Medical device manufacturer, Roche has initiated a medical device field safety corrective action concerning NH3L (catalogue no.: 20766682322) on cobas c 501/502.

The manufacturer is providing a workaround to the affected users if the users have experienced elevated QC or patient recovery over time for the above affected product.

Blank signal may increase due to NH3 formation in R3 as a consequence of NADPH decomposition over the shelf-life of the reagent. This leads to falsely elevated test results over time.

The manufacturer advises users to follow the following procedures if they have the problem of positive drifting recovery of NH3L.

Before use, every new reagent cassette has to be pre-conditioned outside the analyzer for 24 hours at room temperature to allow the NH3 to dissipate from the reagent.

• Unscrew only the grey coloured R3 screw cap using the Open/Close tool. Keep the screw cap.
• Prevent it from contamination.
• Place the reagent cassette in an environment which is free from cigarette smoke, NH3 containing cleaners, and exhaust fumes of any kind.
• Store the cassette safely, in order to prevent it from falling over.
• Prevent the cassette from debris of any kind.
• Protect the open cassette from sunlight, do not store it near the window.
• After 24-hour storage, re-screw the grey screw cap on the R3 bottle.
• Load the cassette into the instrument.
• Manually request a 2-point calibration for each cassette.
• Manually request a blank calibration every 3 days.

According to the manufacturer, the investigations demonstrated the above procedures can maintain a stable recovery of the assay for 3 days.

According to the local supplier, the affected products were distributed in Hong Kong.

If you are in possession of the affected product, please contact your supplier for necessary actions.

Posted on 13 March 2013