Sterile gel may not be necessary for ultrasound-guided foam sclerotherapy (UGFS) using 21-gauge or finer needles: Results of a 30-month retrospective audit of 1,060 patients

Background: The UK Good Infection Prevention Practice (GIPP), mandates the use of sterile ultrasound gel for medical procedures penetrating the skin. Over 25 years, our practice has not used sterile ultrasound gel for ultrasound-guided foam sclerotherapy (UGFS) with 21G or finer needles. This audit aimed to identify post-procedure infections that may have occurred due to the use of non-sterile gel during UGFS.Methods: We reviewed clinical records of all patients undergoing UGFS between January 2024 and July 2026, looking for any post-procedure infections or antibiotic prescriptions. We recorded patient demographics, dates and number of UGFS sessions, diagnosed infections and reasons for any antibiotic prescription. Results: We found 1,060 patients (M 24.3%, F 75.7%), mean age 58.9 years (range 20.1 - 92.9). There were 1,555 UGFS sessions, 965 unilateral leg, 550 bilateral legs, 33 vulval, 6 breast and 1 hand. Three patients had antibiotics prescribed post-UGFS. One was prophylactic before extensive post-foam blood release, and a second was for patient concerns that turned out to be superficial thrombophlebitis. Only one could possibly be for infection. However, this presented 9 weeks post-UGFS in a patient with lipodermatosclerosis and pre-procedure lymphoedema, was bilateral despite having each leg treated at different sessions and did not respond to antibiotics. This was more likely to be an acute flare-up of lymphoedema exacerbated by sclerotherapy. Therefore, our proven infection rate is 0%, but if we count this case as an infection, our rate was 0.13% per session. Discussion: The GIPP guidelines’ criteria for using sterile gel were informed by outbreaks and complications in situations very different from our UGFS practice. Performing UGFS with a 21-gauge needle or finer, using detergent sclerosants and cleaning the probe between patients appears to allow the use of non-sterile ultrasound gel, without exposing patients to a significant risk of infection.