Archives of Academic Emergency Medicine. 2022; 10(1): e50 OR I G I N A L RE S E A RC H Diagnostic Accuracy of Ultrasonography by Emergency Medicine Resident in Detecting Intestinal Obstruction; a Pilot Study Anita Sabzghabaei1, Majid Shojaei2, Miromid Chavoshzadeh1,3∗ 1. Emergency Department, Shohadaye Tajrish Hospital, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2. Emergency Department, Imam Hossein Hospital, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 3. Men’s Health and Reproductive Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Received: March 2022; Accepted: May 2022; Published online: 26 June 2022 Abstract: Introduction: There are many ambiguities regarding the application of ultrasound in detection of intestinal obstruction. This study aimed to evaluate the diagnostic accuracy of ultrasound in diagnosis of intestinal ob- struction. Methods: This cross-sectional study was performed on patients with symptoms and signs of bowel obstruction between November 2019 and July 2020 in Shohadaye-Tajrish and Imam Hossein General Hospitals, Tehran, Iran. After a brief explanation and getting verbal consent, the patients underwent ultrasound examina- tion in the emergency department by the emergency medicine resident. The results of ultrasound were com- pared with the surgical findings as the gold standard. Results: 24 patients with the mean age of 57.50±18.26 (range: 28 – 81) years were studied (58.3% male). Ultrasonography findings revealed the lumen diameter ≥ 2.5 cm in 21 (87.5%) cases, wall thickness ≥ 3 mm in 3 (12.5%) cases and inter-loop free fluid in 3 (12.5%) cases. Sen- sitivity, positive predictive value, and accuracy of ultrasound in detection of intestinal obstruction were found to be 85.00% (95%CI: 61.13 – 96.03), 80.95% (95%CI: 57.42 – 93.71), and 70.83% (95%CI: 48.91 – 87.38), respectively. Conclusion: It seems that point-of-care ultrasound has good sensitivity and accuracy in detection of intestinal obstruction when performed in the emergency department by a trained emergency medicine resident. Keywords: Intestinal Obstruction; Point-of-Care Testing; Ultrasonography; Emergency Service, Hospital Cite this article as: Sabzghabaei A, Shojaei M, Chavoshzadeh M. Diagnostic Accuracy of Ultrasonography by Emergency Medicine Resident in Detecting Intestinal Obstruction; a Pilot Study. Arch Acad Emerg Med. 2022; 10(1): e50. https://doi.org/10.22037/aaem.v10i1.1628. 1. Introduction Gastrointestinal obstruction is relatively a common problem requiring appropriate diagnostic and therapeutic interven- tions. This situation can occur anywhere along the gastroin- testinal tract, and its clinical symptoms often vary based on the level of obstruction (1). Intestinal obstruction is mostly due to intra-abdominal adhesions, malignancy, or intesti- nal hernias and its clinical manifestations generally include nausea and vomiting, colicky abdominal pain, and inabil- ity to pass stool or gas (2). The classic findings of physi- cal examination, abdominal distention, tympanic sounds in percussion, and high-pitched intestinal sounds, might help ∗Corresponding Author: Miromid Chavoshzadeh; Men’s Health and Repro- ductive Health Research Center, Shohadaye Tajrish Hospital, Shahrdari Av- enue, Tajrish Square, Tehran, Iran. Email: omid.chavoshzadeh@gmail.com, Tel: 00989121370587, ORCID: https://orcid.org/0000-0002-7344-5890. to diagnose the disease in a timely manner; however, imag- ing modalities can confirm the diagnosis and be a useful ad- junct in cases where the diagnosis is uncertain (3). In this re- gard, although the definitive diagnosis of bowel obstruction is made on clinical assessment followed by abdominal plain radiography or computed tomography (CT) scan, in many cases we encounter false negatives leading to failure in di- agnosis as well as considerable complications (4). Addition- ally, applying contrast-based modalities such as CT scan are frequently time-consuming, expensive, and intolerable for some patients and lead to radiation exposure (5). Therefore, employing safe, available and cost-effective devices such as ultrasound have been recently considered for assessing in- testinal obstruction. In some studies, this method has been shown to be more specific and sensitive than