A patient with recent loss of hypeension control and creatinine- 4.2 mg/dL. Renal USG shows size discrepancy in kidneys and no sign of obstruction .What should be the next investigation ?

As patient has history of loss of control of hypeension and raised creatinine , Renal USG is warranted . USG findings and clinical history raise suspicion of Renovascular hypeension . Next Investigation of choice is Ultrasound Doppler as it confirms diagnosis of Renovascular hypeension in vasculature .