A Practical Guide to Haemostasis

Thrombotic Microangiopathies:
Thrombotic Thrombocytopaenia Purpura [TTP]

The Thrombotic Microangiopathies are rare but potentially fatal disorders. They are characterised by a microangiopathic haemolytic anaemia [MAHA], microthrombi and as a consequence, ischaemic tissue damage. Prompt diagnosis is essential to identify such patients and to allow appropriate management to be commenced immediately.

See References for the ISTH recommendations on the diagnosis and management of TTP.

A number of scoring algorithms have been developed to aid with both the diagnosis of TTP and also their stratification as to risk.


The BENTLEY score published in 2010 was the first clinical diagnostic scoring system for TTP.   The BENTLEY score is a risk prediction model for TTP that was derived from a retrospective analysis of 110 patients that included 11 patients with severe ADAMTS13 deficiency. 

Click HERE to access the BENTLEY score algorithm.

The French TMA Reference Center Score

The French TMA score is based upon the national registry and was developed to allow the identification of acquired ADAMTS13 deficiency in the absence of an ADMTS13 assay being readily available. 

Click HERE to access the French TMA Reference Score algorithm.

The French MITS Score

The French Mortality in TTP Score [MITS] is based on a national database and was used to develop the MITS prognostic risk stratified score aimed at identifying hospitalised TTP patients at the highest probability of a fatal outcome and therefore, who would potentially benefit from additional/more intensive treatments

Click HERE to access the French MITS algorithm.


The PLASMIC score is a clinical prediction rule for the diagnosis of TTP associated with severe ADAMTS13 deficiency - defined as <15% normal activity.

Click HERE to access the PLASMIC algorithm.