It's "Just Phlebitis"... Or Is It?

Meet Margaret. She’s 84 years old, has a long history of varicose veins and comes into the clinic with a painful, erythematous, tender cord running up her calf. She assumes it's "just phlebitis” as she has been told in previous years and would like a prescription for topical NSAIDS. 

Traditionally, we may have nodded in agreement, advised NSAIDs, a warm compress, and reassured her that it would settle within a week or two.

But should we be so quick to dismiss SVT as serious?

Superficial Vein Thrombosis (SVT), commonly referred to as ‘superficial thrombophlebitis’, has traditionally been viewed as a relatively benign self-limiting condition. It often occurs within a varicose vein and, in many patients, resolves with conservative measures. 

A recent editorial in the BJGP highlights that SVT is not always as harmless as we may believe. Given the lack of UK national guidance, it discusses European recommendations and international research to guide our management in general practice.

Concerningly, a systematic review found that 18.1% of patients presenting with SVT also had a deep vein thrombosis (DVT), while 6.9% had a pulmonary embolism (PE). Furthermore, progression from SVT to DVT may occur for up to three months after the initial presentation. Suddenly, that tender superficial vein deserves a little more attention!

So why is Margaret at higher risk?

SVT develops through the mechanisms described by Virchow's triad: vessel wall injury, venous stasis and hypercoagulability. Risk factors for thromboembolic complications include advanced age, previous venous thromboembolism, recurrent SVT, active malignancy, extensive SVT, and thrombus extending close to the deep venous system. Patients without varicose veins may also warrant greater suspicion for an underlying prothrombotic condition.

Current European guidelines recommend an anatomy-based approach. Ideally, all patients with suspected lower limb SVT should undergo a whole-leg duplex ultrasound scan to determine the clot's location and extent.  Yet, access to USS for all would be a substantial change in practice and often is not part of the current management pathway in local guidance. Therefore, clinical judgement remains central to decision-making.

However, management as per European guidelines would recommend care delivery being guided by the scan findings:

• SVT within 3 cm of the deep venous junction, such as the saphenofemoral junction, should be treated using the DVT pathway with therapeutic anticoagulation. 

• SVT measuring 5 cm or more and located at least 3 cm from the deep venous system generally warrants 45 days of anticoagulation. 

  • Fondaparinux is the preferred injectable and only licensed option within the UK. Although evidence shows Low Molecular Weight Heparins and rivaroxaban may be suitable alternatives, and, as the latter is given by oral route, it may improve compliance. 

• Smaller isolated SVTs without high-risk features can usually be managed conservatively.

The evidence for anticoagulation is difficult to ignore. The landmark CALISTO trial demonstrated an 85% reduction in DVT and PE with 45 days of fondaparinux compared with placebo.

Before reaching for the prescription pad, however, bleeding risk and renal function should always be assessed, with anticoagulant choice tailored to the individual patient.

Conservative management still has an important role for all patients. NSAIDs, limb elevation, warm compresses and compression therapy remain useful adjuncts for symptom control.

The challenge, of course, is that UK primary care lacks both national guidance for SVT and consistent access to timely duplex ultrasound. This means clinical judgement remains central to decision-making. 

For patients with high-risk features, initiating anticoagulation while awaiting imaging, following an appropriate bleeding risk assessment, may represent the safest approach.

So, the next time a patient says, "It's only phlebitis", it may be worth considering that it may be something more serious. As in an older patient with high-risk features like Margaret, it may also be the first clue to a potentially significant venous thromboembolic event.