Measurement Protocol v1.0

On this page 18 sections

1. Current status
2. Why a clinic is publishing a protocol at all
3. What can be measured, and what is a judgement
4. Defining transection
5. Donor density
6. Punch
7. Classifying hair pattern
8. Skin thickness and firmness
9. Disease activity before surgery
10. Complications
11. Outcome at 6, 9 and 12 months
12. Photograph standardisation
13. Missing data
14. Follow-up, and what we will not publish without it
15. Inclusion and exclusion
16. Retrospective and prospective data are never mixed
17. Changes to this protocol
18. Comments

This is a measurement protocol, published before any data has been collected. No study has started. Nothing on this page is a result.

We publish it now, in advance, for one reason: a protocol written after the numbers are in is not a protocol. It is a description of whatever happened to be favourable. Putting the definitions on the record first is the only way anyone — including us — can tell the difference later.

Why a clinic is publishing a protocol at all

While researching this site we went looking for a published transectionTransection Cutting through a follicle during extraction, damaging or destroying the graft. rate specific to tightly coiled hair. We did not find one. The closest study measured it in six coiled-hair patients out of 152, and concluded that scalp thickness and firmness affected the rate more than curl did.

That gap is recorded on our verification page as something we could not source. But we are a clinic that performs these procedures. We are in a position to measure the thing we could not find measured — and continuing to write “no data exists” while sitting on an unpublished dataset would be a strange kind of honesty.

So this is the protocol we intend to work to. It is deliberately conservative, and several of its rules make our numbers look worse rather than better. That is the point.

What can be measured, and what is a judgement

Confusing these two is the most common failure in clinic-published data. A number that came out of someone’s opinion is not a measurement, however many decimal places it carries.

Rule: judged variables may be recorded and reported, but never presented as measurements, and every one of them carries the name of the person who made the judgement.

Defining transection

This is the definition most easily bent, so it goes first.

Transection is not one event. A study we read separates graft damage into five kinds — transection, paring, fracture, dermal papilla injury and partial bulb injury.^[1] A single “transection rate” hides four of them.

More importantly, the same study examined the same grafts twice: 7.40% under a loupe, 6.34% under a microscope. The instrument changes the number. A transection rate published without its magnification cannot be compared to anyone else’s, including ours.

Transected follicle: a hair follicle whose integrity has been disrupted by cutting during extractionGraft extraction A distinct step in the procedure, attributable to a named person., visible at ×10 magnification or greater. Paring, fracture and papilla injury are recorded separately and are not counted as transection.

Mandatory fields with every rate: magnification · instrument (loupe or stereomicroscope) · who counted.

The denominator

A follicular unit contains one to four hairs. If one hair of a three-hair unit is cut, is that a lost graft? The literature answers this inconsistently, which is why rates from different clinics are rarely comparable.

We will report both:

• Primary: transected follicles ÷ total follicles in the grafts examined
• Secondary: grafts containing ≥1 transected follicle ÷ grafts examined

Sampling: 100 randomly selected grafts per case. Counting all of a three-thousand-graft session is not realistic, and pretending otherwise would be the first lie in the dataset.

Blinding: the person who extracted a graft does not count its transection. A different technician counts, without knowing who performed the extraction. This is the minimum condition under which the number means anything.

Donor density

Recorded with instrument, magnification, measurement sites and unit. Two units, separately, because they are routinely confused: follicular units per cm² and hairs per cm².

Sites: occipital midline plus two lateral points, against fixed anatomical references.

Measured on trimmed or shaved scalp. Visual counting through unshaved coiled hair is not reliable, and a density figure taken that way is a guess with a number attached.

Punch

• Outer diameter in millimetres. Not gauge — gauge is ambiguous between systems.
• Type: sharp / dull / hybrid / flared / curved
• Motion: rotary / oscillating / manual
• Speed, where applicable
• If the punch changes mid-case, both are recorded. A single “punch diameter” field would hide the most interesting thing that happened.

