Q: I wanted you to determine if I would be a candidate for FUE (to camouflage a scar). After reading through your vastly informative website, I had become aware that the Fox test is necessary to determine patient viability for FUE. When I mentioned the test, I believe I heard you say it was unnecessary. Unfortunately, I can’t help but think there was miscommunication between us, as your letter states that I should schedule a Fox test if I am considering FUE. Please confirm if a Fox test is, in fact, necessary. — N.S., Garden City, N.Y.

A: I perform FOX tests on all patients when I am considering a FUE hair transplant. I do not routinely perform FOX tests before repairs (or on eyebrow transplants) where the number of grafts is relatively small.

The purpose of FUE is to identify those patients in whom FUE is inefficient — i.e. there is a greater than average risk of damage during the harvest. If this is the case, I would not perform the hair transplant since even slight inefficiencies create a significant problem when thousands of grafts are transplanted.

Remember, compared to Follicular Unit Transplant (FUT), FUE is a relatively inefficient procedure. Even when a small FUE hair transplant is performed (i.e., in a Norwood Class 3) we have to anticipate that eventually the person will need a large amount of grafts, so a FOX test is still important.

However, when the total number of grafts is small, such as in scar revisions or eyebrow restoration, small inefficiencies are not as important.

In addition, with repairs, the donor area is altered so that extraction in different areas may be very be different, rendering a FOX test in scar revisions far less useful.

Finally, if a FUE hair transplant is started, but then aborted due to extraction difficulties, the patient must either be reverted to a strip (which was not the preferred means of harvesting or a FUT would have been planned to begin with) or the patient will be left with a partial procedure – both less than ideal situations. However, if a FUE repair has to be aborted due to the inability to efficiently harvest hair, no harm was done; we just won’t be able to achieve our goal.