Question

What is NOT true about congenital PUJ (pelviureteric junction) obstruction?

• A. It is due to compression by an aberrant vessel rather than due to intrinsic causes
• B. Retrograde pyelography is useful to find the site of obstruction
• C. Whitaker's formula is useful for classification and treatment assessment
• D. Antenatal diagnosis is possible

Hint:

Congenital PUJ obstruction is mostly intrinsic, not from vessel compression.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks which statement about congenital pelviureteric junction (PUJ) obstruction is FALSE. PUJ obstruction blocks urine flow from the renal pelvis into the ureter, and it can come from a defect in the ureter wall itself (intrinsic) or from pressure by an outside structure (extrinsic), such as a lower pole crossing vessel.

Step 2: Key Formula or Approach:
In children, most cases of congenital PUJ obstruction come from an intrinsic problem, a segment of ureter with poor muscle development (an adynamic segment) that fails to carry urine forward normally. An aberrant crossing vessel compressing the PUJ is a real cause too, but it is seen less often than the intrinsic type, and it is more typical in older children and adults.

Step 3: Detailed Explanation:
Check each statement against this fact.
"Due to compression by an aberrant vessel rather than due to intrinsic causes": this reverses the real pattern. Intrinsic causes are more common in congenital PUJ obstruction, not vascular compression. This statement is false.
"Retrograde pyelography is useful to find the site of obstruction": true. Dye passed up the ureter outlines the pelvis and ureter from below and marks exactly where the narrowing starts.
"Whitaker's formula is useful for classification and treatment assessment": true. The Whitaker test measures pressure and flow across the PUJ and helps decide if the obstruction is bad enough to need surgery.
"Antenatal diagnosis is possible": true. PUJ obstruction is one of the most common causes of antenatal hydronephrosis picked up on routine fetal ultrasound.

Step 4: Final Answer:
Three of the four statements are correct facts about congenital PUJ obstruction. Only the claim that vascular compression outweighs intrinsic causes is wrong, since intrinsic narrowing is the more common cause in children. \[ \boxed{\text{Due to compression by an aberrant vessel rather than due to intrinsic causes}} \]