S5175 Acute Hemorrhagic Spontaneous Bacterial Peritonitis (SBP) as a Consequence of Serositis

Introduction: Spontaneous bacterial peritonitis (SBP) is a common complication of known liver disease, however, its association with acute rheumatologic disease is not well cited in the literature. We present a case of woman who developed recurrent hemorrhagic ascites in the setting of nonbacterial serositis. Case Description/Methods: A 42-year-old woman with end-stage renal disease secondary to lupus nephritis, antiphospholipid antibody syndrome (APLA) presented for generalized abdominal pain. She had prior peritoneal dialysis, discontinued with catheter removal a year prior due to peritonitis. On presentation, she was hemodynamically stable. Labs showed a hemoglobin of 7.7 g/dL, and troponin 39 ng/L. Computed tomography (CT) abdomen/pelvis demonstrated substantial ascites. Paracentesis removed 3.6 L bloody fluid, and fluid analysis revealed a neutrophil count of 387, consistent with SBP. She completed a 7-day course of antibiotics. Her hemoglobin continued to drop below 7 g/dL, however, she refused blood transfusions due to religious beliefs. She was started on 40,000 units of epoetin-alfa (EPO) daily but redeveloped ascites. Another paracentesis removed 2L of bloody fluid with a neutrophil count of 16,429. Antibiotics were broadened to piperacillin-tazobactam. CTA abdomen/pelvis and tagged RBC scans were negative for bleeding. She was unresponsive to EPO therapy; Hgb remained between 6.6-6.9 g/dL with hypotension. ESA resistance was ruled out. The patient was empirically started on methylprednisolone for concern of rheumatologic involvement. Her hemoglobin improved to 7.8 g/dL with 3 days of steroids. Further rheumatologic workup, including ds-DNA and complement levels were negative, consistent with acute nonbacterial serositis. Discussion: Acute anemia with hemodynamic instability is often supportively managed with blood transfusions and interventions targeting the underlying cause. However, in cases where transfusions are not an option and conventional diagnostic pathways fail to localize a source, alternative etiologies must be explored. This highlights the diagnostic complexity of recurrent hemorrhagic ascites in a patient with lupus nephritis and APLA, ultimately attributed to acute nonbacterial serositis. Although her rheumatologic disease appeared controlled with immunosuppression, a steroid trial led to rapid hemoglobin improvement, suggesting an inflammatory mechanism. This underscores the importance of considering serositis as a high-priority differential in patients with systemic autoimmune disease, even without active serologic markers.