Influence of storage time on pleural fluid adenosine deaminase activity.

BACKGROUND: Storing pleural fluid samples for research purposes is a common practice, but whether adenosine deaminase (ADA), an enzyme used for the diagnosis of tuberculous pleuritis, is stable over long periods of time is unknown. METHODS: We evaluated the stability of pleural ADA concentrations in 223 samples frozen at -800C as compared to values obtained immediately following the initial thoracentesis. Sample storage time ranged from several months to slightly more than 10 years. RESULTS: ADA activity was stable for up to 2.6 years. Afterwards, it decreased 6 to 8 U/L, enough to drop 2 (3.3%) tuberculous patients below the diagnostic ADA cutoff. CONCLUSIONS: As far as ADA enzymatic activity is concerned, pleural fluid samples are viable for extended periods of time. However, some caution in interpreting results from specimens stored for > 2.6 years is prudent.

Diagnostic yield of fine-needle aspiration puncture for cytology of multifocal liver lesions: a comparison between image-guided and blind aspirations.

BACKGROUND: In patients with palpable hepatomegaly and space occupying lesions demonstrated by imaging techniques, blind fine needle aspiration puncture (FNAP) at the patient's bedside is feasible. OBJECTIVE: To compare the diagnostic yield of the fine needle aspiration puncture (FNAP) performed blindly or under radiological control in patients with hepatomegaly and multiple solid space occupying lesions in the liver, demonstrated by ultrasonography. METHODS: A retrospective study was made of 169 consecutive FNAPs of liver tumors performed either blindly at the bedside by an internist (55 patients) or imaged-guided by a radiologist (114 patients). RESULTS: The diagnostic yield of the technique performed blindly to demonstrate malignancy was 78% (95% confidence interval [CI]: 66-87%) versus 83% (95% CI: 75-89%, P=.42) obtained in the image-guided FNAPs. The diagnostic yield did not vary based on type of tumor invading the liver. CONCLUSION: Blind FNAP procedures in patients with palpable enlarged liver due to solid space occupying lesions is as effective as those performed under radiological control.