Reflux. These are images from a micturating cystourethrogram (MCUG). The main indication for this test is suspected vesico-ureteric reflux. A Foley catheter is inserted, and the bladder is filled with iodinated contrast under intermittent fluoroscopic screening. In severe cases of reflux, it may be visible during passive filling of the bladder. To diagnose milder cases, we then remove the catheter and ask the patient to urinate, again while using fluoroscopy to observe what happens. In this example, there is reflux of contrast as far as the kidney, and the ureter and renal calyces are dilated, making this grade 5 (of 5) reflux. For a reminder of how we grade reflux, click here.