You need to do a medical exam before you send your application.
But DO NOT do this early because the doctor must be signed within 60 days of accepting your application by Chicago Lockbox. If you do it early and your package accepted after 60 days, then you have to the medical exam again before the interview.
Not all doctor can do the medical exam, go to USCIS find doctor page to find the civil surgeon (CS) near you.
Then go to medical examination page on USCIS download the form I-693 and fill only the first part. ( see the example below) (DO NOT sign it yet, sign it when CS tells you to do so)
Pro tip: Call few Civil surgeons near you and ask for prices. Usually cost around $100 to $450 (depends on the region). Also, if you have free or cheap options to have vaccinations then do it before you see the CS.
Even if you have all the required vaccines your CS need to test you for 3 blood and urine test. Also, CS will do a physical and mental test.
Tuberculosis (Blood test) ( if this becomes positive, then you need to do a chest X-Ray)
Syphilis (Blood test)
Gonorrhea (Urine test)
Vaccines you must have:
Usually you need to have (if you are around 30-40 years old)
1. Td or Tdap 2. MMR 3.Varicella 4.Flushot( if you file during the flue season Oct 1st- March 31st)
But refer the Table 1 of CDC page to see all age appropriate vaccine for immigration purposes.
After you done the medical exam, the CS will ask you to signed the form I-693. You will need to wait until the lab results are done. Then you may go back to CS to pick up the Sealed I-693. Do not open the envelop and you should include this with your application as it is. The CS should give you a copy of the I-693 form. Check on the copy if everything is correctly filled by CS. If not ask CS to correct them.
Pro tip: if your CS located very far from where you live, ask them to mail the form to you, so you don’t need to visit CS twice.