- 1. Why Do You Need To Fast Before the Scan?
- 2. How to fast?
- 3. What Foods Can You Eat?
- 4. What Foods to Avoid?
- 5. How to Break Your Fast?
- 6. الكلمات الأخيرة
Medical imaging or scan is a technique used by health professionals to create visual representations of the internal body structures, including organs and tissues. The purpose of a medical scan is to diagnose a particular health condition and perform clinical analysis.
X-ray, CT, and MRI are some examples of medical scanning techniques. These scans help health professionals diagnose a wide range of health conditions, from mental trauma to foot pain.
Each medical scan or exam works differently, and some of them use radiation, magnetic fields, and sound waves. It is important to learn about preparing for a medical scan so that everything goes smooth.
If your doctor has told you to fast before a medical scan, you should refrain from eating and drinking for a specific period. It can be a few hours or 10 to 12 hours before the test. Eating and drinking normally lead to the absorption of food and beverages into your bloodstream, which can hinder the procedure. For instance, the scanning machine may not produce accurate images. Read on!
Why Do You Need To Fast Before the Scan?
Optimum conditions for medical scans require little or no gas in the digestive tract. In particular, this is true for an ultrasonic exam of the abdominal organs. Studies show that thin patients are easy to examine than overweight and obese patients because doctors can use high-frequency transducers to improve resolution.
Better Abdominal Ultrasound Results
Most doctors instruct their patients to come fasting for medical scans, particularly ultrasounds, for 12 hours. Fasting allows for less contraction of the gall bladder and digestive organs. Patients who fast before the medical scan have less gas in the colon and duodenum.
A recent study found that a medical scan can produce favorable results with a low-calorie diet, liquid laxatives, and fasting. Your health provider will instruct you fast for at least 8-12 hours before a medical scan.
Otherwise, the presence of undigested food in your stomach and urine in the bladder will block the radiation or sound waves. As a result, the machine won’t produce clearer and accurate images, prohibiting the doctor from diagnosing the health condition.
Keep in mind that medical scans, such as ultrasound for blood vessels, joints, and thyroid, do not need fasting. On the other hand, abdominal ultrasound requires 6-8 or 10-12 hours of fasting. It is important to follow your doctor’s instructions to streamline the procedure.
Contrast-Enhanced CT and MRI
Generally, health professionals recommend patients to fast for 6 to 8 hours before CT or MRI. It is necessary when you are performing contrast enhancement. The purpose is to avoid the adverse effects of contrast agents. Although the side effects are rare, contrast agents can cause nausea and vomiting.
When you have eaten food, you may have asphyxia when lying down on the exam table. The food blocks the airway and may cause aspiration. Therefore, fasting is important for avoiding situations like asphyxia and aspiration.
Moreover, the reasons for fasting in the abdominal CT are that stomach and small bowel are filled with water, which is a neutral contrast agent. Additionally, it is essential to empty the colon by fasting before a doctor performs CT colonography. The purpose is to fill it with carbon dioxide gas to generate clearer images that easily and accurately help the doctor find lesions.
How to fast?
Fasting before a medical exam is when patients are told not to drink or eat anything other than water. It is important to know that some scans don’t require fasting. However, if you are undergoing abdominal scans, it is necessary to fast according to the doctor’s instructions.
Knowing how and when to fast before a medical scan can help reduce problems. Not only does fasting protect you from nausea and vomiting, but it also enables the doctor to interpret the images and find the problem. Here a few tips that you can use for fasting and better prepare for a medical scan. Continue reading!
Drink Lots of Water
Mild dehydration can cause dry mouth, fatigue, headaches, and thirst. Therefore, it is essential to drink plenty of water on a fast. Most health professionals recommend drinking eight glasses of water before the fast to stay hydrated.
Many patients aim to drink 2-3 liters of water during a fast. However, your thirst levels should tell you when you need more water. Therefore, listen to your body and drink as much water as possible to keep your body hydrated. Moreover, don’t leave yourself dehydrated. Avoid drinking tea, milk, juice, or anything else but water.
The type of medical scan will determine whether you need to consume water for the test. For example, it is better to drink lots of water during a fast if you undergo a pelvic ultrasound. Some doctors recommend at least 40 ounces of water 1-2 hours before the appointment time.
Keeping your body hydrated allows for reduced gas in the digestive system, causing the gall bladder to contract. A full bladder allows the machine to better scan the pelvic organs like ovaries, uterus, and prostate. It is not easy to capture or see these organs without a full bladder.
Eat a Large Meal 12 Hours Beforehand
Fasting keeps your digestive organs inactive and empties your stomach, which provides optimal conditions for the machine to capture clearer images. Fasting allows an ultrasound machine to capture the gall bladder, which is impossible when you have a full stomach.
