Send to Haematology ASAP. (Maximum delay to testing laboratory must not exceed 3hrs as testing must be completed within 4hrs of collection).
Minimum collection of 1 sodium citrate tubes required (2.7 mL). Do not use the Greiner MiniCollect Sodium Citrate tubes or any other plastic-based sodium citrate tubes. For small blood volumes the BD Vacutainer 1.8 mL sodium citrate tube is recommended. Please contact the laboratory with any queries. An EDTA for FBC should be collected with PFA test. All investigations of platelet function are strongly dependent on the correct method of blood collection. If collecting several citrate tubes, it is very important to identify which tube was collected first (i.e. number all coag tubes in order of collection).
When collecting, use a 21G or larger needle. Blood should be drawn directly into evacuated sodium citrate tubes. After collection ensure proper mixing with anticoagulant by gently inverting the tube by hand 3 or 4 times. If there is venous collapse or stoppage of blood flow during collection, discard the specimen as it will not be suitable for PFA testing.
Handle specimen gently after collection - send to laboratory immediately. Do not send to laboratory via Pneumatic Tube System. Put in a red bag for priority in CSR.
A FBC should be requested with PFA test. Platelet count must be >100x109/L and HCT > 35%
APPLICATION: Evaluation of the closure time with the PFA analyser allows a rapid and simple determination of vWF dependant platelet function. This system is sensitive and reproducible for the screening of vWD, although the closure time can be normal in type 2N vWD. It is important to include a detailed drug/medication/diet history to identify those patients with acquired platelet dysfunctions. PFA closure times may be prolonged as a result of anaemia (haematocrit < 35%) or thrombocytopaenia (platelet count <100). Time of day, patient age may also influence the results (shorter closure times in the morning and in elderly patients). Patients taking ASPIRIN give a typical picture of a prolonged CEPI closure time but a NORMAL CADP closure time
THIS TEST HAS REPLACED BLEEDING TIME AND BLEEDING TIME – IVY.