What Happens During an Ultrasound Scan? A Step-by-Step Guide

Preparation requirements vary by scan type. Abdominal scans (liver, gallbladder, kidneys, pancreas, spleen) require 4–6 hours of fasting to ensure the gallbladder is distended and the bowel gas is minimised. Pelvic scans require a comfortably full bladder — drink 500–750 ml of water one hour before your appointment. Pregnancy scans from 10 weeks onwards also benefit from a full bladder. MSK, vascular, and cardiac scans require no specific preparation.

Please arrive 10 minutes before your appointment time to complete a brief patient registration form. Our reception team at Weymouth Street will confirm your scan type and preparation. If you have any previous scan reports, blood test results, or medical letters relevant to your scan, please bring them — they help your sonographer contextualise the findings.

You will be greeted by your HCPC Registered sonographer, who will introduce themselves, confirm your identity and the scan type, and ask a brief clinical history relevant to the examination. This is your opportunity to mention any symptoms, previous diagnoses, or specific concerns you would like addressed during the scan.

All sonographers at our CQC Compliant Marylebone clinic are registered with the Health and Care Professions Council (HCPC) — the same regulatory body that governs NHS sonographers. They will explain the procedure before starting and answer any questions you have.

You will be asked to lie on a couch and expose the area to be scanned. A small amount of warm ultrasound gel is applied to the skin — this ensures good contact between the probe and the skin surface, allowing sound waves to pass through without air gaps. The gel is water-based and washes off easily.

The sonographer moves the probe (transducer) over the skin, applying gentle pressure to obtain different views. The scan is displayed in real time on a monitor. You may be asked to breathe in, hold your breath, or change position to improve the view of certain structures. The procedure is painless for most patients, though gentle probe pressure may cause mild discomfort if the area being scanned is tender.

For pelvic and early pregnancy scans, a transvaginal scan may be recommended to obtain clearer images. A slim, smooth probe is covered with a protective sheath and gel, then gently inserted a few centimetres into the vagina. The procedure is not painful for most women, though it may cause mild discomfort.

You will always be asked for your explicit consent before a transvaginal scan is performed. If you prefer not to have a transvaginal scan, a transabdominal scan will be performed instead — your sonographer will explain if this affects the quality of the images obtained. You can ask for the procedure to stop at any time.

At the end of the scan, your sonographer will discuss the preliminary findings with you. They will explain what was seen, whether any abnormalities were identified, and what the next steps might be. You will receive a written report within 24 hours — typically by email — that documents the findings in clinical detail.

The written report is formatted to meet NHS clinical documentation standards and can be shared with your GP, consultant, or midwife. If urgent findings are identified — such as a suspected ectopic pregnancy, DVT, or significant abnormality — your sonographer will advise you on immediate next steps and may contact your GP directly.

"Your sonographer will discuss preliminary findings with you at the end of the scan. A written report is provided within 24 hours — formatted to NHS clinical documentation standards."

Ultrasound is an excellent first-line imaging tool for most soft tissue structures, but it has limitations. It cannot image structures obscured by bone (such as the brain or spinal cord) or gas (such as the bowel lumen). It has limited penetration in patients with a high BMI. For these situations, MRI or CT may be more appropriate.

Ultrasound also cannot definitively characterise all tissue abnormalities — a suspicious lesion identified on ultrasound may require MRI, CT, or biopsy for definitive diagnosis. Your sonographer will recommend appropriate further investigation when the ultrasound findings are inconclusive or require confirmation.