This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Surgery
The most reliable urine specimen is obtained by: 
Select and explain. 
A. urethral catheterization, B. Catheter aspiration, C. Midstream voiding, D. Suprapubic aspiration
D: Suprapubic aspiration
Answer: D: Suprapubic aspiration 
Explanation: Suprapubic aspiration avoids potential contamination Urinary Tract infection Most often, the urine is often obtained from a voided specimen. In children, who are not toilet trained, a urine collection device, such as bag, is placed over the genitals, and the urine is cultured from the bagged specimen Suprapubic aspiration avoids potential contamination; however due to its invasiveness, it is rarely used except in children and selected patients Urine obtained from a urinary catheter is less invasive than a suprapubic aspiration and is less likely to be contaminated than that from a voided specimen. Ref: Smith 18th edition Pgno: 200