Emergency (****); * (*): *-* This open-access article distributed under the terms of the Creative Commons Attribution Non Commercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 11 Emergency (2016); 4 (1): 11-15 ORIGINAL RESEARCH The Accuracy of Urinalysis in Predicting Intra-Abdominal Injury Following Blunt Traumas Anita Sabzghabaei1, Majid Shojaee2, Saeed Safari3, Hamid Reza Hatamabadi2, Reza Shirvani2* 1Department of Emergency Medicine, Loghmane Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2 Department of Emergency Medicine, Imam Hossein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 3 Department of Emergency Medicine, Shohadaye Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. *Corresponding Author: Reza Shirvani; Emergency Department, Imam Hossein Hospital, Shahid Madani Avenue, Imam Hossein Square, Tehran, Iran. Postal code: 1989934148; Tel/Fax: 00982122721155 Email: Rshirvani.md@gmail.com Received: February 2015; Accepted: April 2015 Abstract Introduction: In cases of blunt abdominal traumas, predicting the possible intra-abdominal injuries is still a chal- lenge for the physicians involved with these patients. Therefore, this study was designed, to evaluate the accuracy of urinalysis in predicting intra-abdominal injuries. Methods: Patients aged 15 to 65 years with blunt abdominal trauma who were admitted to emergency departments were enrolled. Abdominopelvic computed tomography (CT) scan with intravenous contrast and urinalysis were requested for all the included patients. Demographic data, trauma mechanism, the results of urinalysis, and the results of abdominopelvic CT scan were gathered. Finally, the correlation between the results of abdominopelvic CT scan, and urinalysis was determined. Urinalysis was consid- ered positive in case of at least one positive value in gross appearance, blood in dipstick, or red blood cell count. Results: 325 patients with blunt abdominal trauma were admitted to the emergency departments (83% male with the mean age of 32.63±17.48 years). Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios of urinalysis, were 77.9% (95% CI: 69.6-84.4), 58.5% (95% CI: 51.2-65.5), 56% (95% CI: 48.5-63.3), 79.6% (95% CI: 71.8-85.7), 1.27% (95% CI: 1.30-1.57), and 0.25% (95% CI: 0.18-0.36), respectively. Conclusion: The diagnostic value of urinalysis in prediction of blunt traumatic intra-abdominal injuries is low and it seems that it should be considered as an adjuvant diagnostic tool, in conjunction with other sources such as clin- ical findings and imaging. Key words: Urinalysis; abdominal injuries; abdomen; tomography, X-Ray computed Cite This Article as: Sabzghabaei A, Shojaee M, Safari S, Hatamabadi HR, Shirvani R. The accuracy of urinalysis in predicting intra- abdominal injury following blunt traumas. Emergency. 2016;4(1):11-15. Introduction: bdominal trauma is the most common cause of mortality in people under 45 years old. In cases of blunt trauma, evaluating and diagnosing the pos- sible intra-abdominal injuries is still a challenge for the physicians involved with these patients (1). Frequent clinical examinations, aspiration and diagnostic perito- neal lavage, ultrasonography, computed tomography (CT), biochemical and urine tests are among the most common diagnostic tools in this regard (2). In trauma pa- tients, physical examination of the abdomen might not give accurate information on the state of intra-ab- dominal injuries. This problem is even worse in patients with a decreased level of consciousness as a result of us- ing alcohol, drugs, brain trauma, and hemodynamic in- stability (3-5). Abdominal CT scan with intravenous (IV) contrast media is considered a standard diagnostic im- aging and has the ability to diagnose solid organ injuries, accurately (1). Yet, this method cannot be used on pa- tients with emergency exploratory laparotomy indica- tion, restlessness, a history of allergy to contrast mate- rial, and hemodynamic instability(6, 7). Urinalysis ac- companied by frequent physical examination has been proposed as an initial method for evaluating those af- fected by blunt abdominal trauma, especially children (8-10). Some of the studies believe that patients with normal urinalysis and abdominal physical examination rarely have intra-abdominal injuries (8, 11, 12). In con- trast, another