Foam Sclerotherapy

Philip Coleridge Smith DM FRCS
Reader in Surgery, UCL Medical School, London, UK

Contents

Summary
Foam sclerotherapy has become widely used in the management of superficial venous incompetence in many countries. It has gained limited acceptance in the UK. In contrast to conventional sclerotherapy, treatment is directed first towards incompetent saphenous trunks which are injected under ultrasound control. The aim is to obliterate the saphenous veins and abolish potential sources of filling of varicosities. Varices are also treated by foam injection in order to remove these. The main advantage of this treatment in comparison with surgery or the newer technique of endovenous laser therapy and radiofrequency closure is that it is painless. Injections may be given without anaesthesia or with limited local anaesthetic in an outpatient setting. No complex or special equipment is required other than an ultrasound machine. The cost of management of varicose veins performed in this way is therefore low in comparison to surgical interventions. Patients can normally continue their usual work following treatment.
The complications of this treatment include local skin necrosis due to the sclerosant, thrombophlebitis and deep vein thrombosis. Transient visual disturbance and chest problems may also arise. None of these is a frequent problem. In contrast to surgery, peripheral nerves are not at risk during this treatment.
Foam sclerotherapy has been used in very large varices (up to 20 mm diameter) and may also be used to manage 1 mm dia reticular varices. Primary and recurrent veins can be treated whether arising from saphenous trunks or tributaries.
Data from clinical series which have been reported suggests that after 3 years 85 – 90% of treated saphenous trunks remain occluded. This is probably comparable with other modern techniques of treating varices. However, no comparative clinical trials have been published as yet.

Introduction
Sclerotherapy has been used to treat varicose veins for 150 years. Many authors have published their techniques and results but only a few are mentioned here for brevity. A more detailed review of the history of this subject has been published recently. One of the first descriptions of a method of sclerotherapy that resembles the techniques used today was published in a monograph by Dr R Thornhill in 1929. The apparatus used to make the injections included a syringe which had been modified to include a small glass window between the syringe and the needle. This was used to aspirate blood from the vein to be injected in order to confirm that the tip of the needle was in the lumen of the vein. Thornhill used a solution of quinine and urethane to treat veins.
Fegan devised his own injection-compression technique which involved firm bandaging of the lower limb following injection of a sclerosant. This method along with strategies described by other European authors has been widely used for more than half a century. In the UK and other northern European countries sclerotherapy is substantially less popular than in southern European countries such as France, Spain and Italy. The reasons for this are not entirely clear but there was a diminishing of interest in sclerotherapy in the UK following the publication of a randomised study between sclerotherapy and surgery published by Hobbs in 1974. This showed that the outcome of surgical treatment after ten years was substantially better than conventional sclerotherapy. Many took this to mean that sclerotherapy was not a very useful treatment in the management of varicose veins and its use declined in the UK and northern European countries.
Ultrasound guided sclerotherapy
In the 1980s ultrasound was introduced for the diagnosis of venous disease of the lower limb. In France, where enthusiasm for the use of sclerotherapy had remained strong, this led Schadeck and Vin to improve the efficacy of their treatment by using ultrasound imaging to guide the placing of injections into incompetent saphenous trunks. , This method of treatment was found to achieve obliteration of the saphenous trunks in a substantial proportion of patients resulting in long term relief from varices. As with conventional sclerotherapy, the problem of recanalisation of veins was encountered in up to one quarter of patients at one year. Proponents of sclerotherapy argue that even if recurrence occurs the resulting varices and incompetent saphenous trunk are easily managed by further sessions of sclerotherapy.

Foam sclerotherapy – the origins
In 1944 Orbach described the ‘air block’ technique. A small volume of air is included in the syringe with the sclerosant. The air is injected ahead of the sclerosant in order to prevent blood diluting the sclerosant and reducing its efficacy. In 1950 Orbach published a further paper described the use of a foam which he created by vigorously shaking a syringe containing air and sclerosant to produce a froth. He modestly records that this method was also suggested by Foote. Fegan refers to the use of sodium tetradecyl suphate (STS) as a foam in the management of vulval varices of pregnancy in his book on sclerotherapy, originally published in 1967.
The next significant advance came in 1993 when Cabrera suggested that foam could be created using carbon dioxide mixed with a polidocanol, a detergent sclerosant. Cabrera published a further article in 1997 describing his experience in 261 limbs with long saphenous varices and 8 patients with vascular malformations. He had used sclerotherapy with foam, guiding his injections by ultrasound imaging. Some of the varicose veins reached 20 mm in diameter. He considered that foam greatly extended the range of vein sizes which could be managed by sclerotherapy. He felt that the increased efficacy of foam was attributable to it displacing blood from the treated vein and increasing the contact time between the sclerosant and the vein. He used a ‘microfoam’, that is a foam made of very small bubbles which was created by the use of a small rotating brush.

