A young man presented with urinary retention, approximately one week following a football injury which had been managed conservatively in hospital.
The inferior pole of the kidney has an irregular hypoechoic region from the contusion. No flow is seen in this area on color Doppler. There is residual perinephric fluid (best seen on the transverse images).
The patient also had a large bladder haematoma which caused his retention (see case)
Ultrasound may miss significant intra-abdominal injury in the setting of trauma, particularly if there is no free fluid. Solid organ injuries are often easier to appreciate many days later as the echogenicity of the clot reduces.