What is best to eat before an ultrasound?

November 15, 2025 •

4 min read

According to imaging experts, improper dietary preparation is a leading cause of unclear ultrasound results, potentially necessitating a repeat appointment. To maximize the accuracy of your diagnostic imaging, understanding what is best to eat before an ultrasound is essential for proper pre-test preparation.

Quick Summary

Preparing for an ultrasound requires specific dietary adjustments, which vary depending on the type of scan. Abdominal and gallbladder tests necessitate fasting, while pelvic and urinary exams require a full bladder. Avoiding gas-producing foods is crucial for clearer images.

Key Points

Fasting is not universal: Only abdominal and gallbladder ultrasounds typically require fasting (8-12 hours).
Fat and gas are image blockers: For upper abdominal scans, avoid fatty, fried, and gas-producing foods to prevent blurry results.
Hydration is key for pelvic scans: Drink about 32 ounces of water an hour before a pelvic ultrasound to fill your bladder and improve visibility.
Different scans, different rules: For transvaginal scans, you should have an empty bladder, while other scans like thyroid or vascular require no dietary prep.
Always confirm with your provider: The most accurate instructions will come directly from your healthcare provider, so always clarify the specific requirements for your test.
General low-fat diet helps: For non-fasting abdominal scans, a light, low-fat meal with items like lean protein, toast, or clear broth is ideal.

Preparing for an ultrasound is not a one-size-fits-all process. The instructions from your doctor are tailored to the specific area of your body being examined. Following these guidelines is critical, as undigested food and gas can obstruct sound waves, leading to blurry images and potentially inaccurate results.

Preparing for an Abdominal Ultrasound

An abdominal ultrasound examines organs in your upper abdomen, including the liver, gallbladder, pancreas, and spleen. The primary goal of preparation is to reduce gas and ensure the gallbladder is in a relaxed, distended state.

What to eat before an abdominal ultrasound

For most abdominal ultrasounds, you should fast for 8 to 12 hours before the exam. Fasting helps prevent the gallbladder from contracting, which would make it difficult to evaluate. Your last meal should be light and fat-free.

Lean protein: Boiled or grilled chicken, fish, or egg whites.
Plain starches: Toast with jelly (no butter), plain boiled potatoes, or low-fat cereals like puffed rice.
Certain fruits: Applesauce, bananas, or canned fruits.
Fat-free liquids: Clear fruit juices (no pulp), black coffee, or plain water. Avoid sugary or high-fat beverages.

What to avoid before an abdominal ultrasound

Fatty and fried foods: These stimulate the gallbladder, causing it to contract.
Gas-producing foods: Legumes (beans, lentils), raw vegetables (especially cabbage), and whole milk.
Carbonated drinks: Soda, sparkling water, and other fizzy beverages introduce gas into your digestive system.
Dairy products: These can cause bloating and gas, especially if you are lactose intolerant.

Preparing for a Pelvic or Kidney Ultrasound

For pelvic ultrasounds, which examine the uterus, ovaries, and bladder, a full bladder is necessary to obtain clear images. For some kidney ultrasounds, this may also be a requirement.

Dietary and fluid instructions

Drink plenty of water: Typically, you'll be instructed to drink 32 ounces (about 4 glasses) of water approximately one hour before the exam and refrain from urinating.
Eat as usual: Fasting is generally not required for pelvic ultrasounds, but it's still best to avoid foods that cause excessive gas or bloating.
Transvaginal ultrasounds: If you are having a transvaginal scan, which is often performed after the transabdominal portion, you will be asked to empty your bladder right before the procedure.

Preparing for Other Ultrasound Types

Transvaginal ultrasound

This internal scan of the pelvic organs requires an empty bladder. You can typically eat and drink as you normally would before the appointment.

Thyroid, vascular, and musculoskeletal ultrasounds

These exams typically require no dietary restrictions. You can eat and drink normally beforehand, but it is often recommended to avoid creams or lotions on the area to be scanned.

Comparison of Ultrasound Preparations

This table provides a quick overview of the different preparation requirements based on the type of ultrasound.


Ultrasound Type	Eating Restrictions	Fluid Requirements	Preparation Details
Abdominal (Upper)	Fast for 8-12 hours. Last meal should be light and fat-free.	Only plain water in small sips may be allowed.	Avoid fatty, fried, and gas-producing foods. No chewing gum.
Pelvic (External)	No strict fasting, but avoid gas-producing foods.	Drink 32 oz (4 glasses) of water one hour prior. Do not urinate.	A full bladder is essential for clear imaging.
Pelvic (Transvaginal)	No restrictions, eat and drink normally.	Empty bladder just before the exam.	Offers clearer images than the external method.
Gallbladder	Fast for 8-12 hours and eat a fat-free meal the night before.	Only plain water may be allowed in small amounts.	Fasting prevents gallbladder contraction.
Kidney	May require fasting for 8-12 hours or no preparation at all.	Varies by specific test; may need a full bladder.	Follow your provider's instructions carefully.

Following Specific Instructions

In all cases, the most important step is to follow the specific instructions provided by your healthcare provider or the imaging department. If you have a medical condition, such as diabetes, that affects your ability to fast, always consult your doctor beforehand. They may adjust the preparation protocol to ensure your safety and comfort during the exam. It is also wise to wear comfortable, two-piece clothing to your appointment to allow easy access to the area being scanned.

Conclusion

While a one-size-fits-all diet does not exist for ultrasound preparation, the general rule is to follow your doctor's specific guidance. For abdominal and gallbladder scans, fasting is key to obtaining clear images of these organs. For pelvic and some kidney ultrasounds, ensuring your bladder is full is necessary to improve visualization. By adhering to the correct protocol, you can help ensure an accurate and successful procedure, avoiding the need for repeat scans. For more detailed information on specific medical procedures, consult reliable sources like the Mayo Clinic to prepare thoroughly for your appointment.

Frequently Asked Questions

Fasting before an abdominal ultrasound, especially for the gallbladder, liver, or pancreas, prevents the gallbladder from contracting and reduces gas in the intestines. This allows for clearer and more accurate imaging of the organs.

For most fasting ultrasounds, a small amount of plain water is acceptable. However, for some abdominal scans, your provider may advise against water for a few hours before the exam. Always confirm with your healthcare provider.

If you eat before a required fasting ultrasound, the technician may get blurry images, making it difficult to interpret the results. This can lead to an inconclusive report and a rescheduled appointment.

A full bladder acts as a sonic window, pushing the bowel out of the way and improving the visibility of the uterus, ovaries, and other pelvic structures. This ensures clearer images for the diagnostic assessment.

Yes, you can generally eat and drink as usual before a transvaginal ultrasound. This internal scan requires an empty bladder, so you will be asked to urinate just before the procedure.

To prevent gas, avoid consuming beans, lentils, raw vegetables like cabbage, dairy products, carbonated drinks, and high-fat foods in the days leading up to your scan, especially if it's an abdominal exam.

Preparation for a kidney ultrasound varies. Some exams require no preparation, while others may require fasting or a full bladder, particularly if the bladder is also being evaluated. Always follow your specific medical instructions.