Having an ultrasound: everything you need to know
Your doctor has ordered an ultrasound, and you may be wondering how to prepare. Ultrasound waves behave differently depending on the tissues they pass through. For example, gas in the intestines can obscure organs in the background, while a full bladder acts as an acoustic window that provides a clearer view of the pelvis. This is why some exams require strict fasting, while others require proper hydration. Following these instructions enables the radiologist to obtain clear images that support an accurate diagnosis. Here is everything you need to know to prepare for your ultrasound with peace of mind.
Key points to remember
- Ultrasound preparation varies depending on the area of the body being examined;
- The specific instructions provided by the clinic when you book your appointment always take precedence over general guidelines;
- Never stop taking prescribed medications unless your doctor has explicitly instructed you to do so;
- For an injection procedure, remember to bring the prescribed products with you;
- A medical referral and a valid health insurance card are required for all ultrasound exams;
- Ultrasound is a painless medical imaging exam that uses sound waves to view internal structures and does not involve ionizing radiation.
Abdominal ultrasound
An abdominal ultrasound provides images of digestive organs such as the liver, gallbladder, pancreas, and spleen. For sound waves to pass through without interference, the stomach and intestines should contain as little gas and food as possible.
Fasting: You will generally be asked to fast for approximately 6 hours before the exam. Do not eat or drink during this period (except for small sips of water if needed to take your medications).
Diet: The evening before the exam, choose a light meal that is low in fat and fibre to limit intestinal gas.
Tip — Avoid smoking or chewing gum before your appointment. Both can cause you to swallow air and may also produce gas.
Pelvic ultrasound
A pelvic ultrasound is used to examine the uterus, ovaries, and fallopian tubes, most often to determine the cause of pelvic pain, abnormal bleeding, or menstrual problems. A full bladder is needed to view these deep structures clearly.
Filling your bladder: You will generally be asked to drink 1 to 2 large glasses of water during the hour before your exam and not urinate afterward.
Good to know — A full bladder pushes the loops of bowel out of the way and also serves as an acoustic window.
Transvaginal ultrasound
A transvaginal pelvic ultrasound provides a detailed view of the internal reproductive organs using a specially designed probe that is gently inserted into the vagina.
Unlike a suprapubic pelvic ultrasound, this exam requires your bladder to be completely empty so the probe can be positioned as close as possible to the pelvic structures.
Good to know — A pelvic ultrasound is often combined with a transvaginal ultrasound performed immediately afterward. You should therefore arrive with a full bladder for the first part of the exam, then empty it before the second part.
Prostate ultrasound
A prostate ultrasound is performed to assess the size of the gland or look for abnormalities. It is most often ordered for urinary problems or abnormal laboratory findings (PSA levels).
The exam is performed using an external suprapubic approach. You will lie on your back, and the radiologist will place the probe above your pubic bone after applying a gel that helps transmit the ultrasound waves.
Filling your bladder: You need to have a full bladder for this ultrasound. Follow the hydration instructions provided by the clinic, and do not urinate before the exam.
Pregnancy ultrasound
An obstetric ultrasound is used to monitor fetal development and assess the placenta and the amount of amniotic fluid. Because it does not use radiation, this medical imaging technique is the standard examination during pregnancy and poses no risk to the unborn baby.
Preparation varies depending on the stage of pregnancy:
First trimester: A full bladder is generally required because the uterus is still positioned low in the pelvis.
Second and third trimesters: A full bladder is often no longer necessary because the amniotic fluid, the height of the uterus, and the fetus's position provide sufficient visibility.
Kidney and bladder ultrasound
This exam specifically targets the kidneys, ureters, and bladder to detect stones, cysts, or other structural abnormalities.
Hydration: As with a pelvic ultrasound, a full bladder is required. You will be asked to drink a specified amount of water and refrain from urinating until the end of the first part of the exam.
Thyroid and neck ultrasound
A neck ultrasound examines the thyroid gland, parathyroid glands, and lymph nodes in the neck. It is primarily used to investigate a palpable nodule, swelling in the neck (goitre), difficulty swallowing or speaking, or an abnormal laboratory result identified by your doctor.
No special preparation: You do not need to fast or change how much you drink.
Tip — Wear comfortable clothing with a neckline that can easily be moved aside to provide access to your neck, and avoid bulky jewellery.
Joint ultrasound (shoulder, elbow, wrist, hip, knee, ankle)
A joint ultrasound is used to examine tendons, ligaments, muscles, and joints. It can help identify tendinitis, fluid buildup, or tears.
No preparation required: You do not need to fast or restrict your water intake.
Tip — Wear loose-fitting clothing that allows the area being examined to be uncovered. A gown will be provided if needed. Avoid applying lotions, creams, or fragrances to the area being examined, as these products may interfere with contact between the probe and your skin.
Doppler and vascular ultrasound
Doppler ultrasound combines conventional ultrasound with the Doppler effect to examine blood vessels and view blood flow in real time. As with a standard ultrasound, the radiologist applies gel to the skin over the area being examined (neck, arms, legs, or abdomen) before placing the probe on it.
