Final answer:
The most indicative sign of an expanding AAA from the options provided is an increased abdominal girth. Significant and sudden back pain can also be a symptom of an expanding AAA but is not listed as the top choice among the options provided. Weakened radial pulses and decreased urine output are not specific indicators of an expanding AAA.
Step-by-step explanation:
If a nurse suspects that a client has an expanding abdominal aortic aneurysm (AAA), one primary sign to look for is increased abdominal girth. An expanding AAA can cause the abdomen to enlarge as the aneurysm grows, which may be noticeable upon physical examination. Other signs and symptoms that could indicate an expanding or rupturing AAA include severe abdominal or back pain, which might be abrupt in onset and intense. The pain from an expanding AAA is often deep and steady, and can radiate to the back or legs.
While weakened radial pulses could be associated with vascular issues, they are not typically specific indicators of an AAA. Similarly, a decrease in urine output (UO) could point to other critical situations like kidney failure or cardiovascular problems, but is not a direct sign of an AAA. Therefore, the most indicative sign/symptom of an expanding AAA in the options provided is increased abdominal girth.