AI-assisted ultrasound helps most suspected blood clot patients receive a clinical decision within 30 minutes at Chelsea and Westminster Hospital

Chelsea and Westminster Hospital has demonstrated how artificial intelligence can speed up the diagnosis of deep vein thrombosis (DVT), a blood clot that usually develops in a deep vein in the leg. During a three-month pilot, most patients received a clinical decision following their first appointment, with the typical time from starting a scan to receiving a clinical decision taking less than 30 minutes. 

The hospital has piloted innovative technology for blood clot detection that combines a handheld ultrasound device with real-time artificial intelligence (AI). The technology enables clinicians to carry out an ultrasound examination at the patient’s first appointment, potentially reducing the need for the patient to return to hospital for a sonographer-led scan. 

Developed by ThinkSono, the technology guides clinicians through the scanning process, while the ultrasound images are reviewed remotely by specialist sonographers or radiologists. This allows clinicians to determine more quickly whether a patient requires further investigation or treatment. 

During the three-month pilot, clinicians completed 120 examinations, ruling out DVT in 97 cases. The typical time from starting a scan to receiving a clinical decision was less than 30 minutes, with 80% of patients safely discharged following their first scan. This helped many patients avoid longer waits, repeat appointments and unnecessary treatment while awaiting a diagnosis. 

Fewer than 20% of patients required a follow-up departmental ultrasound after their ThinkSono scan. For patients who did require further investigation, the average wait time from first presentation to diagnosis was reduced from 19 hours to 9 hours. This meant that patients who were diagnosed with DVT could receive their diagnosis on the same day. 

DVT is a potentially serious condition caused by blood clots forming in deep veins and affects around one in every 1,000 adults each year. It can lead to life-threatening complications including pulmonary embolism. Diagnosis typically relies on ultrasound imaging performed by specialist sonographers, creating delays for patients and additional pressure on diagnostic services. 

This initiative was funded by CW+, the official charity of Chelsea and Westminster Hospital NHS Foundation Trust, and delivered through CW Innovation, the Trust's joint innovation programme with CW+. Conducted in Same Day Emergency Care (SDEC) at Chelsea and Westminster Hospital, it examined ThinkSono Guidance, an AI-powered point-of-care ultrasound platform designed to speed up the assessment of patients with suspected DVT. 

Within four weeks of introducing the new AI-supported pathway, the number of patients receiving a scan report within the NICE-recommended four-hour timeframe had risen from 18% to 51%. 

Following the successful evaluation, the Trust is exploring opportunities to expand the use of the technology, supporting faster diagnosis and improved patient experience. 

The innovation was highlighted in Chelsea and Westminster Hospital NHS Foundation Trust's recent Outstanding Care Quality Commission (CQC) report, published on 7 August 2026, as demonstrating a forward-looking approach to service delivery, with the potential to reduce unnecessary admissions and improve waiting times.