Which is not required for visualisation of gallbladder in oral cholecystography –
Visualization of the gallbladder in OCG depends on:-

Ingestion of dye
Absorption of dye in gut
Blood flow to liver (Entero-hepatic-circulation)
Take up in liver (functional liver), ability of liver to excrete dye into the bile (functional liver)
The ability of gallbladder to concentrate the excreted dye (by absorbing water)
Patency of hepatic & cystic duct system
Functioning liver
Motor mechanisms of gall bladder
Patency of cystic duct
Ability to absorb water