The public is often confused by conflicting claims and counterclaims about exclusive "follicular unit" transplanting (FUT) in advertisements that can cost their sponsors millions of dollars annually. What follows is Dr. Unger's view of what the scientific evidence, to-date, reveals.

If you feel you would be satisfied with light or moderate hair density, you may want to consider using only FUs for your transplanting. There are important advantages to such an approach.  Some can be found in the section of this website that discusses the various “Types of Grafts”.  In brief:

1. FUs cause the least damage to any existing hair in the recipient area.
2. FUs produce the least amount of post-operative crusting.
3. FUs generally grow somewhat faster than other types of grafts.
4. FUs produce absolutely no clumping or plugginess, and therefore produce remarkably natural looking results after even a single session in an area that is bald or destined to become bald.
5. Most patients will not have sufficient donor reserves to transplant the entire evolving bald area relatively densely; therefore, FUT provides the most flexibility in the distribution of the donor tissue that is available.  This is because single sessions can be used in less cosmetically critical areas—such as the crown and still produce natural-looking results, while other areas can be treated more than once—for example, the frontal area—to create higher hair densities.

Transplanting an entire bald head in one "megasession" of even 3000 or more FUs will not result in what most people would call cosmetically acceptable hair density.  On the other hand, when the area to be treated is relatively small, for example the front third or half of a typically sized area of MPB, such a session can produce very acceptable results (See Figures 3-7 in "Types of Grafts").

Only a small minority of hair transplant surgeons carry out "megasessions". Why? There is very little difference in work or staff requirements between doing a 1500 graft session for each of two patients in a day or doing a 3000 graft session on a single patient. If anything, there is slightly more work and staff requirements if two patients are treated instead of one. It is also more convenient for patients to have a single session than several sessions to the same area, and it is, therefore, certainly more "saleable" to more patients. The answer to the question of why so few surgeons employ "megasessions" lies with differing opinions about patient safety and hair survival when such large sessions are utilized.

Megasessions of 3000 or more FUs typically involve 10 to 12+ hours of surgery. They are, therefore, more physically and emotionally stressful than more standard sized sessions. The increased risk associated with such long sessions can be minimized by careful monitoring of blood oxygen levels, blood pressure, and pulse rates, as well as continuous intravenous fluids and drugs. Most physicians, nevertheless, feel that the increased risks outweigh the benefits for what is, after all, a cosmetic procedure. The choice between patient convenience and safety seems to them to be properly weighed towards the latter.

1. “Dense packing” of 40, 50, or more FUs/cm² in a single session does produce a greater hair density than using a graft density of 20 to 25 FUs/cm².  Thus, photos showing the results of such dense packing can be very impressive.  There is, however, a substantial body of evidence suggesting that dense packing FUs results in reduced hair survival.  There is a limited number of FUs available for transplanting and anything that might endanger their survival should be avoided.
   
   The smaller the graft, the more easily it can be injured by technicians (as each hair is closer to the edge of the graft). Three thousand incisions in the scalp obviously will cut more blood vessels than 2000 or 1500 incisions. While most megasessions produce what appear to be adequate yields, a minority produces very little hair. It is likely that there are many patients between those two extremes who will grow hair, but less than they would have if a more conventional approach had been used. In a similar fashion, the current competition amongst some hair restoration surgeons to see who can transplant the most FUs/cm² seems to be ignoring the vascular damage caused by high density FUs/cm², and its effect on hair survival.  For example, 50 FUs/cm² requires a total length of 5 cm of incisions in each 1 cm² box if the recipient sites are made with needles or blades that only create 1 mm long incisions.  (An 18-g needle produces an incision that is approximately 1.2 mm long.)  Making 5 cm of incisions in every 1 cm² box of scalp tissue would intuitively lead one to expect massive vascular damage in that small area and consequently lower rates of hair survival than could be expected with less FUs/cm².  Yet some practitioners are suggesting even higher FUs/cm² densities. 

How then does one explain claims of 100% hair survival by proponents of megasessions and dense packing and photos of excellent looking results after only one or two sessions?

1. The claims of 100% or more survival have been based on studies in which FUs have been inserted into holes made in small areas (1 cm²) that were surrounded by otherwise intact, untreated skin.  This is not at all comparable to what actually happens during a typical transplant session in which thousands of additional incisions or holes are made, each one of which severs some blood vessels and thus reduces the blood supply to the recipient area, which in turn could reduce hair survival rates.

2. Apparent hair density is not dependent only on the number of hairs/cm². The less contrast between the hair and skin color, the more curl or wave, the more "frizziness" to the hair and the higher the hair caliber, the thicker or denser the hair will appear to be. An increase in hair shaft diameter of only 0.01 mm for example will increase hair volume by 36%.¹  Thus, the impressive results seen in photos of selected patients by proponents of megasessions and dense packing are both possible and real. Nothing that has been said here should in any way be construed to mean that I believe intentional deception is being used by anyone. Even if 35% or more of the hair transplanted by a few proponents is dying, if enough hairs are transplanted densely enough the results may, in fact, look excellent after two sessions or, less commonly, after one session if the patient's hair characteristics are particularly advantageous.
   
   Given the fragility of the FU graft, FUT is obviously very dependent on perfect technique.  Good hair survival is possible if technique and quality control of technicians are excellent.  It should be recognized, however, that hair count studies are notoriously difficult to do, with results that may or may not be scientifically valid, and therefore it would appear to be wise to use micrografts/FUs without megasessions or "dense packing" whose intention is a completed result after a single session.  “Dense packing”, if used, should also only be employed in limited areas until such a time as good hair survival rates in an entire recipient area (not, for example, a 1 cm² box) are documented by independent evaluators.