Three-dimensional endoanal ultrasound is accurate and reproducible in determining type and height of anal fistulas.

AIM: Surgical treatment of high anal fistulas is associated with the potential risk of faecal incontinence and recurrence. The primary aim of this study was to determine the accuracy of three-dimensional endoanal ultrasound (3D-EAUS) in the assessment of height and type of anal fistulas, compared to the intra-operative findings (gold standard). The secondary aim was to evaluate the inter-observer reproducibility of 3D-EAUS. METHOD: The study design was a prospective analysis of retrospective data. 299 patients (202 men), mean age 45.3 years, who underwent surgery for anal fistulas, were included. All patients were preoperatively assessed by 3D-EAUS. Two readers independently reviewed the volumes to determine the type and height of fistulas. Sensitivity, specificity, positive and negative predictive values, proportion of agreements and Cohen's kappa coefficient (κ) were calculated for both examiners. Ultrasound findings were compared with intra-operative data (reference standard), evaluated blindly by the surgeons. RESULTS: At surgery, 201 (67%) were transsphincteric, 49 (16%) suprasphincteric, 47 (16%) intersphincteric and two (1%) extrasphincteric fistulas. Intra-operatively, 177 (59%) were low and 122 (41%) high fistulas. The overall accuracy of 3D-EAUS was 91% for fistula type (271/299 fistulas: 97% transsphincteric, 100% intersphincteric, 57% suprasphincteric, 0% extrasphincteric) and 92% for fistula height (275/299 fistulas: 80% high and 100% low). Both readers reported very good agreement with surgery in the assessment of fistula type (proportion of agreement 0.88, κ = 0.89) and height (proportion of agreement 0.90, κ = 0.91). CONCLUSIONS: 3D-EAUS is an accurate and reproducible modality for the assessment of type and height of anal fistulas.

Ultrasonographic evaluation of anal endometriosis: report of four cases.

BACKGROUND: The presence of endometriosis in the anal canal and perianal tissues is rare and difficult to suspect at clinical examination. We report our experience with preoperative ultrasound evaluation of four cases of anal endometriosis. METHODS: Four patients were evaluated by transperineal and high-resolution three-dimensional endoanal ultrasonography. RESULTS: In 3 of 4 women, the lesions involved old episiotomy scars. Anal endometriosis appeared as hypoechoic cystic lesions with areas of microcalcification, not well delimited and highly vascularized. The lesions either involved the anal sphincter (n = 2, one within the rectovaginal septum) or were localized superficially in the ischiorectal space (n = 2). Surgery and pathologic exam confirmed the ultrasonographic findings. CONCLUSIONS: Ultrasonographic findings of anal endometriosis are characteristics and may allow accurate preoperative staging of the disease.