It is crucial to schedule your medical scan appointment for early in the morning. That way, you will spend more of your “fasting” sleeping at night. Prepare a large meal 12 hours before your appointment.
Each a large meal so that your stomach is full, and make sure you avoid eating food items that are fried and salty. Because you will go to sleep, these types of foods can cause stomach irritation. It is important to avoid consuming alcohol at this meal.
Low Glycemic (GI) Food
Generally, a low glycemic diet is based on the glycemic index. Research studies have highlighted that low GI food can reduce blood sugar levels, promote weight loss, and lower the risks of Type-II diabetes and cardiovascular diseases.
Low GI foods contain carbohydrates, and when you eat them, your body breaks down starches and sugars into glucose. Remember, glucose is the main source of energy for your body cells.
Fiber passes through your body undigested. Insulin and glucagon are two hormones that regulate glucose in your bloodstream. As a result, your body remains energetic and keeps a balance in blood glucose.
If you eat a high glycemic food, it will make your fasting more difficult. You will end up with an empty feeling in your stomach that would cause you to eat again. On the other hand, you won’t feel hungry if you choose food items that are lower on the glycemic index scale.
All forms of high-intensity exercise before a medical scan can interfere with the diagnostic results, which will produce false positives. In simple words, the health professional will find other problems or abnormalities from the images that do not relate to your disorder, pain, or dysfunction.
Therefore, it is important to reduce intense muscle activity 12-24 hours before undergoing a medical exam, such as an MRI scan. Research shows that abnormal MRI scans result from heavy exercise and intense muscle activity.
Most often, a health professional performs an MRI scan without injections of contrast agents. However, when health professionals want clearer images of your injury or condition, they may inject you with a contrast agent like gadolinium.
A doctor injects gadolinium in your body before the medical scan to obtain clearer images of your body. Muscles exercised before a medical scan take up higher glucose levels, making it difficult for health professionals to make the right distinction.
Therefore, increase physical activity before a medical scan can result in misdiagnosis. The bottom line is that you can avoid heavy physical activity and perform exercises like walking, stretching, swimming, Tai Chi, Yoga, trim trails, and other activities like house chores.
What Foods Can You Eat?
When it comes to fasting before a medical scan, it is important to eat the right food items. For example, you can eat grilled chicken or with skin removed. You can also eat homemade gravy without fat, white fish, and all vegetables.
You can eat either boiled steamed or raw vegetables. Note: if you are undergoing a colonoscopy exam, it is recommended to avoid eating raw veggies. The whole meal, granary, and high fiber white bread, crackers, boiled rice, noodles, pasta, and crispbreads are allowed. Moreover, you can consume all fruit, fresh, tinned or stewed, dried, fruit juice, marmalade, and plain meringues.
What Foods to Avoid?
There are certain food items that you must avoid before you fast for a medical exam, such as CT or ultrasound. These include all milk and dairy products like cheese, butter, yogurt, and ice cream.
Although you can eat grilled chicken, it is wise to avoid poultry skin, meat fat, goose, beef, lamb, burgers, black pudding, sausages, ham, bacon, eggs, nuts, and luncheon meat. Avoid eating oily fish like eels, whitebait, herring, and mackerel.
You must also not eat fish in batter, fish in sauces, prawns, and canned fish, including tuna, sardines, and pilchards. When it comes to vegetables, we suggest you avoid vegetables tossed in butter, salad oil, margarine, mayonnaise, or cooked in oil, fat, creamed soups, and coleslaw.
Do not eat cereals, creamy pasta sauces, and fried rice. Avoid all types of oil, lard, suet, dripping, butter, margarine, and fried food. All desserts, including biscuits, chocolates, custards, and cakes, must also be avoided 12-15 hours before undergoing a medical scan.
How to Break Your Fast?
You can break your fast after a medical scan or exam. There are no further restrictions after the exam, and you may break your fast. It is important to break your fast with small portions of foods that your stomach can digest easily.
Breaking your fast with food items that are high in sugar, fat, and fiber can result in poor digestion and cause discomfort and bloating. Doctors recommend avoiding high-fiber raw produce, seeds, and nuts because your stomach won’t digest them easily.
In contrast, you can have nutrient-rich foods, a bit of protein, and healthy fats to break your fast gently. Some of the best food items and drinks to break your fast with smoothies, dried fruits, soups, avocados, vegetables, and fruits.
Most medical imaging or scans do not require a patient to fast. However, some scanning techniques like ultrasound, CT, and MRI of the abdomen require a person to “fast” 8-12 hours before the exam. It is important to “fast” the right way. Follow the tips and tricks mentioned above to streamline the entire process. Good Luck!