**Core Concept**
A triradiate pelvis is a congenital anomaly characterized by an abnormal shape of the pelvic inlet, outlet, and midpelvis. This condition is associated with an abnormal formation of the pelvic bones during fetal development, resulting in a characteristic triangular shape.

**Why the Correct Answer is Right**
The triradiate pelvis is typically seen in cases of cloacal exstrophy, a rare congenital anomaly. Cloacal exstrophy is a type of cloacal malformation where the rectum and urinary bladder are exposed on the abdominal wall due to a failure of the cloacal membrane to close during embryonic development. The triradiate pelvis is a result of the abnormal formation of the pelvic bones, which are often associated with this condition.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a triradiate pelvis is not typically seen in cases of sacral agenesis, which is a condition characterized by the absence or underdevelopment of the sacrum.

**Option B:** This option is incorrect because a triradiate pelvis is not associated with pelvic fractures or osteoporosis, which are conditions that affect the strength and density of the pelvic bones.

**Option C:** This option is incorrect because a triradiate pelvis is not typically seen in cases of uterine anomalies, which are conditions that affect the shape and structure of the uterus.

**Clinical Pearl / High-Yield Fact**
In cases of cloacal exstrophy, the triradiate pelvis is often associated with other congenital anomalies, such as bladder exstrophy and imperforate anus. Awareness of these associated conditions is crucial for accurate diagnosis and management.

**Correct Answer:** D. Cloacal exstrophy.