Radiology of the ileoanal reservoir

Superior mesenteric artery syndrome: Diagnosis and management

Superior mesenteric artery (SMA) syndrome (also known as Wilkie's syndrome, cast syndrome, or aorto-mesenteric compass syndrome) is an obstruction of the duodenum caused by extrinsic compression between the SMA and the aorta. The median age of patients is 23 years old (range 0-91 years old) and predominant in females over males with a ratio of 3:2. The symptoms are variable, consisting of postprandial abdominal pain, nausea and vomiting, early satiety, anorexia, and weight loss and can mimic anorexia nervosa or functional dyspepsia. Because recurrent vomiting leads to aspiration pneumonia or respiratory depression via metabolic alkalosis, early diagnosis is required. The useful diagnostic modalities are computed tomography as a standard tool and ultrasonography, which has advantages in safety and capability of real-time assessments of SMA mobility and duodenum passage. The initial treatment is usually conservative, including postural change, gastroduodenal decompression, and nutrient management (success rates: 70%-80%). If conservative therapy fails, surgical treatment (i.e., laparoscopic duodenojejunostomy) is recommended (success rates: 80%-100%).

Radiology of the Ileal J-Pouch — Anal Anastomosis (IPAA)

Forty-four consecutive patients operated on with ileal J-pouch-anal anastomosis (IPAA) and diverting ileostomy were examined with barium contrast medium of the pouch before closure of the ileostomy. CT was performed in 4 of the patients. The anatomy of the ileal reservoir as well as complications were assessed. As normal postoperative anatomy we found a “blind loop” at the upper part of the reservoir in 29 patients and a contrast lucency at the anastomosis between the anal channel and the pouch in 5 patients. Complications were revealed at barium contrast medium examinations in 13 patients, including stenoses at the anastomosis between the pouch and the anal channel in 8 patients and fistulas in 5 patients. CT was especially valuable in the exact diagnosis and location of a pelvic abscess in 3 patients, none of which was shown at pouchography.

Utility of Contrast Enema for Detecting Anastomotic Strictures After Total Proctocolectomy and Ileal Pouch–Anal Anastomosis

OBJECTIVE

The purpose of our study was to determine the utility of contrast enemas for detecting clinically relevant anastomotic strictures after total proctocolectomy and ileal pouch-anal anastomosis and to facilitate management by defining a critical anastomotic caliber at or below which obstruction is likely to develop after ileostomy closure.

MATERIALS AND METHODS

Our radiology database revealed 42 patients with contrast enemas after total proctocolectomy and ileal pouch-anal anastomosis who fulfilled our exclusion criteria. The initial postoperative contrast enemas were reviewed blindly to determine the diameter of the ileoanal anastomosis. The diagnosis of a stricture was made only if the patient had signs of intestinal obstruction after ileostomy closure with confirmation on follow-up contrast enema or sigmoidoscopy and clinical improvement after anastomotic dilatation. The data were then correlated to determine if there was a critical anastomotic caliber at or below which such strictures were likely to develop. Using this threshold value, the sensitivity and specificity of routine contrast enemas for detecting clinically relevant anastomotic strictures were then determined.

RESULTS

Six (14%) of the 42 patients who underwent total proctocolectomy and ileal pouch-anal anastomosis had strictures at the ileoanal anastomosis on contrast enemas. The mean diameter of the anastomosis was 5.8 mm in the six patients with anastomotic strictures versus 15 mm in the 36 patients without strictures (p = 0.0002). If an anastomotic diameter of 8 mm is defined as the critical caliber at or below which clinically relevant strictures are present, the sensitivity of contrast enemas for detecting strictures at the ileoanal anastomosis was 100% (six of six patients) and the specificity was 92% (33 of 36 patients).

CONCLUSION

Routine contrast enema after total proctocolectomy and ileal pouch-anal anastomosis is a sensitive test for detecting clinically relevant strictures at the ileoanal anastomosis when an anastomotic diameter of 8 mm or less is used as the threshold value for diagnosing these strictures. Such patients may need dilatation procedures to decrease the risk of anastomotic obstruction after ileostomy closure.

