European Journal of Radiology 61 (2007) 424–432 Acute colonic disease: How to image in emergency Stefania Romano ∗ , Patrizia Lombardo, Teresa Cinque, Giovanni Tortora, Luigia Romano Department of Diagnostic Imaging, A. Cardarelli Hospital, Viale Cardarelli 9, 80131 Naples, Italy Received 13 November 2006; accepted 13 November 2006 Abstract The diseases affecting the large intestine represent a diagnostic problem in adult patients with acute abdomen, especially when clinical symptoms are not specific. The role of the diagnostic imaging is to help clinicians and surgeons in differential diagnosis for an efficient early and prompt therapy to perform. This review article summarizes the imaging spectrum of findings of colonic acute disease, from mechanical obstruction to inflammatory diseases and perforation, offering keys to problem solving in doubtful cases as well as discussing regarding the more indicated imaging method to use in emergency, particularly MDCT. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Colon; Acute abdomen; Perforation; Obstruction; Appendicitis; Diverticulitis; MDCT In the evaluation of patients with acute abdomen from suspected colonic disease, diagnostic imaging may play a first-line important role for the patient management. From the basic imaging techniques, such as abdominal plain film and sonography, to the more sophisticated multidetector row computed tomography, it is essential to know the radiologic findings correlated to the different affections that can involve the large bowel in emergency. However, although signs and symptoms can be of added value for an effective diagnosis, it is also important to be aware of the patients clinical conditions and to know about his clinical history, laboratory data and results of eventual radiologic examinations previously performed, in order to operate a correct differential diagnosis in case of doubtful findings or mimics conditions. The aim of this review should be not just to describe the imaging findings of colonic major emergency (appendicitis, diverticulitis, perforations, obstructions, hemorrhage, ischemia) but to give a key of interpretation and role of each imaging method that could be of help for a final diagnosis. Although multislice helical CT seems to increasingly replacing ultrasonography for the evaluation of patients with acute abdominal pain , it still has a role for the basic imaging techniques. Abdominal radiograph is often performed in the ∗ Corresponding author at: Via G. Fava 28 Parco la Piramide, 80016 Marano di Napoli (NA), Italy. Tel.: +39 333 276 0431. E-mail address: [email protected] (S. Romano). 0720-048X/$ – see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2006.11.021 evaluation of adult patients presenting to the emergency department with acute abdomen, however, despite the great role that it has in the past, recent data described this technique as not sensitive. In fact, in a large series of 871 patients, abdominal plain film showed non-specificity in 68% of patients, normal findings in 23% and abnormalities in 10% of cases . However, the initial radiological evaluation of patients with acute abdomen with abdominal plain film, despite diagnostic limitations , is widely used. In fact, traditional indications for plain film, such as intestinal obstruction and perforation, are questioned by helical CT . Sonography can be used as basic imaging technique in acute abdomen , however, this methodology may present some limitations, mostly related to the habitus of the patients. Unlike sonography, in acute conditions CT can easily image patients obese, with gaseous distension of the intestine; moreover, MDCT technology has further enhanced the usefulness of this method in imaging patients with acute abdominal pain . Concerning the pathologies affecting the adult colon in emergency, appendicitis is a common disease. Acute appendicitis is frequently clinically suspected, however, in a recent review study it has been stated that about 50% of emergency room patients with such a diagnosis do not have acute appendicitis and between 20 and 25% of patients undergoing appendectomy based on clinical diagnosis have a normal appendix . Because of this reason, the role of the diagnostic imaging in evaluating suspected appendicitis seems to be of some relevance. Sonography S. Romano et al. / European Journal of Radiology 61 (2007) 424–432 Fig. 1. Sonographic axial (a) and longitudinal (b) show marked thickening of the appendix in a 25-year-old woman with acute appendicitis. can be useful in diagnosing parietal thickening of the appendix (Fig. 1), the presence of wall stratification and inhomogeneity of the peripheral fat in the adult patient with acute disease, however, in some cases it could be difficult to effectively investigate the lower right quadrant (i.e. intestinal gaseous distension, retrocecal appendix, scarce experience of the sonographist for gastrointestinal disease). In most institutions there is a frequent use of CT in evaluating patients with suspected appendicitis (Fig. 2). It seems that with the increase of the CT use, there are less evidences of severe imaging findings, including the absence of periappendiceal stranding . Moreover, in a recent reported study, the use of CT seems to allow also a significant decrease in surgical-pathologic severity of appendiceal disease and hospital stay . However, in the daily practise the combination between abdominal plain film and sonography as well as clinical symptomatology and signs can be sufficient for diagnosing an acute appendicitis, although some cases may require additional CT examinations. This method is mandatory to use in evaluating 425 Fig. 2. Abdominal plain film in a 35-year-old