abdominal X- ray in confirming or ruling out intestinal obstruction in ad- dition to determining the progression via repeated scans (6, 7). Moreover, point-of-care ultrasound can help in finding This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem A. Sabzghabaei et al. 2 intestinal wall abnormalities such as interloop free fluid and thickened walls (8) or even deleterious problems like aortic dissection (9), which need prompt treatment. In addition, using Doppler ultrasound can help assess the blood flow in intestinal wall and detect wall necrosis or differentiate be- nign or malignant lesions (10, 11). The availability of ultrasound in the emergency department, speed and ease of use, lower cost, and lack of ionizing radi- ation, have made it a desirable option for diagnosing small bowel obstruction (12-15). In addition to making the diag- nosis of obstruction, ultrasound has been used to detect its etiology by some practitioners (16, 17). Despite these stud- ies, there are many ambiguities regarding the accuracy of ul- trasonography in confirming or rejecting/ruling out obstruc- tion and it is not yet used as standard practice. In this study, we aimed to evaluate the accuracy of ultrasound in diagnosis of intestinal obstruction. 2. Methods 2.1. Study design and setting This cross-sectional pilot study was performed on patients admitted to the emergency departments of Shohadaye- Tajrish and Imam Hossein Hospitals, Tehran, Iran, with signs and symptoms of intestinal obstruction, between Novem- ber 2019 and July 2020. After clarifying the possibility of intestinal obstruction, explanation of the ultrasound and the purpose of performing it, and obtaining oral con- sent, the patients underwent abdominal ultrasonography by the trained emergency medicine resident. Then the findings of ultrasonography regarding intestinal obstruction were compared with surgery findings as the gold standard. The study protocol was approved by Ethics Committee of Shahid Beheshti University of Medical Sciences (Ethics code IR.SBMU.MSP.REC.1398.216). 2.2. Participants Not giving consent, being referred with probable diagnosis of obstruction, bringing any imaging that suggests obstruc- tion, hemodynamic instability, life threatening conditions, and not undergoing surgical treatment (as our gold standard of diagnosis) were considered as the exclusion criteria. 2.3. Data gathering and procedure Demographic findings (age, gender) as well as abdominal ul- trasonography and surgery findings were collected using a predesigned checklist. A second-year emergency medicine resident (MC) underwent training by an emergency medicine associate professor, for four hours containing abdominal ul- trasound of five patients. Patients were evaluated with the ul- trasound device Honda HS-2100 in Shohadaye-Tajrish Hos- pital and Sonosite Edge in Imam Hossein Hospital by the same operator. Using a low frequency (2.5-5 MHz) curvi- linear probe, patients underwent ultrasound in supine posi- tion. The sweep like scan begins from the right iliac region, moves superiorly to right hypochondriac region, then epigas- tric region and goes downward to hypogastric region, and fi- nally left iliac region to left hypochondriac region with the transducer in both cephalocaudal and transverse planes to cover the whole area of abdomen. Since examining peristal- sis needs a couple of minutes to be correctly done and there is limited time in the busy emergency department, it was not considered. When the diameter was more than 2.5 cm, and to ensure that a small bowel loop is scanned, we looked for pli- cae circularis, which is a characteristic feature of small bowel. Evidence of small bowel obstruction was considered as in- testinal lumen diameter more than 2.5 cm or wall thickness more than 3 mm or inter-loop free fluid (figure 1). The pa- tients’ surgical technique was similar in all samples. 2.4. Statistical analysis Findings were presented as mean ± standard deviation (SD) for quantitative variables and frequency (percentage) for cat- egorical variables. To determine the diagnostic value of ul- trasound in diagnosis of intestinal obstruction compared to the gold standard (surgery), screening performance charac- teristics were calculated and presented with 95% confidence interval (CI). 