Answers to RVV Questions

Back to our earlier discussion of the old Russell viper venom time (RVV, not the “new” dilute Russell viper venom time, DRVVT).  Joe Lamb came up with the name, Stypven Time. The purpose was to differentiate between a factor VII deficiency (prothrombin time prolonged, DVV normal) and factor X deficiency (both long). With improvements to the partial thromboplastin time and the ready availability of factor assays, the RVV has grown obsolete. To learn where “Stypven” came from, I turned to Mary Ann McLane, PhD, MLS, University of Delaware. Dr. McLane is immediate past president of the American Society for Clinical Laboratory Science and an expert in coagulation-related snake venoms. Using an online dictionary, she reports that “styptic” originated from the Latin and Greek words meaning “to contract”… as in styptic pencils used to stop bleeding from shaving cuts or minor wounds (which are made of alum, a combination of aluminum phosphate and aluminum sulfate). “Ven” was simply a contraction for “venom.”  She speculates that “Stypven” was a trademark develop by Merck in the 1950s or 1960s. Is there anyone from Merck among our participants who is old enough to confirm Merck’s involvement in the name?