Implication of foam sclerosant inactivation by human whole blood in a laboratory setting.

Background During sclerotherapy, it has been recommended to confirm intravenous placement of the needle by aspirating blood into the sclerosant syringe. This may inactivate some, or all of the sclerosant. Aims To quantify the volume of human blood needed to completely inactivate 1 ml of sodium tetradecyl sulphate, and comparing fresh blood and blood that has been stored in an ethylenediaminetetraacetic acid tube. Methods A series of manual titrations were carried out following a procedure developed at STD Pharmaceutical Products Ltd (Hereford, UK) and listed in the British Pharmacopeia. Three percent of sodium tetradecyl sulphate stock solutions were made with increasing volumes of blood and titrated against benzethonium chloride to determine the active concentration (% w/v) of sodium tetradecyl sulphate remaining in the solution. Results A calculated approximation showed 0.3 ml of blood is required to fully inactivate 1 ml of 3% sodium tetradecyl sulphate when made into a foam. A comparison was made between the use of fresh blood and blood stored in ethylenediaminetetraacetic acid tubes. Blood stored in ethylenediaminetetraacetic acid tubes showed more inactivation of sodium tetradecyl sulphate, but this was not significant at the P ≤ 0.05 level. Conclusion The data from our study have shown that a minimum of 0.3 ml of fresh blood is required to inactivate 1 ml of 3% sodium tetradecyl sulphate as a foam and it is not significantly affected by storing blood in an ethylenediaminetetraacetic acid tube. Our methodology suggests that during foam sclerotherapy treatment, blood should not be aspirated into the syringe to confirm position, and that ultrasound guidance is more appropriate for needle placement.

A description of the 'smile sign' and multi-pass technique for endovenous laser ablation of large diameter great saphenous veins.

Aims To report on great saphenous vein diameter distribution of patients undergoing endovenous laser ablation for lower limb varicose veins and the ablation technique for large diameter veins. Methods We collected retrospective data of 1929 (943 left leg and 986 right leg) clinically incompetent great saphenous vein diameters treated with endovenous laser ablation over five years and six months. The technical success of procedure, complications and occlusion rate at short-term follow-up are reported. Upon compression, larger diameter veins may constrict asymmetrically rather than concentrically around the laser fibre (the 'smile sign'), requiring multiple passes of the laser into each dilated segment to achieve complete ablation. Results Of 1929 great saphenous veins, 334 (17.31%) had a diameter equal to or over 15 mm, which has been recommended as the upper limit for endovenous laser ablation by some clinicians. All were successfully treated and occluded upon short-term follow-up. Conclusion We suggest that incompetent great saphenous veins that need treatment can always be treated with endovenous laser ablation, and open surgery should never be recommended on vein diameter alone.