woman with acute lower right quadrant pain showing the irregular distribution of intestinal meteorism with some little air-fluid levels on the right (a). CT was performed, demonstrating acute appendicitis; note the hyperdense structure in the right iliac fossa, with inhomogeneity of the surrounding fat plane, from acute appendicitis (b). suspected clinical complications not detected by basic imaging tools as well in cases in which clinic evaluation is not specific and a more accurate diagnostic technique is requested to make a differential diagnosis (Figs. 3–5). For example, right-sided diverticulitis is easily confused with acute appendicitis; in this case CT findings suggesting acute right-sided diverticulitis can be helpful, depicting a thickening of the intestinal wall and the pericolonic inflammation [7,8], with normal appearance of the appendix (if not involved in a more generalized flogosis). Acute pain may involve the left lower abdominal quadrant; this eventuality is frequently caused by diverticulitis, especially in elderly patients . Sonography and CT are the imaging methods of choice to differentiate between benign and self-limited disorders and those which require immediate intervention , being accurate in verifying diverticulitis as in establishing alternative diagnoses , whereas the role of plain abdominal film 426 S. Romano et al. / European Journal of Radiology 61 (2007) 424–432 Fig. 4. CT axial image (a) of a large abscess originating in the right iliac fossa from complicated appendicitis, well appreciable in its extension at the coronal reconstruction (b). Fig. 3. Predominantly gaseous distension of intestine in a 31-year-old man with acute lower right quadrant pain; note the rounded hyperdensity in the right iliac fossa (a) at the CT scout-view. Axial CT scan shows that the calcific formation is an appendicolith (b); note the dishomogeneous hyperdensity of the surrounding fat plane, in which a little bubble of extraluminal gas can be noted (arrowhead) and the small amount of peritoneal fluid. may be complimentary, showing an abnormal intestinal gaseous pattern or distribution as well as reactive ileus, especially when the disease is not in the early phase (Fig. 6). In effect, computed tomography seems a valuable imaging tool to determine the degree of acute perforated sigmoid diverticulitis, and it can be also of assistance in surgical planning . A study exploring the CT and demographic unfavourable outcome of nonoperative treatment in patients with a first event of colonic diverticulitis  showed interesting results. In this study, the 32% of nonoperative treatment failed; the presence of abscess or extraintestinal gas collection represented the CT findings significantly associated with failure of non-surgical therapy, whereas sex and age appeared not significantly associated with unfavourable outcome . The attention to the parietal findings and the eventual presence of free peritoneal or retroperitoneal air or abscess have to be strongly kept whatever imaging technique is used, but especially evaluating CT images (Fig. 7). The CT imaging pro- tocol to be used in intestinal emergency can be a source of some debate, however, despite the undoubtful help that intravenous contrast administration can give in evaluating intestinal wall enhancement, some reports about low dose unenhanced multidetector row CT are known. In particular, this technique seems to have similar diagnostic performance to that of contrast enhanced standard dose MDCT examination in patients with suspicion of acute diverticulitis ; however, because the clinical suspicion is often not specific, administration of intravenous contrast medium performing CT is useful for a differential diagnosis: considering the acute left-sided colonic diverticulitis, different diagnosis includes tumors, inflammatory and ischemic diseases as well as infarctions of epiploic appendages and omentum majus . Acute epiploic appendagitis represents a not extensively known pathology that most commonly manifests with acute lower quadrant pain; its clinical features are similar to those of acute diverticulitis or, less commonly, of acute appendicitis . The location is most commonly adjacent to the sigmoid colon, whereas the acute omental infarction is typically located in the right lower quadrant . CT features of acute epiploic appendagitis include lesion of smooth margins with attenua- S. Romano et al. / European Journal of Radiology 61 (2007) 424–432 427 Fig. 5. CT images of 81-year-old patient with acute abdomen; note the presence of an abscess in the right iliac fossa, continuous to the extremity of an hyperdense appendix (black arrow in a); the small amount of peritoneal fluid and the thickened reactive appearance of the sigmoid colon (white arrow in a), appreciable also in a more cranial scan (b); in the pelvis, the abscess caused a flogistic reaction also of some small bowel loops (arrow in c). Surgery confirmed the evidence of complicated abscessualized appendicitis. tion similar to the fat with surrounding inflammatory changes, located anteriorly to the sigmoid colon wall . CT features of acute omental infarction include the presence of a triangular or oval fatty mass with peripheral stranding between the anterior abdominal wall and the transverse or ascending colon . Another diagnostic problem in emergency evaluation of the colon for acute disease is represented from the intestinal hemorrhage (Fig. 8), a common clinical problem which accounts for 1–2% of acute hospital admissions . The colon is responsible for approximately 87–95% of all cases of lower gastrointestinal bleeding . Although urgent colonoscopy identified a definite source of lower gastrointestinal