Establishing the normal ranges of female and male anal canal and rectal wall vascularity with color Doppler anorectal ultrasonography / Estabelecendo padrões normais da vascularização do canal anal e da parede retal em indivíduos do sexo masculino e feminino com ultrassom anorretal com Doppler colorido

ABSTRACT Study objectives: To evaluate blood supply in the anal canal, rectal wall and mesorectal fat of men and women, using color Doppler endorectal sonography to establish normal ranges for vascular parameters. Methods: A prospective cross-sectional study conducted at a tertiary-care hospital recruited asymptomatic volunteers (≤50 years). Vascularity percentage and index were calculated for defined regions. Results: Vascularity percentage and index were significantly higher in the puborectalis, mid-level external and upper internal anal sphincter compared to the low anal canal; these parameters were higher in men than in women at upper and middle levels of the inner anal canal structures. At mid-level, vascularity was greater in the external compared to the internal anal sphincter in both sexes; however, at the upper level it was greater in the puborectalis compared to the internal anal sphincter in women. Vascularity was greater in the rectal wall compared to the mesorectal fat, with no difference between middle and lower levels. Conclusions: Blood supply is highest at upper levels of the anal canal; however, inner structures are better irrigated in men. Moreover, the rectal wall is better irrigated than the mesorectal fat. Establishing normal ranges may permit future comparisons of the studied structures in disease states as well as the hormonal and age related changes.

RESUMO Objetivo: Avaliar vascularização do canal anal, parede retal e gordura mesorretal em homens e mulheres, usando ultrassonografia endorretal com Doppler colorido para estabelecer parâmetros vasculares de normalidade. Métodos: Estudo prospectivo transversal incluindo voluntários assintomáticos com até 50 anos. Medidos os valores da porcentagem e do índice de vascularização foram calculados para regiões escolhidas. Resultados: Valores da porcentagem e do índice foram significativamente maiores no puborretal, esfíncter externo (canal anal médio) e o esfíncter interno (canal anal superior) comparado ao canal anal inferior; esses parâmetros foram maiores em homens que em mulheres no canal anal médio e alto. No médio, a vascularização foi maior no esfíncter externo comparado ao interno em ambos os sexos; contudo, no canal anal superior, foi maior no puborretal comparado ao esfíncter anal interno em mulheres. A vascularização foi maior na parede retal comparada à gordura mesorretal, sem diferenças entre os níveis. Conclusões: O suprimento sanguíneo é maior nos níveis altos do canal anal. As estruturas internas são mais irrigadas nos homens. A parede retal é mais irrigada que a gordura mesorretal. Os parâmetros vasculares estabelecidos permitirá futuras comparações das estruturas estudadas nos casos de doenças, assim como, alterações que ocorrem com a idade e mudanças hormonais.

Anatomic characteristics of anal fistula on three-dimensional anorectal ultrasonography.

BACKGROUND: Surgery for anal fistula is often associated with continence disorders due to the transection of sphincter muscles. Extensive knowledge of anal canal anatomy and anal fistula can help prevent this outcome. OBJECTIVE: This study aimed to correlate the anatomical conformation of the anal canal, the fistula track, and the internal opening according to sex and hemicircumference (anterior vs posterior) by use of 3-dimensional ultrasonography. METHODS: One hundred sixty-five patients with fistula were evaluated with 3-dimensional ultrasound and grouped according to sex, fistula type, internal opening, and track position. Fistulas were transsphincteric in 128 subjects and intersphincteric in 37 subjects. The study measured the external and internal anal sphincter, the puborectalis, the distance from the internal opening to the distal edge of the external and internal sphincter, the length of the internal and external sphincter compromised by the track, and the percentage of compromised muscle. RESULTS: The anal canal muscles were longer in males. The distance from the internal opening to the internal sphincter was greater for the posterior hemicircumference. The point where the fistulous track crossed the anterior external sphincter was similar for the 2 sexes, but the percentage of compromised muscle was greater in females. The point where the fistulous track crossed the internal sphincter was similar for the 2 sexes, but the percentage of compromised internal sphincter was greater in males for the posterior hemicircumference. The study was limited by the absence of testing for interobserver and intraobserver agreement. CONCLUSION: The anal canal muscles are longer in males and the pectinate line is asymmetrical. In females, the percentage of compromised external sphincter was greater in the anterior hemicircumference because of the shorter external sphincter, whereas in males the percentage of compromised internal sphincter was greater in the posterior hemicircumference.