This exam can be used to:
- Assess blood flow through the arteries to look for narrowing, a blockage, or a clot, such as in the carotid arteries or legs.
- Diagnose phlebitis (venous thrombosis) or monitor varicose veins.
- Provide additional information when examining an organ or tissue by assessing its blood supply.
Instructions vary: In the vast majority of cases, no preparation is necessary. However, if the Doppler exam involves blood vessels in the abdomen (such as the aorta or renal arteries), you may be required to fast for a few hours to reduce intestinal gas.
Ultrasound-guided injection
An ultrasound-guided injection is a procedure distinct from diagnostic ultrasound. It is performed to treat inflammation, relieve pain, or improve mobility in a joint. Using precise ultrasound guidance, the radiologist injects a medication such as a corticosteroid, local anaesthetic, or hyaluronic acid (viscosupplementation).
Preparation: Some products must be purchased by the patient from a pharmacy before the appointment with a doctor's prescription. Wear clothing that provides easy access to the area being treated.
Tip — After an injection, 24 to 48 hours of rest is generally recommended to ensure the product is effective and to prevent inflammation. Avoid driving immediately afterward and significantly limit walking, especially if the lower limb was treated. We recommend arranging for someone to drive you home.
The Radiologie Dix30 centre in Brossard, on Montreal's South Shore, performs ultrasounds by appointment. The clinic is open 365 days a year, Monday to Friday from 8 a.m. to 9 p.m. and Saturday and Sunday from 8 a.m. to 8 p.m. You can send your referral to our team by fax at 450-904-0405 or by email at info@radiologiedix30.com to schedule your exam.
To learn more about what to expect during the exam, result turnaround times, or RAMQ coverage, visit our Ultrasound page.
Ultrasound preparation summary table
To help you plan your visit, here is a practical summary of the instructions for each type of ultrasound:
| Type of ultrasound | Fasting required | Full bladder required | Special instructions |
|---|---|---|---|
| Abdominal | Yes (approximately 6 hours) | No | Eat a light meal low in fat and fibre the evening before; avoid gum and smoking |
| Pelvic | No | Yes (1 to 2 large glasses of water) | Do not urinate before the exam |
| Transvaginal | No | Empty bladder | Often combined with a pelvic ultrasound and performed immediately afterward (empty your bladder between the two) |
| Obstetric (first trimester) | No | Yes | Do not urinate before the exam |
| Obstetric (second and third trimesters) | No | Generally no | onfirm with our team based on your stage of pregnancy |
| Prostate (suprapubic approach) | No | Yes | Do not urinate before the exam |
| Kidney / bladder | No | Yes | Drink the requested amount of water in advance and refrain from urinating until the end of the first part |
| Thyroid / neck | No | No | Avoid jewellery and clothing with tight necklines |
| Joint | No | No | Wear loose-fitting clothing; avoid creams, lotions, and talcum powder on the area being examined |
| Doppler / vascular | Sometimes, if the abdominal area is being examined | No | Confirm with our team based on the area being examined |
| Ultrasound-guided injection | No | No | Bring the prescribed products; arrange for someone to drive you home and plan to rest for 24 to 48 hours afterward |
Practical checklist for the day of your appointment
Good organization will help you arrive at your exam feeling at ease. Here are the essential items to remember:
- Medical referral: Make sure you have a valid medical referral with you.
- Health insurance card: Bring your RAMQ card and a valid piece of government-issued identification so we can verify your file.
- Previous medical records: Bring any previous imaging reports or medical reports if the radiologist needs to compare changes in your condition.
- Medications: Unless your treating physician has explicitly told you otherwise, continue taking your usual medications with a small amount of water if needed.
- Suitable clothing: Choose loose, comfortable clothing that is easy to remove or adjust depending on the area being examined.
Ultrasound FAQs
Can I drink coffee or tea if I need to fast?
No. Fasting for an abdominal ultrasound means not consuming any solid food or liquids, including coffee, tea, milk, and juice. Generally, only a minimal amount of plain water is permitted to take essential medications.
What happens if I cannot hold my urine for my pelvic ultrasound?
Tell our reception staff or the technologist as soon as you arrive. We may be able to adjust the protocol or ask you to drink a little more water on site if your bladder is not full enough to obtain clear images.
Should I stop taking my medications before an ultrasound?
Under no circumstances should you stop taking your prescribed medications unless your treating physician or our medical team has instructed you to do so.
Are there any fees for an ultrasound at the Radiologie Dix30 clinic?
Our diagnostic ultrasound imaging services are covered by RAMQ. A valid medical referral and your health insurance card are required for every exam.
Sources
Government of Prince Edward Island. Preparing a patient for an ultrasound. https://www.princeedwardisland.ca/fr/information/sante-i-p-e/preparation-du-patient-en-vue-dune-echographie
CHUM. Ultrasound during pregnancy. https://www.chumontreal.qc.ca/sites/default/files/2022-03/325-3-echographie-en-cours-de-grossesse.pdf
CHU de Québec. Abdominal ultrasound. https://www.chudequebec.ca/patient/maladies-soins-et-services/traitements-et-examens/examens/echographie-abdominale.aspx
