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PRACTICE: Rebecca Greenhalgh, C Richard Cohen, David Burling, and Stuart Andrew Taylor Investigating perianal pain of uncertain cause BMJ 2008; 336: 387-389 [Full text]

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Alternative imaging for perianal sepsis

Mohammed A Butt, Jean Yong, F1 general medicine, Worthing Hospital   (19 February 2008)

Alternative imaging for perianal sepsis 19 February 2008
Mohammed A Butt, ST2 general medicine Worthing Hospital, BN11 2DH, Jean Yong, F1 general medicine, Worthing Hospital Send response to journal: Re: Alternative imaging for perianal sepsis	Greenhalgh et al. highlight endoanal ultrasound (EAU) and magnetic resonance imaging (MRI) as the two major modalities when investigating perianal pain secondary to perianal sepsis [1]. However, when performing EAU and MRI with receiver endocoils in the anal canal, transducer placement and manoeuvring can be excruciating. Furthermore, the rigid probes used in EAU do not allow assessment of disease extension into the perineal region. Alternative imaging techniques include transperineal ultrasound (TPU) and transvaginal ultrasound (TVU). Stewart et al [2] confirmed the effectiveness of both TPU in men, and TPU with TVU in women with perianal infections. In their study, 22 (85%) of 26 patients with positive ultrasound findings had their diagnoses of perianal fistulas, sinus tracts or perianal complex masses confirmed following operative treatment. The procedures were well tolerated and easy to perform, with most experienced sonographers achieving competence after approximately 12 procedures. The augmentation of EAU with TPU in both sexes, and TVU in women, has also been used to more accurately assess the integrity of the anal sphincters and acute or chronic perianal inflammation [3]. TPU is successful in virtually all women and most men. The transducer is placed on the perineum, and the ultrasound beam directed to allow perpendicular scanning of the anal canal. The advantages of TPU over EAU include a better tolerated, non-invasive procedure with a wider field of view including visualisation of the buttocks, labia and scrotum [3]. In women, TVU provides longitudinal and cross-sectional views of the rectum and anal canal. It is especially useful in documenting the course of fistulous and sinus tracts; and its accuracy in the assessment of the anal sphincter has also been shown [4]. The relationships between fluid collections, fistulous and sinus tracts and the internal and external sphincters are essential when planning surgery for perianal sepsis. TPU and TVU are alternative forms of imaging suitable for patients with perianal pain who are intolerant of endoanal techniques. In certain patients, the combination of these techniques with EAU allow for a more accurate assessment of perianal sepsis than EAU alone. Bibiolography: 1. Greenhalgh R, Cohen CR, Burling D, Taylor SA. Investigating perianal pain of uncertain cause. BMJ 2008; 336; 387-389 2. Stewart LK, McGee J, Wilson SR. Transperineal and transvaginal sonography of perianal inflammatory disease. AJR 2001; 177:627-632 3. Berton F, Gola G, Wilson SR. Sonography of benign conditions of the anal canal: an update. AJR 2007; 189: 765-773 4. Stewart LK, Wilson SR. Transvaginal sonography of the anal sphincter: reliable or not? AJR 1999;173:179–185 Competing interests: None declared