Diagnosis and clinical management of drug allergies in obstetrics and gynecology: an expert review.

Drug allergies, specifically antibiotic allergies, are frequently encountered in obstetrics and gynecology, with 10% of the US population reporting a penicillin allergy. This poses a particular challenge to the obstetrician-gynecologist, as beta-lactam antibiotics are indicated as first-line therapy for the treatment and prevention of most specialty-specific infections. Alternative antibiotic use in the setting of a reported allergy is not benign and has been associated with increased cesarean delivery, endometritis, wound complication, length of hospital stay in pregnant patients, Group B Streptococcus sepsis, neonatal length of stay, neonatal laboratory draw in neonates born to patients with allergies, and surgical site infection in gynecologic patients. Furthermore, alternative antibiotic use leads to increased antibiotic resistance, toxicity, and healthcare cost. In addition, the administration of antibiotics in a patient with a history of type I immediate hypersensitivity reaction poses a risk of anaphylaxis with repeat exposure. Fortunately, >90% of patients who report a penicillin allergy are not truly allergic and would tolerate penicillins if administered. This can be due to either mislabeling of the index reaction as an allergy (when it was due to a drug intolerance or a viral exanthem) or waning immunoglobulin E-mediated immunity over time. Given this, allergy evaluation is widely recommended, even in pregnancy. Allergy evaluation involves detailed patient history and allergy testing with skin testing and/or oral challenge, as appropriate. These tools have been found to be safe and effective in gravid and nongravid individuals and to result in increased use of first-line antibiotics when used appropriately. Furthermore, even in the setting of a true penicillin allergy, cross-reactivity with cephalosporins is extremely low and estimated at 2% to 3% among patients with a verified penicillin allergy and considerably lower than this among patients with an unverified penicillin allergy. Guidelines support the routine use of cephalosporins without testing or additional precautions in patients with an unverified nonanaphylactic penicillin allergy and the routine use of structurally dissimilar cephalosporins (specifically Ancef) even in patients with an anaphylactic penicillin allergy. In cases in which there is no appropriate alternative antibiotic than that for which the patient is allergic, such as syphilis in a pregnant patient with penicillin allergy, desensitization can be performed. This process involves temporary induction of drug tolerance through exposure to small amounts of the allergen until a therapeutic dose is achieved and has been safely performed in pregnancy. Desensitization requires expert supervision and is most often performed in the intensive care setting with a multidisciplinary team. The other 2 most common antibiotic allergies encountered in the field of obstetrics and gynecology are cephalosporin and metronidazole allergies. Cephalosporin allergies are managed similarly to penicillin allergies with readily available skin testing and oral challenge. Skin testing for metronidazole allergy lacks sensitivity and specificity, and thus, oral challenge or desensitization procedure is the preferred approach for low-risk and high-risk patients, respectively. When it comes to drug allergies, specifically antibiotic allergies, the role of the obstetrician-gynecologist is to identify patients with reported allergies and to refer patients to a specialist for further evaluation as soon as possible. Allergy evaluation using a detailed patient history and allergy testing (skin testing and/or oral challenge) when indicated has been shown to be safe and effective and is an important part of antibiotic stewardship.