DVT Diagnosis and Varicose Veins: A Guide for GPs

Deep vein thrombosis (DVT) diagnosis rests on seeing the clot on ultrasound, ideally within 4 hours of the suspicion, not on a D-dimer test. D-dimer is sensitive but non-specific, and it can be normal in a DVT that is a few days old. A positive scan means anticoagulation. When the Wells score makes DVT likely, a D-dimer has a role only after a negative scan; when DVT is unlikely, a negative D-dimer can rule it out without a scan.

That was the message Dr. Biswarup Purkayastha, Consultant – Heart & Lung Transplant and Vascular Surgery, Artemis Hospitals, Gurugram, India, most wanted general practitioners to take from his masterclass on vascular surgical problems. "We definitely need to move out of the D-dimer business for DVT," he said in closing. This article covers the venous half of the session: varicose veins and the CEAP classification, the Doppler study a GP should order, laser ablation, superficial thrombophlebitis, the diagnosis of DVT, pulmonary embolism, and anticoagulation with rivaroxaban and apixaban. The referral principles that apply to every vascular case are in the complete guide to vascular problems in general practice, and arterial disease is covered in peripheral arterial disease treatment and aneurysm repair.

Common venous problems in general practice

Almost all venous disease in a general or surgical practice falls into four conditions, in Dr. Purkayastha's account: varicose veins, deep vein thrombosis, chronic venous insufficiency and superficial thrombophlebitis. Each has a different urgency. DVT is a diagnosis to confirm the same day; varicose veins and chronic venous insufficiency can usually be graded, treated conservatively and referred with the right study; superficial thrombophlebitis is mostly managed in the clinic.

Varicose veins: use the CEAP classification, not "mild, moderate or severe"

Dr. Purkayastha no longer wants varicose veins described as mild, moderate or severe. The language of referral is the CEAP classification (clinical, aetiological, anatomical and pathophysiological), which grades the clinical picture from C0 to C6:

• C0: no visible or palpable signs of venous disease;
• C1: spider veins (telangiectasias) or reticular veins;
• C2: varicose veins;
• C3: oedema;
• C4: skin changes from venous disease, such as pigmentation, eczema or hardening of the skin;
• C5: a healed venous ulcer;
• C6: an active venous ulcer.

Grading matters because it decides whether the patient needs to travel at all. When a patient is referred as C1 or C2, Dr. Purkayastha often does not need to see them in clinic. A couple of photographs are enough for him to advise compression stockings or medication, which saves the patient an entire trip to another country for a non-invasive treatment.

The three-position Doppler study

For any varicose vein referral, Dr. Purkayastha asks for a venous Doppler study done in three ways: "always, always, always". The scan should be performed:

1. with the patient standing;
2. with the patient lying down;
3. with the patient lying down and performing a Valsalva manoeuvre (bearing down against a closed airway, which raises the pressure in the abdomen and the leg veins).

The third position catches reflux that the others miss. A saphenofemoral junction (SFJ), the point in the groin where the great saphenous vein joins the common femoral vein, can look competent and of normal dimensions at rest, yet start to leak the moment Valsalva raises the pressure against it. That leak identifies SFJ regurgitation, which changes the treatment.

He asks referring doctors to request three things in the Doppler report: whether the SFJ is regurgitant, the size of the perforator veins (the veins connecting the superficial and deep systems), and the CEAP grade.

Start compression before referral

Once a varicose vein problem is identified, Dr. Purkayastha advises starting some form of compression stocking before the patient is sent to him. By the time the patient arrives, the CEAP class may have improved by one grade, for example from C3 to C2.

Never dismiss a varicose vein as cellulitis

He called one error the most common mistake in clinical medicine: dismissing a varicose vein problem as cellulitis of the leg, prescribing a course of antibiotics and sending the patient away. Too often, every swollen leg is labelled either cellulitis or chronic venous insufficiency. In the discussion he called the antibiotics-and-dismiss approach "the wrongest possible thing" and stressed that these are real situations from GP clinics, not constructed scenarios. His rule is that any swollen leg should be investigated with, at minimum, a Doppler ultrasound of the deep veins of the lower limb to rule out a DVT.

Laser ablation or surgery for varicose veins

Asked what determines the outcome of endovenous laser ablation (EVLA), a minimally invasive treatment in which a laser fibre passed into the vein seals it from inside, Dr. Purkayastha described where it works and where he prefers surgery. Laser ablation is good for superficial spider veins and for one or two perforators, and works well up to the perforator level. He performs it routinely; his most recent case was two or three days before the session. For perforators and superficial veins it has an excellent prognosis, and even where there are only superficial varicose veins with no leaking perforators, laser ablation may be the way forward.

