The Potential Value of Adding Colonic Sonography to Routine Abdominal Protocol in Patients With Active Pain

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1 407198JDM / Legault Kingstone et al.journal of Diagnostic Medical Sonography Original Research The Potential Value of Adding Colonic Sonography to Routine Abdominal Protocol in Patients With Active Pain Journal of Diagnostic Medical Sonography 27(3) The Author(s) 2011 Reprints and permission: sagepub.com/journalspermissions.nav DOI: / Lysa Legault Kingstone, MAppSc, RDMS, RVT, CRGS, CRVT, RT (MR) 1, Ania Z. Kielar, MD, FRCPC 1, Matthew McInnes, MD, FRCPC 1, and Hans Swan, BSc (Hons), PhD 2 Abstract Abdominal sonography examinations include evaluation of solid intra-abdominal organs but do not routinely include assessment of the colon. The focus of this study was to determine the utility of colonic sonography in addition to abdominal imaging in the prospective evaluation of patients with nonspecific acute or subacute abdominal symptoms. Patients referred for abdominal sonography for investigation of abdominal pain were evaluated by performing routine abdominal sonography followed by a detailed colonic sonographic examination. Final diagnosis was established by a clinical history questionnaire. Twelve colon (46%) or colon-related pathologies were identified, occurring in the cohort of 26 patients with a mean age of 23 years (range, years). Sonographic findings included normal colon (n = 13), inflammatory bowel diseases (n = 6), diverticular disease (n = 5), and colon-related ancillary findings (n = 1). The dedicated colon sonographic examination yielded a sensitivity of 91.6%, specificity of 92.8%, positive predictive value of 91.6%, and negative predictive value of 92.8% (P <.17). Integrating the dedicated colon sonographic examination in addition to the routine abdominal sonography identified significant bowel disease and provided additional information regarding causes of patient symptoms. As this is a pilot study, additional prospective studies in larger populations are required to confirm the results and conclusions. Keywords colon, abdominal, disease, subacute, sonography In tertiary care hospitals, abdominal sonography is commonly the first imaging study performed in patients presenting with abdominal pain. 1 3 Abdominal sonography examinations include evaluation of intra-abdominal and retroperitoneal organs but do not routinely include assessment of the colon. The potential value of evaluating the colon with abdominal sonographic imaging during a routine abdominal sonogram may identify potential causes for the pain and help achieve a proper diagnosis in a more efficient manner. 1,2,4 6 Identification of bowel pathology by sonography may also decrease the need for radiation exposure that would occur with additional cross-sectional computed tomography () imaging. In addition, efficiency of final diagnosis and patient disposition may be increased by enabling streamlined triage of the cases that have been evaluated with colonic sonography. 1 Published studies 2 10 have evaluated the accuracy of colon imaging, including the range of pathological conditions identifiable using sonography. Pathologic processes that affect the colon include inflammatory, infectious, ischemic, and neoplastic conditions; these conditions can be identified and assessed on sonography using a highresolution transducer. 1,2,4,7,10 Based on previously published results, the inclusion of a detailed colon interrogation for patients experiencing acute or subacute abdominal pain may be beneficial for diagnosing abnormalities that may be related to the gastrointestinal tract. 1 The objective of this prospective study was to determine the utility of colonic sonography in addition to routine abdominal sonographic imaging in the prospective evaluation of patients 1 Department of Diagnostic Imaging, The Ottawa Hospital, Ottawa, Ontario, Canada 2 School of Dentistry and Health Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia Corresponding Author: Lysa Legault Kingstone, MAppSc, RDMS, RVT, CRGS, CRVT, RT (MR), Department of Diagnostic Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada lysa19@rogers.com