Classifying hair pattern

We use the 3A–4C scale across this site because readers use it. It is worth being clear about what it is: a scale devised for a hair-care product line, not a clinical instrument, and its agreement between observers is poor.

That makes it acceptable for communication and unacceptable as a study variable. So three things are recorded:

1. Walker type — judged, with the name of whoever classified it
2. An objective proxy: complete turns per centimetre on a stretched lock, or curl diameter in mm
3. Hair shaft cross-section, where available

Skin thickness and firmness

Two published series report that these affected transection more than curl did. A protocol that does not record them is broken before it starts.

We will record an ordinal grade together with the name of the person grading, and state plainly that it is an operator judgement rather than an instrument reading. Where a published grading scale is used, we will name it and note that its author has a commercial interest in the devices it was developed alongside.

Disease activity before surgery

v1.0 recorded active scarring alopeciaScarring alopecia Alopecia in which the follicle is destroyed and replaced by scar tissue. and active traction alopeciaTraction alopecia Hair loss caused by sustained tension on the follicle, concentrated at the hairline and temples. as separate cohorts without saying how active is decided. That is not an oversight peculiar to us. the authors of the systematic review state that they were unable to find evidence on how to precisely diagnose disease activity, or on when after disease activity it is appropriate to perform surgery. They also state that the commonly suggested two-year rule for hair transplantHair transplantation Surgical relocation of follicles from a donor area to a recipient area. surgery after disease activity was not substantiated in their review^[2]

We cannot close that gap. We can stop concealing it, by recording activity with a named instrument and publishing which one was used, when, and what it is worth:

Recorded at the pre-operative assessment and again on the day of surgery, with the date of each and the name of whoever scored it. The interval between the two is reported, because a single score taken on the morning of an operation tells you nothing about whether the disease is settled.

Why a biopsy is not the activity measure. The intuitive answer to “how do you know the disease is quiet” is to take a biopsy. in a series of 32 patients with lichen planopilaris, a different scarring alopecia, surgery was performed only on inactive disease, and graft survival was 78.62 percent at twelve months and 79.96 percent at twenty-four months. The histopathology variables examined at the time of transplantation, including epidermal atrophy, fibrosis and inflammatory infiltrate, were not found to have any effect on graft survival^[4] That series was lichen planopilaris rather than CCCA, and it is the only test of the assumption we could find. Biopsy stays in this protocol, because it is how a diagnosisDiagnosis A distinct step in the procedure, attributable to a named person. is confirmed and how one scarring alopecia is told from another. It is not being used here as evidence that surgery is safe to perform.

No threshold is set in this version. We are not going to invent a score above which we decline to operate and present it as though it came from somewhere. What is fixed is that the number is taken, recorded, and published with every result.

Complications

A complication rate without a time window is meaningless. Each is defined with the point at which it is assessed:

The two native-hair rows are new in v1.1, and their absence from v1.0 was a real inconsistency: this site publishes a long page on shedding of the patient’s own hair after surgery while its own protocol had no field in which to record it. Two windows because the literature describes both an early shed and a question about permanence that only a year can answer.

Poor growth is not a complication at three months. It is the expected course. Assessing it early inflates the rate and tells the patient something untrue about their own result.

Outcome at 6, 9 and 12 months

Twelve months is the minimum for a final assessment. Six and nine months are interim and will never be presented as final.

Two independent axes, because they diverge more often than clinics admit:

• Objective: target area hair count (TAHC), target area hair width (TAHW) and the terminal-to-vellus hair ratio, from standardised macro photographs with a reference marker in frame^[5]
• Subjective: blinded independent assessors, plus patient-reported outcome

Those measure names are borrowed deliberately. v1.0 said “hair counts in a defined recipient zone”, which is a private unit comparable to nobody. objective trichoscopic assessment in studies of androgenetic alopeciaAndrogenetic alopecia Genetically driven progressive hair loss following a recognised pattern. is reported using named measures: target area hair count, target area hair width, and the terminal-to-vellus hair ratio, each recorded in defined scalp regions, alongside a physician global assessment and a patient-reported outcome questionnaire Whether they behave the same way in tightly coiled hair is not established, and any figure we publish will say so.