How is foam made?
A series of authors has described methods of preparing ‘home-made’ foam which may be used for ultrasound guided sclerotherapy. Monfreux described a method necessitating a glass syringe which produced small quantities of polidocanol foam which he used in a series of patients with truncal varicose veins. Sadoun described a method of preparing foam using a plastic syringe avoiding the need for reusable glass syringes. Subsequently Tessari has described a method of preparing foam using two disposable syringes and a three-way tap. This method can be used to produce large quantities of foam suitable for treating saphenous trunks and large varices. Frullini has added his own method of producing foam to this increasing list based on that of Fluckinger.
The most widely used method is that of Tessari which is readily achieved using materials available in most clinics (fig 1). Two syringes are connected using a 3-way tap. These can be either 2 ml or 5 ml syringes or a combination. A mixture of sclerosant and air is drawn into one syringe at a ratio of 1 part of sclerosant to 3 or 4 parts of air. I usually use 0.5 ml of sclerosant and 1.5 ml of air to produce 2 ml of foam. The sclerosant can be STS 1 – 3% (Fibrovein STD Pharmaceuticals, Hereford, UK) or polidocanol 0.5 – 3% (Sclerovein, Resinag AG, Zurich, CH). Low concentrations of polidocanol (0.5%) make better foam when mixed 1:1 with air. The mixture is oscillated vigorously between the two syringes about 10 or 20 times. The tap can be turned slightly to reduce the aperture and increase the smoothness of the foam. The foam produced in this way is stable for about 2 minutes so it should be injected immediately it has been created. The use of 2 ml aliquots of foam encourages the use of smaller overall volumes of foam.

How is the foam used?
Sclerosant foam can simply be used instead of liquid sclerosant in the management of varicose veins and reticular varices not associated with truncal saphenous incompetence. I suggest that nothing stronger than 1% STS foam is injected into saphenous varices and 0.5% polidocanol into reticular varices since stronger concentrations may cause thrombophlebitis and encourage skin pigmentation over injected veins. The advantage of using foam in these veins is that more varices appear to be treated per injection and lower volumes of sclerosant are required. Since veins injected with foam have blood displaced from them and develop spasm it is usually obvious which veins have been treated without the need for ultrasound imaging.

