**Core Concept**
A bicornuate uterus is a congenital anomaly characterized by a partially divided uterus, resulting from incomplete fusion of the Müllerian ducts during embryonic development. This anomaly can lead to issues such as recurrent miscarriages, preterm labor, and infertility. The investigation of choice for diagnosing a bicornuate uterus involves imaging studies that can accurately visualize the uterine structure.

**Why the Correct Answer is Right**
Magnetic Resonance Imaging (MRI) is the investigation of choice for a bicornuate uterus due to its high resolution and ability to provide detailed images of the uterine anatomy. MRI can clearly visualize the presence of a septum or a cleft in the uterus, distinguishing it from other uterine anomalies such as a septate uterus. This is particularly useful in planning surgical management and counseling patients about their reproductive options.

**Why Each Wrong Option is Incorrect**
**Option A:** Ultrasound may be used as an initial screening tool, but it may not provide sufficient detail to accurately diagnose a bicornuate uterus, particularly in cases where the anomaly is subtle.
**Option B:** Hysterosalpingography (HSG) is a diagnostic tool that involves injecting a contrast agent into the uterus and fallopian tubes to visualize their structure. However, it is not the investigation of choice for a bicornuate uterus, as it may not provide sufficient detail and can be associated with complications such as pelvic pain and infection.
**Option C:** Hysteroscopy involves inserting a scope into the uterus to visualize its interior. While it can be useful in diagnosing some uterine anomalies, it is not the investigation of choice for a bicornuate uterus, as it may not provide a complete view of the uterine structure.

**Clinical Pearl / High-Yield Fact**
A bicornuate uterus should be distinguished from a septate uterus, as the latter is typically associated with a complete division of the uterus and may require a different surgical approach.

**Correct Answer: C. Hysteroscopy involves inserting a scope into the uterus to visualize its interior. While it can be useful in diagnosing some uterine anomalies, it is not the investigation of choice for a bicornuate uterus, as it may not provide a complete view of the uterine structure.**