1. Prepare a blank sheet of paper and drawing tools, such as pencils and rulers.

2. Draw a vertical line segment on the paper with a ruler and pencil, which will be the main part of the catheter.

3. At the top of the line segment, draw an arrow shape with a curve to indicate the position where the catheter is inserted into the patient.

4. At the bottom of the arrow, draw some horizontal curves along the vertical line segment to form the shape of "fishbone".

5. At the end of the horizontal line, short straight lines and small semicircles are used to represent the side holes of the catheter.

6, according to the need, you can add some details to highlight the catheter and the patient's body parts, such as drawing the patient's abdomen or inserting a catheter.