Traumatic haemorrhage in a renal cyst: US and CT findings

Clinical History

A 75-year-old woman presented to the emergency department of our hospital after blunt abdominal trauma, with right flank pain and haematuria. In the blood tests HCT and HGB were within normal range, whereas urine test showed abundant red blood cells. An abdominal ultrasound was requested by the clinician.

Imaging Findings

A cortical cyst with hyperechogenic material inside was depicted in the right kidney, compatible with intracystic haemorrhage in a pre-existing simple renal cyst, known from the patient's history (it had been demonstrated on a previous CT).
Computed Tomography prior to and after contrast material administration showed a renal cyst, approximately 5.5 cm in diameter with haemorrhage inside, without enhancement, confirming the ultrasound finding. Delayed CT examination (excretory phase) demonstrated communication of the cyst with the collecting system of the right kidney and contrast material in the cyst. Small reactive perirenal haematoma without enhancement was also depicted. Bone window did not show fractures.
The patient was managed conservatively and haematuria gradually subsided. She was discharged 5 days after the accident. Repeat ultrasound 20 days later showed absorption of the haemorrhagic material.

Discussion

The kidneys are relatively well protected from blunt trauma by their anatomic location, lying high in the retroperitoneum with the abdominal viscera anteriorly, the back muscles and spine posteriorly, as well as the lower thoracic cage circumferentially. A kidney with preexisting abnormality is at increased risk for injury even with relatively trivial blunt trauma, as its anatomic location is no longer adequate to protect it [1]. Such injuries include: rupture of a renal cyst with subcapsular or perirenal haematoma, intracystic haemorrhage with or without communication with the collecting system, rupture of a tumour and disruption of renal pelvis in patients with hydronephrosis or extrarenal pelvis [2, 3, 4].
Patients with intracystic haemorrhage usually present with haematuria and flank pain. These manifestations are out of proportion to the nature of the injury and the clinician should suspect the existence of a (known or unknown) preexisting lesion [5].
Ultrasound often is the first diagnostic imaging examination, showing the intracystic haemorrhage as hyperechogenic material inside the cyst.
Computed Tomography - the best imaging modality in renal trauma - should be performed before and after contrast material administration. Acute haemorrhage is depicted as hyperdense (attenuation of 50 to 100 HU) on non-contrast images and typically the cyst does not enhance. Delayed images (excretory phase) are useful to demonstrate possible communication of the cyst with the collecting system [3, 4]. In those cases where there is not a known history of a simple renal cyst, follow up imaging with CT about 6 weeks later is recommended, in order to exclude a cystic renal tumour that bled after trauma.
The management in patients with intracystic haemorrhage is usually conservative and haematuria often clears off gradually. Follow up imaging (with ultrasound or CT) is useful to detect possible residual intracystic haemorrhage. Ureteral stent placement can be used in persistent haematuria, whereas surgical intervention is desirable in complicated cases [6, 7].

Differential Diagnosis List

Final Diagnosis

Traumatic haemorrhage in a renal cyst

URL:	https://www.eurorad.org/case/12757
DOI:	10.1594/EURORAD/CASE.12757
ISSN:	1563-4086