A 22-year-old woman comes to the office for an initial prenatal visit. The patient is 19 weeks gestation by her last menstrual period. She emigrated from India 3 weeks ago and, as found on her medical screening, had a positive interferon gamma release assay. The patient otherwise has no medical conditions and no fever, cough, or weight loss. Temperature is 36.7 C (98.1 F), blood pressure is 100/70 mm Hg, and pulse is 70/min. BMI is 23 kg/m². There is no lymphadenopathy. The lungs are clear to auscultation. The uterus is palpated just below the umbilicus. Transabdominal ultrasound shows a singleton intrauterine pregnancy at 19 weeks gestation and a normal fetal heart rate. Routine prenatal laboratory results, including HIV screening, are normal. Which of the following is the best next step in management of this patient?

Question

Quizplus · Accepted Answer

This woman has a positive interferon gamma release assay, which means that she has been infected with tuberculosis (TB). Tuberculin skin testing (TST) and interferon gamma release assay (IGRA) are safe, reliable methods for screening for tuberculosis during pregnancy. Screening is recommended in those who report close contact to a person with known TB, travel from a high-risk country (like this patient), or are exposed to a high-risk setting (eg, homeless shelter). The next step after a positive screening test is to differentiate active disease from latent infection. Latent TB is defined as a reactive TST or IGRA with a negative chest x-ray and absence of symptoms. Therefore, the optimal next step in management is to obtain a screening chest x-ray. Chest x-ray during pregnancy is safe with appropriate shielding and should be pursued if it immediately affects management, as in this patient. If the chest x-ray is abnormal, active TB disease is likely, and sputum cultures should be obtained. If the chest x-ray is normal, latent TB is confirmed. (Choices A and B) Isoniazid is an option for prophylaxis once latent TB has been confirmed. The optimal timing of prophylaxis depends on the patient and the type of exposure, but the medication can be delayed until after delivery in some circumstances. However, this woman has not yet been diagnosed with latent versus active TB. (Choice D) TST is an option for the initial diagnosis of TB infection but can be falsely positive in patients who have received the bacille Calmette-Guérin (BCG) vaccine. In contrast, IGRA is not positive after BCG immunization. There is no benefit to retesting this patient with a different assay when she already has a positive IGRA. (Choice E) Pregnancy does not cause a false-positive IGRA; there is no need to repeat the assay after delivery. (Choice F) This patient has not been diagnosed with active versus latent TB, so it would be inappropriate to begin multidrug therapy for active TB disease. Given her absence of symptoms, latent TB is more likely, but a chest x-ray is indicated to confirm the diagnosis. Educational objective: Pregnant women should be evaluated for tuberculosis using the same diagnostic approach as nonpregnant patients. A positive tuberculin skin test or interferon gamma release assay should be followed with chest x-ray to differentiate latent infection versus active disease. References: Latent tuberculosis in pregnancy: a systematic review. (http://www.ncbi.nlm.nih.gov/pubmed/27149116) Migration and infectious diseases. (http://www.ncbi.nlm.nih.gov/pubmed/28336382)

A 22-Year-Old Woman Comes to the Office for an Initial