Final answer:
The procedure most often performed for a patient with a clinical history of regional enteritis is endoscopic retrograde cholangiopancreatography (ERCP), which allows for detailed imaging of the biliary and pancreatic ducts to evaluate the small intestine.
Step-by-step explanation:
The student has asked about the most often performed procedure for a patient with a clinical history of regional enteritis. Although procedures like single contrast barium enema, double contrast barium enema, and intubation small bowel series are relevant in some gastrointestinal conditions, the clinical history suggests this patient's condition may be best evaluated using endoscopic retrograde cholangiopancreatography (ERCP). This procedure involves the insertion of a tube down the throat, into the stomach, and then into the small intestine, with dye injection allowing X-ray visualization of the biliary and pancreatic ducts. ERCP can provide insight into the state of the small intestine and is beneficial in the diagnosis and management of conditions such as regional enteritis, commonly known as Crohn's disease.