Endoscope system

An endoscope system comprising:

• an endoscope including an image sensor configured to pick up an image of a lumen organ of a subject;
• a first memory configured to record three-dimensional image information of a lumen organ of the subject acquired from a medical diagnosis apparatus different from the endoscope;
• and
• a processor comprising hardware, wherein the processor is configured to:
• estimate a position of a distal end of the endoscope;
• acquire, on the basis of the three-dimensional image information recorded by the first memory, a lumen diameter of the lumen organ of the subject at the position of the distal end of the endoscope estimated;
• determine, on the basis of the lumen diameter acquired and a reference lumen diameter set in advance, whether the lumen diameter acquired is smaller than the reference lumen diameter;
• detect, when the processor determines that the lumen diameter acquired is smaller than the reference lumen diameter, a change amount of a predetermined parameter concerning an endoscopic image picked up by the image sensor involved in an inserting action of the endoscope, from the endoscope image;
• and
• generate, on the basis of the three-dimensional image information recorded by the first memory, a virtual endoscopic image endoscopically rendered from any visual point position,
• wherein the endoscope system further comprises:
• a second memory configured to record, when the change amount of the predetermined parameter concerning the endoscopic image detected is larger than a reference set value set in advance, the position of the distal end of the endoscope and the virtual endoscopic image corresponding to the position of the distal end of the endoscope.