3. Results 24 patients with the mean age of 57.50±18.26 (range: 28 – 81) years were studied (58.3% male). Ultrasonography find- ings revealed lumen diameter ≥ 2.5 cm in 21 (87.5%) cases, wall thickness ≥ 3 mm in 3 (12.5%) cases, and inter-loop free fluid in 3 (12.5%) cases. The sonographic evidence of small bowel obstruction was observed in 21 (87.5%) cases, while 17 (true positive) patients were confirmed to have obstruc- tion in surgery (4 false positives). In three patients without ultra-sonographic evidence, obstruction was confirmed fol- lowing surgery (false negative). Four cases with false posi- tive results had perforated gangrened appendix with exten- sive pelvic and retroperitoneal abscess, peritonitis due to cirrhosis and ascites, emphysematous pyelonephritis, and herniated abdominal wall. Considering surgery as the gold standard for diagnosis of small bowel obstruction, sensitiv- ity, positive predictive value, and accuracy of ultrasound in detection of intestinal obstruction were found to be 85.00% (95%CI: 61.13 – 96.03), 80.95% (95%CI: 57.42 – 93.71), and 70.83% (95%CI: 48.91 – 87.38), respectively (table 1). 4. Discussion In recent years, with the widespread use of ultrasound in dif- ferent fields of medicine, it has been used in the diagnosis This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 3 Archives of Academic Emergency Medicine. 2022; 10(1): e50 Figure 1: Increased small bowel lumen diameter more than 2.5 cm (A); increased small bowel wall thickness more than 3 mm (B); inter-loop free fluid (C). Table 1: Screening performance characteristics of ultrasonography in detection of intestinal obstruction Character Value (%) 95% Confidence Interval Lower Limit (%) Upper Limit (%) Sensitivity 85.00 61.13 96.03 Specificity 0 0 60.42 Positive predictive value 80.95 57.42 93.71 Negative predictive value 0 0 69.00 Positive likelihood ratio 4.25 1.717926 10.514134 Negative likelihood ratio Infinity NaN Infinity Accuracy 70.83 48.91 87.38 NaN: The calculation cannot be performed because the values entered include one or more instances of zero. of patients with suspected small intestine obstruction in sev- eral studies. Because of the ease of use, low cost, high ac- cessibility, and high accuracy reported in these studies, ul- trasound has the potential to reduce many of the inherent limitations of traditional imaging. The use of ultrasound for a patient with suspected intestinal obstruction is convincing because of its potential to reduce the use of CT scans, being less expensive, limiting the use of contrast media, and reduc- ing imaging time. The present study was performed to evalu- ate the diagnostic value of ultrasound in small bowel obstruc- tion and the results showed that the sensitivity of ultrasound in diagnosis of small bowel obstruction was 85%. According to the results of this study, the positive predictive value for ul- trasound was 80.95%, which means that if the test is positive in someone, they are 80.95% likely to have obstruction. The accuracy of ultrasound is also 70.8%, which means that ultra- sound gives the correct answer in 70.8% of cases compared to the gold standard. In total, high diagnostic performance has been reported for ultrasound in detection of intestinal ob- struction in previous studies. In a meta-analysis performed on 15 studies by Lin et al. in 2021, the pooled sensitivity and specificity of ultrasound in detection of bowel obstruction were found to be 92% (95% CI: 89%-95%) and 93% (95% CI: 85%-97%), respectively (18). Although sensitivity was similar in studies across different continents, specificity was lower in the North America, in the emergency department, and when computed tomography was used as the only reference standard. The different findings in our study could be the result of the ultrasound operator proficiency and the ultra- sonography machine. In another meta-analysis by Gottlieb et al. on 11 studies in 2018 (19), the pooled sensitivity and specificity of ultrasound was estimated to be 92.4% (95% CI 89.0% to 94.7%) and 96.6% (95% CI 88.4% to 99.1%), respec- tively. A meta-analysis conducted by Taylor and Lalani (20) to evaluate the method of choice for diagnosing small bowel obstruction in adults showed