Gender reassignment is a process where a person decides to change the gender that they assigned at birth. In other words, female characteristics are substituted for males and vice versa.
Yes, I have watched a few shows about gender reassignment. Seems to be a very difficult surgery.
I would think the surgery would be very difficult where body parts are reconstructed and a trans gendered person's physical appearance and function are altered to socially align with the identity they choose.
Yes, I know they have to take quite a bit of medication to alter their hormones as well. Where women mimic male hormones and vice versa. 
It is a treatment for transgendered people for gender dysphoria in order to help them align with their gender identity.
I can't imagine my own self doing that. No doubt it is very emotionally hard too.
I'm sure it is very emotional as gender dysphoria is something an individual goes through as a result of the gender they are assigned at birth but one they do not relate to.