Cytomorphological Profile of Body Fluids in a Tertiary Care Centre: A Retrospective Cross-sectional Study

ABSTRACT Background: Examination of body fluids provides a rapid and minimally invasive means of assessing inflammatory, reactive, and neoplastic processes. Cytomorphological evaluation is particularly useful in serous effusions, where standardized terminology can support communication between the laboratory and treating clinicians. This study evaluated the cytomorphological profile of body-fluid specimens received at a tertiary care centre and assessed the distribution, benefits and pitfalls of diagnostic categories among serous effusions. Materials and Methods: This retrospective, hospital-based cross-sectional study was conducted in the Department of Pathology over one year, from January to December 2025, after institutional ethical clearance. Body-fluid specimens from the pleural, peritoneal, pericardial, cerebrospinal, and synovial cavities received during the study period were included. Gross examination and cell counts were done. Fluids were processed by centrifugation, and smears were stained with Giemsa or Haematoxylin & Eosin (H&E). Serous effusions were categorized using the International System for Reporting Serous Fluid Cytopathology (TIS). Cerebrospinal and synovial fluids were assessed using conventional cytomorphological criteria. Results: A total of 185 specimens were evaluated, including 98 pleural (52.9%), 61 peritoneal (33.0%), 22 cerebrospinal (11.9%), and 4 synovial (2.2%) fluids; no pericardial fluid was received. A male preponderance was noted (M:F = 1.23:1). Among the specimens for which transudate/exudate classification was applicable, transudates constituted 71.1% and exudates 28.9%. Among serous effusions, 91.8% of cases were negative for malignancy, 1.9% were non-diagnostic, 0.6% showed atypia of undetermined significance, 1.3% were suspicious for malignancy, and 4.4% were malignant. Suspicious and malignant diagnoses were confined to pleural and peritoneal fluids. Cerebrospinal and synovial fluids showed no malignant or suspicious cytological findings in this series. Conclusion: Body-fluid cytology remains a useful first-line laboratory investigation in appropriate clinical settings. Standardized reporting of serous effusions using TIS can provide a structured framework for communicating the degree of concern for malignancy. The relatively small number of indeterminate and malignant specimens in this single-centre series limits further analysis and highlights the need for larger studies with systematic clinical or histopathological follow-up. Keywords: Body fluids, serous effusion, pleural fluid, peritoneal fluid, cytopathology, International System for Reporting Serous Fluid Cytopathology.