Abdominal and Visceral Vascular
Aortic measurement
Measure an aneurysm outer wall to outer wall, anteroposterior, in a plane perpendicular to the vessel axis. A tortuous aorta measured obliquely is falsely enlarged, a classic distractor. Infrarenal aorta above 3 cm is aneurysmal. Report maximal diameter, extent, renal and iliac involvement, and mural thrombus; measure the outer wall, never the flow lumen. Shorten surveillance intervals as size increases; rapid growth, roughly 0.5 cm in six months or 1 cm per year, prompts referral. After endovascular repair, look for endoleak, sac enlargement and graft limb flow.
Renal and mesenteric arteries
Normal renal artery PSV is below roughly 180 to 200 cm/s; a renal-aortic ratio above 3.5 supports significant stenosis. Kidney length is normally 9 to 12 cm; a small kidney with resistive index above 0.7 suggests parenchymal disease rather than correctable stenosis. For mesenteric ischemia, evaluate the celiac axis and superior mesenteric artery in sagittal and axial views. The SMA is high resistance when fasting and becomes low resistance after eating, so a postprandial study can mask or mimic disease.
Worked example
A 4.2 cm infrarenal aorta measured at a steep angle through a tortuous segment may truly be 3.5 cm. Re-measure in two planes and perpendicular to the axis before you commit to a diameter, and always state the measurement method in the report.