2 104 Journal of Diagnostic Medical Sonography 27(3) with symptoms of nonspecific abdominal pain. It is hypothesized that the inclusion of a dedicated sonographic evaluation of the colon in patients presenting with acute and subacute abdominal pain, in addition to the routine abdominal examination, can help to evaluate and diagnose pathologic conditions affecting the colon. Materials and Methods The pilot study protocol and use of this sonographic method were approved by the Research Ethics Committee of the Ottawa Hospital and Ottawa Hospital Research Institute Methods Centre. Written informed consent was obtained from all patients. Patients From January to August 2009, 30 patients were prospectively enrolled. The final study population consisted of 26 patients experiencing nonspecific acute to subacute abdominal pain who underwent abdominal sonography in the radiology department referred from the emergency department, family medicine care, and inpatient or outside physicians. Inclusion criteria consisted of requests for abdominal sonographic imaging in patients with one or multiquadrant, epigastric, abdominal, and/or flank pain. Reasons for requests were for right, upper, left, lower, and epigastric quadrant pain and anorexia or loss of appetite in patients with active abdominal pain. Sonography was performed during regular working hours. After-hours scanning of patients who had acute abdominal pain was not possible for the purpose of this study, and thus the patients were nonconsecutive. Research participants excluded from this study included patients who were pregnant, not fasting for the test, or unable to provide consent to the study or answer the medical questionnaire because of a disability that prevented the full understanding of what was being consented to. Furthermore, patients who had sonographic requests specific for renal disease, including hematuria, biliary disease (cholecystitis, cholelithiasis, choledocholithiasis), pancreatic disease (pseudocyst, pancreatitis), liver disease (hepatitis, cirrhosis, metastatic disease, parasitic disease), and splenic disease (infarction, neoplastic disease), as well as patients with a history of morbid obesity (body mass index >40 kg/m 2 ) or with a history of prior gastrointestinal (GI) surgery, were excluded from the study. Because of the large number of requests for various indications for abdominal imaging, it was not possible to keep track of all excluded patients. Sonographic Examination and Analysis Routine abdominal sonography was completed by staff sonographers. Subsequently, the radiologist or a sonographer who was experienced in bowel sonography performed a detailed colonic sonographic examination. A Philips IU22 real-time sonographic system was used (Philips Healthcare, the Netherlands). The examination began with a systematic overview using a 4- to 7-MHz curvilinear transducer followed by more detailed imaging using a 9- to 12-MHz linear transducer. 2,6 Patients were scanned in a range of positions, and the transducer was placed in various orientations such as coronal or oblique sectional imaging to evaluate anatomic portions posterior to pockets of bowel gas. 1,5 Graded compression was also used. Deep inspirations were elicited to visualize some of the upper segments of the colon. 2 The colon was examined starting in the right upper quadrant by identifying the ascending colon and hepatic flexure adjacent to the curvature of the liver. 1 The colon was followed along the right flank to the right lower quadrant (RLQ), until we could identify the cecum, visualized as a blind-ending loop. 1 The terminal ileum was then identified, medial to the cecum, and if visualized, the appendix was examined. The ascending colon was interrogated to the transverse and then to the descending colon, toward the left side of the abdominal cavity. The sigmoid colon was followed down into the left lower quadrant into the pelvis, where the rectosigmoid colon was assessed. Generally, the rectosigmoid portion of the colon was visualized only if the patient had a distended urinary bladder. 1 Static images of the rectum (when available), sigmoid, and descending transverse and ascending colon were documented in both longitudinal and transverse planes. In addition, the cecum, ileocecal valve, and terminal ileum were documented, and if visualized, the appendix was imaged. Three to five distinct bowel wall layers (Figure 1) were evaluated during the sonographic evaluation, with loss of this multilayered appearance being characterized as abnormal. 11 For the purpose of this study, the symmetry, echo texture, and stratification of mucosa, submucosa, and muscularis propria were evaluated according to published literature. 2 Compression of the colon was used to minimize intraluminal gas, properly measure the true wall thickness, and assess the compressibility of the colonic segment, which can be indicative of bowel wall abnormality. 1 Any abnormal colonic segments were assessed for vascularity by evaluating the involved segment using color or power Doppler imaging. Inflamed segments demonstrated an increased vascularity with Doppler. Finally, perienteric soft tissues/fat were assessed for the presence of any adenopathy, fat echogenicity alterations, free fluid, fluid collections, or fistulas. 1,2 Colon sonography was considered abnormal if one or more of the above findings were present.

