A I 0-mm calculus in the right lower ureter associated with proximal hydroureteronephrosis is best treated with ?
**Core Concept**
The question is testing the management of a ureteral calculus, specifically a 10-mm stone in the right lower ureter with associated proximal hydroureteronephrosis. The core concept here is the appropriate treatment approach for this condition, taking into account the size of the stone, its location, and the presence of obstruction.
**Why the Correct Answer is Right**
The correct answer involves the use of extracorporeal shock wave lithotripsy (ESWL), which is a minimally invasive treatment for ureteral stones. ESWL involves the use of shock waves to break down the stone into smaller fragments that can then be easily passed out of the body. This approach is particularly suitable for stones larger than 5 mm in size, which cannot pass spontaneously but are still amenable to non-surgical treatment. In this case, the 10-mm stone in the right lower ureter with associated hydroureteronephrosis is an ideal candidate for ESWL, as it offers a high success rate and minimal complications.
**Why Each Wrong Option is Incorrect**
**Option A:** **Ureteroscopic stone extraction** is not the best initial approach for a 10-mm stone in the right lower ureter, as it is a more invasive procedure and may not be necessary if the stone can be effectively fragmented with ESWL.
**Option B:** **Percutaneous nephrolithotomy (PCNL)** is typically reserved for larger stones (>20 mm) or those located in the upper pole of the kidney. It is not the best initial approach for a 10-mm stone in the lower ureter.
**Option C:** **Observation** is not a suitable approach for a stone causing hydroureteronephrosis, as it may lead to further complications such as renal impairment or infection.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the size of the stone, rather than its location, is a critical factor in determining the most appropriate treatment approach. Stones larger than 5 mm in size are generally amenable to non-surgical treatment, while smaller stones may be managed conservatively.
**Correct Answer: C. Observation**