Horizontal inclination of the longitudinal axis of the colonic J-pouch: defining causes of evacuation difficulty

PURPOSE

Functional outcome after low anterior resection for rectal cancer is improved by the construction of a colonic J-pouch. One disadvantage of this type of reconstruction is evacuation difficulty, which has been associated with large pouches. The purpose of this study was to elucidate the causes of evacuation difficulty in large pouches using pouchography.

METHODS

The angle between the longitudinal axis of the pouch and the horizontal line (pouch-horizontal angle) on lateral pouchography was determined in 26 patients with 10-cm J-pouch reconstructions (10-J group) and 27 patients with 5-cm J-pouch reconstructions (5-J group). Measurement were made at three months, one year, and two years after surgery. Clinical function was evaluated using a questionnaire one year postoperatively.

RESULTS

The pouch-horizontal angle in the 10-J group was significantly smaller than that in the 5-J group at all three time points. In both groups the pouch-horizontal angle at one year was significantly smaller than that at three months. There were no significant differences between the pouch-horizontal angles at one and two years. An evacuation difficulty was significantly more common in the 10-J group than the 5-J group.

CONCLUSIONS

The evacuation difficulty observed in patients with large colonic J-pouch reconstructions may be attributed to the development of a horizontal inclination within one year of surgery.

Enlargement of colonic pouch after proctectomy and coloanal anastomosis: potential cause for evacuation difficulty

PURPOSE

Although the functional outcome after low anterior resection for rectal cancer using colonic J-pouch reconstruction is superior to that using conventional straight reconstruction, the one drawback of colonic J-pouch reconstruction is difficulty with evacuation. Recently it has been suggested that construction of a larger colonic J-pouch causes the evacuation difficulty. The purpose of this study was to elucidate the cause of evacuation difficulty with colonic J-pouch reconstruction.

METHODS

We compared pouchography of 26 patients with 10-cm colonic J-pouch reconstructions (10-J group) and 27 patients with 5-cm colonic J-pouch reconstructions (5-J group) at three months, one year, and two years after surgery. Functional assessments were performed one year postoperatively. Clinical function was evaluated using a questionnaire. Evacuation function was evaluated by the balloon expulsion and saline evacuation tests.

RESULTS

The greatest width of the pouch in the 10-J group in the anteroposterior view was significantly greater than that in the 5-J group at all three measurement times (3 months, 4.9 vs. 4 cm; P = 0.0011; 1 year, 9 vs. 5.6 cm; P < 0.0001; 2 years, 9.2 vs. 5.8 cm; P < 0.0001). The value in the 10-J group at one year after surgery was 1.9 times that at three postoperative months; in the 5-J group this ratio was 1.4. There was a significant difference between these ratios (P < 0.0001). No significant difference existed between the values at two years and one year after surgery in either the 10-J or the 5-J group. An evacuation difficulty was significantly more common in the 10-J group than the 5-J group. Evacuation function in the 10-J group was significantly inferior to that in the 5-J group.

CONCLUSIONS

The evacuation difficulty observed in patients with larger colonic J-pouch reconstructions is associated with excessive distention of the pouch occurring within one year of surgery.

Complications of the ileal pouch: is the pouchogram a useful predictor?

A series of ileal pouchograms from 25 consecutive patients has been analysed retrospectively. Ileal pouchography may demonstrate abnormalities which delay closure of the covering ileostomy. The aim was to determine whether disruption of the ileoanal anastomosis and/or leak at pouchography correlated with pelvic sepsis after ileostomy closure. Disruption of the stapled ileoanal anastomosis is a sensitive (88%) but not specific predictor (57%) for subsequent pelvic sepsis. The predictive value of a negative test is high (89%). Leak of contrast from the anastomosis is specific (81%) but not sensitive (56%) for pelvic sepsis. No significant relationship was demonstrated between width of the presacral space and the presence of pelvic sepsis. No significant relationship was demonstrated between diameter of the ileoanal anastomosis and symptoms of stricture. The presence of anastomotic disruption or leak at pouchography prior to ileostomy closure are useful predictors of potential pelvic sepsis.

