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SPONTANEOUS FREE PERFORATION OF THE ILEUM IN CROHN DISEASE: CT DEMONSTRATION

Philip Goodman’, Bharat Raval’ and Gregory D. Pottefi ‘The University of Texas Medical School at Houston, Department of Radiology, ‘Department of

Internal Medicine, Division of Gastroenterology, 643 1 Fannin, Houston, TX 77030

(Received 27 February 1989)

Abstract-A case of spontaneous free perforation of the ileum in Crohn disease is presented. This rare compli- cation was demonstrated by computed tomography (CT) before becoming evident on plain films.

Key Words: Crohn disease, Pneumoperitoneum, Gastrointestinal tract, Perforation, Computed tomography

INTRODUCTION

Computed tomography has been shown to be a valu- able method in the evaluation of Crohn disease, par- ticularly in identifying inflammatory involvement of the bowel wall and adjacent mesentery. Spontaneous free perforation of the bowel in Crohn disease is rare and its diagnosis by CT has not been previously re- ported. Our case demonstrates the ability of CT to detect this potentially lethal complication.

CASE REPORT

A 33-year-old woman with a five year history of Crohn disease presented with increasing abdominal pain and a palpable right lower quadrant mass. She had experienced multiple exacerbations of her disease while on chronic steroid therapy.

On admission, a smail bowel study and CT of the abdomen showed deformity and mass-effect in the ileocecal region (Fig. 1). Despite a four week course of high-dose intravenous steroids, sulfasalazine, and bowel rest, the patient’s abdominal pain became con- stant and severe. An abdominal series including an erect chest film showed no free intraperitoneal air, but a repeat CT scan done later that day demon- strated free air anterior to the liver (Fig. 2). This find- ing was confirmed on a repeat abdominal series done later the same day (Fig. 3).

At surgical exploration, there was adherence of multiple loops of ileum with a small perforation in the distal ileum. A long segment of distal ileum was resected and primary reanastomosis was performed.

Address all correspondence to: Philip Goodman, M.D., Uni- versity of Texas Medical School at Houston, Department of Radi- ology, 2 134 MSMB, 643 1 Fannin, Houston, TX 77030.

Pathological examination of the resected specimen revealed Crohn disease with extensive ulceration. The patient had an uneventful postoperative course.

DISCUSSION

Crohn disease is a chronic inflammatory dis- order of the gastrointestinal tract which often in- volves the bowel wall and adjacent mesentery. Extra- mucosal abnormalities including fistulae and sinus tracts, abscesses and mesenteric lymphadenopathy are common and are easily detected by CT (1, 2). However, spontaneous free perforation of bowel in Crohn disease is rare with an incidence varying from approximately 0.7% in the ileum to 1.3% in the colon and 6.0% in the jejunum (3, 4, 5).

Transmural ulcerations are usually sealed by ad- herent loops of bowel, omentum, or other viscera,

Fig. 1. CT scan on admission shows a poorly defined soft tissue mass in the ileocecal region (arrows).

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Computerized Medical Imaging and Graphics November-December/l989, Volume 13, Number 6

Fig. 2. Repeat CT scan shows free intraperitoneal air ante- rior to the liver (arrows).

thereby preventing free flow of intestinal contents into the peritoneal cavity. Several mechanisms have been proposed for the development of pneumoperi- toneum in Crohn disease in the absence of a ruptured abscess or toxic megacolon. These include oblitera- tive endarteritis which causes vascular thrombosis and subsequent ischemia or infarction. It has also been suggested that increased distention of diseased bowel proximal to an obstruction may cause a fissure or ulceration to become transmural and perforate. The role of steroid therapy in bowel perforation is controversial and may be related to delayed sealing of a perforation, decreased effectiveness of immune de-

Fig. 3. Erect chest fiIm shows free intraperitoneal air under the right hemidiaphragm (arrows).

fense mechanisms, or masking of clinical symptoms of perforation with resultant delayed diagnosis (4, 5).

With early diagnosis and surgical treatment, the mortality from free perforation in Crohn disease can be markedly reduced. It has been shown that CT may detect small amounts of free air which are not easily seen on erect chest films (6). This may have particular importance in patients with Crohn disease. In a re- view of 19 patients with spontaneous free perforation of the small bowel, only one of nine patients with Crohn disease or malignancy had pneumoperito- neum seen on plain films compared with six of nine patients with perforation from other causes (3).