A technique for treating saphenous trunks.
However, foam sclerotherapy as described by Cabrera was intended to be used to treat saphenous trunks as an alternative to surgery. This requires ultrasound guided injecting since the saphenous trunks cannot be readily treated safely and effectively without imaging control. Cabrera described canulation of the affected saphenous trunk followed by injection of foam until the vein has been completely filled along with its tributaries. Any unfilled tributaries were managed by injection using a Butterfly needle. Other strategies are possible and it is common practice in France to inject the saphenous trunk using a needle and syringe. The complete length of the incompetent vein and tributaries is managed by several injections carried out over a number of sessions. Direct needle injection has the advantage of simplicity but in some regions, such as the popliteal fossa, a number of large arteries may lie adjacent to the small saphenous vein. Inadvertent intra-arterial injection causes disastrous results and therefore I recommend that injection of saphenous trunks is carried out through an intravenous catheter or Butterfly which facilitates checks to ensure that the intended vein is injected. Therefore anyone carrying out this treatment should be familiar with the ultrasound anatomy of the lower limb veins and have gained competence at foam injecting under the guidance of an experienced sclerotherapist.
It may be tempting simply to inject the foam into a large tributary of the saphenous vein but my experience of this strategy is that it does not work! It is essential that the saphenous trunk is filled with sclerosant foam without contamination from blood arriving from any source. Blood appears to inhibit the effect of foam so even a large tributary joining the saphenous trunk proximal to the level of the injection may allow the vein above this level to remain patent, even though foam reached the vein. (fig. 2). In treating the great saphenous vein (GSV) I usually place an 18 g IV canula at the level of the knee or just above. I then search for any large tributary (>3 mm dia) which joins the saphenous trunk proximal to this level and inject the tributary with 2 ml of foam before commencing work on the saphenous trunk. If I have decided to treat the GSV in the calf as well I place as 23 g Butterfly in this vein 10 – 15 cm below the knee. When treating the small saphenous vein (SSV) I place the canula 10 – 15 cm below the popliteal skin crease and the Butterfly in the distal half of the calf. (fig 3).
I place all canulas and Butterflies in the limb with the patient recumbent, lying on one or other side to facilitate access to the saphenous trunk to be treated. There is no need to place the limb in the dependent position to facilitate canulation although some practitioners use a tourniquet placed proximally on the limb to increase the size of veins.
It is important to check that the needle or canula is correctly placed. It should be possible to aspirate dark venous blood from the vein. Injection of 0.9% saline under ultrasound monitoring is used to confirm that the solution enters the intended vein and does not extravasate.
If there are any varices I especially want to treat in the first session I inject these before commencing work on the saphenous trunks. I then elevate the limb to empty the veins, resting it in a simple sling attached to a drip pole. (fig. 4) I start with the most distally placed canaula or Butterfly and inject 1% fibrovein or polidocanol foam in the calf. In the GSV in the thigh and in the proximal SSV I inject 3% fibrovein to maximise the effect in the most important regions.
A wide range of accounts of different volumes of foam which should be injected are reported. Cabrera injected up to 100 ml of his foam whereas other authors have averaged 1 – 2 ml in a single session. My usual practice is to inject 6 – 8 ml of foam into the GSV in the thigh and about 4 ml in the calf. In the SSV I inject 6 ml proximally and 2 ml distally. I inject 2 ml at a time with a pause of half to one minute between injections. I consider that this allows the treated vein to go into spasm and maximises the contact time between the injected foam and the vein. It also slows the rate of entry of foam into the main veins. Cabrera described compression at the sapheno-femoral junction (SFJ) and sapheno-popliteal junction (SPJ) to minimise this but I consider that it is inevitable that foam will reach the deep veins. I promote mixing of the foam with the blood in the deep veins by asking the patient to perform active dorsiflexions at the ankle to promote mixing of blood from deep and superficial veins. This strategy has minimised the number of occasions on which thrombosis has spread from superficial veins to the muscle veins of the calf.
Following completion of a session of treatment I apply firm compression bandaging. Sclerotherapists usually employ a short stretch or limited stretch bandage rather than an elastic stocking (fig. 5). The latter readily allows veins to expand and is ineffective at preventing thrombophlebitis. The time for which bandaging should be applied has not been established by any scientific work! Fegan recommended uninterrupted compression for 6 weeks, but I find that the most my patients will tolerate is 1 – 2 weeks!
At subsequent sessions the extent of occluded veins is established by duplex ultrasonography. Unoccluded sections of saphenous trunk are re-treated along with all residual varices. Further bandaging is applied over the treated regions. If thrombus distends superficial saphenous varices or trunks then I aspirate this under ultrasound control using a suitably large needle inserted under local anaesthetic. This strategy is also effective should post-sclerotherapy thrombophlebitis develop.
My experience is that 1 or 2 sessions of treatment are required to treat one leg completely. If both legs are treated in the same course of treatment then 3 sessions are usually required, though more may be necessary if extensive varices are present.
Appropriate patients to treat by foam sclerotherapy
The patients who are the easiest to treat are those with primary GSV or SSV varices where the saphenous trunk is 5 – 8 mm dia. The vein is easy to canulate and the varices are not usually too extensive. Smaller veins take a little practice in canulation and larger veins are associated with more extensive varices. Experts in ultrasound guided injection commonly treat veins in the range 0.5 – 1 mm in diameter. Recurrent varices are more complex since they are often not straight, unless there is a residual saphenous trunk. Canulation is therefore a little more difficult. However, my experience is that ultrasound guided injecting of these veins is much less complex than recurrent varicose vein surgery and as effective as injecting primary incompetent saphenous trunks.
The question as to which patients are the most suitable for this type of treatment depends on a number of factors, not least the patient’s expectations. Those with modest sized saphenous trunks and varices of limited extent are ideal and can often be managed in a single session if only one limb is affected. Some patients have a mortal fear of hospitals and anaesthesia and are happy to agree to anything that will avoid this. Elderly patients and those with leg ulcers often fall into this group and are pleased to have avoided surgical intervention. Even those with very large or extensive varices may be treated without apparent disadvantage, although more sessions may be required. I have managed a small number of patients with ultrasound evidence of previous deep vein thrombosis using foam sclerotherapy. In this group, as with surgery, I give a five day course of low molecular weight heparin at prophylactic doses. I have not seen any DVT in these patients.
Few patients are unsuitable for foam sclerotherapy. Those who are very anxious or needle-phobic are probably best managed surgically. I occasionally decline to treat very elderly or frail patients or those with severe concurrent medical conditions. Where treatment for varicose veins is clinically indicated e.g. for bleeding or ulceration, foam sclerotherapy is the least invasive intervention in frail patients.

