Laboratory Medicine Updates - October 15, 2003
University of Virginia Health System
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LABORATORY MEDICINE UPDATE
October 15, 2003
Immunofluorescent Staining for C4d
The Division of Surgical Pathology/Histology now offers an immunofluorescent test for C4d, a complement degradation product. This stain will be done automatically on all renal and heart transplant biopsies for which immunofluorescent analysis is requested.
The detection of C4d in peritubular capillaries, together with light microscopic findings and serum panel-reactive antibodies, is indicative of acute humoral/vascular renal allograft rejection. The distinction between acute humoral and acute cellular rejection is pathologically difficult and is probably frequently missed on light microscopy alone.
Diagnosis of acute humoral rejection is important because the short-term prognosis for the renal allograft is significantly worse than for acute cellular rejection and evidence is accumulating that different therapies should be used for the two types of rejection.
The use of this test for renal allograft biopsies was strongly endorsed at the recent Seventh Banff Conference on Allograft Pathology. Its use on cardiac biopsies is less well characterized, but is also recommended.
Rapid Flu Screen Availability
In order to maintain the highest sensitivity for the rapid flu screen, the test is only offered November 1 through April 30 unless there are documented cases of Influenza prior to November 1 in the community. If you strongly suspect a patient to have symptoms consistent with Influenza Virus infection, please page the Microbiology Director on-call to discuss the possibility of the laboratory performing the rapid test before November 1. The recommended test before November 1 on respiratory specimens is a viral culture for all respiratory viruses.
Inoculation of Blood Culture Bottles
Blood Culture bottles should only be inoculated using a syringe and needle and the needle must be removed prior to submitting the bottles to the Medical Laboratories. The needle-less system designed for removing medication from medication vials, such as the Interlink Vial Access Cannula, is not recommended as it punctures a large hole in the septum that may leak and/or allow contamination of the culture. Additionally, these cannulas cannot be removed from the blood culture bottles and thus pose a potentially serious health risk to laboratory personnel.