Magnetic resonance characteristics of intrapelvic haematomas.

Although haematomas in the female pelvis are not rare, their magnetic resonance (MR) appearance has not been well characterized. Accordingly, we analysed the MR appearances of various stages of haematomas in the female pelvis. A retrospective analysis of 35 haematomas in 28 patients sequentially imaged with a 1.5 T MR unit was performed. The time interval between the insult and MR imaging was determined and the appearances of the haematoma were evaluated. The results were compared with those in the central nervous system. The evolution of haematomas in the pelvis appeared similar to that of haematomas in the brain, and four stages (acute, early subacute, late subacute and chronic) were identified according to the signal intensity pattern on T1 and T2 weighted images. Pelvic haematomas differed from intracranial haematomas in the following features: (1) The speed of evolving pelvic haematomas was gradual. (2) In the centre of acute haematomas, slightly hyperintense areas were seen on both sequences, suggesting residual oxyhaemoglobin. (3) Haematomas evaluated in the early subacute stage had complex appearances. (4) In older haematomas, central intermediate signal intensity areas, presumably due to diamagnetic hemichromes, became predominant on T1 weighted images. In conclusion, although the evolution of a pelvic haematoma is similar to that of a brain haematoma, its speed is gradual and MR appearances are somewhat different due to environmental differences.