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UK Royal Society of Medicine Venous Forum VTE Advice 2020

The Venous Forum of the Royal Society of Medicine (RSMVF) has recently produced Advice on Venous ThromboEmbolism (VTE) Prophylaxis for patients who have Varicose Vein Procedures (Figure 1). It perceived an unmet need, because absence of evidence in this area has led to practices that vary substantially, with potential risks for patients. The Advice focuses on which patients ought to receive pharmacological prophylaxis and for how long. The Advice specifies three levels of risk for patients – low risk patients, for whom no good evidence exists to guide practice; high risk patients, who should receive prophylaxis because of their obvious risk factors; and an intermediate group at “additional risk”, who probably should receive adequate pharmacological prophylaxis but commonly do not. For both of the latter groups, the Advice recommends more prolonged prophylaxis than that typically used by many clinicians. The risks of DVT and of bleeding must be considered and documented for all patients having procedures for varicose veins. The main procedures concerned are catheter-based thermal and non-thermal endovenous interventions for truncal saphenous veins, with or without surgical ligations and phlebectomies, performed under local anaesthesia (LA) with or without sedation; and foam sclerotherapy. There are no comparative studies of the effect of prophylactic measures (and specifically pharmacological prophylaxis) on the occurrence of VTE after these LA varicose vein procedures. The available information comes from uncontrolled case series, which show that DVTs occur in 0.5–4.4% of cases, and there is a mortality of up to 1% when DVT occurs. Symptomatic pulmonary embolism (PE) is rare but PE deaths have been reported – some in young, fit patients. Based on these observations and on inferences from other types of surgery, the RSMVF has concluded that failure to risk-assess properly and to give adequate pharmacological prophylaxis to patients with wellrecognised risk factors is suboptimal practice. Most of these risk factors are easily identifiable preoperatively. Reduced mobility, an important factor, may be obvious before the procedure: but some previously mobile patients may be slow to mobilise thereafter, and attempts to anticipate that should be part of preoperative planning. For patients with no apparent risk factors, there is no evidence for or against using pharmacological prophylaxis. The fact that varicose veins are included in most lists of risks factors for VTE, based on studies of abdominal and pelvic surgery, leads to some concern that any varicose vein procedure may be associated with a significant risk of VTE, but there is no good evidence that this is so. Practice varies greatly for low risk patients, ranging from never giving prophylaxis; to using a single or multiple doses of LMWH depending on the perception of the patient and clinicians’ individual preferences. There is no good evidence for any of these practices and this is likely to remain the case because of the very low incidence of VTE in this patient group. Because these are not the patients of primary concern the RSMVF Advice simply includes the regimes that are commonly used. For patients at high risk, the main focus of the Advice is the duration of prophylaxis, because evidence from the time-incidence of post-procedure VTE supports longer administration of anticoagulants than has hitherto been practiced. These include patients with multiple risk factors or a single dominant risk factor (such as personal history of unprovoked VTE). In the new environment of COVID, this will also include patients who have venous interventions who have had or who are at high risk of acquiring COVID, with its intrinsic tendency to thrombotic problems. The intermediate group – namely patients with single risk factors – was seen as especially important,