In the study by Karsten et al [64], 38 patients were evaluated with fluoroscopic water-soluble contrast enema, which was 100% sensitive and 69% specific for detection of significant pathology, but that pathology was equally detected Anorectal Disease on digital rectal examination and endoscopic examinations such that fluoroscopic water-soluble contrast enema could be used selectively on patients with abnormal clinical findings. The superior contrast resolution of MRI compared with CT makes it an ideal modality for the evaluation of clinically suspected anastomotic or IPAA-related fistulas or sinus tracts. In a study of 44 patients with ulcerative colitis and IPAA with pelvic symptoms, MRI with and without IV gadolinium contrast material detected 23 of 26 fistula for a sensitivity of 88%, specificity of 100%, PPV of 100%, and NPV of 85% [65]. The authors reported that high diagnostic confidence was obtained with the IV gadolinium-enhanced sequence compared with the T2-weighted fat-saturated sequence. MRI was obtained in 23 of the 66 postoperative patients reported by Tang et al [62]. MRI had a sensitivity and specificity for the diagnosis of small-bowel and inlet strictures of 33.3% and 100%, pouch outlet strictures of 0% and 92%, fistula of 57.1% and 88.9%, sinus of 0% and 70.8%, and pouch leak of 0% and 91.7%, respectively. Radiography Abdomen and Pelvis Radiographs may be helpful in evaluating postoperative patients when there is a suspected bowel obstruction by confirming or excluding small-bowel obstruction. Radiographs may also show free air if there is a suspected postoperative perforation or ectopic air, or bubbly lucencies in the case of abscess, fistula, or sinus tracts that contain air. However, radiographs will frequently be inconclusive and additional imaging will be needed for those patients with abnormal radiographs; additional imaging is often necessary to confirm the suspected diagnosis and to add more specificity to the findings.
Anorectal Disease. In the study by Karsten et al [64], 38 patients were evaluated with fluoroscopic water-soluble contrast enema, which was 100% sensitive and 69% specific for detection of significant pathology, but that pathology was equally detected Anorectal Disease on digital rectal examination and endoscopic examinations such that fluoroscopic water-soluble contrast enema could be used selectively on patients with abnormal clinical findings. The superior contrast resolution of MRI compared with CT makes it an ideal modality for the evaluation of clinically suspected anastomotic or IPAA-related fistulas or sinus tracts. In a study of 44 patients with ulcerative colitis and IPAA with pelvic symptoms, MRI with and without IV gadolinium contrast material detected 23 of 26 fistula for a sensitivity of 88%, specificity of 100%, PPV of 100%, and NPV of 85% [65]. The authors reported that high diagnostic confidence was obtained with the IV gadolinium-enhanced sequence compared with the T2-weighted fat-saturated sequence. MRI was obtained in 23 of the 66 postoperative patients reported by Tang et al [62]. MRI had a sensitivity and specificity for the diagnosis of small-bowel and inlet strictures of 33.3% and 100%, pouch outlet strictures of 0% and 92%, fistula of 57.1% and 88.9%, sinus of 0% and 70.8%, and pouch leak of 0% and 91.7%, respectively. Radiography Abdomen and Pelvis Radiographs may be helpful in evaluating postoperative patients when there is a suspected bowel obstruction by confirming or excluding small-bowel obstruction. Radiographs may also show free air if there is a suspected postoperative perforation or ectopic air, or bubbly lucencies in the case of abscess, fistula, or sinus tracts that contain air. However, radiographs will frequently be inconclusive and additional imaging will be needed for those patients with abnormal radiographs; additional imaging is often necessary to confirm the suspected diagnosis and to add more specificity to the findings.