In asymmetrical IUGR, which organ is not affected?
**Core Concept**
Asymmetrical Intrauterine Growth Restriction (IUGR) refers to a condition where the fetus experiences restricted growth, particularly in the abdominal organs, due to inadequate placental perfusion. This results in a disproportionate distribution of growth, with the head and extremities being relatively spared, while the abdominal organs are affected.
**Why the Correct Answer is Right**
In asymmetrical IUGR, the kidneys and liver are typically affected due to their high metabolic demands and dependence on adequate blood flow. The kidneys, in particular, are sensitive to changes in renal perfusion, leading to decreased urine production and potential oligohydramnios. The liver, being a major site of glucose and lipid metabolism, also shows signs of growth restriction. However, the central nervous system, including the brain, is relatively spared due to its higher priority for blood flow and oxygenation.
**Why Each Wrong Option is Incorrect**
**Option A:** The brain is indeed affected in asymmetrical IUGR, as it requires a significant amount of blood flow and oxygenation to support its growth and development.
**Option B:** The kidneys are a correct answer, as they are a common site of growth restriction in asymmetrical IUGR.
**Option C:** The liver is also a correct answer, as it is a major site of glucose and lipid metabolism and shows signs of growth restriction in asymmetrical IUGR.
**Clinical Pearl / High-Yield Fact**
A key feature of asymmetrical IUGR is the presence of oligohydramnios, which is a result of decreased urine production by the kidneys. This can be an important clue in the diagnosis of asymmetrical IUGR.
**Correct Answer:** D.