Radiographic changes after colonoscopic decompression for acute pseudo-obstruction

Radiographic Changes After Colonoscopic Decompression for Acute Pseudo-Obstruction Tam N. Pham, M.D.,* Bard C. Cosman, M.D., M.P.H.,*

Pauline Chu, M.D.,t Thomas J. Savides, M.D.t From the Departments of*Surgery, tRadiology, and }Medicine, San Diego Veterans Affairs Healthcare System and University of California, San Diego, California PURPOSE: Colonoscopy has been the principal tool for decompression in acute colonic pseudo-obstruction, known as Ogilvie's syndrome. The objectives of this study were to determine the immediate effect of colonoscopy on the cecal diameter (measured on supine radiographs) and to delineate possible correlations in the diameters of dilated segments of the colon. METHODS: The charts and radiographs of 24 patients who had colonoscopic decompression for acute colonic pseudo-obstruction between 1992 and 1997 at the San Diego Veterans Affairs Medical Center and the University of California, San Diego Hospitals were reviewed. We measured cecal, transverse, descending, and sigmoid colon dianleters on serial radiographs up to the point of clinical resolution. RESULTS: Mean + standard deviation cecal diameter change (between initial and postdecompression films) was -2 + 3.4 cm at four hours and -2.2 + 3.3 cm one day after decompression. On the daily radiographs between colonoscopic decompression and clinical resolution, there was a close correlation between the diameter of the cecum and that of the transverse colon (P < 0.05). There was no correlation between the cecal diameter and that of the descending or sigmoid colon. CONCLUSIONS: Colonoscopic decompression only causes a small decrease in cecal size in the patient with acute colonic pseudo-obstruction. Dilation patterns of the cecum and transverse colon are significantly correlated in acute colonic pseudo-obstruction. This correlation provides additional support to the contention that the same pathophysiology affects these two segments of the colon. [Key words: Colonic pseudo-obstruction; Ogilvie's syndrome; Colonoscopy; Decompression] Pham TN, Cosman BC, Chu P, Savides TJ. Radiographic changes after colonoscopic decompression for acute pseudo-obstruction. Dis Colon Rectum 1999;42:1586-1591.

have been reported since Ogilvie's first description in 1948,1 and the cause of the syndrome remains unknown. The goals of therapy are to avoid perforation, n o w a rare complication of treated ACPO, 2 and to temporize until the syndrome runs its course. Colonoscopic decompression was introduced by Kukora and Dent in 19773 and has b e c o m e the most widely accepted treatment to avoid perforation w h e n conservative, nonprocedural measures fail to relieve the dilation. Based on recent literature, parasympathomimetic medications such as neostigmine may be gaining ascendancy, 4 but urgent colonoscopy is still a standard treatment. Although the clinical benefit of colonoscopic decompression has been demonstrated in ACPO, 5-s Strodel et al.7 have suggested that early clinical improvement does not necessarily correlate with radiographic changes in cecal diameter. This article retrospectively examines 24 cases of colonoscopically treated ACPO to assess the immediate effects of colonoscopy on the cecal diameter measured by plain abdominal films. It also looks at correlations between cecal diameter and the diameters of other colonic segments (transverse, descending, and sigmoid) during the resolution phase of the syndrome.

PATIENTS AND METHODS

n acute colonic pseudo-obstruction (ACPO), widely k n o w n as Ogilvie's syndrome, the patient rapidly develops a functional large-bowel obstruction. Signs include abdominal distention and massive cecal dilation on abdominal x-ray. Hundreds of cases

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Presented at the joint meeting of the Northwest Society of Colon and Rectal Surgeons, Northern California Society of Colon and Rectal Surgeons, and Southern California Society of Colon and Rectal Surgeons, Incline Village, Nevada, August 18 1:o21, 1999. Address reprint requests to Dr. Cosman:Surgical Service(112E), VA Medical Center, 3350 La Jotla Village Drive, San Diego, California 92161-5017.

We looked retrospectively at the records of 24 patients w h o underwent colonoscopic decompression for ACPO. This study was approved by the University of California, San Diego Human Subjects Committee. Each procedure was performed at the San Diego Veterans Affairs Medical Center or one of the two UniversitT of California, San Diego Hospitals between January 1992 and February 1997 The criteria for ACPO were defined as rapid development of abdominal distention, abdominal x-ray showing right colon

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X-RAYS AFFERDECOMPRESSIVECOLONOSCOPY

gaseous distention with cecal diameter >- 9 cm, predominance of right colon dilation (to exclude chronic idiopathic megacolon), and no mechanical obstruction at colonoscopy. The indication for colonoscopic decompression was uniformly the clinicians' concern about impending perforation, given the large cecal diameter. Individual records were reviewed for medical history, current diagnoses, and outcome, including death in the hospital and death within a year of decompression. All patients underwent initial attempts at conservative management before colonoscopic decompression. These measures included nasogastric decompression, serum electrolyte measurement and repletion, and minimization of narcotics consistent with pain control. Colonoscopic decompressions were performed by both gastroenterologists and surgeons. Long colonic tubes, rectal tubes, or no postcolonoscopy intubation were used variably, according to clinician preference. Colonoscopy reports were reviewed for complications and for subjective success of decompression. Successful colonoscopy was defined as reaching the right colon or cecum. We reviewed all pertinent x-rays and excluded nonsupine films. Cecal diameter was measured on supine abdominal radiographs; these films included those taken before colonoscopic decompression (initial, baseline measurement), within four hours after decompression, and one day after decompression (Fig. 1). In addition, patients had daily x-rays until their abdominal distention resolved and normal bowel function returned. Colon segments were de-

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fined as cecum and right colon, transverse, descending, and sigmoid. In each radiograph, visible segments were marked and measured at their widest diameter. These measurements were done by two investigators (TNP and BCC). Films in which segmental definition was unclear were submitted to an experienced gastrointestinal radiologist (PC) for consultation. An abnormal cecal diameter was defined as more than 9 cm, following the criterion of Lowman and Davis. 9 Radiographic resolution was defined as the return to a normal gas pattern on plain abdominal radiograph. Clinical resolution was defined as the return to normal colonic function without additional endoscopic or operative intervention. Results are given as mean + standard deviation. Comparisons were made with Student's t-test and Spearman's rank correlation test. Significance was defined as P < 0.05. RESULTS The study included 24 patients with ACPO, including 20 males, with an average age of 65 (range, 34-85) years. Fifteen patients (62 percent) had significant comorbidity, including burns (2 patients), metastatic cancer (2 patients), pneumonia and respiratory failure (7 patients), severe infection or sepsis (1 patient), advanced neurologic disease (2 patients), and toxic epidermal necrolysis (1 patient). The other nine patients (38 percent) were postoperative patients. Orthopedic, cardiothoracic, and urologic procedures each accounted for three patients. Two patients died during the same hospitalization (from sepsis and mul-

Figure 1. A. Radiograph before clinically successful colonoscopic decompression. B. Radiograph one day after clinically successful colonoscopic decompression. Cecal diameter is decreased, but not dramatically. A long tube was placed in the cecum in this patient.

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verse colon measurements followed the cecum closely, with a mean cecum-to-transverse ratio of 1.4 ( P < 0.05). On the other hand, descending and sigmoid diameters of -