Abdominal Pain Management and Point-of-care Ultrasound in the Emergency Department: A Randomised, Prospective, Controlled Study

By Yesim Durgun¹, Yusuf Yurumez², Necip Gokhan Guner¹, Nuray Aslan¹, Ensar Durmus¹, Yavuz Kahraman³

Affiliations

1. Department of Emergency Medicine, Sakarya Training and Research Hospital, Sakarya, Turkey
2. Department of Emergency Medicine, Faculty of Medicine, Sakarya University, Sakarya, Turkey
3. Department of General Surgery, Faculty of Medicine, Sakarya University, Sakarya, Turkey

doi: 10.29271/jcpsp.2022.10.1260

ABSTRACT
Objective: To determine the effect of point-of-care ultrasound (POCUS) performed during the initial evaluation phase of patients with acute abdominal pain.
Study Design: Randomised controlled, parallel-group trial.
Place and Duration of Study: Sakarya University Training and Research Hospital, Sakarya, Turkey, from October 2019 to March 2020.
Methodology: Patients who presented to the Emergency Department (ED) with acute abdominal pain were included in the study. Exclusion criteria were permanent mental disability, age <18 years, abdominal trauma within the last 24 hours, pregnancy, morbid obesity, repeated admissions, referral from an external centre to the ED, and missing patient information. Patients were divided randomly into two groups: The control group where standard diagnostic strategies were applied and the POCUS group where POCUS was performed together with standard diagnostic strategies. The length of stay (LOS), differential diagnoses, cost and hospitalisation or discharge from ED were compared.
Results: The application of POCUS reduced the average number of preliminary differential diagnoses from four to two (p <0.001). Regarding patient outcomes, POCUS reduced LOS in ED in both the discharged and hospitalised patients (p = 0.003, and p = 0.049, respectively). In all patients, POCUS reduced LOS in ED but led to no significant changes in cost (p <0.001, p = and 0.403, respectively).
Conclusion: POCUS in patients with acute abdominal pain is very useful in reducing the number of differential diagnoses and LOS in ED.

Key Words: Abdominal pain, Cost, Emergency department, Length of stay, Point-of-care ultrasound.

INTRODUCTION

Acute abdominal pain is one of the most common causes of admission to the emergency department (ED) and accounts for approximately 10% of all ED admissions. However, patients can sometimes describe their complaints as stomach pain, cramping, or spasms instead of abdominal pain.¹ The fact that abdominal pain can occur owing to a wide range of causes, ranging from mild and self-limiting conditions to life-threatening diseases, often puts clinicians in a difficult position during the diagnostic approach.²

The age of the patient, detailed anamnesis, and physical examination findings constitute the main elements of the standard diagnostic approach.¹ However, when these are insufficient, additional examinations including laboratory parameters and imaging studies (X-ray, ultrasonography [USG], computed tomography [CT], and magnetic resonance imaging [MRI]) are generally required.³

Another method that has gained traction in diagnostic approach in recent years is point-of-care ultrasound (POCUS). Point-of-care ultrasound refers to the practice of trained medical professionals using ultrasound to diagnose problems wherever a patient is being treated, whether that's in a modern ED or an ambulance. Unlike regular ultrasound, certain points in terms of pathologies are selected as focus and evaluated as positive or negative. Worldwide, the application of POCUS has come to the forefront by supporting physicians in advanced diagnosis and treatment processes of patients, especially in emergency care.⁴ In fact, studies on POCUS have reported excellent diagnostic accuracy for common diseases.^5-7 POCUS in the diagnostic evaluation may also reduce costs and morbidity and mortality rates.⁸ Therefore, the idea of using POCUS as an integral part of the examination is becoming increasingly common in the medical community.⁹ However, despite the body of evidence and approaches, additional studies are needed on the effect of POCUS on diagnosis and treatment processes in ED.⁷

In this study, it was hypothesised that POCUS will contribute positively to the diagnosis of patients admitted to the ED, reduce the length of stay (LOS) in the ED, and reduce average hospitalisation and healthcare costs. Therefore, this study aimed to evaluate the effect of hepatobiliary, renal, and upper and lower abdominal POCUS on diagnostic processes, LOS in ED, hospitalisation, and costs in patients presenting to the ED with acute abdominal pain.