study expressed that the presence or ab- sence of blood in urine is not an accurate and safe tool to predict the existence of intra-abdominal injuries (13). Also other studies have shown that biochemical tests, A This open-access article distributed under the terms of the Creative Commons Attribution Non Commercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com Sabzghabaei et al 12 evaluating urobilinogen and urine bilirubin accompa- nied by urinalysis, cannot be an effective tool for ab- dominal trauma screening in children (14-16). Meaning, despite urinalysis being a valuable diagnostic tool, it might not be efficient in cases of traumatic abdominal in- juries (17, 18). Therefore, performing urinalysis when clinical examination and ultrasonography results are normal and the patient does not show any hemodynamic instability or decrease in consciousness, wastes lots of time and resources in the overcrowded trauma centers. In addition, at times the positive urinalysis leads to un- necessary further diagnostic tests. This study was aimed to assess the accuracy of urinalysis in predicting intra- abdominal injuries following blunt traumas. Methods: This diagnostic accuracy assessment study evaluated urinalysis in predicting traumatic intra-abdominal inju- ries. Abdominopelvic CT scan with IV contrast was con- sidered as gold standard test. Patients aged 15 to 65 years with blunt abdominal trauma who were admitted to emergency departments of Imam Hossein and Sho- hadaye Haftome Tir Hospitals, Tehran, Iran between March and September 2013, were enrolled. Women on their menstrual cycle, people with underlying diseases such as cancer or chronic kidney diseases, and people with penetrating abdominal trauma were excluded. Uri- nalysis and abdominopelvic CT scan with IV contrast were performed for all patients, simultaneously. Demo- graphic data, trauma mechanism (motor vehicle acci- dents, pedestrian motor crash, or falling), the results of urinalysis (gross appearance, presence or absence of blood in the dipstick, and red blood cell count), and the results of abdominopelvic CT scan were gathered using a pre-designed checklist. All patients were examined with a multi-slice CT scanner (Siemens Medical Solution, USA). A radiologist who was blind to the results of uri- nalysis and clinical characteristics did interpretation of the patients’ CT scan. In addition, a laboratory technician who was blind to the patients’ clinical data did urinalysis. In the end, the relationship between the results of ab- dominopelvic CT scan, and urinalysis was assessed. The ethics committee of Shahid Beheshti University of Medical Sciences approved this study. In addition, the re- searchers adhered to the principles of Helsinki Declara- tion and confidentiality of patient information over the course of the research. Written informed consents were obtained from all patients. In this study, clear gross appearance of urine was de- fined as the ability to read a text through the urine-con- taining glass. In addition, semi-clear urine was defined as urine being a little turbid while a text can still be read through the glass. Semi-turbid and turbid urines were also defined as urines being a little to completely cloudy so that the text could not be read through the glass con- taining them. Urinalysis was considered positive in case of at least one positive value in gross appearance, blood in dipstick, or red blood cell count. Red blood cell counts were categorized to 0-9, 10-40, and more than 40. Con- sidering 59% sensitivity, 10% specificity and a confi- dence interval of 95%, the minimum sample size was cal- culated 93 patients. Data were analyzed using SPSS ver- sion 21.0. Screening performance characteristics of uri- nalysis (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likeli- hood ratio (PLR), and negative likelihood ratio (NLR)) with 95% confidence interval (95% CI) in comparison with the results of abdominopelvic CT scan were calcu- lated. p<0.05 was considered as the level of significance. Results: Finally, 325 patients with blunt abdominal trauma with the mean age of 32.63±17.48 years were evaluated (83% male). Trauma mechanism in 36% was motor vehicle collision. Most patients had clear urine appearance (59.1%), blood negative dipstick (48%), with 0-9 red blood cells per high power field (58.8%). The results from the patients’ urinalysis can be found in table 1. 