Which of the following intravesical agents least commonly causes cystitis?

Correct Answer: B

Rationale: Gemcitabine least causes cystitis better tolerated intravesically, less irritative than anthracyclines or alkylators. Doxorubicin, mitomycin, and epirubicin (similar class) frequently irritate bladder chemical cystitis common. Gemcitabine's milder profile distinguishes it, critical for patient comfort in NMIBC, unlike irritative agents.

Correct Answer: A

Rationale: Serum ACTH isn't a screening test for Cushing's differentiates cause (pituitary vs. adrenal) post-diagnosis. Late-night salivary cortisol, low-dose dexamethasone suppression, and dexamethasone-CRH screen hypercortisolism detect excess. ACTH's diagnostic role distinguishes it, key to etiology, not initial screening, unlike cortisol-based tests.

Correct Answer: C

Rationale: Grade III varicocele alone isn't a surgical indication size doesn't mandate unless symptomatic (e.g., atrophy). Left atrophy (volume loss), bilateral atrophy, and abnormal semen (fertility risk) justify repair functional impact. Grade III's lack of standalone need distinguishes it, critical for evidence-based intervention, unlike atrophy or semen-based triggers.

Correct Answer: C

Rationale: Drained volume >1000 mL predicts trial without catheter (TWOC) failure large residuals suggest poor bladder function or obstruction (e.g., BPH), needing prolonged catheterization. Absence of prior LUTS indicates better baseline favorable. Age <65 years ties to stronger detrusor supports success. High detrusor pressure aids voiding positive factor. High volume's negative impact distinguishes it, critical for TWOC prognosis, unlike factors enhancing bladder emptying potential.

Correct Answer: A

Rationale: Vasa recta surround the loop of Henle, enabling countercurrent exchange, unlike peritubular capillaries (PCT/DCT), interlobular arteries (cortex), or efferent arterioles (glomerulus). This specifies medullary circulation, key for urine concentration, contrasting with cortical vessels.