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Keywords:

  • antiphospholipid syndrome;
  • paroxysmal nocturnal haemoglobinuria;
  • venous thrombosis;
  • thrombophilia

It was with great interest that we read the review regarding splachnic vein thrombosis in myeloproliferative neoplasms (Sekhar et al, 2013). We were surprised by the fact that screening for two important diseases predisposing to a splachnic vein thrombosis (SVT), namely antiphospholipid syndrome (APS) and paroxysmal nocturnal haemoglobinuria (PNH), was not mentioned in the ‘algorithm for the management of portal vein thrombosis/Budd Chiari syndrome’, which does not refer exclusively to patients with myeloproliferative neoplasms. In this algorithm, F5 R506Q (Factor V Leiden, FVL) and F2 G20210A (prothrombin G 20210A) mutation screening is detailed. We are not clear why the authors do not mention other inherited thrombophilias, such as antithrombin, Protein C and Protein S deficiency alongside the two aforementioned as potential risk factors for SVT. However, as many guidelines recommend anticoagulation with a vitamin K antagonist after SVT, to prevent further thrombotic events (De Stefano & Martinelli, 2010), the rational for screening for inherited thrombophilias is poor because there are no studies showing that such practice changes clinical management. The British Society for Haematology guidelines on thrombophilia testing state that ‘testing for heritable thrombophilias after a first episode of intra-abdominal vein thrombosis has uncertain predictive value for recurrence (C). Decisions regarding duration of anticoagulant therapy in relation to the results of testing are not evidence-based’ (Baglin et al, 2010).

Regarding acquired thrombophilia, there is only a general heading of ‘Thrombophilia screen for acquired factors as appropriate’. However we consider that APS and PNH need naming because they are both important to exclude diagnostically, for they are both eminently treatable and APS is not an uncommon cause.

The prevalence of APS in patients with SVT has been estimated to be between 5% and 15% (Leebeek et al, 2012) being one of the predominant risk factors for portal vein thrombosis (Plessier et al, 2010). Screening for APS includes testing for lupus anticoagulant, anticardiolipin antibodies and anti-β2-glycoprotein 1 antibodies (Miyakis et al, 2006). It is well recognized that the risk of recurrent thrombosis is dramatically reduced by the long-term use of oral anticoagulants (Erkan et al, 2005). The association between PNH and Budd-Chiari syndrome has been well characterized (Hoekstra et al, 2009), with PNH accounting for 9–19% of Budd-Chiari syndrome cases in some published series (Leebeek et al, 2012). In fact, hepatic vein thrombosis is the commonest thrombotic event in PNH, accounting for approximately 40% of cases, while being responsible for the majority of deaths related to PNH (Ziakas et al, 2007). Screening for PNH is by detection of blood cell populations deficient in glycosylphosphatidylinositol-linked membrane antigens, most commonly CD55 and CD59, by flow cytometry. Current treatment of PNH with the complement inhibitor eculizumab is reducing the risk of VTE recurrence and possibly also prolongs survival (Parker, 2011).

We believe that this omission was unintentional. As the British Journal of Haematology aims at a broad audience, from experienced physicians to junior trainees, however, it should be emphasized that APS and PNH account for a substantial proportion of cases and screening for these conditions should always be included in the investigation of patients with unexplained SVT, as either diagnosis significantly changes the management of these patients.

References

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  2. References
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  • De Stefano, V. & Martinelli, I. (2010) Splanchnic vein thrombosis: clinical presentation, risk factors and treatment. Internal and Emergency Medicine, 5, 487494.
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