## Core Concept
Gestational trophoblastic neoplasia (GTN) is a malignant condition that can follow any type of pregnancy, often molar pregnancy. The diagnosis of postmolar GTN relies on specific criteria that help differentiate it from a persistent gestational trophoblastic disease (GTD) or other conditions.

## Why the Correct Answer is Right
The FIGO (International Federation of Gynecology and Obstetrics) criteria are commonly used for the diagnosis of GTN. These include:
- The hCG level plateau for 3 weeks or more (plateau defined as <10% decline in hCG levels over 3 weeks). - A rise in hCG levels on 2 or more consecutive measurements over 2 weeks or more. - The presence of metastases. ## Why Each Wrong Option is Incorrect - **Option A:** This option might list a criterion such as hCG level plateau for 3 weeks or more, rise in hCG levels, or presence of metastasis, which are indeed criteria for GTN. - **Option B:** Similarly, this might include another valid criterion such as the interval from index pregnancy to start of symptoms or elevated hCG levels being more than 100,000 IU/L for more than 2 weeks after evacuation. - **Option D:** Could represent another criterion like brain or liver metastases, indicating more aggressive disease. ## Why the Correct Answer is Incorrect in Context - **Option C:** Typically, uterine size larger for dates is a feature that might suggest molar pregnancy itself but isn't specifically a criterion for diagnosing GTN. GTN diagnosis focuses more on hCG dynamics and presence of metastasis. ## Clinical Pearl / High-Yield Fact A key point to remember is that the diagnosis of GTN often relies on the trend of hCG levels post-evacuation of a molar pregnancy. A plateau or rise in hCG levels over specified periods strongly suggests GTN. ## Correct Answer: C. uterine size larger for dates.