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). 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.

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Figure 1.

The Royal Society of Medicine Venous Forum 2020 Advice on VTE prophylaxis for varicose vein procedures.

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. ² 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. ³ Symptomatic pulmonary embolism (PE) is rare but PE deaths have been reported – some in young, fit patients.^4,5

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 well-recognised risk factors is suboptimal practice. Most of these risk factors are easily identifiable pre-operatively. 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. ² 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.^6,7 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, because there is evidence that these patients may not receive deserved pharmacological prophylaxis, probably because endovenous procedures are perceived as low-risk for VTE. ² This is the group in whom the occasional occurrence of VTE is most likely, with adverse potentially very serious consequences for both patient and clinician. There is unlikely to be a good defence if legal action is taken against a clinician who has failed to provide prophylaxis for a patient with demonstrable risk factors. In the absence of robust evidence or guidance we recommend administering anticoagulant prophylaxis for the longer duration of 7 to 14 days based on UK NHS Hospital Episode statistics data that showed the median time to presentation for patients who developed DVT to be 11 days. ⁶

Our understanding of VTE prophylaxis for ambulatory varicose vein procedures would benefit from publication of more relevant evidence: but the low incidence of VTE and the difficulties of conducting cogent trials make this unlikely in the foreseeable future. That is the reason for the RSMVF Advice, which adopts a pragmatic approach, based on the little available evidence and its interpretation by experienced venous specialists, together with some consideration of established practice.

The two main aspects which demand the attention of all clinicians treating varicose veins are VTE risk assessment for all patients, and a renewed perspective of the duration of pharmacological prophylaxis for those at risk.