Three zones, counted separately, never pooled:

• Recipient zone — where grafts were placed.
• Retained marginal zone (the fringe) — the strip of the patient’s own surviving hairs along the frontal and temporal rim, where one is present. Outlined on the pre-operative photograph and counted as its own target area.
• Donor zoneDonor area The region grafts are taken from, typically the occipital and lateral scalp. — at the density measurement sites.

The middle one is the reason this section changed. In traction alopecia the retained fringe is not decoration: its presence is how the diagnosis is made. Pooling it into a recipient-zone count would let a gain in transplanted hair hide a loss of the patient’s own. If the fringe is not outlined before surgery, nobody can say afterwards what happened to it — which is one reason nobody has published an answer.

Assessors will not be told which photograph is before and which is after, and images will be presented in randomised order where practical.

Photograph standardisation

Without a standard, a twelve-month photograph looks better simply because the hair is longer. Fixed:

• Distance, focal length and lighting — a fixed rig, not a phone held at arm’s length
• Five to seven set angles, in the same order every time
• The same hair length. This is the most frequently broken rule and the most misleading.
• A scale marker in frame
• Same background; no flash variation; wet-or-dry state held constant

Missing data

Blank fields are not allowed. Every absence is coded with the reason for it:

NOT_MEASURED · NOT_RECORDED · PATIENT_DECLINED · LOST_TO_FOLLOWUP · NOT_APPLICABLE

No imputation. Missing data carries information — often about the cases that went least well — and filling it in destroys exactly that.

Follow-up, and what we will not publish without it

v1.0 had LOST_TO_FOLLOWUP as a code and nothing else. A code records the problem; it does not commit us to anything about it.

The problem is large and it is specific to this population. in a retrospective review of 216 patients with traction alopecia at a single institution in the Bronx, 98.6 percent of whom were women and 72.7 percent Black or African American, 49.1 percent attended a follow-up visit. Of those who did, 42.5 percent noted improvement in hair loss or symptoms across all visits^[6] That was medical management rather than surgery, and it is the closest figure we have. A five-year outcome cannot be measured in a group that mostly does not return, and that is a substantial part of why the surgical literature for these conditions is three case reports and a borrowed curve.

What we commit to:

• Every result we publish carries its follow-up rate at that time point, stated as a fraction with the denominator visible — not a percentage on its own.
• Below 70 per cent follow-up at a time point we will not publish a rate for it. We will publish the count, the denominator and the fact that it fell short. A rate computed from the third of patients who came back is a rate about the patients who came back.
• Follow-up is scheduled and paid for by the clinic at 6, 9 and 12 months, and the photographs are taken on our rig rather than sent in. A follow-up visit that costs the patient a day and a fare is one we should expect them not to make.
• Remote follow-up is recorded as a distinct category, never merged with an in-person assessment. Photographs taken by the patient cannot meet the standardisation rules above and will not be counted as objective measurements.
• Patients who decline follow-up are coded PATIENT_DECLINED and are reported separately from those we could not reach.

The seventy per cent threshold is ours. We could not find a published norm for follow-up rates in this surgery, and we are not going to imply one exists. It is a number we are choosing in advance and binding ourselves to, which is the only thing that makes it worth anything — and it is written here before any data exists, so nobody can claim it was set once the attrition was known.

Inclusion and exclusion

Written before collection begins. Criteria added afterwards are not criteria; they are selection.

Included: Afro-textured hairAfro-textured hair Tightly curled hair type, the umbrella descriptor used across this site. as defined by the objective proxy above · primary FUEFollicular unit excision Extraction of individual follicular units from the donor area with a punch. · consent recorded

Recorded as separate cohorts, never merged into the main analysis:

• Active scarring alopecia — with biopsy inflammation status recorded
• Previous transplantation in the same area (repair cases behave differently)
• Active traction alopecia where the causative tension is ongoing

Retrospective and prospective data are never mixed

This is the strictest rule here, because it is the easiest one to break by accident.

