<s>[INST] Our teenage son plays soccer and recently was kicked by accident in his lower back, we had to go to emergency room becuase there was blood in his urine, how soon would he be able to return to the playing field. There were several tests done and determined he bruised his kidney. [/INST] Hi, Thanks for writing in. Your son might have suffered a grade I traumatic renal injury. General recommendations include 3-month follow-up that comprises a physical examination, urinalysis, blood pressure measurement, and assessment of renal function. There are few published data regarding the role of follow-up imaging and a repeat scan might help to know the healing process. At least 3 months off the field may be required to give sufficient time for the injury to get healed properly. </s>