This can be done by following the 4 steps below:
Hands by your sides
Look at your breasts with your arms at your sides while slowly rotating your upper body from side to side.
Hands on your head
Next, put your hands on your head and look for dimples or bulges in your breasts, particularly underneath. Dimples which are equal in size, shape and occur in both breasts are normally harmless.
Hands over your head
Then raise your arms high above your head and look again for any changes, especially in the nipple area.
Hands on your hips
Finally, rest your palms on your hips and press down firmly while holding the shoulders back so that your chest muscles are flexed. Check for any changes in appearance.