METHODOLOGY

This study was conducted as a prospective, randomised, controlled, and parallel-group study in the Emergency Department, Sakarya University Training and Research Hospital, between October 2019 and March 2020. Informed consent was obtained from all participants involved in the study. In addition, all procedures were performed in accordance with the ethical standards of the institutional and/or national research committee and the 1964 Helsinki Declaration and subsequent amendments or comparable ethical standards. The study was approved by the Ethics Committee of Clinical Research at Sakarya University Faculty of Medicine (Decision no: 152 of 20.09.2019). This study was registered with ClinicalTrials.gov, No. NCT05402774.

Patients who presented to the ED with acute abdominal pain were included in the study. Exclusion criteria were permanent mental disability, age <18 years, abdominal trauma within the last 24 hours, pregnancy, morbid obesity, repeated admissions, referral from an external centre to the ED, and missing patient information.

Patients were randomly assigned to POCUS (n=103) or control groups (n=104). The responsible researcher randomised the assignment of patient forms to the study groups using a random number generator before the study was initiated. When the patients admitted to the ED, it was determined in advance which number form was in which group. The POCUS operator worked different shifts at the ED, thus allowing patients from different hours and days to be included in the study.

All patients admitted to the emergency department underwent primary clinical evaluation by their responsible physician. After primary clinical evaluation, the demographic data of all patients; character, location, spread, duration of abdominal pain, and preliminary diagnosis of the responsible physician were recorded in the study form. No advice or direction was given to the responsible physician regarding any procedure of the patients.

There were no restrictions on the responsible physician requesting a full blood count, biochemical analyses and urine examination, and electrocardiogram and other imaging methods (lung and direct abdominal X-ray, CT, USG, and MRI) among the standard tests in ED, and all test results were available within approximately two hours.

At this stage, the patients were divided into two groups: POCUS was applied to patients in the POCUS group after primary clinical evaluation. This procedure was performed in the first hour after the primary clinical evaluations of the patients by evaluating the predetermined parameters in the study form for hepatobiliary, renal, and upper and lower abdominal findings. All processes and results for patients in the control group were followed without any intervention and the results were recorded in the study form.

POCUS was performed according to the American College of Emergency Physician imaging criteria. All POCUS procedures were performed by an experienced operator who did not take part during the primary clinical evaluation. Xario 100 (Toshiba, Japan) USG system was used.

POCUS findings were presented to the responsible physicians. Preliminary diagnoses, diagnostic tests and treatment were re-evaluated by the responsible physician. Afterwards, all processes were recorded in the study form without interference.

After all these processes were completed, the final diagnoses of the patients were made by a supervisory emergency specialist who was blinded to POCUS findings and did not know who the patient's responsible physician was. The emergency specialist reached the final diagnoses by evaluating the epicrisis forms of hospitalised patients and ED patient examination forms of discharged patients, together with laboratory and imaging examinations.

The primary endpoint was to determine the effect of POCUS on LOS in the patient presenting with acute abdominal pain in ED. Secondary endpoints were to determine the effect of POCUS on patients' mean cost, rate of change in physician's pre-diagnosis, hospitalization, and discharge rate in patients presenting to the ED with acute abdominal pain.

Normality of measurable variables was assessed with Shapiro-Wilk Test. For both groups, categorical endpoints were presented as the number and percentage of patients corresponding with 95% confidence interval (CI). Continuous endpoints were presented as mean, standard deviation, median, and range. The rule of three was used to calculate 95% CI in categories with no events. According to distributions the Mann–Whitney U-test was used for comparison of continuous endpoints, and either McNemar or Wilcoxon test was used for comparison of endpoints expressed as counts and percentages. All tests were conducted with a two-tailed significance of 5%. For each endpoint, the absolute and relative effects and their corresponding 95% CIs were calculated as recommended by Altman et al.¹¹ All analyses were performed using IBM SPSS 21.

Table I: Patient characteristics in the POCUS and control groups.