Permitted use of retrospective records: feasibility only — estimating how many eligible cases exist, and designing the collection form. Always labelled as feasibility.

Not permitted: publishing any transection rate or outcome figure derived from retrospective records. There is no way to make such a number trustworthy after the fact, and presenting one alongside prospective figures would contaminate both.

Changes to this protocol

Each version is published with a number and a date. If a definition changes after collection has begun, the change is shown here with its reason, and any affected figures are reported under both definitions.

We would rather publish an awkward protocol history than a clean one nobody can check.

v1.1 — 17 September 2026

No definition in v1.0 was changed and no data existed, so nothing is reported under two definitions. Four things were added, each because writing three other pages on this site ran into the same wall:

• Disease activity before surgery. v1.0 used “active” as a cohort criterion without saying how it is determined. Named instruments are now recorded with their validation status.
• Native hair loss added to the complications table, in the recipient and donor areas, at two time points. Its absence was an inconsistency between this protocol and our published pages.
• Outcome measures given their established names (TAHC, TAHW, terminal-to-vellus ratio) instead of our own wording, and split into three separately counted zones including the retained marginal fringe.
• A follow-up commitment with a threshold below which we will not publish a rate.

Why now rather than at v1.0: we had not yet read the literature that exposed these gaps. a systematic review of platelet-rich plasma as an adjunct to hair transplantation identified only three eligible prospective controlled studies, covering 217 participants. It reported that none of those studies employed standardized evaluation tools or trichoscopic analysis, which limited the consistency and comparability of their findings^[7] We looked for a published standard to adopt instead of writing our own and did not find one: a PubMed search on 17 September 2026 returned no core outcome set for alopecia, four records in total for patient-reported outcomes in hair transplantation, and no norm for follow-up rates in this surgery.

Comments

If you work in this field and think a definition here is wrong, tell us before we start collecting. Corrections are far cheaper now than they will be in twelve months, and a protocol improved by someone outside the clinic is worth more than one written entirely inside it.

Clinical references

1. Park JH, You SH. Various Types of Minor Trauma to Hair Follicles During Follicular Unit Extraction for Hair Transplantation. Plastic and reconstructive surgery. Global open. 2017;5(3):e1260. view source →
2. Ekelem C, Pham C, Atanaskova Mesinkovska N. A Systematic Review of the Outcome of Hair Transplantation in Primary Scarring Alopecia. Skin Appendage Disord. 2019;5(2):65-71. view source →
3. Qadri A, Will E, Aguh C. Using Disease Symptomatology to Guide Treatment in Patients with Central Centrifugal Cicatricial Alopecia: Introduction of C-CAT Scoring Tool. Skin Appendage Disord. 2025;11(4):309-315. view source →
4. Daruwalla SB, Dhurat R, Ghate S, Bhatt K. Long-Term Utility of Follicular Unit Excision in Lichen Planopilaris-Correlation of Graft Survival With Histopathological and Ultrasound Biomicroscopic Parameters. Dermatol Surg. 2021;47(9):1243-1248. view source →
5. Piraccini BM, Rapparini L, Quadrelli F, Pampaloni F, Cedirian S, Bruni F, Iorizzo M, Starace M. Effectiveness and Safety of Topical Finasteride for Male Androgenetic Alopecia: Real World Data. Int J Dermatol. 2026;65(10):2102-2107. view source →
6. Balazic E, Hawkins K, Choi J, Konisky H. Traction alopecia: assessing the presentation, management and outcomes in a diverse urban population. Clin Exp Dermatol. 2023;48(9):1030-1031. view source →
7. Sindhusen S, Tawanwongsri W, Eden C. Efficacy of Platelet-Rich Plasma as an Adjunct to Hair Transplantation: A Systematic Review. Cureus. 2025;17(10):e94116. view source →

References are checked on the dates recorded in our evidence library. If a source has been superseded, tell us and we will update it.