(562) Miliary TB in a Pregnant Patient

Introduction: Tuberculosis (TB) remains a public health issue, with prevalence ranging from 0.06% to 0.25% in low-prevalence countries and 0.07% to 0.5% in high-prevalence regions. TB in pregnancy is challenging to assess due to symptom overlap with pregnancy-related complaints. Pregnant women are more susceptible to TB due to immune changes that occur. These changes include partial inhibition of cellular immunity through cytokines like IL-10 and TGF-β, which, while necessary for fetal protection, also heighten vulnerability to TB.

Description: A 24-year-old woman with alpha-thalassemia trait, at 33 weeks of gestation, presented with a one-month of fever, sore throat, and shortness of breath. She was initially treated at another facility for an upper respiratory tract infection with antibiotics. Diagnostic workup included negative respiratory viral and HIV tests and nonreactive RPR; a chest CT angiography showed a diffuse miliary pattern, raising suspicion for TB. Subsequent T-SPOT and QuantiFERON tests were positive but 2 MTB-PCR samples collected from 2 bronchoscopies were negative. Empiric TB treatment with rifampicin, ethambutol, and isoniazid was initiated due to her developing acute hypoxic respiratory failure. She required high-flow nasal cannula and given betamethasone for fetal lung maturation. An emergency cesarean section was performed due to non-reassuring fetal heart tones, and postoperatively, she had a bronchoscopy and lung cryobiopsy which revealed multiple necrotizing granulomas. She also had adhesions on her uterus and ovaries, suggestive of genitourinary TB. The placenta was negative for AFB. Despite elevated transaminases, the patient improved with gradual reintroduction of quadruple TB therapy, and she continues to be monitored by ID and pulmonary teams while her baby remains well.

Discussion: The negative results from 2 separate bronchoalveolar lavage samples using PCR, despite the high sensitivity of these tests for detecting TB, are atypical. This anomaly suggests that miliary TB in this case was hematogenous. However, cultures eventually yielded positive results after a four-week incubation period. This case underscores the importance of cultures as the gold standard for TB diagnosis, as caseating granulomas, while indicative, are insufficient for a definitive diagnosis.