Assess for transsexualism using ICD-10 criteria
STEP 1 — Gather Information
Collect: patient's expressed desire to live and be accepted as a member of the opposite sex, wish to make body congruent via surgery/hormone treatments; duration of transsexual identity; presence of comorbid mental disorders, genetic conditions, DSD, or chromosomal abnormalities.
STEP 2 — Rule In / Rule Out
Does the patient have a persistent desire to live and be accepted as a member of the opposite sex, accompanied by the wish to make the body as congruent as possible through surgery and hormone treatments?
- Yes → proceed to Step 3
- No → rule out transsexualism (does not meet criterion 1)
STEP 3 — Classify or Stratify
Has the transsexual identity been present persistently for at least 2 years?
- Yes → proceed to Step 4
- No → rule out transsexualism (does not meet criterion 2)
STEP 4 — Decide
Is the disorder not a symptom of another mental disorder, genetic, DSD, or chromosomal abnormality?
- Yes → patient meets ICD-10 criteria for transsexualism (F64.0)
- No → rule out transsexualism (does not meet criterion 3)
Clinical Guardrails / Mimics / Pitfalls
Do not confuse with DSM-5 gender dysphoria; ensure persistence is continuous, not intermittent; rule out body dysmorphic disorder, psychotic disorders, or DSD/chromosomal conditions that may mimic gender incongruence; avoid diagnosing if criteria are met only during transient phases of identity exploration.
Concrete Clinical Example
A 28-year-old assigned male at birth reports a 3‑year history of desiring to live as female, wishes to start hormone therapy and undergo surgery, denies any other mental illness, and has no known DSD or chromosomal abnormality → meets all three ICD-10 criteria for transsexualism.
Source: Endocrine Treatment of Gender-Dysphoric/Gender-Incongruent Persons, Endocrine Society, 2017, doi:10.1210/jc.2017-01658