Preparation for gastroscopy insertion: check air and water delivery, patient position, moderate head tilt back, too tilt easy to enter the trachea. Mirror body coated or sprayed with lubricant, so that the mirror into the smooth. At this time, the left and right knobs can be fixed. Gastroscope insertion: send the mirror, left hand horizontal position, left hand first slowly up, see the pear-shaped fossa (more take the left side), left hand gently down, and have a slight internal rotation of the action, right hand gently send the mirror. If it does not enter smoothly, ask the patient to do the swallowing action, raise the left hand, slightly internally rotate it, and gently send the mirror in smoothly at the moment of swallowing completion. Or try to deliver the mirror from the right pear-shaped fossa, and after passing the root of the tongue, the left hand is slightly externally rotated and the right hand delivers the mirror. After passing through the pharynx, the left hand is held upright and rotated slightly inward to see the esophagus in the middle of the field of view. Esophagogastric junction: After entering the entrance of the esophagus, the left and right rotation buttons remain fixed, and the air is delivered, while observing the presence of lesions such as diverticula, strictures, tumors and varices, and slowly delivering the scope. Gastric sinus: After entering the stomach, the air delivery is minimized and the sinus is reached through the body of the stomach. When passing through the gastric body, the left hand is in horizontal position, and when reaching near the gastric angle, the left hand is erected to become vertical, while slightly up, and continue to enter the scope. The anterior wall of the duodenal bulb ~ the upper wall: facing the pylorus, the left hand is still in vertical position, do not adjust the left and right knobs, just adjust up and down and the left wrist gently rotate internally and externally to adjust, and enter after seeing the pylorus open. After entering the duodenum, adjust the fixed knob to free, enter the bulb and send some air to stretch it slightly, and observe the front wall to the upper wall. Lower wall of the duodenal bulb to the posterior wall: The scope is slightly backward and stops when it seems to feel like it is going to exit from the bulb, and the lower wall of the posterior wall is observed. (slightly internally rotated). Duodenal descending part: the left hand is forced up the large knob and the small knob to the right, while the left hand is rotated internally and even the upper body is rotated clockwise, and the right hand sends the mirror to the descending part. At this time, most of them are inserted blindly according to the above technique, so great care should be taken when there is ulcer or deformation in the bulb. Anterior wall of the gastric sinus ~ small curved side: When slowly retreating the mirror to the pyloric antrum, force up, send the mirror slightly forward, rotate the left hand externally, and observe the gastric sinus from the small curved side to the anterior wall. Posterior wall of the gastric sinus to the lesser curvature side: The mirror is slightly retracted, the left hand is rotated internally, and the gastric sinus is observed from the lesser curvature to the posterior wall. Gastric angle: Maintain the force up, continue to retreat the mirror body, and see the gastric angle. The left hand is rotated externally to observe the anterior wall side of the gastric angle and internally to observe the posterior wall side of the gastric angle. It is also possible that no matter how up, the gastric angle is not seen, or you can give up first and try again at the final examination. From the gastric angle straight up to the lower small curved side of the gastric body, continue to back up and cross the gastric angle to see the lower small curved side of the gastric body, at this time the field of view can also see the lower anterior posterior wall of the gastric body (left hand external rotation or internal rotation), observation. Continue to retreat and observe the middle less curved side of the gastric body; continue to retreat and observe the upper less curved side of the gastric body. Cardia frontal (reversed): still keep up, the left hand 180 degrees of internal rotation, see the cardia frontal, at this time can be seen in the picture 1/3 of the mirror body. At this time, the relationship between the anterior wall and the posterior wall is the same as the opposite when observing the less curved side of the gastric body. The fundus of the stomach (reversed), slightly down (originally force up), sufficient air delivery, and observation of the fundus of the stomach. If there is mucus in the mucus pool, the patient may be aspirated or made to lie on the right side. In order not to attract to the mucosa, the front end of the gastroscope should be submerged under the liquid parallel to the liquid surface to attract. The small curved side of the cardia, again force up, the left hand is slightly externally rotated, the position of the mirror body also changes, and the small curved side of the cardia is observed. Gastric angle contralateral to the greater curvature: force up, left hand 180 degrees of external rotation, return to the original position, then release the size of the left and right spiral, send the mirror to the contralateral side of the gastric angle, start the examination. First, observe the large curve contralateral to the gastric angle, then back the mirror to observe the large curve in the upper part of the lower middle of the gastric body, and rotate the left hand externally or internally to observe the anterior or posterior wall. When reaching the upper part of the gastric body, the air inside the stomach is attracted. The esophagus is examined again for any missed lesions when the scope is finally retired.