Ristocetin-induced platelet aggregation


5-10 mL blood in citrate (usually after prior arrangement with the laboratory).


See Platelet aggregometry.

Reference Interval:

Consult laboratory.


Investigation of patients with a history suggestive of an inherited bleeding disorder.


An insensitive test for reduced levels of von Willebrand factor (classical von Willebrand disease). However, the test is useful for the detection of variant von Willebrand disease (especially Type 2 VWD and pseudo [platelet-type] VWD).

Ristocetin-induced platelet aggregation (RIPA) is absent in Bernard-Soulier syndrome, a rare autosomal recessive bleeding disorder. This is due to the absence of the receptor for ristocetin on the platelet surface.


Favaloro EJ. Clin Haematol 2001; 14: 299-319.

Rodeghiero F et al. Thromb Haemost 1990; 64: 349-352.