In IVP, Adder head appearance is seen in:
**Core Concept**
The Adder head appearance in Intravenous Pyelography (IVP) refers to a radiographic finding where the renal pelvis and calyces resemble the head of a snake. This occurs due to the contrast material accumulating in the renal calyces, giving a characteristic appearance.
**Why the Correct Answer is Right**
The Adder head appearance is typically seen in cases of **obstruction of the ureteropelvic junction (UPJ)**. When the UPJ is obstructed, the contrast material accumulates in the renal pelvis and calyces, leading to the characteristic "adder head" appearance. This is because the obstruction prevents the normal flow of contrast material from the renal pelvis into the ureter. The renal pelvis and calyces become distended and fill with contrast material, giving the characteristic appearance.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the Adder head appearance in IVP.
**Option B:** This option is not specific to the Adder head appearance and could refer to other radiographic findings.
**Option C:** This option is incorrect as the Adder head appearance is not typically seen in cases of renal calculi.
**Clinical Pearl / High-Yield Fact**
In IVP, the Adder head appearance is a classic sign of UPJ obstruction, which can lead to chronic kidney damage and renal failure if left untreated.
**Correct Answer: C. Renal calculi.**