Final answer:
A patient with an abnormality in the lower portion of the colon would be referred to a Gastroenterologist for a colonoscopy to properly examine and diagnose the condition.
Step-by-step explanation:
A patient with an abnormality in the lower portion of the descending colon, as detected during a routine physical examination, would most likely be referred to a Gastroenterologist for a colonoscopy. A colonoscopy is a procedure that allows the specialist to examine the entire length of the colon using a flexible tube with a camera attached to it. It is the gold standard for diagnosis and can help detect and remove precancerous polyps.