Adolescent Menstrual Disorders and PCOS
On this page
Direct answer
Adolescent menstrual disorders are mostly physiological in the first two years after menarche, but primary amenorrhoea, heavy bleeding and persistent irregularity need structured evaluation. Primary amenorrhoea is defined as no menarche by age 15 years, or three years after breast development began, and the work-up combines examination, pregnancy test, hormone profile and pelvic imaging, with karyotype when indicated. In teenagers, polycystic ovary syndrome is diagnosed by hyperandrogenism and ovulatory dysfunction after other causes are excluded.
What you must remember
- Primary amenorrhoea: no menarche by 15 years, or three years after thelarche; absent breast development by 13 years also warrants investigation.
- Gonadal dysgenesis: Turner syndrome (45,X) with short stature, webbed neck and streak gonads, confirmed by karyotype.
- Mullerian agenesis: normal 46,XX karyotype with absent uterus and upper vagina, but normal breast development and pubic hair.
- Androgen insensitivity: 46,XY karyotype with female external genitalia, absent uterus and intra-abdominal or inguinal gonads.
- Outflow obstruction: imperforate hymen or transverse vaginal septum causes cyclical lower abdominal pain and haematocolpos.
- PCOS in adolescents: persistent hyperandrogenism and irregular cycles beyond one to two years after menarche (the 2023 international guideline counts cycles irregular beyond one year), with other causes excluded; ovarian morphology carries less weight than in adults.
Comparing causes of primary amenorrhoea
The first question is whether breasts have developed and whether a uterus is present, since the answer splits the differential sharply. Each cause has a typical karyotype and examination clue.
| Cause | Karyotype | Uterus | Key clue |
|---|---|---|---|
| Constitutional delay | 46,XX | Present | Family history, delayed bone age |
| Turner syndrome | 45,X | Present, streak gonads | Short stature, webbing, coarctation |
| Mullerian agenesis | 46,XX | Absent | Normal breasts and pubic hair |
| Androgen insensitivity | 46,XY | Absent | Female habitus, inguinal testes |
| Imperforate hymen | 46,XX | Present | Cyclical pain, bluish bulge |
Constitutional delay is a diagnosis of exclusion, so the karyotype and uterine status must be checked before reassurance. Absent uterus with normal breasts points to Mullerian agenesis or androgen insensitivity, which the karyotype separates cleanly. Weight, pubertal staging, family history and signs of hyperandrogenism are recorded at the first visit, as they guide every later step. Pregnancy should be excluded in any adolescent with an irregular cycle, since it is easily missed.
Where the exam tries to catch you
Adolescent gynaecology vignettes test whether the candidate avoids reflex labels such as PCOS or constitutional delay.
- Trap: labelling every irregular cycle in the first two years as PCOS Correct: anovulation is normal early after menarche, so PCOS needs persistence and hyperandrogenism.
- Trap: assuming primary amenorrhoea with normal breasts is always constitutional delay Correct: an absent uterus with normal breasts suggests Mullerian agenesis, which needs karyotype and pelvic imaging.
- Trap: treating heavy bleeding without screening for bleeding disorders Correct: von Willebrand disease and platelet disorders are recognised causes of heavy menses in teenagers.
- Trap: attributing cyclical abdominal pain with amenorrhoea to constipation Correct: imperforate hymen with haematocolpos needs examination and ultrasound.
Frequently asked questions
At what age is primary amenorrhoea diagnosed?
Primary amenorrhoea is diagnosed when menarche has not occurred by 15 years, or three years after breast development began. Absent breast development by 13 years is also an indication for evaluation.
Why is karyotype essential in primary amenorrhoea?
Karyotype separates Turner syndrome and androgen insensitivity from disorders with a normal 46,XX pattern, which changes both management and counselling. It is an essential first test when the uterus is absent or breast development is missing.
How is PCOS diagnosed in adolescent girls?
PCOS in adolescents needs persistent hyperandrogenism with ovulatory dysfunction after other causes are excluded, typically beyond two years after menarche. Ultrasound morphology is interpreted cautiously, because polycystic-appearing ovaries are common in healthy teenagers.
What is the first-line treatment for heavy menstrual bleeding in adolescents?
Heavy menstrual bleeding in adolescents is managed with tranexamic acid or hormonal therapy such as oral contraceptives or progestins, along with correction of anaemia, while bleeding-disorder screening is sent before treatment starts. The choice depends on haemodynamic stability and patient preference.
Which bleeding disorder is linked with heavy periods in adolescents?
Von Willebrand disease is a common bleeding disorder linked to heavy menstrual bleeding in adolescents. Screening for it is advised before attributing heavy bleeding to hormonal causes alone.