담도의 경우 몸 속 깊숙이 위치해 위나 대·소장처럼 내시경을 넣어 의사가 직접 내부를 살펴볼 수 없었기 때문이다.
In the case of biliary, it was located deep inside the body, so the endoscope was inserted like the stomach, large, and small intestine, so the doctor could not look inside himself.