	POCUS group (n = 103)	Control group (n = 104)
Age (Years; Mean [SD])	52.42 (19.85)	48.8 (18.94)
Gender Male Female	44 (43%) 59 (57%)	52 (50%) 52 (50%)
Medical history Diabetes mellitus Coronary artery disease Hyperlipidemia Heart failure Arterial hypertension Stroke Chronic kidney disease Chronic obstructive pulmonary disease Asthma Malignancy Intra-abdominal operation history	5 (5%) 2 (2%) - 3 (3%) 19 (19%) 3 (3%) 4 (4%) - 1 (1%) 5 (5%) 19 (18%)	10 (10%) 2 (2%) 1 (1%) 3 (3%) 8 (8%) 1 (1%) 2 (2%) 1 (1%) - 5 (5%) 1 (1%)
*Vital signs at admission Respiratory rate (breaths per min) Saturation (%) Systolic blood pressure (mmhg) Diastolic blood pressure (mmhg) Heart rate (beats per min) Temperature (°C)	12 (11–12) 98 (97–99) 120 (110–140) 70 (70–80) 85 (77–88) 36.7 (36.5–36.9)	12 (12–14) 98 (96–98) 120 (110–140) 75 (70–80) 86 (78–93) 36.7 (36.5-36.9)
Patient-reported symptoms Nausea Vomiting Diarrhoea Anorexia Dysuria	54 (52%) 26 (25%) 4 (4%) 11 (11%) 4 (4%)	43 (41%) 10 (10%) 2 (2%) 3 (3%) 2 (2%)
Character of acute abdominal pain Colic Continuous	46 (45%) 57 (55%)	15 (14%) 89 (86%)
Location of acute abdominal pain Whole abdomen Upper right quadrant Lower right quadrant Right flank Upper left quadrant Lower left quadrant Left flank Epigastric Suprapubic Periumbilical	46 (45%) 20 (20%) 25 (24%) 3 (3%) 3 (3%) 9 (9%) 3 (3%) 9 (9%) 5 (5%) 6 (6%)	44 (42%) 16 (15%) 21 (20%) 7 (7%) 1 (1%) 3 (3%) 6 (6%) 7 (7%) 7 (7%) 3 (3%)
Intensity of acute abdominal pain Mild Moderate Severe	2 (2%) 61 (59%) 40 (39%)	- 72 (69%) 32 (31%)
Physical examination findings Tenderness in right lower quadrant Tenderness in right upper quadrant Tenderness in costovertebral angle Tenderness in left lower quadrant Tenderness in left upper quadrant Tenderness in suprapubic Palpable mass Tenderness in whole abdomen Tenderness in epigastric area Rebound pain	39 (38%) 21 (21%) 3 (3%) 11 (11%) 3 (3%) 13 (13%) 1 (1%) 37 (36%) 19 (18%) 5 (5%)	23 (22) 15 (14%) 11 (11%) 3 (3%) 1 (1%) 7 (7%) 1 (1%) 43 (41%) 7 (7%) 2 (2%)
Imaging methods X-ray Ultrasonography Computed tomography	42 (41%) 49 (48%) 58 (56%)	48 (46%) 29 (28%) 89 (86%)
Hospitalisation of patient Discharged Hospitalised	60 (58%) 43 (42%)	79 (76%) 25 (24%)
Data are presented as number (%) or mean unless otherwise indicated.;  *The median values ​​(25p–75p).

RESULTS

In total, 207 patients were selected randomly and included in the study. The mean age was 52.42 ± 19.85 years in the POCUS group and 48.8 ± 18.94 years in the control group. While it was seen that the number of women was higher in the POCUS group (n=59; 57%), the gender distribution was found to be equal in the control group. Arterial hypertension was the most common comorbid disease in the POCUS group (n=19; 19%), while diabetes mellitus was found in the control group (n=10; 10%). Patient characteristics are presented in Table I.

