Diagnostic test waiting times

We examine how long patients have to wait for a diagnostic test or procedure.



Last updated: 25/04/2024


Diagnostic tests or procedures are a critical part of the care of many patients. Shorter waiting times are beneficial as they help people get quicker access to the treatments they need.

The six-week diagnostic wait was initially introduced as a ‘milestone’ in March 2008 to support the achievement of the 18-week referral to treatment (RTT) target. Diagnostic waiting times are now part of the NHS Constitution, which pledges that patients should wait less than 6 weeks for a diagnostic test from the time that the request has been sent.

NHS England published new guidance in May 2021 for the prioritisation of waiting lists for diagnostic procedures. It states that waiting lists should be reviewed and prioritised according to clinical need rather than waiting time in areas where more than half of patients have been waiting for more than six weeks. In February 2022, NHS England proposed in the elective recovery plan that testing capacity will increase to 9 million more diagnostic tests and that 160 community diagnostic centres will be rolled out by 2025. As of March 2024, 155 centres opened in England deliver more than 7 million diagnostic tests, which puts the government on track to meet its target for the following year. Regarding this achievement as a success would be premature as the expansion of diagnostic centres has to be accompanied by sufficient funding in diagnostic equipment and in workforce recruitment and retention.

These indicators measure the waiting times of patients still waiting for any of 15 key diagnostic tests or procedures at the end of the month, not including testing for Covid-19. See ‘About this data’ for the full list of tests included.

Waiting list for diagnostic tests

The introduction of the six-week target in March 2008 had an impact on the total number of patients on the waiting list for a diagnostic test or procedure. In December 2008, the waiting list fell to a low of just over 400,000 patients. Over time the list has increased, reaching more than one million people waiting for a diagnostic test in February 2020. This should be seen in the context of an increase in the number of diagnostic tests being undertaken each month: in July 2007, 995,098 diagnostic tests were carried out, and this almost doubled to reach 1.9 million in February 2020.

However, both the waiting list and number of diagnostic tests carried out fell as a result of the Covid-19 pandemic. Between February and April 2020, the waiting list fell by 22% to 841,049 and the number of tests carried out fell by 68% to 610,219. Since then, the waiting list has increased to almost 1.6 million in January 2024. The number of tests carried out has increased to around 2.3 million, higher than pre-pandemic levels. The sharp drops in the number of diagnostics tests throughout 2023 could be an effect of the industrial action in which radiographers participated. With the increase in diagnostic testing capacity proposed in NHS England’s guidance, waiting lists may decrease in the future. 

Wait times of six weeks or more for a diagnostic test

From July 2006, the proportion of patients waiting six weeks or more for a diagnostic test fell until March 2008, when the diagnostic wait ‘milestone’ was introduced. In June 2010, central performance management of targets was relaxed, and this corresponded to a small increase in waits of six weeks or more in the summer of 2011. The NHS Operating Framework 2012/13 introduced a further expectation that fewer than 1% of patients should wait six weeks or longer for a diagnostic test. The impact of this can be seen clearly: from February 2012 to November 2013 the proportion stayed at around 1%. However, since then the 1% target has not been met. The 2024/25 NHS priorities and operational planning guidance set the objective to increase the percentage of patients that receive a diagnostic test within six weeks by March 2025.

In March 2020, the percentage of patients who had been waiting six weeks or more for a diagnostic test began to increase dramatically, reaching 58% in May 2020 – the highest level since records began. This corresponds to a sharp fall in the number of diagnostic tests performed, from 1.9 million in February 2020 to a low of 610,219 in April 2020, as non-urgent elective care was put on hold to free up capacity for the response to the Covid-19 pandemic. Performance has since improved but remains considerably worse than before the pandemic. As of January 2024, 26% of patients had been waiting six weeks or more for a diagnostic test, equating to 414,353 people.

Wait times of six weeks or more by diagnostic test type

Of the 15 key diagnostic tests, the graph displayed above presents data from seven diagnostic tests with the largest test volumes (at least 50,000 tests conducted in January 2024).

In January 2024, 728,182 non-obstetric ultrasounds and 711,662 computed tomography or CT scans were conducted; these respectively accounted for 31% and 30% of the total volume of diagnostic test activity for that period. 369,414 magnetic resonance imaging tests or MRI scans were conducted, representing 16% of total diagnostic test activity. The rest of the tests each accounted for less than 7% of total activity.

In general, tests that were more common (ultrasounds and CT scans) seemed to have a relatively low proportion of patients waiting over six weeks compared with the tests that were less common. In January 2024, 21.3% of people waiting for a non-obstetric ultrasound waited over six weeks – a decrease from the previous year (28%). CT scans, despite having a similar volume of activity as ultrasounds, had a smaller percentage of people waiting over six weeks for a test (16%). MRI scans had half the total volume of activity that non-obstetric ultrasounds did, but a similar percentage of people waiting over 6 weeks (22%). Audiology assessments, echocardiographies, gastroscopies, and colonoscopies together accounted for only 17% of the volume of activity, but each had between 31-41% of people who needed a test waiting over six weeks. 

Median wait times for a diagnostic test

In addition to looking at the proportion of people waiting six weeks or more for a diagnostic test, we can examine changes in the median waiting time. In February 2008, the median waiting time fell to 1.9 weeks in anticipation of the introduction of the national target. The lowest median wait of 1.5 weeks occurred in January 2009.

Since then, the overall median wait has been slowly increasing. This is demonstrated by the rise in the 12-month rolling average, from 1.7 weeks in 2009 to 2.1 weeks up until the onset of the Covid-19 pandemic. In general, the median wait peaks in December every year – this is likely due to people not being able to schedule or attend appointments over the Christmas holidays.

In May 2020, the median wait increased dramatically to 8.6 weeks, following the reduction in the number of diagnostic tests being carried out due to the Covid-19 pandemic. Since then, the median wait has decreased but remains consistently higher than it was before the pandemic. In January 2024, the median wait was 2.6 weeks – 0.3 weeks less than in January 2023 (2.9 weeks).

About this data

These indicators measure the waiting times of patients still waiting for any of 15 key diagnostic tests or procedures at the month end. The waiting times are for patients who have been referred for a test, but whose test had not taken place by the end of the reporting period.

Once a decision has been made that a patient needs a diagnostic test or procedure and the request has been sent, they are on the waiting list and the clock starts for their diagnostic test waiting time. The clock stops once they have had their diagnostic test or procedure.

The 15 key diagnostic tests are:


  • Magnetic resonance imaging (MRI)
  • Computerised tomography (CT)
  • Non-obstetric ultrasound
  • Barium enema
  • Dual-energy x-ray absorptiometry (DEXA) scan

Physiological measurements

  • Audiology assessments
  • Echocardiography
  • Electrophysiology
  • Neurophysiology – peripheral neurophysiology
  • Respiratory physiology – sleep studies
  • Urodynamics – pressures and flows


  • Gastroscopy
  • Colonoscopy
  • Flexible sigmoidoscopy
  • Cystoscopy

For further guidance on this data, please see the NHS England website.