Ultrasound is useful to evaluate which structures and to diagnose obstructions of the biliary or urinary tract.

• A. Intrapersonal and Retroperitoneal
• B. Intraperitoneal and Retroperitoneal
• C. Intrapelvic and Retroperitoneal
• D. Intrapersonal and Intraperitoneal

Answer: (A)

Ultrasound is effective because it images organs in both the intraperitoneal and retroperitoneal spaces. The biliary system (liver, gallbladder, bile ducts) sits in the intraperitoneal compartment, where ultrasound can detect stones, duct dilation, or inflammation causing biliary obstruction. The urinary tract, including the kidneys and ureters, lies in the retroperitoneal space, where ultrasound can reveal hydronephrosis or upstream obstruction.

So the best pairing reflects evaluation of structures in both compartments: intraperitoneal and retroperitoneal. The other terms refer to body areas that aren’t the standard anatomical spaces for this purpose, so they don’t fit as well.