Diagnosis: Mayer-Rokitansky-Küster-Hauser (MRKH) Syndrome
The diagnosis is Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome (Option A), not complete androgen insensitivity syndrome. This 17-year-old female presents with the classic triad of MRKH: primary amenorrhea, normal secondary sexual characteristics (normal breast development and pubic hair), and normal testosterone levels 1, 2.
Key Diagnostic Features Supporting MRKH
MRKH syndrome is characterized by congenital aplasia of the uterus and upper two-thirds of the vagina in women with normal development of secondary sexual characteristics and a normal 46,XX karyotype 1, 2, 3. The critical distinguishing features in this case include:
- Normal testosterone levels - This is expected in MRKH because ovarian function is completely normal 1, 4
- Normal breast development - Indicates normal estrogen production from functional ovaries 2, 3
- Normal pubic hair - Reflects normal androgen production from functional ovaries and adrenal glands 2, 3
- Primary amenorrhea - Results from uterine and upper vaginal aplasia, not hormonal dysfunction 1, 5
Why Not Complete Androgen Insensitivity Syndrome (CAIS)
Complete androgen insensitivity syndrome would present with elevated or high-normal testosterone levels (in the male range), because these patients have functioning testes producing testosterone that cannot be utilized due to androgen receptor defects. Additionally, CAIS patients have:
- Absent or sparse pubic and axillary hair - Because hair growth in these areas requires functional androgen receptors
- Blind vaginal pouch similar to MRKH, but with absent uterus due to Müllerian inhibiting substance from testes
- 46,XY karyotype (not 46,XX)
The presence of normal pubic hair development in this patient definitively excludes CAIS, as androgen insensitivity would prevent normal androgenic hair growth.
Diagnostic Workup for MRKH
Magnetic resonance imaging (MRI) is the gold standard for confirming MRKH syndrome, as it can demonstrate uterine agenesis, vaginal aplasia, and associated renal or skeletal anomalies in a single non-invasive examination 1, 5. Pelvic ultrasonography can also reveal complete uterine agenesis and should show normal ovaries 1, 4.
MRKH occurs in two types 2, 3:
- Type I (isolated) - Uterovaginal aplasia only
- Type II (MURCS association) - Associated with renal anomalies (unilateral renal agenesis or ectopic kidney in 40% of cases), vertebral defects, and less commonly cardiac or auditory defects 1, 4, 2
Laboratory evaluation should confirm normal ovarian function: normal FSH, LH, estradiol, and testosterone levels with 46,XX karyotype 1, 4, 3.
Clinical Implications
MRKH affects at least 1 in 4,500 women and is one of the most common causes of primary amenorrhea in women with normal secondary sexual characteristics 2, 3, 5. The ovaries are normal and functional, meaning these patients have normal endocrine status and will undergo normal puberty except for menarche 1, 2.
Examination reveals normal external female genitalia with a blind vaginal pouch of variable depth 4, 2. This is a critical physical finding that should prompt imaging evaluation.
Common Pitfall
The most common diagnostic error is failing to recognize that normal pubic hair development excludes complete androgen insensitivity syndrome. In CAIS, the lack of functional androgen receptors prevents androgenic hair growth, resulting in absent or markedly sparse pubic and axillary hair despite high testosterone levels. The presence of normal pubic hair in this patient, combined with normal (not elevated) testosterone levels, makes MRKH the only viable diagnosis.