Figure 7b. Intrapelvic disease in two patients with Crohn perianal fistulas. (a) Sagittal T2-weighted two-dimensional turbo SE (3,427/150) MR image shows a presacral fluid collection (arrow) with connection to the bladder (not shown) and sigmoid colon (arrowhead) that was correctly diagnosed as a presacral abscess that drained to the bladder and sigmoid colon. (b) Sagittal T2-weighted two-dimensional turbo SE (3,427/150) MR image depicts a fistula track (arrowhead) that connects the rectal lumen (bullet arrow) with the vaginal lumen (arrow), which is suggestive of a rectovaginal fistula and was confirmed at surgery.