BACKGROUND: The intragastric balloon is filled with saline and methylene blue 
dye, to detect balloon deflation early and prevent bowel obstruction, by 
monitoring the patient's urine for changes in color.
METHODS: An intragastric balloon filled with 590 ml of saline plus 10 ml of 
methylene blue was endoscopically placed under sedation in a 22-year-old man 
with morbid obesity (BMI 42 kg/m2). 3 days later, the patient's urine changed to 
dark green, and, suspecting a leaking balloon, endoscopy was repeated under 
sedation.
RESULTS: No signs of balloon deflation were seen, and the urine returned to 
normal color. The next day, the urine turned green again. 7 days later, the 
urine discoloration finally disappeared.
CONCLUSION: Propofol, a sedative commonly used by anesthesiologists during 
endoscopic procedures, is known to have several side-effects, and urine 
discoloration is one of them, albeit rare. This benign side-effect must be known 
to obesity surgeons to avoid pointless medical expenditure, unnecessary balloon 
removal and distress for patients and clinicians.