FUE complications after Hair transplant: should I be concerned about a missing patch of hair? (Photos)

Over harvesting using the Follicular Unit Extraction (FUE) technique can leave bald spots and patchy looking donor hair.

Interesting question here. Was this patch here before the surgery or after? If this patch was after the surgery it could very well be a simple area of shock loss. In this case you should be ok and the return of hair will be within a few months. If this patch of no hair was before the surgery then it could be a a case of Alopecia Areata. In this scenario, you need to consult with a dermatologist and/or an experienced hair restoration specialist for proper diagnosis and treatment. This may or may not come back.

Sometimes  there may be such a early phase alopecic, bald spots  in donor areas after FUE surgery,  but fortunatelly most are transient. İt may happen because of over harvesting or transient post traumatic shedding /shock loss. Any way it heals and hair regrow in 4-5 months of hair restoration surgery .

It's  called halogen effluvium and usually occur after hair transplant...but noting to worry it's temporary...all you ha e to do is apply 5% minoxidil twice a day over this area for 16 to 20 weeks and after that hairs will grow back...

If you had a missing patch of hair on the day the hair transplant was done, then I would be concerned. If it appeared after, I would not worry

This is a possible case of over harvesting of donor area. You could wait for some time and wait for the hair to grow and You must consult your hair transplant surgeon for this concern of yours. As a solution some more grafts can be put to cover this patch of missing hair. 

The two top concerns would be over harvesting of donor area resulting in localized shock loss or Alopecia Areata which is unrelated. You should see your surgeon in followup for diagnosis and treatment.