Gastrointestinal Barium Enema Preparation

Day Before Exam
8:00 a.m. Eat light meal.
9:00 a.m. Drink 8 oz. clear liquid.
10:00 a.m. Drink 8 oz. clear liquid.
11:00 a.m. Drink 8 oz. clear liquid.
12:30 p.m. Take magnesium citrate effervescent laxative. To 6 oz. of cold water, slowly add contents of packet while gently stirring. After effervescence stops, stir again and drink. Or, drink 10 fluid oz. of magnesium citrate oral solution.

Eat a light liquid meal (bouillon, fruit juice, and plain gelatin). No solid foods. No dairy products (milk, cream, or cheese).
2:00 p.m. Drink 8 oz. clear liquid.
3:00 p.m. Drink 8 oz. clear liquid.
4:00 p.m. Drink 8 oz. clear liquid.
6:00 p.m. Eat a light liquid meal (bouillon, fruit juice, and plain gelatin). No solid foods. No dairy products (milk, cream, or cheese).

After eating, take four yellow bisacodyl tablets. Swallow tablets whole with a full glass of water. Do not chew or dissolve tablets.

Day of Exam
Eat no breakfast.

If you are being treated for a renal failure, consult your renal physician for special preparation.

Object Contrast

Apart from subject contrast and image contrast which you know very well, there is a third 'contrast' in medical imaging called object contrast - yes.
Object contrast is simply the differences in the anatominal deatails of the patient's body part to be exposed. For more info, check out http://faxil.leeds.ac.uk/learning/iq/contrast/object.xml