bleeding more often than a standard care algorithm based on angiography and expectant colonoscopy, the approaches are not different regarding important outcome . CT seems to be a safe, convenient and accurate diagnostic tool for acute lower GI haemorrhage; positive CT may allow directed therapeutic angiography, while negative CT will triage patients into alternative management pathways . Diseases affecting the normal colonic transit may be of various origins: functional, mechanical, reactive and inflammatory. Ischemic disease of the colon is certainly a well-defined clinical and radiographic entity , encompassing a wide spectrum of pathologic and clinical findings, ranging from a self-limiting 428 S. Romano et al. / European Journal of Radiology 61 (2007) 424–432 Fig. 6. Forty-three-year-old woman with history of diverticulosis and acute abdominal pain; abdominal plain film shows the irregular distribution of intestinal air with evidence of some air-fluid level (a); CT shows thickening of the left colon with evidence of diverticular formations (b) and the presence in the pelvis of a large abscessual mass from complicated diverticulitis (c); note also the presence of fibromiomatous formation of the utherus on the right (c). form to bowel infarction and perforation . A recent imaging staging of disease from ischemia to infarction of the large bowel using MDCT has been proposed . However, because the imaging findings can be similar, potentially inducing an error in diagnostic evaluation, it is essential to know the clinical history of the patient in order to operate a pertinent differential diagnosis with other conditions, especially acute parietal damage induced by chemotherapy. Intestinal obstruction of the colon (Figs. 9–11) represents an emergency condition when at the late stage of disease. Fecaloma, foreign body and tumors are more frequently observed in colonic occlusion, however, colonic volvolus may also represent a condition to consider. Main problem of the diagnostic imaging method in evaluation of intestinal occlusion is to determine the grade of compression of the wall, its viability and perfusion, in order to help surgeons to choose a more indicated timing to perform the intervention if the ischemia of the affected bowel segment is not present. In patients with large intestine obstruction due to colon cancer, it is important to keep attention to the imaging findings; in particular, cecal pneumatosis does not always indicate transmural infarction, because it may be related to a viable bowel when similar to bubblelike pattern or when it is not associated to other findings of ischemia . S. Romano et al. / European Journal of Radiology 61 (2007) 424–432 Fig. 7. This patient came to the attention of the surgical department because of occlusive symptomatology and abdominal left quadrant pain. CT shows the presence of a large inhomogeneous fluid collection in the pelvis, simulating a hyperdistended sigmoid colon (a), that surgery revealed to be a fecaloid collection from descending colon rupture, appreciable in the coronal reformation (b); note the presence of free peritoneal air (arrowheads in c). 429 Fig. 8. Elderly woman in treatment with anticoagulant drugs presenting acute rettorrhage; MDCT shows the presence of hyperdensity in the lumen of left colon (a), well depicted in the MIP coronal and sagittal reformations (b and c) from active bleeding. 430 S. Romano et al. / European Journal of Radiology 61 (2007) 424–432 Fig. 10. CT images of intestinal obstruction due to a descending colon neoplasm (long arrow in a and arrow in b); note the parietal pneumatosis of the right colon (short arrow in a) not due to colonic infarction. Fig. 9. Intestinal obstruction in a patient with colostomy (a), CT shows the fluid distension of the entire intestine (b) due to a recurrence of tumors at level of the transverse colon (c). Gaseous distension of the intestine without evidence of reactive ileus or a transition point may be a functional disorder, the so called Ogilvie’s syndrome, that is a clinical entity characterized by massive non-toxic dilatation of the colon in the absence of mechanical obstruction . This pseudo-obstruction is a potentially malignant early form of colonic dysmotility: colonscopic decompression can achieve reversal of colonic dilatation S. Romano et al. / European Journal of Radiology 61 (2007) 424–432 431 Fig. 11. CT images of intestinal obstruction from sigmoid colon volvolus; note the engorgement of the torsion point (arrow in a) and the impressive coronal reformation (b). in most cases, but in some cases a prophylactic laparotomy may be indicated for prevention of the perforation and additional complications [21,22]. Other different condition of marked distension of the large bowel is related to the toxic megacolon, that represents the severe stage of a flogistic process (i.e. ulcerative colitis), where additional late findings are parietal pneumatosis and perforation. Mechanical obstruction of the colon can be easily demonstrated by basic imaging technique, however, MDCT may be of added value to discover location of the cause of the interruption of the intestinal transit. Although if post-operative evaluation of the colon in most cases do not represent an emergency condition, complications of major surgery or recurrence of disease in case of malignancy may cause acute disease and perforations (Fig. 12). Despite the undoubtful usefulness of the basic imaging methods in evaluating the acute colonic disease, MDCT examination may be of further help for an effective therapeutic management of the patients, providing prompt valuable informations in differ- Fig. 12. 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