A 36-year-old primigravida at 24 weeks gestation comes to the emergency department due to dry cough and shortness of breath since last night. The patient has a history of diabetes mellitus type 1 and mild, intermittent asthma. Six days ago, she went to an urgent care clinic due to urinary frequency and dysuria and was started on nitrofurantoin. The patient smokes 5 cigarettes daily, down from one pack daily prior to her pregnancy. Temperature is 38.2 C (100.8 F), blood pressure is 137/92 mm Hg, pulse is 104/min, and oxygen saturation is 92% on room air. Lung examination reveals crackles at the bases bilaterally. On cardiac auscultation, a 2/6 ejection-type murmur is heard at the left upper sternal border. The extremities are warm to the touch. There is 1+ edema of the ankles bilaterally. Laboratory results are as follows: Chest x-ray reveals bilateral parenchymal opacities, predominantly in the mid and lower lung zones. Which of the following is the most likely diagnosis?

Question

A 36-year-old primigravida at 24 weeks gestation comes to the emergency department due to dry cough and shortness of breath since last night.  The patient has a history of diabetes mellitus type 1 and mild, intermittent asthma.  Six days ago, she went to an urgent care clinic due to urinary frequency and dysuria and was started on nitrofurantoin.  The patient smokes 5 cigarettes daily, down from one pack daily prior to her pregnancy.  Temperature is 38.2 C (100.8 F), blood pressure is 137/92 mm Hg, pulse is 104/min, and oxygen saturation is 92% on room air.  Lung examination reveals crackles at the bases bilaterally.  On cardiac auscultation, a 2/6 ejection-type murmur is heard at the left upper sternal border.  The extremities are warm to the touch.  There is 1+ edema of the ankles bilaterally.  Laboratory results are as follows:  Chest x-ray reveals bilateral parenchymal opacities, predominantly in the mid and lower lung zones.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

This patient with new-onset shortness of breath, fevers, dry cough, and bilateral mid- and lower-lung opacities likely has acute nitrofurantoin-induced pulmonary injury. Both short- and long-term use of nitrofurantoin can result in lung injury. Short-term use is associated with an acute hypersensitivity involving the lungs, whereas long-term use can lead to interstitial lung disease. In acute disease, there is commonly a delay of 3-9 days from medication initiation to the onset of symptoms. Examination reveals basilar crackles, and imaging demonstrates bilateral, basilar opacities. An erythematous, maculopapular rash may be present. Pleural effusions also occur and are typically unilateral. The diagnosis is based on characteristic symptoms, suggestive laboratory findings (eg, leukocytosis, eosinophilia), imaging, and the timing of nitrofurantoin exposure; testing to exclude other diagnoses (eg, pneumonia, heart failure) can be considered. Management involves cessation of the drug, which typically leads to symptomatic improvement within 1-2 days. (Choice A) Although drug-induced acute interstitial nephritis (AIN) can present with fevers and eosinophilia, it most commonly presents with nonspecific symptoms of acute kidney injury such as nausea and vomiting. This patient's pulmonary symptoms and normal creatinine are not consistent with AIN. (Choice C) Peripartum cardiomyopathy is generally not seen before 36 weeks gestation and presents with signs and symptoms of heart failure, including dyspnea, cough, orthopnea, and peripheral edema. This patient's peripheral edema and her cardiac murmur are likely due to normal physiologic changes in pregnancy (eg, fluid retention, increased cardiac output). (Choice D) Preeclampsia is characterized by new-onset hypertension (≥140/90 mm Hg) and proteinuria. It can also be accompanied by other symptoms, including headache, visual abnormalities, and chest or abdominal pain. However, preeclampsia would not explain this patient's fevers or eosinophilia. (Choice E) Pulmonary embolism most commonly presents with dyspnea, pleuritic chest pain, and cough. Bibasilar opacities, fever, and eosinophilia shortly after nitrofurantoin exposure make drug-induced pulmonary injury more likely. (Choice F) Pulmonary sarcoidosis is characterized by bilateral hilar adenopathy and reticular opacities in the upper zone. Other manifestations such as skin lesions (eg, erythema nodosum) and eye disease (eg, uveitis) are common. This patient's predominance of lesions in the lower lung zones and recent nitrofurantoin exposure make the diagnosis less likely. Educational objective: Acute nitrofurantoin-induced pulmonary injury is due to a hypersensitivity that can present with fevers, shortness of breath, dry cough, and erythematous rash. Symptoms usually begin 3-9 days from medication initiation. Bilateral basilar opacities and pleural effusions are common. Treatment involves cessation of nitrofurantoin. References: Nitrofurantoin related pulmonary disease: a clinical reminder. (http://www.ncbi.nlm.nih.gov/pubmed/23729707)

A 36-Year-Old Primigravida at 24 Weeks Gestation Comes to the Emergency