3 Legault Kingstone et al. 105 Statistical Analysis Figure 1. Longitudinal view of the five normal layers of the colon wall (arrows). The first echogenic central line represents the interface between the thin epithelium and the lumen (A). The second is a hypoechoic line representing the muscularis mucosa (B). Next, there is a moderately hyperechoic layer that is the submucosa (C). Following is a more pronounced hypoechoic layer, which consists of the circular and longitudinal muscle layers or the muscularis propria or externa (D). Finally, the outer hyperechoic layer represents the interface between the serosa and the adjacent peritoneal fat (E). The utility of colon sonography with regard to the presence or absence of colon disease was evaluated by calculating the sensitivity, specificity, and positive and negative predictive values together with 95% confidence intervals. Accuracy cannot be definitively calculated since there was no gold-standard surgical or cross-sectional follow-up test for each patient. In the absence of a gold standard, the clinical course was based on the questionnaire answers to determine the final diagnosis or outcome for every patient. History, gender, prospective sonographic diagnosis, segment of colon affected, focal versus diffuse disease, abnormal colonic wall thickening, ancillary findings, clinical diagnosis, additional imaging examinations, and clinical findings were each considered categorical explanatory variables. Degree of concordance was measured between the sonographic classification of disease and disease classification based on the additional imaging and clinical/ surgical findings. A logistic regression analysis model was created using quasi-separation of data points to measure our data. This method allowed us to assess the significance of the association between the positive colon sonographic examination and the probability of true colon disease. This analysis was also used to estimate the rate of false-positive and false-negative diagnoses. Any pathological segments were imaged more extensively, with possible inclusions of cineloop and/or power or color Doppler imaging. Results of the routine abdominal scan were reported without any changes to the standard of care for a routine abdominal sonogram. If any significant colon abnormalities were detected, the radiologists also reported these findings. Results of abnormalities detected on abdominal sonography were directly communicated to the ordering physician. Institutional patient medical records were reviewed for outcome information, when available. Additional follow-up information was obtained on all patients through the completion of a clinical questionnaire. The questionnaire included information relating to the patient s current health status, clinical workup, and outcome since having the sonographic examination, including additional imaging, surgery, laboratory workup, or physical examinations done by their own or referred physician. The questionnaire was conducted by telephone three months after the sonographic examination, and all patients, regardless if they had follow-up imaging or surgical intervention, completed the questionnaire. Gold-standard cross-sectional imaging or surgical exploration of the colon was unavailable in all patients, but for those who underwent any gold-standard imaging or follow-up, sensitivity and specificity of the colon sonographic examination were calculated in comparison to the gold standard. Results Of the 30 patients initially identified, 26 were included in the final analysis for this pilot study. Two patients were unable to provide follow-up and were therefore excluded from the study. Two patients initially recruited were pregnant, which led to their exclusion from the study. The cohort of the 26 patients had a mean age of 23 years (range, years). The group was composed of 3 men (12%) and 23 women (88%). The clinical indications of the patients included pain in the right lower quadrant (27%), general abdominal pain (15%), right upper quadrant pain (15%), epigastric pain (11.5%), right-sided pain (11.5%), left lower quadrant pain (11.5%), and left-sided pain (8%). The dedicated colon interrogation took between 3 and 10 additional minutes to complete. All 26 (100%) of the patients included in the study had clinical follow-up with their physicians or had additional cross-sectional imaging. Thirteen patients (50%) had additional cross-sectional imaging within three months of the sonographic examination, confirming the normal or abnormal findings. Twelve (46%) colon or related abnormalities were identified with the additional colon visualization. Nine of the 12 colonic abnormalities identified with sonography were confirmed with (n = 5), magnetic resonance imaging (MRI; n = 1), or surgical pathological report (n = 3) within three months of the

