Obstetric penicillin allergy evaluations

Background: Penicillin allergy is reported in 5% to 15% of the world population, with 3% to 10% of pregnant women reporting the same. However, more than 90% of these patients can tolerate penicillin after appropriate evaluation. Penicillin is indicated for various issues that arise in pregnancy, and a history of allergy can have negative individual and public health consequences.

Objective: Our aim was to prospectively evaluate the feasibility, safety, and select obstetric outcomes of obstetric penicillin allergy evaluations arranged through a direct referral phone line from obstetric practices to an employed allergy/immunology practice.

Methods: Patients were referred via direct phone line for evaluation during their antenatal visits between May 2019 and May 2022. Patients underwent skin prick testing, and those with a negative penicillin skin testing (PST) result were subjected to amoxicillin challenge. In select cases of patients with a low-risk history, direct oral challenge was performed. Data were analyzed using descriptive statistics.

Results: Of the 324 patients referred between May 2019 and May 2022, a total of 251 (77.5%) presented for in-office evaluations. Of those 251 patients, 239 (95.2%) underwent PST followed by oral challenge if the PST result was negative; 12 patients (4.8%) underwent direct challenge without skin testing, and all of them passed the challenge. Of the patients undergoing PST, 230 (97.2%) had a negative result and 229 tolerated subsequent oral amoxicillin doses, with 1 patient experiencing a delayed reaction to the amoxicillin. The group of patients who presented for evaluation included more people living in ZIP codes described as being of high socioeconomic status than in the no-show group (73.7% vs 63.3%).

Conclusion: To our knowledge, ours is the largest study to date to demonstrate the safety and feasibility of a phone line for obstetric penicillin allergy referrals. We demonstrate a better show rate than previous analyses, with most of the patients presenting for evaluation being successfully delabeled.