An endoscopy uses an endoscope—a flexible tube equipped with a light and camera—to visualize the interior lining of the upper digestive tract, including the esophagus, stomach, and duodenum. This procedure allows physicians to diagnose and sometimes treat conditions affecting the gastrointestinal system. Proper dietary preparation is mandatory, as it directly impacts the safety of the procedure and the clarity of the images obtained. Following specific instructions ensures the digestive tract is clear for a successful examination.
Food Restrictions Beginning Days Before
Dietary modifications typically begin three to seven days prior to the endoscopy to reduce residue in the digestive tract. The goal is to transition to a low-fiber diet that minimizes bulky waste material that could obscure the mucosal lining.
Patients must eliminate high-fiber items, including whole grains, raw vegetables, and fruits with skins or seeds. Specific items known to linger, such as nuts, corn, and seeds (like poppy or sesame), must be avoided. Instead, focus on easily digestible, low-residue foods like white bread, refined cereals, lean meats, and cooked or canned fruits and vegetables without skins.
Temporary cessation of certain supplements and medications is also required. Iron supplements can leave a dark residue that may obscure tissue or mimic blood. NSAIDs and blood thinners may need to be paused, as they increase the risk of bleeding, especially if a biopsy is performed. Patients must consult their physician for personalized instructions on managing all prescription and over-the-counter medications.
The Clear Liquid Diet: What Is Permitted
The final 12 to 24 hours before the procedure requires shifting to a clear liquid diet—liquids you can see through that leave no solid residue. This phase ensures the stomach and upper tract are free of particulate matter that could interfere with the endoscope’s view. Staying hydrated with permitted liquids is encouraged before the final fasting period.
A wide range of options is allowed:
- Plain water.
- Clear fruit juices without pulp (e.g., white grape or apple juice).
- Clear broth (chicken, beef, or vegetable).
- Clear sodas (e.g., ginger ale or Sprite) and sports drinks.
- Black coffee or tea without cream or dairy.
- Plain gelatin and popsicles, provided they contain no fruit pieces or cream.
Avoid any clear liquids containing red, purple, or blue dyes, as these pigments can be confused with blood during the examination. Items like red gelatin or purple sports drinks are forbidden. Opaque liquids, such as milk, cream, juice with pulp, and alcoholic beverages, are prohibited because they leave residue.
The Final Fasting Window
The final and most restrictive stage is the absolute fasting period, known as NPO (nothing by mouth), which typically begins several hours before the procedure. All intake must cease to ensure the stomach is completely empty. The American Society of Anesthesiologists (ASA) recommends stopping solid food six to eight hours before the procedure and clear liquids two to four hours prior.
This final fast is a safety precaution designed to prevent pulmonary aspiration, a serious complication where stomach contents are inhaled into the lungs during sedation. The risk of aspiration is elevated when the stomach contains food or liquid. Stopping even small amounts of water or clear liquids at the designated time minimizes this danger.
Patients must refrain from chewing gum, sucking on hard candy, or smoking during this window. These activities stimulate the production of saliva and stomach acid, compromising the emptiness required for safe sedation and a clear examination. Adhering precisely to the final cutoff time for all oral intake, as specified by the physician, is essential.