Final answer:
A CT scan of the abdomen is the most suitable method to assess for intraperitoneal bleeding in a trauma patient with normal and stable hemoglobin levels, as it provides detailed images and can detect small amounts of bleeding.
Step-by-step explanation:
To assess for intraperitoneal bleeding in a patient with trauma to the left leg and back, and with a normal and stable hemoglobin level, CT of the abdomen is the most appropriate imaging modality. A CT scan provides a detailed view of the abdominal organs and can detect even small amounts of bleeding within the peritoneal cavity. Diagnostic peritoneal lavage (DPL) is an older technique that is invasive and generally used less frequently due to the higher sensitivity and specificity of CT scans. Abdominal ultrasound could be considered as a rapid bedside assessment, particularly the FAST (Focused Assessment with Sonography for Trauma) exam, to quickly identify free fluid in the abdomen, though it is less sensitive than CT. A flat plate of the abdomen provides limited detail and is not adequate for assessing intraperitoneal bleeding in this context.