This was a case involving a common medical problem – the DVT. There were a number of important points
1) Idiopathic DVT (i.e. those not provoked by a risk factor such as surgery, plaster casts, pregnancy and medications) require careful thought and consideration. Malignancy is a major cause of unprovoked VTE and therefore careful history and examination are required – even in young patients. NICE currently recommends that all patients should undergo history and examination as well as routine haematology and biochemistry tests as well as urinalysis and chest radiograph. Patients over forty should have a CT abdomen and pelvis and women over 40 should have mammography. Other investigations should be guided by the history.
2) Thrombophilia screening.
Testing for inheritable thrombophilia is a matter of debate. It is a frequently requested test but one which can be fraught with problems. Firstly testing during an acute event may alter results of functional assays and secondly anticoagulation also interferes with results. In addition to laboratory problems knowing the presence of an inherited thrombotic tendency should not alter management of the venous thromboembolism. Also, there may be other thrombophillic states that cannot be easily tested for so having a negative thrombophilia screen is therefore not necessarily reassuring. Genetic and acquired risk factors interact and although patients with inherited thrombophilia are at increased risk of VTE this risk mainly occurs during ‘at risk’ periods of time e.g. surgery. Genetic tests may cause angst in families and there is no concrete proof that testing reduces incidence.
Thrombophilia testing should occur:
- If suspected purpura fulminans in neonate
- If adult and skin necrosis with warfarin check protein C&S
- Women with previous non-oestrogen-related VTE provoked by minor RF
- Second trimester miscarriages (RCOG not BCSH!)
- If family history of thrombophilia which is causing VTE and want to go on COCP
The INR should only be requested when monitoring warfarin or calculating liver scores. In all other circumstances check only the PT. The INR is only validated for monitoring warfarin.
4) Risk verses benefit
Our patient was anaemic with evidence of iron deficiency and a history of bleeding. When starting anticoagulation one must always weigh up the risks and the benefits. In this case in order to prevent a fatal pulmonary embolism anticoagulation must be started. Unfractionated heparin is far easier reversed by protamine than LMWH and has the advantage that it can be stopped and the half life is short. However it is cumbersome to administer and prone to errors on general hospital wards. It seems sensible to optomise the patients haemoglobin with an intravenous iron infusion and this may prevent the use of red cells.
5) IVC filters
Filters should be considered in those with a contraindication to anticoagulation. Common indications include acute VTE and subsequent need for urgent or emergency surgery as in our case, VTE close to delivery in pregnant patients, bleeding following acute VTE if anticoagulation cannot be optimised and bleeding can’t be locally/radiologically controlled. Filters reduce the risk of PE but increase the risk of DVT and a clear survival benefit has not been found. Complications include being unable to retrieve and migration. Anticoagulation should ideally be re-started and the filter removed as soon as able (e.g. within two weeks of insertion).
Underwent total abdominal hysterectomy and followed up by radiotherapy. Her IVC filter was removed successfully two weeks post op and she continued on LMWH for six months when she was declared in remission and no longer at risk.
- NICE DVT guideline: http://pathways.nice.org.uk/pathways/venous-thromboembolism/diagnosing-venous-thromboembolism-in-primary-secondary-and-tertiary-care.pdf
- BCSH IVC filter guidelines: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2141.2006.06226.x/full
- BCSH thrombophilia guidelines: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2141.2009.08022.x/pdf
- INR testing in patients not on warfarin: http://www.bcshguidelines.com/documents/INR_in_Patients_not_on_Vitamin_K_Antagonists_2007.pdf