Introduction CT pulmonary angiography (CTPA) is the recommended imaging modality for suspected pulmonary embolism (PE). Current NICE guidelines recommend using clinical prediction scoring systems to estimate the probability of PE and guide further investigation[i]. A low or intermediate probability score, coupled with a negative D-dimer, reliably excludes PE, thereby avoiding the need for CTPA.

Objectives We undertook a retrospective audit to examine adherence to NICE guidelines for diagnosis of suspected PE in patients admitted to a district general hospital, and identify patients who may have undergone unnecessary CTPA.

Methods We obtained a list of all CTPAs undertaken in our hospital between December 2012 and February 2013. D-dimer tests are poorly specific within hospitalised patients; therefore, we excluded post-surgical and obstetric patients, and pre-existing inpatients where primary admission was not for suspected PE. We also excluded outpatient CTPAs. We searched the records for contemporaneous PE probability scores and D-dimer results. For patients without a probability score result, we reviewed the clinical notes and calculated a probability score retrospectively using a local scoring system adapted from BTS guidelines.

Results There were 115 CTPAs during the study period – 36 were excluded and 4 patients’ case notes were unavailable. 75 patients fulfilled the inclusion criteria (mean age 68.2 years), and PE was confirmed in 20%. 50 patients (66.7%) had a contemporaneous documented clinical probability score. There were 5 patients (6.7%) with a low/intermediate probability score and negative D-dimer, who underwent unnecessary CTPA (PE excluded in each case). There were 9 patients (12%) with retrospectively calculated low/intermediate clinical probability scores and no D-dimer result, who may have avoided CTPA had D-dimer been undertaken (CTPA excluded PE in each case).

Conclusions In our district general hospital, the underuse of clinical probability scoring and D-dimer testing in patients with suspected PE is contributing to unnecessary CTPAs. Introducing mandatory documentation of PE clinical probability score on CTPA request forms may reduce the number of unnecessary CTPAs.

References

1. National Institute for Health and Clinical Excellence (2012) Venous thromboembolic diseases: the management of venous thromboembolic diseases and the role of thrombophilia testing. Clinical Guideline 144. London: NICE.