Although experimental studies have shown that as little as l-2 ml of intraperitoneal air may be de- tected on plain films, this requires optimal position- ing and technique (7). CT’s superior contrast and ab- sence of overlap on cross-sectional images allow dem- onstration of small amounts of free air which may not be evident on suboptimal plain radiographs of an acutely ill patient. The air is best demonstrated on CT at the anterior aspect of the liver using a wide window technique (8).

In bowel perforation studied by CT, it is more common to see air than orally administered contrast in the peritoneal cavity. Although the reason for this is uncertain, we suspect that it may represent an in- creased incidence of perforation at the anterior aspect of the bowel as seen with the patient in supine posi- tion. Another possibility is that air is more likely than contrast to pass through a small perforation due to differences in viscosity.

Since many patients with Crohn disease receive large doses of steroids, the clinical and laboratory diagnosis of free perforation may be obscured since fever and leukocytosis may be blunted (5). For this reason, recognition of pneumoperitoneum should be an important part of the CT evaluation of Crohn disease.

SUMMARY

A case of spontaneous free perforation of the ileum in Crohn disease is presented. This rare occur- rence may be demonstrated on CT before becoming evident on plain films. Recognition of this possibility may lead to prompt surgical treatment and subse- quent reduction in mortality.

REFERENCES

1. Goldberg, HI.; Gore, R.M.; Margulis, A.R.; Moss, A.A.; Baker, E.L. Computed tomography in the evaluation of Crohn disease. Am. J. Roentgenol. 140~277-282; 1983.

Spontaneous free perforation 0 P. GOODMAN, B. RAVAL and G. D. POTI-ER 415

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Fishman, E.K.; Wolf, E.J.; Jones, B.; Bayless, T.M.; Siegelman, S.S. CT evaluation of Crohn’s disease: effect on patient man- agement. Am. J. Roentgenol. 148537-540; 1987. Orrinaer. R.D.: Coller. J.A.: Viedenheimer. M.C. Spontaneous free p&oration of the small intestine. D&. Colon. Rectum. 26:323-326; 1983. Greenstein, A.J.; Mann, D.; Sachar, D.B.; Aufses, A.H., Jr. Free perforation in Crohn’s disease: a survey of 99 cases. Am. J. Gastroenterol. 80~682-689; 1985. Greenstein, A.J.; Sachar, D.B.; Mann, D.; Lachman, P.; Hei- mann, T.; Auf&, A.H., Jr. Spontaneous free perforation and perforated abscess in 30 patients with Crohn’s disease. Ann. Surg. 205172-76; 1987. Jeffrey, R.B.; Federle, M.P.; Wall, S. Value of computed to- mography in detecting occult gastrointestinal perforation. J. Comput. Assist. Tomogr. 7:825-827; 1983. Miller, R.E.; Nelson, S.W. The rocntgenologic demonstration of tiny amounts of free intraperitoneal gas: experimental and clinical studies. Am. J. Roentgenol. Radium. Ther. Nucl. Med. 112:574-585; 1971. Nakagawa, N.; Nakajima, Y.; Kaji, T.; Ashida, H.; Ishikawa, T. Diagnosis of pneumoperitoneum with CT. Radiology 165(P) Supplement:424; 1987.

About the Author--PHILIP GOODMAN was born in Binghamton, New York in 1954. He received his B.A. degree from Cornell Uni- versity in 1976 and his M.D. degree from the University of Roches-

ter in 1980. He was a resident in diagnostic radiology at Rochester General Hospital in Rochester, New York from 198 1 to 1984 and a fellow in gastrointestinal radiology at the Hospital of the University of Pennsylvania in Philadelphia during 1986 and 1987. He is cur- rently an Assistant Professor of Radiology at the University of Texas Medical School at Houston, and Chief of Gastrointestinal Radiology at Hermann Hospital.

About the Author-GREGORY D. POTTER is a native of Seattle, Washington, born in 1948. He graduated from Pacific Lutheran University with a B.S. in chemistry and received his M.D. from the University of Southern California in 1974. He is now an Associate Professor of Medicine at the University of Texas Medical School at Houston where his primary research interest is the effect of bile acids on ion transport in the developing colon. He is a member of the American College of Physicians, the American Gastroentero- logical Association, and the American Physiological Association. In addition, he is also an active member of the clinical staff of the gastroenterology unit at Hermann Hospital.

About the Author-BHARAT RAVAL graduated with a degree in Medicine from Makerere University Medical School in Uganda in 1971. He undertook internship and residency training at St. Mi- chael’s Hospital in Toronto. Currently, he is a Professor of Radiol- ogy at the University of Texas Medical School at Houston and Chief of Body Computed Tomography at Hermann Hospital. His interests and publications are in the fields of computed tomography and magnetic resonance imaging of the abdomen.