This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
A I 0-mm calculus in the right lower ureter associated with proximal hydroureteronephrosis is best treated with ? 
Select and explain. 
A. Extracorporeal shockwave lithotripsy, B. Antegrade percutaneous access, C. Open ureterolithotomy, D. Ureteroscopic retrieval
D: Ureteroscopic retrieval
Answer: D: Ureteroscopic retrieval 
Explanation: Ans. is 'd' i.e., Ureteroscopic Retrieval "Ureteroscopic stone extraction is highly efficacious for lower ureteral calcui" - Smith's Urology A ureteroscope is a long endoscope that can be passed transuretherally across the bladder into the ureter. The stones can be caught in baskets or endoscopic forceps. Those that cannot be removed baskets or endoscopic forceps, are fragmented using ureteroscopic lithotrites. Any renal calculi that is 4 mm or less in size, is allowed some time (approx. 4 weeks) to pass spontaneously. Indications for surgical removal of a ureteric calculus (Ref: Bailey & Love 25/e p1301) stone is too large to pass spontaneously urine is infected repeated attacks of pain and the stone is not moving stone is enlarging stone is causing complete obstruction stone is obstructing solitary kidney or there is bilateral obstructions.