The application of POCUS revealed a total of 113 pathological findings in 66 patients (64%). The most common of these was stone or mud in the gallbladder (n=23, 22%), while the least common were hepatorenal free fluid (n=1, 1%) and free fluid in the Douglas (n=1, 1%). In the POCUS group, POCUS findings were confirmed by USG or CT performed by an expert radiologist, and six additional pathologies were detected in 5 patients (5%). Detection of a pathology in POCUS had no significant effect on hospitalisation rate, LOS in ED, and average costs (p = 0.151, 0.557, and p = 0.171, respectively).

It was observed that the responsible physician made an average of four preliminary diagnoses based on patient history and physical examination. The average number of preliminary diagnoses decreased from four to two after POCUS (p <0.001). A significant difference was found in the preliminary diagnoses of appendicitis, cholecystitis, cholelithiasis, pancreatitis, nephrolithiasis, pyelonephritis, ileus, and although ureterolithiasis with POCUS where major portion of ureter is not visualised, ureterolithiasis after POCUS (p<0.001, p<0.001, p = 0.008, p<0.001, p<0.001, p<0.001, p<0.001, and p<0.001, respectively).

In addition, the application of POCUS reduced LOS in patients that presented with both colic and continuous pain (p=0.034, and p=0.004, respectively). With regard to pain moderate or severe, the application of POCUS significantly reduced LOS in ED in the moderate pain group (p=0.030, and p=0.006, respectively). Regarding preliminary diagnoses, POCUS was found to reduce LOS in the emergency department in patients with cholelithiasis, pancreatitis, nephrolithiasis, ileus, and ovarian diseases (p=0.042, p=0.012, p=0.015, p=0.013, and p=0.024, respectively) while costs were reduced only in the patient group with suspected bowel perforation (p=0.021, Table II). Therefore, CT combined with POCUS significantly increased average costs (p=0.026). In the discharged patient group, the application of POCUS reduced LOS in ED (p=0.001). When the entire patient group was evaluated, the application of POCUS in the ED was found to significantly reduce LOS in ED, but did not have a significant effect on average costs (p<0.001, Table II).

DISCUSSION

Acute abdominal pain is a clinical condition affected in terms of incidence and clinical reflection by demographic characteristics such as age, gender, ethnicity, family history, sexual orientation, cultural practices, and geography. In addition to detailed anamnesis and physical examination, POCUS can also be used in the diagnostic approach. Diagnostic evaluation with POCUS may have a positive contribution to improving health care as well as reducing costs, LOS in ED, morbidity, and mortality.⁴ In fact, Lindelius et al. reported that POCUS contributes to diagnostic efficiency in abdominal pain.¹⁰ However, in literature no randomised controlled clinical trials was found that investigated the effect of POCUS on LOS in ED and costs in patients who presented to the ED with acute abdominal pain. The present study and its results are therefore important.

Table II: Effects of POCUS on the length of stay and average costs.

