a diagnostic method of separately determining the functional state of each kidney and of the upper urinary tract by means of a dye. After the blue dye indigo carmine is injected intravenously or intramuscularly (2–3 ml of a 0.4 percent solution), its excretion from the ureteral orifices is observed. The dye is normally excreted from the orifices of both ureters three to six minutes after intravenous injection and ten to 15 minutes after intramuscular injection. Delayed or slow excretion of the dye is indicative of renal or ureteral disease and is most commonly observed in renal colic. Consequently, chromocystoscopy helps distinguish this disease from appendicitis, cholecystitis, and other diseases marked by symptoms of acute abdomen.