Reduced decision on surveillance

Amy WrightAAA Screening Technician

Cambridgeshire, Peterborough, West Suffolk

What’s going on?

• How common?

• What is reduced surveillance?

• Prior to scan look at previous measurements and locations

01/09/14

4.2 cm 12 monthly surveillance

25/08/15

4.5 cm 3 monthly surveillance

15/02/16

4.1 cm 12 monthly surveillance

Patient Conversation

• Duration of scan – reassurance to patient• Explain variation in measurements, screeners,

time of day etc.• Explained QA process• Pathway and surveillance intervals• Follow up by phone call if needed

What happens next

• ‘Reduce Decision’ on Northgate• QA• Option of reducing or staying the same• Follow up with patient if needed

AAA Screening Variance

• Inter observer variance (variance between technicians) of 3mm in measuring aortas (1.4 to 6.0 cm range) using inner to inner. (Hartshorne et at 2010).

• Adding a tortuous aorta which is difficult to measure can compound the variance/measurement error.

Ultrasound Measurement of Aortic Diameter in a National Screening Programme - T.C. Hartshorne, C.N. McCollum, J.J. Earnshaw, J. Morris, A. Nasim

Ultrasound Errors

“Errors are present, to varying degrees, in most measurements and can arise from the instrumentation, the ultrasound propagation properties of tissue and the equipment provider”Diagnostic Ultrasound: Physics and Equipmentedited by Peter R. Hoskins, Kevin Martin, Abigail Thrush

Advice from our CSTWhen confronted with a situation where screeners are measuring aortas significantly different in size to the previous scan (>3mm) it is important the screener carries out the following steps and discuss findings with the CST:

• Ensure that the correct echoes are being used for measurement (ensure you are measuring the walls and not other echoes eg. spine). Using TV and Long planes can help with this.

• Check and re-measure, a slightly different approach may produce a different measurement.

• Ensure measurement orientation is correct.