<prompt> A 18 year old with pain and tenderness in left scrotum, and normal right scrotum, what should be the investigation done ?B mode USGColor dopplerCT scanMRI  <response>: Colour doppler should be done to look for the testicular aery pulsation as this is most probably a case of torsion testis on left side.Reference : page 1082 SRBs manual of surgery 5th edition 