that ultrasound performed by an emergency physician had excellent diagnostic accuracy compared to other modalities, and was even superior to CT- scan and MRI. They also showed that ultrasound has the po- tential to play a greater role in diagnosis of small bowel ob- struction in the emergency department. Musoke and col- leagues conducted a research in Uganda in 2003, which com- pared the accuracy of ultrasound and abdominal radiogra- phy for diagnosing bowel obstruction (14). They reported 100% specificity, 93% sensitivity and accuracy, 100% PPV, and 73% NPV. The reason for its high accuracy could be the age of patients, which were between 3 days to two years old, and the different main cause of obstruction, which was hernia (in- stead of adhesions). Ultrasonography in Jang and colleagues work (15) has higher sensitivity than our study, which can be due to comparing the ultrasound with CT-scan results as well as looking for both increased lumen diameter and de- creased peristalsis. Schmutz et al. found 91% accuracy when they excluded ‘gassy’ patients and 81% overall (17), which This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem A. Sabzghabaei et al. 4 might be because of the higher skills of radiologist opera- tors. In general, different results could be related to the op- erators’ abilities, doing the ultrasound at the crowded emer- gency ward with less concentration and time, and not using the modality options like various probes and Doppler, in ad- dition to limited number of patients and their demographic characteristics. Likewise, it should be noted that the accu- racy of ultrasonography in diagnosis of intestinal obstructive lesions depends on various factors, including the experience of the operator performing the ultrasound scan, anatomical status, the level of obstruction, and patient cooperation. It is worth emphasizing that ultimately, the diagnosis of ob- structive pathological lesions such as the etiology of obstruc- tion will be possible based on surgery or biopsy, and imaging techniques are mainly auxiliary and screening tools for the disease. In addition, because of the increasing use of ultrasound in di- agnostic and therapeutic procedures, especially in the emer- gency department, equipping these departments with ad- vanced devices and improving users’ abilities in applying and interpreting ultrasound findings is recommended. 5. Strengths and Limitations The advantage of our study was comparing the results of ul- trasound with surgery as the gold standard and performing point-of-care ultrasound by the emergency medicine resi- dent. The major limitation of the present study was studying a limited number of patients. In fact, due to concurrence of the plan and the COVID-19 pandemic, and since the venues were referral centers for COVID-19 patients, the study could not be performed with a larger number of patients. Also, due to the special conditions of the emergency department and its crowdedness, peristalsis, which is one of the indicators of small bowel obstruction in some studies, was not evaluated. 6. Conclusion It seems that point-of-care ultrasound has good sensitivity and accuracy in detection of intestinal obstruction when per- formed in the emergency department by a trained emer- gency medicine resident. 7. Declarations 7.1. Acknowledgments We would like to thank all participants in the study and also SBMU Emergency department mentors and residents. 7.2. Authors’ contributions All authors meet the standard criteria of authorship contri- bution based on the recommendations of the International Committee of Medical Journal Editors. 7.3. Funding and supports No funding was received for this study. 7.4. Conflict of interest There is no conflict of interest in this study. References 1. Catena F, De Simone B, Coccolini F, Di Saverio S, Sartelli M, Ansaloni L. Bowel obstruction: a narrative review for all physicians. World J Emerg Surg. 2019;14(1):1-8. 2. Jackson P, Cruz MV. Intestinal obstruction: evaluation and management. Am Fam Physician. 2018;98(6):362-7. 3. Pujahari AK. Decision making in bowel obstruction: a re- view. J Clin Diagn Res: JCDR. 2016;10(11):PE07. 4. Denham G, Smith T, James D, McKiernan S, Evans T-J. 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