Answer
Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
The commission you mentioned is really from the patients because if it is deducted, the fees that patients pay will be decreased. So, it is not allowed to take such commissions.
In his response to your question, Prof. Dr. Monzer Kahf, Professor of Islamic Finance and Economics at Qatar Faculty of Islamic Studies, states:
This is a kick back, claiming it is from the pocket of hospitals or labs is incorrect. But it is in fact from patients. If it is eliminated, the rates of services will go down!
It is against the law in many countries such as the US and Canada and most European countries, but I know it is unfortunately practiced is India and Pakistan.
As long as the patient is not informed, it is not permissible to take the commission. The patient must be informed about it; it’s a kind of bribe and not permissible to take or give.
Allah Almighty knows best.