A girl has primary amenorrhea with normal ovaries, absent internal genitalia but normal external genitalia. Most probable diagnosis?
**Core Concept**
The underlying principle being tested involves **Müllerian duct anomalies**, which are congenital disorders affecting the female reproductive system. These anomalies can result in various forms of **genital tract malformations**, including absence or abnormalities of the uterus and vagina.
**Why the Correct Answer is Right**
Given the girl has **primary amenorrhea** with **normal ovaries**, **absent internal genitalia** (such as the uterus), but **normal external genitalia**, the most probable diagnosis is related to a condition where there's an issue with the development of the internal genitalia from the Müllerian ducts. This scenario is typical of **Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome**, where individuals have normal ovarian function (hence normal external genitalia due to the presence of female hormones) but are born without a vagina and uterus due to the failure of the Müllerian ducts to develop.
**Why Each Wrong Option is Incorrect**
**Option A:** This choice would be incorrect because it doesn't specify a condition that matches the given clinical presentation.
**Option B:** Similarly, this option does not align with the symptoms described.
**Option D:** This choice is also incorrect as it does not correspond to the clinical scenario of having normal external genitalia and absent internal genitalia.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that individuals with MRKH syndrome have **normal female karyotype (46,XX)** and **normal secondary sexual characteristics** due to functioning ovaries, but they lack the internal genital organs derived from the Müllerian ducts.
**Correct Answer:** Correct Answer: D. Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome.