A study of 36 children with perianal fistulizing Crohn disease study found that a maximum fistula length of <2.5 cm predicted treatment response, and a length >2.5 cm predicted disease progression [6]. Another pediatric study based on the Van Assche MRI scoring system demonstrated interval decrease in score following treatment compared with the baseline score at diagnosis (P = . 0170) [59]. Because of the superb soft-tissue resolution allowing determination of fistulous tracts and abscesses in relation to the anal sphincter musculature, as well as high diagnostic performance, MRI pelvis with administration of IV contrast in an integral part of care for perianal Crohn disease. US Pelvis Transperineal Transperineal US of the pelvis in children may serve as a useful alternative when perianal imaging is indicated, although anatomic delineation is more limited than MRI. US is an imaging option for perianal Crohn disease. Differing sonographic techniques have been described in adults and children including transcutaneous/transperineal approaches as well as endoanal US. Endoanal US is a technique used in adult patients with variable diagnostic accuracy and can be limited by luminal stenosis [2]. A meta-analysis of endoanal US based on four studies in adult patients showed a sensitivity of 87% and a specificity of 43%, with a specificity inferior to MRI [57]. There is insufficient literature to support endoanal US in children, and technical limitations such as smaller size and need for anesthesia preclude usefulness in pediatric patients. Other US techniques, however, are potentially more feasible in children. Transcutaneous perianal US was studied in 38 pediatric patients using MRI as the reference standard. Transcutaneous perianal US demonstrated a sensitivity, specificity, PPV, and negative predictive value of 76%, 53%, 84%, and 41% for fistulae and 56%, 98%, 90%, and 88%, respectively, for abscess compared with MRI [60]. An adult-focused meta-analysis of transperineal US from Crohn Disease-Child
Crohn Disease Child. A study of 36 children with perianal fistulizing Crohn disease study found that a maximum fistula length of <2.5 cm predicted treatment response, and a length >2.5 cm predicted disease progression [6]. Another pediatric study based on the Van Assche MRI scoring system demonstrated interval decrease in score following treatment compared with the baseline score at diagnosis (P = . 0170) [59]. Because of the superb soft-tissue resolution allowing determination of fistulous tracts and abscesses in relation to the anal sphincter musculature, as well as high diagnostic performance, MRI pelvis with administration of IV contrast in an integral part of care for perianal Crohn disease. US Pelvis Transperineal Transperineal US of the pelvis in children may serve as a useful alternative when perianal imaging is indicated, although anatomic delineation is more limited than MRI. US is an imaging option for perianal Crohn disease. Differing sonographic techniques have been described in adults and children including transcutaneous/transperineal approaches as well as endoanal US. Endoanal US is a technique used in adult patients with variable diagnostic accuracy and can be limited by luminal stenosis [2]. A meta-analysis of endoanal US based on four studies in adult patients showed a sensitivity of 87% and a specificity of 43%, with a specificity inferior to MRI [57]. There is insufficient literature to support endoanal US in children, and technical limitations such as smaller size and need for anesthesia preclude usefulness in pediatric patients. Other US techniques, however, are potentially more feasible in children. Transcutaneous perianal US was studied in 38 pediatric patients using MRI as the reference standard. Transcutaneous perianal US demonstrated a sensitivity, specificity, PPV, and negative predictive value of 76%, 53%, 84%, and 41% for fistulae and 56%, 98%, 90%, and 88%, respectively, for abscess compared with MRI [60]. An adult-focused meta-analysis of transperineal US from Crohn Disease-Child