## **Core Concept**
The question presents a case of primary amenorrhea in a 16-year-old female with bilateral inguinal hernias, normal sexual development, but absence of pubic hair. The ultrasound findings reveal no uterus, ovaries, and a blind-ending vagina. This clinical picture suggests a condition related to abnormal sexual differentiation.

## **Why the Correct Answer is Right**
The correct answer, **Androgen Insensitivity Syndrome (AIS)**, also known as Testicular Feminization, fits the clinical presentation. Individuals with AIS are genetically male (46,XY) but have a resistance to androgen action due to mutations in the androgen receptor gene. This results in the development of testes (which can be undescended or found in the inguinal canal, causing hernias), female external genitalia, and a blind-ending vagina, but no uterus or ovaries. The presence of testes leads to the production of Müllerian inhibiting substance (MIS), which causes regression of Müllerian structures (uterus, fallopian tubes, and upper part of the vagina). The lack of pubic hair is due to the resistance to androgens. Despite the absence of ovaries, these individuals undergo normal puberty due to the peripheral conversion of androgens to estrogens.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Turner syndrome typically presents with short stature, gonadal dysgenesis (streak gonads), and a 45,X karyotype. These individuals usually have a rudimentary uterus and lack of secondary sexual characteristics due to estrogen deficiency, not matching this case.
- **Option B:** Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome involves a normal 46,XX karyotype, absence or underdevelopment of the vagina and uterus, but presence of normal ovaries and secondary sexual characteristics. This doesn't fit with the absence of uterus and ovaries, and the presence of hernias.
- **Option C:** Swyer syndrome is characterized by a 45,X/46,XY karyotype mosaicism, streak gonads, and a female phenotype. These individuals have a uterus and typically present with primary amenorrhea and lack of secondary sexual characteristics. They do not usually have inguinal hernias.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that individuals with Androgen Insensitivity Syndrome (AIS) are at increased risk for gonadal tumors, particularly if the gonads are not removed. They also often require hormone replacement therapy to induce puberty and maintain bone density.

## **Correct Answer:** . Androgen Insensitivity Syndrome.