collecting phase

Last reviewed 01/2018

During the collecting phase, contrast medium is passed into the renal pelvis. Particular examination is made of the calyceal tips.

Hydronephrosis, of increasing severity, is revealed by:

• blunting of the calyces
• clubbing
• the "crescent" sign - contrast collects in the lower parts of grossly dilated calyces

Polycystic kidneys may demonstrate the "cookie cutter sign"; the cysts press into the renal pelvis to give the appearance of semi-circles having been cut out of the contrast in the renal pelvis.

Excretion of contrast down the ureters reveal any filling defects in them.