Information from the Kampala Us Embassy website beloe. I would suggest you cal them to confirm the costs and details. Don't schedule it quite yet - you should wait until closer to your interview which should be in October or possible November.
Panel Physician Information for Immigrant Visa Applicant Medical Examinations
Effective July 1, 2010, the U.S. Mission to Kampala’s Consular Section will begin utilizing the services of Dr. Abdu Ali, International Organization for Migration (IOM), as Embassy panel physician for purposes of conducting medical examinations for all Immigrant Visa applicants.
IOM is located at:
Plot 40 Mackenzie Vale, Kololo
P.O. Box 11431 Kampala, Uganda
Telephone: 0414-236-622 or 0312-261-179
IOM’s working hours are:
Monday to Thursday 8:00am to 5:00pm
Friday 8:00am to 2:00pm
Please contact IOM at the above phone number to schedule an appointment and ensure that you take the following with you to your appointment:
Two (2) passport photos of the applicant (size 2” x 2”)
Valid photo identification for all present at the appointment
Previous medical reports (if any)
Immunization records (if any)
On completion of the medical examination, IOM will forward the medical paperwork to the Consular Section for review and further processing.