Can internal hemorrhoids be spotted by a routine examination by a gastrenterologist? not colonoscopy

With help from scope: Internal hemorrhoids can not be seen with the "naked eye," but many doctors and especially gastroenterologists have scopes shorter than the colonoscope. The flexible sigmoidoscope is 60 cm long (about 2 feet) and can be used with a simple enema prep. Or, an anoscope or anal speculum, which is only 3 to 4 inches long and the width of a large bowel movement, can be used to see inside the anus.

Probably: Some are quite visible! Some require anoscope to see. At your age, a full history, pregnancies, constipation, bowel issue, family etc is important to avoid missing something. Also colonoscopy may be recommended.