What is the recommended first step in evaluating abdominal pain in a post-op cholecystectomy patient?

In the evaluation of abdominal pain in a post-operative cholecystectomy patient, an ultrasound is often the recommended first step. This imaging modality is particularly useful because it is non-invasive, does not involve radiation, and is highly effective in detecting conditions such as fluid collections, bile leaks, retained stones, or abscesses that may occur after gallbladder removal.

The use of ultrasound in this context allows for a quick assessment, which is crucial in managing potential complications after surgery. It can provide valuable information about the presence of any bile duct dilation or obstruction, which can occur post-operatively. Additionally, it can help identify any other structural abnormalities in the abdominal cavity that could be responsible for the patient's pain.

Other imaging options, such as CT scans or MRI, may be used later for further evaluation, but they are not typically the first choice due to considerations such as cost, availability, and the need for radiation exposure in the case of CT. Endoscopy is not usually the first-line investigation for abdominal pain in this specific post-surgical context.