If the SFJ is regurgitant, however, he more often than not opens a small segment at the junction and ligates and clips the tributaries that drain there. The three-position Doppler is what tells him which of these patients he is dealing with. Current guidelines (NICE CG168, ESVS 2022) recommend endothermal ablation as the first-line treatment for confirmed truncal reflux, with open surgery reserved for patients in whom ablation is unsuitable.

Superficial thrombophlebitis treatment: rest, elevation, compression and topical therapy

Superficial thrombophlebitis is the commonest venous problem Dr. Purkayastha sees in women in their forties who are slightly overweight. The veins look dilated, but they are inflamed and thrombosed.

His treatment is simple. Rest the limb, elevate it, apply cold and compress it, the traditional RICE approach, and use a topical ointment containing a heparinoid or hirudin, the anticoagulant originally derived from leeches. This settles the thrombophlebitis and reduces the pain.

Guidelines add two safeguards. A duplex ultrasound is advised, because a superficial vein thrombosis can coexist with a DVT. And where the thrombosed segment is 5 cm or longer, prophylactic-dose anticoagulation for about six weeks is recommended, while a thrombus that reaches close to the saphenofemoral junction is treated as a DVT.

DVT diagnosis: why the answer is ultrasound, not D-dimer

"The answer for DVT is not D-dimer. The answer for DVT is imaging; the answer for DVT is anticoagulation." Dr. Purkayastha asked doctors to keep a very high index of suspicion for DVT and to confirm or exclude the suspicion with imaging.

The ultrasound-first pathway

His pathway follows the current DVT pathway, which starts with a clinical probability score (the Wells score, a points-based estimate of how likely a DVT is):

1. When a DVT is likely, perform an ultrasound scan within the first 4 hours.
2. If the scan is positive, the DVT is diagnosed and anticoagulation starts. A D-dimer is not needed.
3. Only if the scan is negative is a D-dimer done.
4. A negative D-dimer makes DVT unlikely and points towards other diagnoses.
5. A positive D-dimer after a negative scan may still indicate a DVT, and the scan should be repeated in about 6 to 8 days.

When the Wells score makes DVT unlikely, the order is reversed: a D-dimer is done first, a negative result excludes DVT without a scan, and only a positive result leads to ultrasound.

This sequence matches the NICE guideline on venous thromboembolic disease. Where an ultrasound cannot be obtained within 4 hours, NICE advises a D-dimer and interim anticoagulation until the scan is done.

The problem with D-dimer

D-dimer is a fragment released when a blood clot breaks down. Dr. Purkayastha acknowledged its advantages: it is quick and involves no radiation, and a negative result can effectively rule out an acute DVT. But it is a high-sensitivity, low-specificity test with a very high false-positive rate. In his words, there are "half a zillion things", from smoking and exercise to fever and infection, that can raise it.

The less familiar problem is the false negative. Asked during the session whether a patient with a DVT can have a normal D-dimer, he answered yes. If the test is done late, after the acute phase, in a patient who did not present on the day of the pain and tried over-the-counter remedies first, the D-dimer can come back in the low hundreds, perhaps 150 or 200, rather than the thousands. That is not enough to diagnose a DVT on, and the thrombosis will be missed.

An anatomical problem needs to be seen

His reasoning is that DVT is an anatomical problem, and every anatomical problem should be seen. He compared it to a friend outdoors on a Sunday announcing a beautiful rainbow: unless you have a very different personality, you go outside to see it rather than listen to a description of it. "If there is a deep vein thrombosis, I want to see it. I want to see it on an ultrasound."

With point-of-care ultrasound now widely available, he argues, a DVT can be a definite diagnosis rather than an inference from a blood test. The skill is learnable: it took him barely three to four months to pick up vascular ultrasound. Despite the restrictions India places on ultrasound under its law against prenatal sex determination, his unit still trains almost all its trainees to perform routine vascular ultrasound, so they can identify these problems themselves.

The skill does matter. Without an expert hand, a scan can miss a subacute DVT by reading partial recanalisation (a clot through which some flow has returned) as no thrombosis. That is one more reason, he said, to keep the index of suspicion high: D-dimer alone cannot be the whole and sole means of identifying a DVT.