4 106 Journal of Diagnostic Medical Sonography 27(3) Table 1. Comparison of Sonography Colon Findings With Positive Clinical and Imaging Follow-Up Findings Pt No. Pt Age, y/ Sex Final Sonography Findings Clinical, Imaging, or Interventional Follow-Up Final Diagnosis 1 31 F Fluid-filled colon with no peristalsis in Surgery Acute appendicitis RLQ 2 25 F Distended appendix, free fluid RLQ, periappendiceal inflammation Surgery Nonperforated acute appendicitis gangrenous appendicitis 3 19 F Thickened appendix (7 mm), free fluid Surgery Acute appendicitis RLQ 4 77 F Mild diverticulosis sigmoid colon Clinical Mild sigmoid diverticulosis 5 47 F Muscular propria thickening with single Sigmoid diverticulitis diverticulum, surrounding echogenic fat in sigmoid colon acute uncomplicated diverticulitis 6 24 M Free fluid in lower quadrants, prominent peristalsis in large colon Pneumatosis cystoides of large bowel with sparing of rectum 7 72 M Echogenic material in appendix, single diverticulum in sigmoid colon Uncomplicated acute appendicitis and uncomplicated colonic diverticulosis 8 66 F Prominent/abnormal ileocecal valve, diverticula sigmoid Diverticulosis of sigmoid colon by sonography and 9 29 M Severe thickening of ascending colon at hepatic flexure, moderate amount of free fluid F Mild diverticular thickening in sigmoid colon F Borderline prominence of terminal ileum Clinical Clinical Acute uncomplicated diverticulitis of the hepatic flexure Mild diverticulosis Irritable bowel disease F Free fluid in RLQ MRI Acute uncomplicated retrocecal appendicitis, computed tomography; MRI, magnetic resonance imaging; RLQ, right lower quadrant. sonographic examination, corroborating the positive sonogram. The remaining three patients identified with colon abnormalities during sonography were diagnosed and treated solely based on the sonographic findings; concordance with their symptoms was made through clinical follow-up (i.e., true-positive sonograms). Colonrelated ancillary findings such as pericolonic abnormalities, including perienteric fat alterations, free fluid, abscess, fistulas, or adenopathy, were included as a falsenegative sonogram (n = 1). One case identified free fluid in the RLQ that resulted in a diagnosis of a retrocaecal appendicitis confirmed by MRI. The findings and results of the positive colon sonography with follow-up are summarized in Table 1. In one case, the diagnosis of diverticulosis by sonography did not correlate with the MRI s negative results (false positive). In 13 of 14 patients for whom the sonogram was negative for colon disease, follow-up did not detect any colon disease (true negative). In all cases where positive colonic sonography findings were confirmed with another imaging modality, the location and disease type correlated. Using additional cross-section imaging and surgical pathology reports as the gold standard that was available in 50% of the cases, the dedicated colon sonography yielded a sensitivity of 91.6% and a specificity of 92.8% using a 95% confidence interval with a total width of the 30%. The positive predictive value (PPV) was 91.6%, and the negative predictive value (NPV) was 92.8% (Table 2). A significantly higher positive rate of colon disease was observed in patients who underwent additional colon imaging (such as or MRI). The highest sensitivity for sonographic evaluation of the colon was found in the sigmoid colon: 6 of 11. The lowest sensitivity was found in the transverse colon: 1 of 10. Statistically significant (P <.17) correlations were found between the presence of localized pain during sonography and the positive sonographic findings of the abnormal colon.

5 Legault Kingstone et al. 107 Table 2. Concordance Between Sonography, Gold-Standard Diagnosis, and Clinical Correlation in the Diagnosis of Colon Disease in 26 Patients Gold Standard (, MRI, Surgical Intervention) Present (Disease Positive): True Positive Absent (Disease Negative): False Positive Total Sonography positive Clinical Follow-Up Diagnosis Present (Disease Positive): False Negative Absent (Disease Negative): True Negative Total Sonography negative Total , computed tomography; MRI, magnetic resonance imaging. Figure 2. (A) Acute uncomplicated diverticulitis of the hepatic flexure. Sonographic transverse view of the ascending colon adjacent to the curvature of the liver in a man in his late 20s with vague right-sided abdominal pain. Arrow indicates there is diffuse wall thickening with loss of layer stratification and delineation along with pericolonic fat changes (patient 9 in Table 1). (B) Acute uncomplicated diverticulitis of the hepatic flexure. Follow-up computed tomography identified multiple scattered diverticula (arrow) throughout the colon with moderate amount of stranding and pericolonic inflammatory process at the hepatic flexure. Images were consistent with acute uncomplicated diverticulitis of the hepatic flexure of the colon, explaining the right upper quadrant symptomatology (patient 9 in Table 1). Sonographic Findings and Disease Type In 12 cases (46%), an abnormal colonic or related sonographic finding was present. Findings of diverticular diseases were sonographically depicted in five (19%) cases (Figure 2A,B). Inflammatory bowel disease, including appendicitis, was found in six (23%) cases. One of the positive appendicitis findings included a gangrenous appendicitis (Figure 3). Colon-related ancillary findings such as pericolonic abnormalities, including free fluid, were found in one (4%) case. Bowel inflammation, including appendicitis, occurred mainly in the younger population (mean age 35.2 years), whereas the older population (mean age 61.3) tended to have colonic abnormalities

