Donor site of follicular unit excision hair transplantation: the relationship between appearance and actual hair density, and hair diameter.

Donor site morbidity is an important consideration for follicular unit excision (FUE). We examined 103 male patients with adult androgenic alopecia. Patients were divided into three groups (Good, Fair, and Poor) based on visual assessment of the donor site. Hair density and hair diameter were measured using digital photography. A total of 72, 21 and 10 patients were classified into the Good, Fair and Poor appearance groups. The average hair density of each group was 127.8 ± 22.6 hair/cm, 114.8 ± 23.1 hair/cm and 94.9 ± 25.4 hair/cm. The hair density of the Good group was significantly higher than that of the Poor group ( = 0.003). The average hair diameter of each group was 0.0968 ± 0.0267 mm, 0.0754 ± 0.0299 mm and 0.0473 ± 0.0158 mm. The hair diameter of the Good group was significantly higher than that of the Poor group ( = 0.001). Thirty-three of 72 patients whose hair density was >130 hair/cm belonged to the Good group. Seven of 10 patients whose hair density was <105.0 hair/cm belonged to the Poor group, while 31 of 72 patients whose hair diameter was <0.101 mm were included in the Good group. Eight of 10 patients whose hair diameter was less than 0.070 mm were in the Poor group. Donor sites rated Good on appearance had both high hair density and thick hair diameter. To maintain a good appearance after FUE, donor site hair density should not be less than 105.0 hair/cm.