Transvaginal sonographic appearance of thrombosed uterine arteries after uterine artery embolization: the "white snake" sign

PURPOSE: The aim of this prospective study was to describe the appearance of thrombosed uterine arteries on transvaginal sonography performed after uterine artery embolization (UAE) and to assess the prognostic value of the "white snake" sign with regard to symptomatic outcome at 12 months. METHODS: Patients who underwent UAE from January 1, 1999, to July 31, 2000, for the treatment of symptomatic leiomyomas were included in the study. Transvaginal sonography was performed before and at 3, 6, and 12 months after UAE. Patients graded the severity of their symptoms on a scale from 1 to 5, with 1 being the least and 5 the most severe, before and at 12 months after the procedure. The Wilcoxon rank-sum test was used to determine correlations between severity of symptoms and presence of the white snake sign; a p value of less than 0.05 was considered significant. RESULTS: During the study period, UAE was performed in 19 patients with a mean age of 41 years (range, 32-48 years). UAE was technically successful in all patients. Eighteen patients (95%) reported symptomatic improvement at 12 months: 8 patients (42%) by 4 severity-scale points, 5(26%) by 3 points, and 5 (26%) by 2 points. The 1 patient who did not experience improvement had undergone a hysterectomy at 4 months after the UAE. At the 3-month follow-up, transvaginal sonography demonstrated a tortuous echogenic structure in the adnexa (the white snake sign) in all patients; the finding was still apparent in 10 patients at 6 months but in only 2 patients at 12 months. A direct correlation was found between persistence of the white snake sign and the degree of symptomatic improvement at 6 months (p=0.04) but not at 12 months (p=0.08). CONCLUSIONS: After UAE, a thrombosed uterine artery appears on transvaginal sonography as an echogenic tortuous structure in the adnexa. Persistence of this white snake sign at 6 months after UAE may suggest a more favorable symptomatic outcome.