CT for the evaluation of carcinomas in the colon and rectum

The role of conventional CT in assessing patients with colorectal tumors is well established. The low accuracy of CT for identifying early stages of primary colorectal cancers prevents the routine use of CT for preoperative staging. Nevertheless, CT is useful in examining patients suspected of having extensive disease, in deciding whether a patient will benefit from preoperative radiation, in designing radiation ports, and in detecting complications related to the neoplasm. For recurrent colorectal neoplasm, CT has the premier role. CT surpasses colonoscopy in detecting early masslike tumor recurrence at the anastomotic site because of its extrinsic component, and CT and MRI are the only methods that can fully evaluate cases of total abdominoperineal resection. After total abdominoperineal resection, however, CT cannot determine with certainty that a soft tissue density in the surgical bed represents recurrent tumor. In patients with colorectal neoplasms, preliminary results with multiplanar and three-dimensional reconstructions of helical CT images are promising, but their role needs further investigation.

Current CT/MRI examination of the lower intestinal tract

For evaluating primary colonic and rectal malignancies, CT and MRI are often complementary imaging methods which are useful in assessing patients suspected of having extensive disease and in deciding whether a patient will benefit from preoperative radiation. CT is also helpful in designing radiation ports and in detecting complications related to the neoplasm such as perforation with abscess formation. MRI offers excellent tissue resolution which aids in distinguishing between localized colorectal disease and disease which invades muscle. Also, MRI can add information with coronal views for determining whether a sphincter-saving procedure can be performed, and may be of benefit for assessing the subtle extent of tumour into muscle and bone. However, CT and MRI lack the ability to assess depth of neoplastic involvement within bowel wall. This limitation is the major factor which, combined with the inability to diagnose metastatic tumour foci in normal-sized nodes and microinvasion of perirectal fat, prevents optimal tumour staging. Because of the low accuracy for assessing early cancer stages, neither CT nor MRI are recommended for routine use in preoperative staging. CT and MRI have a premier role in the assessment of recurrent colorectal neoplasm, with CT providing a slightly better overall evaluation due to volume imaging, easy image reconstructions in different planes, and availability of excellent oral and intravenous contrast agents. Cross-sectional imaging is the only method to evaluate fully patients with total AP resection, particularly male patients. Neither CT nor MRI can determine with certainty that a soft tissue density in the surgical bed following total AP resection represents recurrent tumour unless a clear mass is present which has increased in size over time. However, both methods surpass colonoscopy for detecting early mass-like tumour recurrence at the anastomotic site due to its extrinsic component. Cross-sectional imaging plays a prominent role in assessing inflammatory disease of the colon. Clinical history, laboratory data and extent of involvement are used together with results from radiographic examinations to reach a specific diagnosis. CT is preferred over MRI in the assessment of extent of inflammatory disease in and beyond the bowel wall. An additional benefit of CT over MRI is the fact that patients with abscesses or large fluid collection can undergo drainage while still in the CT scanner. CT and MRI can aid in the distinction between ulcerative colitis with minimal wall-thickening and Crohn's disease with marked wall-thickening combined with skip lesions and fistula and/or abscess formation.(ABSTRACT TRUNCATED AT 400 WORDS)

Pouchogram: predictor of clinical outcome following ileal pouch-anal anastomosis

Among 914 patients undergoing ileal pouch-anal anastomosis (IPAA) between January 1981 and June 1989, 463 (51 percent) had a pouchogram (meglumine diatrizoate [Gastrografin; E.R. Squibb & Sons, Inc., Princeton, NJ] enema) to assess anastomosis and ileal pouch integrity before closure of the ileostomy. The aim was to determine whether a pouchogram was useful in predicting clinical outcome.

RESULTS

Abnormal findings were present in 74 patients (16 percent). These included anastomotic and pouch leaks and anstomotic strictures. Pouchograms were normal in the remaining 389 patients (84 percent). The incidence of significant anastomotic stricturing requiring dilatation under anesthesia was much higher in the abnormal than in the normal pouchogram group (33 percent vs. 4 percent, respectively; P less than 0.001). More significantly, an abnormal pouchogram was associated with an overall long-term failure rate of 23 percent, compared with 6 percent for a normal pouchogram (P less than 0.001).

CONCLUSION

Abnormal findings in a pouchogram prior to ileostomy closure indicated those patients at high risk of long-term complications following IPAA.