Complications.
Complications arising from foam sclerotherapy are those which may also arise from and have been previously described in connection with conventional liquid sclerotherapy. Problems may arise locally at the site of injection, in the same limb or systemically.
Local complications include extravasation of sclerosant foam associated with skin necrosis. This is more commonly seen with STS than with polidocanol foam which is much less likely to cause problems if it leaks from a vein during treatment. Thrombophlebitis occurs reasonably frequently following sclerotherapy but is readily managed by aspiration of thrombus. Frullini reported 2 cases of skin necrosis and 7 of thrombophlebitis in a series of 196 patients treated by foam sclerotherapy.
Deep vein thrombosis may occur following surgery or sclerotherapy for varicose veins. Gastrocnemius veins in the calf are at risk of exposure to sclerosant foam injected into superficial varices. Frullini also reported one case of gastrocnemius thrombosis and a further case of popliteal vein thrombosis in his series of 196 patients. I have suggested a strategy above in order to minimise the risks of this complication.
Systemic complications which have been described following both liquid and foam sclerotherapy include visual disturbance and chest symptoms, including coughing. These occur in about 1 – 2% of patients. Visual disturbance often occurs in patients with a previous history of migraine associated with a visual aura. They develop a scotoma following treatment which resolves completely within 30 – 60 minutes. There is some evidence that this may be attributable to the passage of bubbles via a patent foramen ovale (PFO, which is in any case present in 10 – 20% of people). There is a rapidly expanding literature on the association of PFO and migraine in the general population. These effects resolve spontaneously without sequelae and can by minimised in patients where they have occurred previously, in my experience, by ensuring that the patient lies supine for 20 – 30 mins following treatment.
Severe allergic reactions to sclerosants are rare but not unknown. These represent the most severe adverse reaction to treatment. Anyone performing sclerotherapy of any type should be suitably equipped to deal with such an event.

Outcomes
Cabrera has published a clinical series of 500 lower limbs treated by foam sclerotherapy. He reported that after three or more years 81% of treated great saphenous trunks remained occluded and 97% of superficial varices had disappeared. This required one session of sclerotherapy in 86% of patients, two in 11% and three sessions in 3% of patients. No DVT or pulmonary embolism was encountered in this series. Frullini and Cavezzi have reported similar data in a series of 453 patients. Early observations showed that 93% of veins remained occluded after treatment with Tessari foam
No randomised study of foam sclerotherapy in comparison to surgery has yet been published, although a multi-centre European study has been conducted. Studies of this type are necessary to evaluate the real differences between these methods of treatment.

Reticular varices and saphenous varices.
Foam sclerotherapy has also been investigated in the management of small varices, including reticular veins and telangiectases. In 1999 Henriet reported his results in 10,000 patients with reticular varices and telangiectases of the lower limb treated between the years 1995-8. He found that the outcome of foam treatment in small varices was excellent and that reduced volumes and concentrations of sclerosant could be employed compared to liquid sclerosants. Benigni reported the findings of a pilot study comparing liquid and foam sclerosants. He measured the outcome using a visual analogue scale to describe the improvement in appearance. He found that foam resulted in a 20% improved appearance compared to liquid sclerosant.

Conclusions
Foam sclerotherapy offers an alternative to surgical intervention for patients with varicose veins. It can be conducted on an outpatient basis and is far less complex than endovenous laser therapy or radiofrequency ablation of saphenous veins. It can also be used in primary or recurrent truncal incompetence as well as in tributaries and small varices. The longevity of this treatment has yet to be established in comparison to surgery. Ultrasound imaging studies suggest that 85 – 90% of veins treated in this way remain occluded after 3 years. This is comparable to endovenous laser therapy and radiofrequency ablation and similar to rates of neovascularisation reported following surgery. This technique promises to be a useful addition to the methods currently in use for managing superficial venous incompetence.

Figure 2.

Figure legends

Fig. 1
Tessari’s method of creating sclerosant foam. A mixture of sclerosant (3% Fbirovein) and air is oscillated between two syringes connected by a 3-way tap.

Fig. 2
Foam treatment of the saphenous vein in the thigh: a large medial thigh tributary of the GSV carries sufficient blood to the saphenous trunk to prevent obliteration of the proximal part of the vein.

Fig. 3.
Ultrasound guided canulation of the SSV. The patient lies supine on her left side. Local anaesthetic is injected and an 18 g IV canula is introduced 10 – 15 cm distal to the SPJ.

Fig. 4.
The limb is elevated and sclerosant foam injected via the canula.

Fig. 5
A compression bandage is applied below the knee. PehaHaft (Hartmann, Germany) is applied over Velband to compress the SSV and varices arising from it.

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