What initial diagnostic study is indicated for a patient over age 55 with new-onset dyspepsia symptoms?

In a patient over age 55 presenting with new-onset dyspepsia symptoms, an upper endoscopy is the recommended initial diagnostic study. This is primarily because individuals in this age group have an increased risk for various gastrointestinal pathologies, including peptic ulcers, esophagitis, and malignancies such as gastric cancer.

Upper endoscopy allows for direct visualization of the upper gastrointestinal tract, including the esophagus, stomach, and duodenum. It can also enable biopsy of any suspicious lesions, which is crucial for distinguishing between benign and malignant conditions.

In contrast, while a PET CT scan may be useful in oncological evaluations, it is not typically the first step in assessing new dyspepsia symptoms. An abdominal ultrasound is generally helpful for evaluating gallbladder disease or biliary issues but does not provide detailed views of the esophagus or stomach. Gastric emptying studies are more focused on motility disorders and are not the first-line approach for evaluating dyspepsia in this age group. Therefore, among the options, upper endoscopy is the most appropriate and effective choice for initial assessment in this clinical scenario.