	POCUS Group LOS                   (min)**	Control Group LOS (min)**	p-value*	POCUS Group Average costs ($)**	Control Group Average costs ($)**	p-value*
Character of abdominal pain       Colic       Continuous	241 (98–341) 217 (90–328)	271 (179–598) 286 (190–395)	0.034 0.004	29 (18–39) 27 (16–39)	29 (18–36) 32 (21–38)	0.615 0.237
Intensity of abdominal pain       Moderate       Severe	221 (95–348) 213 (84–304)	273 (187–393)      301 (184–498)	0.030 0.006	28 (18–38) 27 (16–40)	31 (20–37) 34 (26–40)	0.767 0.225
Preliminary diagnosis       Appendicitis       Cholecystitis       Cholelithiasis       Pancreatitis       GERD****       Nephrolithiasis       Bowel perforation       Ileus       Ovarian disease       Nonspecific abdominal pain	247 (106–417) 232 (95–359) 235 (77–392) 164 (75–309) 235 (85–434) 168 (91–349) 237 (115–496) 196 (83–263) 185 (116–261) 147 (79–346)	286 (230–378) 305 (185–475) 369 (176–487) 266 (145–367) 231 (177–376) 279 (217–477) 288 (184–333) 299 (215–359) 351 (200–490) 198 (160–283)	0.274 0.074 0.042 0.012 0.302 0.015 0.867 0.013 0.024 0.560	31 (22–39) 32 (19–39) 30 (17–39) 32 (17–42) 26 (17–37) 26 (20–37) 27 (19–36) 32 (21–39) 19 (18–37) 19 (12–35)	32 (20–39) 29 (20–39) 28 (20–39) 33 (26–40) 31 (21–37) 28 (18–36) 38 (31–44) 33 (31–41) 26 (18–37) 14 (9–15)	0.994 0.883 0.620 0.867 0.243 0.627 0.021 0.194 0.390 0.088
Imaging methods       X-ray       Ultrasonography       Computed tomography	245 (103–449) 237 (97–336) 230 (105–318)	307 (227–391) 369 (239-532) 300 (198–403)	0.067 0.002 0.005	33 (22–40) 26 (17–39) 37 (29–41)	33 (25–40) 33 (20–37) 33 (26–38)	0.746 0.580 0.026
Diagnosis       Appendicitis       Cholecystitis       Cholelithiasis       Pancreatitis       GERD***       Nephrolithiasis       Bowel perforation       Ileus       Ovarian disease       Nonspecific abdominal pain	290 (99–449) 131 (76–358) 120 (68–550) 338 (187–452) 214 (81–337) 135 (91–176) 176 (115–237) 70 (62–78) 169 (103–487) 245 (80–323)	300 (207–441) 305 (168–448) 521 (439–832) 226 (124–250) 218 (138–615) 258 (186–559) 176 (132–220) 296 (231–312) 367 (222–504) 286 (148–317)	0.688 0.096 0.250 0.222 0.437 0.018 >0.99 0.056 0.152 0.391	35 (22–41) 21 (17–32) 37 (19–47) 40 (20–68) 31 (18–41) 26 (22–45) 28 (27–29) 41 (36–46) 16 (12–37) 31 (15–38)	39 (32–42) 37 (21–40) 28 (24–34) 26 (15–31) 31 (22–37) 32 (22–36) 46 (41–50) 33 (32–38) 22 (15–31) 27 (17–32)	0.277 0.096 >0.99 0.222 0.841 >0.99 0.333 0.222 0.717 0.560
Hospitalisation of patient       Discharged       Hospitalised	209 (93–316) 232 (94–370)	286 (185–401) 266 (182–412)	0.001 0.115	25 (15–37) 33 (22–44)	30 (20–37) 35 (28–42)	0.164 0.611
All patients	218 (94–333)	283 (187–400)	p<0.001	28 (17–39)	32 (21–38)	0.403
*Mann–Whitney U-test was used;  ** Data are presented as median and ranges;  ***GERD: Gastroesophageal reflux disease.

In this study, the data obtained about the demographic characteristics of the patients were consistent with similar studies in the literature. In a study of 5,340 patients with abdominal pain conducted by Cervellin et al., the mean age of the patients was reported to be 49 years. Similarly, the mean age of the patients was 50.6 years in this study. In addition, it was found that most of the patients presenting to the ED with acute abdominal pain were women in this study, which was consistent with the reports of Cervellin et al. and Lindelius et al.^10,12

In patients presenting with acute abdominal pain, the character of pain and the accompanying symptoms are crucial and must be assessed. The character of pain can guide the clinician and aid in diagnostic approach.¹ In the literature, Veliassaris et al. reported that 56.8% of the cases had continuous pain.¹³ Furthermore, Caliskan et al. reported that the most common complaints were nausea, vomiting, and loss of appetite in patients who presented to the ED with abdominal pain.¹⁴ In the present study, the character of pain and accompanying symptoms were consistent with the aforementioned literature.

