There is no exception in IRS Publication 502 to prohibit getting qualified medical care in a foreign country. It just has to satisfy the same rules as in the US - necessary medical procedure and so on.
The rules in the US:
"Medical expenses are the costs of diagnosis, cure, mitigation, treatment, or prevention of disease, and the costs for treatments affecting any part or function of the body. These expenses include payments for legal medical services rendered by physicians, surgeons, dentists, and other medical practitioners. They include the costs of equipment, supplies, and diagnostic devices needed for these purposes.
Medical care expenses must be primarily to alleviate or prevent a physical or mental defect or illness. They don't include expenses that are merely beneficial to general health, such as vitamins or a vacation."
Note, however, this about drugs and medicines:
"Medicines and Drugs From Other Countries
In general, you can't include in your medical expenses the cost of a prescribed drug brought in (or ordered shipped) from another country. You can only include the cost of a drug that was imported legally. For example, you can include the cost of a prescribed drug the Food and Drug Administration announces can be legally imported by individuals.
You can include the cost of a prescribed drug you purchase and consume in another country if the drug is legal in both the other country and the United States."
Both quotes are from IRS Publication 502.
