Analysis of the phenomenon of subdural hematoma observed in postmortem computed tomography disappearing at autopsy

Objectives

We encountered a case in which an acute subdural hematoma (SDH) was observed on postmortem computed tomography (PMCT) but no hematoma was found under the dura mater during autopsy. Subsequent verification led to the conclusion that the SDH was pressing on the brain when PMCT was performed but was not observed because all the subdural blood drained out during craniotomy because the hematoma did not clot.

Materials and Methods

We examined 13 cases of SDH in which PMCT was performed before autopsy to determine the factors related to the presence or absence of blood clots in the SDH, and to determine whether PMCT before autopsy could determine the presence or absence of blood clots in the SDH.

Results

Blood clots were not found in the SDH of individuals with an estimated survival interval of 5 h or less or when the estimated survival interval was 1440 h or more. No particular trend was observed in the relationship between the presence or absence of clots in the SDH and HU values of the SDH.

Conclusion

Early death after injury and chronic SDH are thought not to contain SDH clots. In cases of early death after injury, the autopsy diagnosis of SDH should be made by careful observation of the fluid SDH during craniotomy, as SDH may not contain clots as an indicator of SDH at autopsy. Predicting the presence or absence of a clot within an SDH using PMCT is difficult.