Abstract Introduction A sympathetic pleural effusion (SPE) is a sterile, nonmalignant pleural fluid collection that arises secondary to an inflammatory or infectious process outside the thoracic cavity, most commonly within the abdomen. SPEs are typically unilateral; bilateral involvement is exceedingly rare. We present an unusual case of bilateral SPEs developing in response to right-sided emphysematous pyelonephritis with perinephric hematoma. Case Presentation A 55-year-old woman with uncontrolled diabetes mellitus, hypertension, and hyperlipidemia presented with one week of dyspnea, cough, and pleuritic chest pain. Physical examination revealed right flank tenderness and decreased breath sounds at the left lung base. Laboratory findings included leukocytosis (18 × 103/µL), anemia (7.5 g/dL), hyponatremia (122 mmol/L), and elevated creatinine (3 mg/dL). Urinalysis was consistent with infection. Retroperitoneal ultrasound demonstrated right-sided emphysematous pyelonephritis. CT abdomen revealed a hemorrhagic right perinephric collection with gas. A percutaneous drain was placed, and cultures grew Klebsiella pneumoniae. Drain fluid measuring creatinine levels confirmed a collecting system fistula, prompting ureteral stent placement for source control. Despite improvement in flank pain, the patient developed acute hypoxemia. CT chest revealed bilateral pleural effusions. Left thoracentesis yielded an exudative effusion by Light’s criteria, with negative cultures and cytology. Persistent effusion required chest tube drainage. Subsequent right-sided thoracentesis demonstrated a similarly sterile, nonmalignant exudate. The patient improved with drainage, diuresis, and targeted antibiotics. Follow-up imaging confirmed complete resolution of bilateral effusions and perinephric infection. Discussion This case highlights an uncommon manifestation of sympathetic pleural effusion. SPEs occur due to transdiaphragmatic spread of inflammatory mediators or fluid from subdiaphragmatic infections, increasing pleural vascular permeability. They often mimic infectious or malignant effusions because of their exudative nature, but lack microbial or malignant cells. While unilateral effusions are typical, bilateral SPEs are exceedingly rare. To our knowledge, few reports link bilateral exudative effusions to renal pathology, particularly emphysematous pyelonephritis. Recognition of this entity is critical, as management focuses on treating the underlying source rather than aggressive pleural interventions. This case underscores the importance of considering sympathetic effusion in the differential diagnosis of unexplained exudative pleural effusions—especially in patients with abdominal or retroperitoneal infections—allowing for appropriate, conservative management and avoidance of unnecessary invasive procedures. This abstract is funded by: None
Chen et al. (Fri,) studied this question.