title: Aetiology, imaging features, and evolution of spontaneous perirenal haemorrhage.
abstract: OBJECTIVE
  To evaluate the aetiology, imaging features, and the evolution of spontaneous perirenal haemorrhage detected by imaging.
  
  
  METHODS
  In this retrospective study, the hospital database was searched for all cases of spontaneous perinephric haemorrhage detected by imaging between January 2000 and December 2012. Imaging examinations were reviewed and the following parameters were recorded: the location, extension, and total volume of the haematoma, presence of active extravasation, the haematocrit effect, and highest density. The resolution time was calculated using follow-up imaging. The final aetiology for all cases was assessed via clinical, radiological, and histopathological data. Differences in imaging features of haemorrhage according to aetiology group were analysed with independent samples test and Fisher's exact test.
  
  
  RESULTS
  Eighty-one haematomas were identified in 78 patients during this 13-year period. Causes of perirenal haemorrhage included coagulation disorders (22/81, 27.1%), ruptured renal cyst (11/81, 13.6%), rupture of abdominal aortic aneurysm (9/81, 11.1%), renal cell carcinoma (9/81, 11.1%), adrenal masses (9/81, 11.1%), polycystic kidney disease (7/81, 8.6%), angiomyolipoma (6/81, 7.4%), renal vascular diseases (2/81, 2.4%), and recurrent pyelonephritis (1/81, 1.2%). Haematomas associated with coagulation abnormalities and vascular diseases presented with larger volumes and were more likely to extent to the pararenal space more so than other groups; ruptured renal cyst and renal cell carcinomas tended to be more associated with subcapsular haematomas. The haematocrit effect and haemorrhage involving renal parenchyma were more often observed in the group with coagulation abnormalities.
  
  
  CONCLUSIONS
  Imaging features, such as location and extension, could help radiologists identify possible aetiologies of spontaneous perirenal haemorrhage.
authors.affiliation: Department of Radiology, Chongqing Medical University, No. 1 Youyi Road, Yuanjiagang, Yuzhong District, Chongqing, 400061, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Mao
authors.affiliation: Division of Abdominal Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St., Boston, MA 02114, USA.
authors.forename: I S
authors.initials: IS
authors.lastname: De Oliveira
authors.affiliation: Division of Cardiovascular Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St, Boston, MA 02114, USA. Electronic address: Hedgire.Sandeep@mgh.harvard.edu.
authors.forename: S
authors.initials: S
authors.lastname: Hedgire
authors.affiliation: Division of Abdominal Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St., Boston, MA 02114, USA.
authors.forename: D
authors.initials: D
authors.lastname: Prapruttam
authors.affiliation: Division of Abdominal Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St., Boston, MA 02114, USA.
authors.forename: M
authors.initials: M
authors.lastname: Harisinghani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001778:Blood Coagulation Disorders / Q000175:diagnosis / Q000453:epidemiology*; D001900:Boston / Q000453:epidemiology; D015984:Causality; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D006470:Hemorrhage / Q000175:diagnosis* / Q000453:epidemiology*; D006801:Humans; D007674:Kidney Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology*; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data