In 1975 Health Protection Branch approval was received to distribute125I-Fibrinogen Injection. Since that time over 30,000 vials of this drug have been prepared and used in the detection of venous
thrombosis. Diagnosis of venous thrombosis with fibrinogen leg scanning depends on the incorporation of125I-Fibrinogen into the thrombus, which is then detected by measuring the consequent increase of overlying surface radioactivity
using a small Na(TI) detector. The preparation of the drug relies on careful donor selection to minimize the chance of transmitting
hepatitis. Careful separation of the fibrinogen is necessary to ensure that a high concentration of clottable protein is available
for iodination. Fibrinogen having a clottable protein content in excess of 80% is iodinated using the ICl method. This product
must have a consistent high quality. The control procedures used to examine the quality of each batch are described.