Award Winning FUE Hair Transplantation Clinic

Last modified on Thursday, 25 April 2013 21:43

Musings on Hair Density and Follicular Harvesting

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Considering the many ways of counting follicular units or hairs is important when we discuss hair transplantation surgery. When a patient comes in for an evaluation for hair transplant surgery, the first thing we do is examine the donor area and write down what the follicular density in that area is, which can also be defined as the number of follicular units per unit area, which is usually about a square centimeter. The hair density, which is number of hairs per square centimeter, is also highlighted.

This information is very useful as it gives is an approximate understanding of how much hair can be transferred to the recipient area, where the balding or thinning is taking place to the donor area. Tools such as the densitometer, capillicare, folliscope and trichograph can be used to measure calculate density. However, these might provide fallacious results, because hair counting is more difficult that it actually seems.

Look at the picture below and try to count the number of Follicular Units (FU’s). However, be sure that you count only the groups where the base of the scalp can be seen, where hair is emerging from the scalp. You may have got 28 groups, and therefore its not too tough, is it?

Fig 1

4mm density 1


Next, you have to try and count the number of hairs. This is a little difficult. For this you will have to classify the groups in categories of ones, twos, threes and fours. To arrive at your hair density, you will have to add all these up.Then you have to divide the number of hairs that you get, by the number of Follicular units that you got and you will arrive at the CD or Calculated Density. This number if very important.

Fig 2

4mm density 2

What I’d like to say here, is that it is very difficult to find an accurate hair count when you use optical machinery. Observing the hair in a single plane with the human eye will not prove to be as effective. You will find better results when you use an instrument that can be moved around and when you have the help of forceps to tease the hairs apart. This could mainly be because two hairs often sit adjacent to each other and can look like just one. If you go back to the photographs you will note that the second picture is the same as the first one, but have the number of hairs per FU written on it by hand. Some of them could easily fool you. For example if you were to look at the big “two hair” unit, which is situated at a three o clock position, almost in the center, this is a three, and when you look at the “one hair”, which is a little to the right, it is a two.

This is indeed a problem when counting hairs, and unless there is no real time ability that helps move the hairs or the viewers, correct answers will not be achieved. There is also another problem with CD or calculated density. While working with CIT, we have often noticed that the CD is higher than what is obtained when performing strip surgeries. If you are wondering why, then let us tell you that the answer is relatively simple, you get what you see with strip surgery. If the particular strip has higher number of one’s and two’s, you will have to work with that. There is no real way around it. The patient in the photograph has more one’s and two’s and hardly any fours or fives. The strip that has been taken from here is a low yield strip, in terms of the total number of hairs that are available.

With CIT however, one can decide as harvesting is being done, which follicular units should be taken, and which can be left behind. If the patient has high number of ones and two, then you have to cherry pick. The threes and fours, are calling out to you to be harvested. What method do you think is the best to achieve the best results for coverage on the top of one’s head?

However, if the work is mostly being done on the hairline, and the one’s and two’s happened to be the preferred grafts, you have guessed it right. One can selectively harvest for those also. Therefore, what I am trying to convey is that, CIT is convertible and has a built in flexibility, which only works for the patient’s interest. You can easily find the grafts that you want, and this is not just for follicular unit size. If the hair is fine, then more delicate hair will be needed for exact work on the edge of the hairline, where the transition zone has to be soft and feathered, but would coarser thick hair from the middle of one’s head be a better choice? Not at all.This is in fact the only area that any strip surgeon can harvest from, without making way for a scar that is grossly widened. This is one of the main reasons why, you will see many unnatural looking hairlines, even if the one’s and the two’s have been placed in the front appropriately, it is the caliber of the hair that is too large for the area. Just think about it, how will large pigmented, single hairs look, when they stick out form the hairline. Over here, the hair is supposed to be soft and feathered.

How can CIT be used to surpass this? Well, you should go low towards the nape of the neck. Find appropriate hair that is thin and feathery for the hairline. Everyone sees the hairline when they meet you and therefore it cannot afford to look out of place.

Soon we will publish interesting data, which discusses the changes in density of the donor region in different areas.

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