In a pregnant woman of 28 weeks gestation IUD is earliest demonstrated on X-ray by:
**Core Concept**
Intrauterine death (IUD) in a pregnant woman can be detected through various diagnostic modalities, including X-ray. The detection of IUD on X-ray is based on the presence of calcification in the fetal bones, which appears as a radio-opaque shadow.
**Why the Correct Answer is Right**
The earliest demonstration of IUD on X-ray is possible when the fetal bones start to calcify. This process begins around 14-16 weeks of gestation, but it is not until 20-24 weeks that the calcification becomes significant enough to be visible on an X-ray. The correct answer is based on the fact that the fetal bones, particularly the skull, pelvis, and long bones, start to calcify and become visible on X-ray around 20-24 weeks of gestation. This is the earliest time when IUD can be reliably detected on X-ray.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because IUD is not typically demonstrated on X-ray before 20-24 weeks of gestation, as the fetal bones are not yet calcified enough to be visible.
* **Option B:** This option is incorrect because while IUD can be suspected clinically before 20-24 weeks, it is not reliably demonstrated on X-ray until the fetal bones have calcified.
**Clinical Pearl / High-Yield Fact**
When assessing a pregnant woman for IUD, it is essential to consider the gestational age and the presence of calcification in the fetal bones. Fetal bones typically start to calcify between 20-24 weeks of gestation, making this the earliest time when IUD can be reliably detected on X-ray.
**Correct Answer: C. 20-24 weeks.**