When a DVT reaches the lungs: pulmonary embolism

Dr. Purkayastha's practice is to complete the scanning of a patient being imaged for DVT with a CT pulmonary angiogram (CTPA), the contrast CT that shows clot in the pulmonary arteries. Guidelines reserve CTPA for patients with symptoms or signs suggesting pulmonary embolism, so this reflects his practice rather than a universal standard.

He showed two patterns on CTPA:

• A saddle thrombus: a central clot sitting across the bifurcation of the main pulmonary artery into the right and left pulmonary arteries, named because it resembles a saddle on a horse.
• Branch emboli: clots that have travelled further and separately block the right and left pulmonary arteries rather than the central trunk.

Catheter clot removal

Many devices and interventional procedures can remove pulmonary emboli. The approach Dr. Purkayastha favours is catheter-based mechanical thrombectomy: a device engages the clot with self-expanding discs, breaks it into smaller pieces and removes it piecemeal with suction. For acute pulmonary embolism, anticoagulation is the foundation of treatment; clot removal by thrombolysis, catheter or surgery is reserved for high-risk patients, chiefly those with low blood pressure or shock, and for those who deteriorate despite anticoagulation.

Chronic clot after pulmonary embolism: CTEPH

Pulmonary endarterectomy is the gold-standard operation for chronic thromboembolic pulmonary hypertension (CTEPH). In CTEPH, clot from earlier pulmonary emboli fails to dissolve and becomes organised, scar-like material lining the pulmonary arteries, which keeps the pressure in the lungs high and strains the right heart.

Dr. Purkayastha described the operation. The patient is placed on cardiopulmonary bypass, the heart is stopped and the body is cooled to 18 to 20 degrees Celsius. Circulation to the body and brain is then stopped for somewhere around half an hour to 45 minutes, which gives the surgeon a bloodless field to remove the massive clots from the pulmonary arterial tree. Afterwards, he said, the lungs return to normal, the pulmonary pressures come down and right heart function improves dramatically within a couple of days of surgery.

It is a major undertaking. He trained at a high-volume pulmonary endarterectomy centre, and his own centre performs a large amount of mechanical circulatory support and is prepared to support patients on ECMO (extracorporeal membrane oxygenation, a heart-lung machine used at the bedside) after the operation. His separate masterclass on pulmonary hypertension treatment, including pulmonary endarterectomy covers CTEPH in more depth.

DVT treatment: anticoagulation with rivaroxaban and apixaban

Once a DVT is diagnosed without a pulmonary embolism, the first step is anticoagulation. Today, Dr. Purkayastha more often starts the newer direct oral anticoagulants than the time-tested warfarin and low molecular weight heparin.

Rivaroxaban

Of the available drugs, rivaroxaban has emerged as his drug of choice, whether for DVT, pulmonary embolism or complicated DVT. The first-line treatment is 15 mg twice a day. In the standard regimen, this continues for the first 21 days, followed by 20 mg once daily. For an older clot, presenting perhaps three to four weeks after the DVT developed, he starts with 20 mg once a day. The label counts the 21 days of 15 mg twice daily from the start of treatment, not from the onset of the clot, and sets no separate starting dose for a clot that presents late.

Rivaroxaban is partly cleared by the kidneys, so kidney function should be checked before it is started. Its labelling advises caution when creatinine clearance is 15 to 29 mL/min and advises against use below 15 mL/min.

He noted that rivaroxaban has also become a favoured agent for patients who undergo surgery that leaves them immobile for a long time, such as hip or knee replacement, who benefit considerably from it as protection against clots.

Apixaban and the ABCDs of dose adjustment

Apixaban is the more commonly prescribed of the two, and Dr. Purkayastha teaches what he calls the ABCDs of apixaban dose adjustment. The criteria are age 80 years or older, body weight 60 kg or less, and serum creatinine of 1.5 mg/dL or more. In these patients he halves the dose from 5 mg twice daily to 2.5 mg twice daily.

These are the dose-reduction criteria defined for apixaban in atrial fibrillation, where any two of the three call for 2.5 mg twice daily. For the treatment of DVT, the labelled regimen is different and does not reduce the dose on these criteria: 10 mg twice daily for the first seven days, then 5 mg twice daily, with 2.5 mg twice daily used for extended prevention after at least six months of treatment.

The questions doctors asked during the session, including the exchange on whether a DVT can have a normal D-dimer, are in the Live Discussion from this masterclass.