delivery. The immediate diagnosis, treatment, and cesarean delivery may have led to the good outcomes achieved for both the mother and the newborns.
When treating anaphylaxis during late pregnancy, besides comprehensive treatment, care should be taken to evaluate the fetal condition and to decide the best delivery timing. Primary management of anaphylaxis includes immediate withdrawal of antigen administration, seeking help, airway maintenance, aggressive fluid resuscitation, and adrenaline administration. Examining serum tryptase and histamine levels is useful for diagnosing anaphylaxis. Additionally, obstetric management may involve left uterine displacement and fetal monitoring. Maternal hypotension immediately affects the placental circulation and fetal status. However, the American College of Obstetricians and Gynecologists indicates that, during anaphylaxis, a stable maternal hemodynamic status does not ensure adequate placental perfusion and fetal oxygenation, whereas normal fetal heart rate variability reassures fetal status . Previous studies recommend that emergency cesarean delivery should be considered in cases of persistent maternal hemodynamic instability, despite resuscitation [4, 6]. In the present case, monitoring fetal heart rate was the key for the decision to perform a cesarean delivery. Although the good outcomes were achieved, fetal bradycardia was not recovered by phenylephrine. Administration of adrenaline for anaphylaxis may have increased cardiac output and systemic vascular resistance, resulting in improved uteroplacental perfusion .
Among previous case reports of anaphylactic labor, 46% resulted in adverse fetal neurologic outcomes [8,9,10,11,12,13]. In such cases, the anaphylactic parturients either had a delayed cesarean delivery [8, 9, 13] or did not receive sufficient adrenaline to manage severe hypotension . The fetal neurologic outcome was much better in cases of anaphylaxis occurring during cesarean delivery, which can be attributed to a short duration of fetal cerebral ischemia . The benefits of emergency cesarean delivery for anaphylactic patients refractory to medical treatment need to be balanced against the risks of surgery in pregnant women with an unstable general condition. If the time of gestation is less than 32 weeks, the risks of neonatal morbidity and mortality should also be considered. Anaphylaxis-related cardiovascular disturbance can be enhanced in pregnant patients by inferior vena cava compression. Moreover, neuraxial anesthesia blocks the sympathetic nerve, often causing hypotension. For anaphylaxis occurring during cesarean delivery, maternal morbidity due to severe complications was reported in 20% of cases . In the present case, anaphylaxis occurred during the intrapartum period, and the immediate cesarean delivery exerted a beneficial impact both on the mother and the infants.
Identifying the causative agent of anaphylaxis is essential to prevent allergic reactions. Agents, or known as allergens, administered immediately before an event, are often determined as culprit allergens without subsequent examinations. Had we not pursued the cause of the allergic reaction, we might have mistakenly assumed that the hydroxyethylated starch was the allergen, since anesthetic allergies have rarely been reported. Therefore, it should be kept in mind that the suspected agent may not be the true causative agent, and incorrect speculation may place the patient at risk of further exposure to the true allergen or cause unnecessary avoidance of harmless effective drugs.
The skin prick test is the gold standard to determine the cause of anaphylaxis, although it carries the risk of immediate hypersensitivity reactions. On the other hand, the BAT is an in vitro examination, which poses no risk of anaphylactic reactions. The BAT is based on the upregulation of granule-derived markers expressed at the basophil membrane upon ex vivo activation by the suspected agent. It recently became widely accepted as an additional and reliable tool, with high sensitivity and specificity to identify the causative agent of immediate drug hypersensitivity [14,15,16,17]. Further studies are required to evaluate the usefulness of this tool as a diagnostic approach of anaphylaxis, although diagnostic precision can be improved by combining multiple methods, such as the skin test and the BAT. In the present case, positive reactions to mepivacaine in both the BAT and skin prick test would support the reliability of BAT as a diagnostic tool.
In summary, the present case highlights that, upon anaphylaxis during pregnancy, maternal treatment and fetal heart rate monitoring should be started immediately. If the maternal hemodynamic status does not recover or if persistent non-reassuring fetal heart rate patterns are observed, immediate cesarean delivery should be considered, especially at the intrapartum period. Moreover, pursuing a definite diagnosis of the culprit allergen is beneficial for patients to prevent allergic reactions.