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Impact of Storage Conditions on Bronchoalveolar Lavage Fluid Analysis: A Human Study
Yu Shionoya1, Kanae Maruyama1, Takeshi Kawasaki1
1Department of Respirology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba City 260-8670, Japan.
Insights
Bronchoalveolar lavage fluid (BALF) analysis requires prompt processing. Neutrophil counts in BALF significantly decrease over time, especially at room temperature, impacting interstitial lung disease diagnosis.
Area of Science:
- Pulmonary Medicine
- Clinical Cytology
- Diagnostic Pathology
Background:
- Bronchoalveolar lavage fluid (BALF) analysis is crucial for diagnosing interstitial lung diseases (ILDs).
- Current guidelines exist, but sample handling variability may affect diagnostic accuracy.
- Optimal BALF sample processing conditions require further investigation.
Purpose of the Study:
- To evaluate the impact of different storage conditions on BALF cell counts and differentials.
- To determine the stability of BALF cellular components under varying temperatures and timeframes.
- To provide evidence-based recommendations for BALF sample handling to ensure diagnostic reliability.
Main Methods:
- BALF samples from 40 patients were analyzed.
- Samples were stored at 4°C or room temperature (RT) for 6 or 24 hours.
- Total and differential cell counts were compared across storage conditions.
Main Results:
- Total cell counts remained stable for up to 24 hours at both 4°C and RT.
- Eosinophil, lymphocyte, and macrophage percentages were unaffected by storage.
- Neutrophil percentages significantly decreased over time, particularly at RT and after 24 hours.
Conclusions:
- Neutrophil proportions in BALF are sensitive to storage conditions and time.
- Refrigeration and prompt analysis are essential for accurate BALF cytological interpretation.
- Adherence to optimal sample handling protocols is vital for reliable ILD diagnosis.
Abstract:
Background: Bronchoalveolar lavage fluid (BALF) analysis is essential for the accurate diagnosis and management of interstitial lung diseases (ILDs). Despite established guidelines, variability in sample handling may affect diagnostic accuracy. This study aimed to evaluate how different storage conditions impact BALF cell counts and differentials to guide optimal sample handling practices. Methods: Forty patients who underwent BAL at Chiba University Hospital from June to December 2024 were included. BALF samples were allocated into five groups based on processing conditions: immediate analysis within 1 h, storage at either at 4 °C or room temperature (RT) for 6 h, or storage at 4 °C or RT for 24 h. Total cell counts (TCC) and differential counts were measured and compared among conditions. Results: TCC remained stable over 24 h at both 4 °C (p = 0.86) and RT (p = 0.90). Similarly, the percentages of eosinophils, lymphocytes, and macrophages did not significantly change at either temperature (all p > 0.05). Notably, neutrophil percentages showed a significant decline over time under both storage conditions-at 4 °C (p = 0.02) and at room temperature (p < 0.01). Post hoc tests revealed a notable decreasing trend at 6 h and significant reductions by 24 h at 4 °C (p = 0.09 and p = 0.02, respectively), and significant decreases at both 6 and 24 h at RT (p = 0.01, <0.01). Conclusions: Among the various cell types in BALF, neutrophil proportions are particularly susceptible to storage conditions, showing a significant decline over time-especially at room temperature-while other cell types remain stable for up to 24 h. Therefore, prompt processing or appropriate refrigeration of BALF is essential to ensure reliable cytological analysis and accurate clinical interpretation.