6 108 Journal of Diagnostic Medical Sonography 27(3) Figure 3. Acute gangrenous appendicitis. Longitudinal view of the right lower quadrant showing marked distension of the appendix with loss of appendiceal wall delineation and linear echogenic material (arrows) within the anterior wall. Sonographic evidence of a moderate degree of periappendiceal inflammation and surgical pathological report confirmed gangrenous appendicitis (patient 2 in Table 1). associated with diverticular disease such as diverticulitis. There were no statistically significant relationships identified between colon disease and a particular segment of the bowel, patient gender, or type of pathology. Of the sonographically abnormal cases, 40% of disease was located in the sigmoid colon and 30% in the RLQ; 20% of cases involved both the sigmoid colon and RLQ or the ascending and sigmoid colon, whereas the remaining 10% involved the ascending colon alone. One case of pneumatosis involved the entire colon (Figure 4A,B). In 14 cases (54%), sonography of the colon was normal. For these patients, clinical follow-up was left to the discretion of the referring physician. Abnormal sonographic findings outside the colon were found in five of these patients; these findings included two cases of cholelithiasis, two gynecological abnormalities, two urinary tract findings, and one musculoskeletal abnormality that were believed to explain the origin of pain in these patients. Discussion Sonography is increasingly being used as the first-line imaging tool in the initial evaluation of various causes of abdominal pain, especially in the current era of radiation safety concerns. 2,3,12 Two of the most common causes of acute abdominal pain include appendicitis and diverticulitis. 12 However, abdominal sonography carried out according to conventional methods does not routinely include imaging of the colon. The inclusion of a detailed colon interrogation may help identify the correct diagnosis since abdominal pain is commonly related to gastrointestinal disease. 1 According to Lim, 3 the detection of incidental tumors and other bowel pathology, even in the asymptomatic patient, warrants the inclusion of the colon on a routine abdominal sonogram. As suggested by Gritzmann et al., 5 the gastrointestinal tract should be incorporated into the sonographic examination of the abdomen, especially if the symptoms could be related. Over the past decade, there has been a growing interest expressed in the literature for including the colon as part of the regular imaging protocol when looking for a possible source of abdominal pain. 4 Few available published articles use sonography as the primary imaging tool in patients with a clinical suspicion of colon disease. A study by Parente et al. 8 employed sonography as the initial diagnostic imaging tool to prospectively examine 487 patients with bowel symptoms or signs suggestive of inflammatory bowel disorders. The investigators determined that the overall sensitivity and specificity of colon sonography were 85% and 95%, respectively, whereas the PPV was 98% and the NPV was 75%. By contrast, in one of the two other studies that included patients with symptoms suggestive of colon carcinoma, the global sensitivity of sonography was lower (79%), with an overall specificity of 92% and a PPV and NPV of 81% and 91%, respectively. 10 Differences in the study populations, patient selection, prevalence of disease, type of sonographic equipment, sonographic operator experience, and the use of protocols to distinguish abnormal colon segments by sonography may explain some of the differences in results between these studies. In addition to the limited numbers of available studies, is the primary investigative test recommended for many patients experiencing acute abdominal pain. 6,12 Stoker et al., 12 in a study assessing various imaging strategies for patients with acute abdominal pain, determined that using sonography first and then only for those with negative or inconclusive sonographic examinations resulted in the best sensitivity in addition to reduced radiation exposure. Despite the greater accuracy of after clinical evaluation, the authors determined that sonography resulted in the highest overall sensitivity, with only 6% of urgent conditions missed. Although Puylaert 6 reiterated that sonography is being used less often than in evaluations of the acute abdomen, he delineated specific advantages of sonography over, including the lack of ionizing radiation, a higher spatial resolution for target organs such as the colon, the benefits of dynamic realtime scanning, test availability, and the benefits of direct communication with patients, which often lead to a better diagnostic sonographic examination. However, sonography does have some relevant limitations, such as reduced penetration in patients with a large patient body habitus

7 Legault Kingstone et al. 109 Figure 4. (A) Pneumatosis cystoides of the colon. Sonographic image demonstrating prominent peristalsis in bowel loops with free fluid (arrow; patient 6 in Table 1). (B) Pneumatosis cystoides of the colon with sparing of the rectum. Computed tomography confirmed the presence of a distended bowel with discontinuous (arrows) gas within the bowel wall consistent with evidence of pneumatosis of the entire large bowel (patient 6 in Table 1). Figure 5. Mild diverticulosis. Example of a longitudinal sonogram demonstrating asymmetric thickening (arrow) of the muscularis propria of the sigmoid colon. The sonographic diagnosis of diverticulosis was confirmed with clinical findings (patient 10 in Table 1). and reduced visibility in the presence of overlapping or gas-filled loops of bowel. In addition, there is a suboptimal visualization of the rectum in patients whose bladder is not full. With the increasing momentum of the Image Gently campaign, 13 sonography is beginning to be used more commonly as the first test for nonspecific abdominal symptoms. In a normal colon, three to five depicted layers can be visualized. 11 However, with the potential limitations of sonography, not all five layers can always be seen. When all five layers are visible, the first luminal echogenic line represents the interface between the thin mucosal surface and the bowel contents. The second layer is a hypoechoic line, which represents the deep muscularis mucosa. Next, there is a moderately hyperechoic layer that is the submucosa. Following this is a more pronounced hypoechoic layer, which consists of the circular and longitudinal muscle layers of the bowel or the muscularis propria. Finally, the outer hyperechoic layer represents the interface between the thin outer serosa and the adjacent

