Classification of Hemorrhagic Transformation

Hemorrhagic infarction (HI) describes a heterogeneous hyperdensity in in an ischemic infarct zone.  Parenchymatous hematoma (PH) refers to a more homogenous, dense hematoma with mass effect.  Fiorelli, et al in 1999 refined these definitions to include two subtypes of HI and two subtypes of PH.

Definitions as per Fiorelli (1999):

  • HI is a petechial infarction without space-occupying effect.
  • PH is a hemorrhage (coagulum) with mass effect.
  • 2 subtypes of HI:
    • HI1 (small petechiae)
    • HI2 (more confluent petechiae)
  • 2 subtypes of PH:
    • PH1 (≤30% of the infarcted area with some mild space-occupying effect)
    • PH2 (>30% of the infarcted area with significant space-occupying effect, or clot remote from infarcted area)


Hemorrhages that occur within the first week after stroke were more likely to be PH2-type, whereas hemorrhages that occur later tend to be HI1, HI2 or PH1.  PH2-type was found to be a significant predictor of neurologic deterioration (OR32.3) and of 3 month mortality (OR 18.0) whereas HI1, HI2 and PH1 were not associated with either increased morbidity or mortality.



Subtypes of hemorrhagic transformation: HI1 (top left), HI2 (top right), PH1 (bottom left), and PH2 (bottom right).



Fiorelli, M. et al. “Hemorrhagic Transformation Within 36 Hours Of A Cerebral Infarct : Relationships With Early Clinical Deterioration And 3-Month Outcome In The European Cooperative Acute Stroke Study I (ECASS I) Cohort”. Stroke 30.11 (1999): 2280-2284.

Sussman, Eric S. and E. Sander Connolly. “Hemorrhagic Transformation: A Review Of The Rate Of Hemorrhage In The Major Clinical Trials Of Acute Ischemic Stroke”. Frontiers in Neurology 4 (2013): n. pag.

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