193 (59.6%) patients had normal abdominopelvic CT scan while pelvic fracture were detected in 58 (18%), free abdominal fluid in 37 (11%), kidney damage in 32 (10%), liver damage in 23 (7%), spinal fracture in 22 (7%), and spleen damage in 18 (6%). There was a signif- icant but weak correlation between the gross appear- ance of urine (r=0.28, p˂0.001), the results of urine dip- stick (r=0.42, p˂0.001), and red blood cell count (r=0.37, p˂0.001) and the results of abdominopelvic CT scan. Table 1: The results of urinalysis regarding gross ap- pearance, blood in dipstick, and red blood cell count Urinalysis Number (%) Gross appearance Clear 192 (59/1) Semi clear 77 (23/7) Semi turbid 29 (8/9) Turbid 27 (8/3) Blood in dipstick 0 156 (48) 1 42 (12/9) 2 53 (16/3) 3 40 (12/3) 4 34 (10/5) Red blood cell count 0-9 cells/HPF* 191 (58/8) 10-40 cells/HPF 83 (24/3) 40< cells/HPF 51 (16/9) This open-access article distributed under the terms of the Creative Commons Attribution Non Commercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 13 Emergency (2016); 4 (1): 11-15 Sensitivity, specificity, PPV, NPV, PLR, and NLR of urinal- ysis were 77.9% (95% CI: 69.6-84.4), 58.5% (95% CI: 51.2-65.5), 56% (95% CI: 48.5-63.3), 79.6% (95% CI: 71.8-85.7), 1.27% (95% CI: 1.30-1.57), and 0.25% (95% CI: 0.18-0.36), respectively. In addition, screening per- formance characteristics of gross appearance, dipstick and red blood cell count in predicting the possibility of intra-abdominal solid organ injuries including liver, spleen, kidney and also presence or absence of ab- dominal free fluid are shown in tables 2, 3, and 4, respec- tively. Discussion: The results of this study show that sensitivity and speci- ficity of urinalysis in predicting intra-abdominal injuries is low. It seems that using urinalysis for predicting trau- matic abdominal injuries is not accurate enough. Rapid diagnosis and timely treatment of abdominal traumas is very important and can play an important role in de- creasing mortality rates among patients (19-21). Differ- ent studies express various, and sometimes contradict- ing, opinions on the accuracy of urinalysis in blunt ab- dominal trauma. In a study, Wessel et al. introduced ul- trasonography and urinalysis as the optimal tools for an initial evaluation to exclude renal injury following blunt abdominal trauma (22). In addition, Isaacman et al. demonstrated that the prevalence of laboratory abnor- malities was low in pediatric trauma patients and recom- mended a combination of physical examination and uri- nalysis as a highly sensitive screening tool. They showed that laboratory testing in patients with a normal physical examination and urinalysis rarely identified missed in- tra-abdominal injury (8). Caparo et al. studied the trauma panels’ tests such as sodium, glucose, white blood cell (WBC) count, hematocrit, platelets, prothrom- bin time, activated partial thromboplastin time, aspar- tate aminotransferase (AST), alanine aminotransferase (ALT), amylase, lipase, and urinalysis in pediatric pa- tients with blunt trauma. Their results showed that ab- normal values for glucose, AST, urinalysis, and WBC count were the most commonly observed. They con- cluded that routine trauma panels could not be used as a Table 2: Screening performance characteristics of urine gross appearance in comparison with the results of ab- dominopelvic computed tomography scan Characteristics kidney Spleen Liver Free fluid Sensitivity 60.6 (42.2-76.1) 66.7 (41.1-85.6) 39 (20.4-61.2) 59.4 (42.2-74.8) Specificity 61.3 (55.4-66.8) 60.5 (54.8-66) 50 (44.6-55.3) 61.4 (55.5-67) PPV1 15.0 (9.0-22.5) 9.0 (4.9-15.5) 42.8 (22.3-65.5) 16.5 (10.8-24.2) NPV2 93.2 (88.4-96.1) 96.8 (93-98.7) 92.7 (87.8-95.8) 92.2 (87.2-95.4) PLR3 0.17 (0.11-0.26) 0.09 (0.05-0.2) 0.75 (0.40-1.3) 0.19 (0.1-0.3) NLR4 0.07(0.04-0.12) 0.03 (0.01-0.07) 0.07 (0.04-0.1) 0.08 (0.05-0.1) 1. Positive predictive value; 2. Negative predictive value; 3. Positive Likelihood Ratio; 4. Negative Likelihood Ratio. Table 3: Screening performance characteristics of urine blood in comparison with the results of abdominopelvic computed tomography scan Characteristics kidney Spleen Liver Free fluid Sensitivity 15.9 (10.9-22.5) 8.2 (4.7-13.7) 8.8 (5.2-14.4) 16.5 (11.4-23.2) Specificity 96.1 (91.4-98.4) 97.4 (93.1-99.1) 94.8 (89.8-97.5) 94.2 (89.0-97.1) PPV1 81.8 (63.9-92.3) 77.7 (51.9-92.6) 65.2 (42.8-82.8) 75 (58.4-87.6) NPV2 51.3 (45.4-57.2) 49.5 (43.7-55.2) 49 (43.2-54) 51 (45.1-56.9) PLR3 4.5 (2.1-9.4) 3.5 (1.42-8.59) 1.87 (0.99-3.5) 3.1 (1.7-5.6) NLR4 0.94 (0.8-1.1) 1.01 (0.9-1.1) 1.04 (0.9-1.2) 0.95 (0.8-1.1) 1. Positive predictive value; 2. Negative predictive value; 3. Positive Likelihood Ratio; 4. Negative Likelihood Ratio. Table 4: Screening performance characteristics of urine red blood cell count in comparison with the results of abdominopelvic computed tomography scan Characteristics kidney Spleen Liver Free fluid Sensitivity 18.1(9.5-31.3) 10.9 (4.5-22.9) 9.0 (3.3-20.7) 16.3 (8.2-29.3) Specificity 91.4 (87.3-94.4) 95.5 (92.1-97.5) 93.3 (89.4-95.8) 99.1 (96.7-99.8) PPV1 30.3 (16.2-48.8) 33.3 (14.3-58.8) 21.7 (8.2-44.2) 81.8 (47.7-96.7) NPV2 84.5 (79.8-88.4) 84.0 (79.3-87.8) 83.4 (78.6-87.3) 84 (79.1-87.9) PLR3 0.43 (0.2-0.8) 0.5 (0.24-1.03) 0.27 (0.12-0.62) 4.5 (1.24-16.2) NLR4 0.18 (0.13-0.23) 0.18 (0.14-0.24) 0.19 (0.15-0.25) 0.19 (0.14-0.24) 1. Positive predictive value; 2. Negative predictive value; 3. Positive Likelihood Ratio; 4. Negative Likelihood Ratio. This open-access article distributed under the terms of the Creative Commons Attribution Non Commercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com Sabzghabaei et al 14 screening tool in children with blunt trauma (14). In a study by Stein et al. the degree of hematuria did not cor- relate with the degree of renal injury. Based on their findings, any child with a history of blunt abdominal trauma and any evidence of hematuria should undergo abdominopelvic CT scan for correct diagnosis (23). Ken- nedy et al. showed that urinary dipstick is a safe, accu- rate, and reliable screening test for evaluating the pres- ence or absence of hematuria in patients suffering from either blunt or penetrating abdominal trauma (24). Pe- rez-brayfield et al. declared that abdominopelvic CT scan should only be done when the patient’s urinalysis shows an red blood cell count of 50 or more (25). Yet, in a study by Keller et al. routine laboratory tests such as urinalysis had little value in the management of injured children (16). In other studies, although urinalysis was valuable in specific patient populations, it showed moderate bias in predicting abdominal injury in traumatic children and was not helpful(17, 18). We can conclude that practically it is not possible to distinguish the patients with intra- abdominal injuries from the others solely using urinaly- sis. This study was carried out in centers, which perform uri- nalysis for most of the patients with possible abdominal trauma, but only the patients that are thought to have a higher possibility of abdominal trauma are scanned. Therefore, maybe the results of this study cannot be gen- eralized. To be able to generalize the results of this study a broader study in multiple centers is recommended. Conclusion: The diagnostic value of urinalysis in prediction of blunt traumatic intra-abdominal injuries is low and it seems that it should be considered as an adjuvant diagnostic tool in conjunction with other sources such as clinical findings and imaging. Acknowledgments: This article has been extracted from Dr. Reza Shirvani’s thesis for achieving his specialist degree in emergency medicine from the Faculty of Medicine at Shahid Be- heshti University of Medical Sciences. Conflict of interest: None Funding support: None Authors’ contributions: All authors passed four criteria for authorship contribu- tion based on recommendations of the International Committee of Medical Journal Editors. References: 1. Tan WW, Chen CC, Chiang HJ. The value and role of computed tomography in blunt injury of the abdomen. Zhonghua Yi Xue Za Zhi (Taipei). 1991;48(2):116-20. 2. Feliciano D. Diagnostic modalities in abdominal trauma. Peritoneal lavage, ultrasonography, computed tomography scanning, and arteriography. Surg Clin North Am. 1991;71(2):241-56. 3. Schurink G, Bode P, Van Luijt P, Van Vugt A. The value of physical examination in the diagnosis of patients with blunt abdominal trauma: a retrospective study. Injury. 1997;28(4):261-5. 4. 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