8 110 Journal of Diagnostic Medical Sonography 27(3) fat. 5,11,14 The colon sonographic examination is considered abnormal when one or more of the four following features is identified: 1. Colon wall thickness is greater than 4 mm or there is loss of the layered appearance (Figure 5). Abnormal wall symmetry, echo texture changes, and stratification of the bowel wall, in addition to the location within the wall (e.g., intraluminal, mural, or exophytic), are noted. 1,2,5 2. Lack of compressibility during graded compression. Compression is important for measuring the true thickness of the bowel wall and assessing the compressibility of the segment Focal areas of increased vascularity, as identified with either color or power Doppler imaging 4. Pericolonic abnormalities, including perienteric fat alteration, free fluid, abscess, fistulas, or adenopathy The results of the present pilot study confirm that the integration of a dedicated colon sonographic examination in addition to the routine abdominal sonography identified significant colon disease in patients presenting with nonspecific acute or subacute abdominal pain. In our series of patients, linear regression statistical analysis data concluded that sonography was able to detect 91.6% of colon disease, and each of the positive findings was correlated with, MRI, or surgical pathology reports. The overall specificity of the colonic sonography was 92.8%, and the additional colonic evaluation had a PPV of 91.6% and an NPV of 92.8%. This suggests that negative sonographic findings cannot exclude with certainty all pathologic processes in the colon. The sigmoid colon was the most common site of disease, and inflammatory diverticular disease was commonly detected in this location. Segments of the colon, such as the rectum, were more difficult to image because of overlying gas, deep positioning, and limited visibility. This may have negatively influenced the PPV and NPV of the study, particularly if the patient was symptomatic for inflammatory colon disease such as ulcerative colitis. Other major reported potential pitfalls of colonic sonography are operator dependency and interobserver variability. All these factors could have affected our overall accuracy results. The major weakness of this study includes a lack of consistent cross-sectional or surgical follow-up, such as or MRI, as a gold standard. This was not possible in most patients, although 50% did have one of these types of follow-up. Follow-up scanning in all patients, particularly in those whose symptoms resolve, is not ethical because of radiation exposure considerations. MRI is not as accessible and is not considered a gold standard for evaluating the colon. Follow-up surgery or colonoscopy would also be unrealistic. A longer follow-up period between the original sonographic study and the subsequent telephone interview could potentially be of benefit. Another possibility to reaffirm the value of the colon sonographic examination would be to perform a followup colonic sonographic examination and correlate the findings or to simply follow a larger number of patients and only use those who subsequently have had, MRI, or surgical follow-up to reaffirm the value of the colon sonographic examination. A larger study population is also required to answer the question of value in a more definitive manner. In future studies evaluating utility of sonography for evaluating the colon, exclusion and inclusion criteria should be broadened to include all requests for imaging abdomen pain, regardless of whether there is a specific target organ in mind. This is because the localized area of pain may not stem from the suspected organ on the sonographic request but instead may originate from an adjacent colon loop. Further studies evaluating the use of sonography for evaluation of the colon during pregnancy are also warranted. Although two pregnant patients were excluded from our study, one demonstrated ancillary findings on sonographic evaluation of the colon such that she was referred for MRI, which subsequently confirmed appendicitis. Conclusion Results from this prospective pilot study suggest that inclusion of the colon in the protocol for acute adult abdominal sonography has the potential to be a valuable method for evaluating various pathologies of colon origin. This small prospective study may be the impetus for a paradigm shift in the usual protocol for abdominal imaging, but larger prospective studies are indicated to corroborate these findings. Acknowledgments We thank the sonography staff of the Ottawa Hospital (Ottawa, Ontario) with special gratitude to Micheline Heroux, RDMS, RVT, for her invaluable assistance and Dr Michael Kingstone, MD, for assistance with the manuscript. In addition, we thank Dr Phil Wells, MD, Dr Monica Taljaard, PhD, and James Jaffey of the Ottawa Hospital Research Institute for their assistance with the methodology and statistical analysis. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the authorship and/or publication of this article. Funding The author(s) received no financial support for the research and/or authorship of this article.

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