It is standard procedure nowadays for prospective employers to require would-be employees to undergo medical checks, the results of which would determine whether the employee would be offered the job, or if already employed, to be confirmed in his post. I have worked at so many places and the requirement of each employer is different. No doubt, the most basic of such requirements is the standard chest x-ray, urine test and vision check. Many employers today also ask for a blood test.
I remember when I first got a job in 1984, I had to take the medical check-up at the government hospital. Those days, the hospitals aren't as well-equipped as now and we had to wait quite a long time to go through each of the tests. Chest x-ray images required a week or so to be developed. Same goes for urine samples. Forget about blood samples... it would've taken weeks to get a result.
Nowadays, many private hospitals and some private clinics have the full array of diagnostic equipment to carry out whatever tests the employer wish to check, with most results being made available within a single day. The more complicated blood tests may take a day or two longer.
Earlier today, I went to a private clinic to do a medical. I had to pee into a small container, had my body zapped with x-rays and my arm pricked with a needle to draw blood. The clinic could've given me the result by tomorrow except that my employer wants my blood to be HIV-tested. That would take a few more days. I guess they want to be sure that I am not immune-deficient, have not been taking illicit drugs and be as healthy as I can be while in their employment.