Serum D-dimer should not be used in the diagnosis of venous thromboembolism within 28 days of total knee replacement surgery

• Main Authors: Ethan Toner, Tobenna Oputa, Heather Robinson, Olivia McCabe-Robinson, Andrew Sloan
• Format: Article
• Language: English
• Published: BMC 2020-09-01
• Series: Knee Surgery & Related Research
• Subjects: Total knee replacement; D-dimer; Venous Thromboembolism; Deep vein thrombosis (DVT)
• Online Access: http://link.springer.com/article/10.1186/s43019-020-00068-x

Abstract Background Serum D-dimer is frequently used to rule out a diagnosis of venous thromboembolism (VTE), a recognised complication following total knee replacement (TKR). TKR is known to cause a rise in D-dimer levels, reducing its specificity. Previous studies have demonstrated that D-dimer remains elevated within 10 days of TKR and therefore should be avoided. The aim of this study was to determine whether serum D-dimer tests are clinically appropriate in identifying VTE when performed within 28 days of TKR. Methods Case notes for patients who had a serum D-dimer test performed for clinically suspected VTE at ≥ 28 days following TKR were retrospectively reviewed for a 6-year period. Demographics, D-dimer result, time after surgery and further radiological investigations were recorded. Results Fifty patients underwent D-dimer tests at ≥ 28 days following surgery (median 60 days, range 29–266); 48 of these patients had a positive result. Of these, five had confirmed VTE on radiological investigations. Serum D-dimer was raised in 96% of the patients. Only 10.42% of these patients had confirmed VTE. No patients with negative D-dimers had confirmed VTE. Conclusions These findings suggest that serum D-dimer remains raised for at least 28 days and possibly considerably longer following TKR. Serum D-dimer should not be used in patients with clinically suspected VTE within this period because of its unacceptably low specificity of 4.44% and positive predictive value of 10.42%, which can lead to a delay in necessary further radiological investigations, waste of resources and unnecessary exposure to harm.