Q: When harvesting donor hair, how does the surgeon know when to stop? – D.D., Pleasantville, N.Y.

A: The patient must first decide the shortest length he/she is comfortable wearing his/her hair.

Donor hair can be removed — whether through Follicular Unit Transplantation (FUT) or Follicular Unit Extraction (FUE) — as long as, at this length, the back and sides do not look too thin (i.e. do not have a transparent look) and the donor scars are not visible. The surgeon needs to use his judgment when harvesting, so that this endpoint is not crossed.

Additionally, the surgeon must anticipate that the caliber of hair in the donor area will decrease slightly over time as a normal course of events. The actual number of grafts that can be harvested varies greatly from person to person. It depends on the patient’s donor density, scalp laxity, hair characteristics and size of the donor area.