POCUS, a recommended diagnostic tool in differential diagnosis, is highly useful in making quick and accurate decisions, uncovering pathologies, and shaping preliminary diagnosis. POCUS can detect gallbladder pathologies, liver pathologies, appendicitis, intra-abdominal free fluid, aortic aneurysm, aortic dissection, and several organ pathologies.⁴ POCUS can also be used as an important tool in the verification or rejection of preliminary diagnosis.⁸ In a study conducted by Mancuso et al., the application of POCUS led to a change in preliminary diagnosis in 19% of patients.¹⁵ Similarly, Dhillon et al. reported that the preliminary diagnosis was confirmed in 29% of patients with abdominal pain, an alternative diagnosis was made in 10% of patients, and the preliminary diagnosis was completely rejected in 43% of patients after POCUS.¹⁶ Consistent with the discussed literature, in the present study, there was a statistically significant reduction in the number of preliminary diagnoses that can be evaluated sonographically and the average number of preliminary diagnoses. This indicates that POCUS narrows the pool of options in preliminary diagnosis, making it easier for physicians to reach a definitive diagnosis.
 

In the present study, it was found that POCUS reduced LOS by approximately 65 minutes in patients who presented to the ED with acute abdominal pain and this change was statistically significant. However, this is the first study to evaluate LOS in the ED after POCUS and there are no similar studies on acute abdominal pain to support this result. There are other studies in the literature that investigated the relationship between POCUS and LOS in ED in patients with chest pain, appendicitis, pelvic pain, and bleeding. Guner et al. found that POCUS reduced LOS in ED in patients with chest pain.⁷ Elikashvili et al. and Wilson et al. also conducted studies on patients who presented to the ED with pelvic pain and bleeding complaints, respectively, and reported that POCUS reduced LOS.^6,17 The results of these studies support the hypothesis that POCUS reduces LOS.

Reducing patient care costs is one of the main objectives in the ED.¹⁸ In the present study, POCUS was applied in patients with abdominal pain for this purpose, but no statistical reduction in average costs was detected except for patients with the preliminary diagnosis of bowel perforation. In this study, it could not be comparatively evaluated this result owing to the lack of a similar study on the subject in the literature.

This study has some limitations. First, the study was conducted in a single centre and all sonographic procedures were performed by a single physician. Therefore, the results may not be the same for other EDs and POCUS practitioners. Second, patients could not be recorded sequentially as there was no permanent POCUS practitioner in the ED. Third, the accuracy of USG-assisted decision-making regarding definitive diagnosis was not examined.

CONCLUSION

In patients with acute abdominal pain, the application of POCUS is especially useful in terms of narrowing the pool of options of preliminary diagnoses and reducing LOS in the ED. However, POCUS does not contribute to the reduction of costs. Owing to the limited number of studies on acute abdominal pain, further studies are needed to validate these results.

ETHICAL APPROVAL:
The study protocol was approved by the local ethics committee [IRB No.16214662/050.01.04/152].

PATIENTS’ CONSENT:
Informed consents were obtained from all participants.

COMPETING INTEREST:
The authors declared no competing interest.

AUTHORS’ CONTRIBUTION:
YD, YY, NGG: Conceived and designed the study.
YD: Conducted the acquisition of the data.
NGG: Analysed the data and provided statistical expertise.
YD, NA, ED, YK: Interpreted the data.
YD, YY, NGG: Drafted the manuscript. 
All the authors have contributed substantially to its revision and approved the final version of the manuscript to be published.

REFERENCES

1. Tinninalli JE, Ma OJ, Yealy DM, Meckler GD, Stapczynski JS. Acute abdominal pain: A comprehensive study guide, 9th edition: Mcgraw-Hill Education ve 2019.S:473-481.
2. Lameris W, Van Randen A, Wouter van Es H, P M van Heesewijk J, Van Ramshorst B, Bouma WH, et al. Imaging strategies for detection of urgent conditions in patients with acute abdominal pain: Diagnostic accuracy study. BMJ 2009; 338:b2431. doi.org/10.1136/bmj.b2431.
3. Gans SL, Pols MA, Stoker J, Boermeester MA. Guideline for the diagnostic pathway in patients with acute abdominal pain. Dig Surg 20015; 32(1):23-31. doi.org/10.1159/ 000371583.
4. Ultrasound guidelines: Emergency, point-of-care and clinical ultrasound guidelines in medicine. Ann Emerg Med 2017; 69(5):27-54. doi.org/10.1016/j.annemergmed. 2016.08.457.
5. Laursen CB, Sloth E, Lassen AT, Christensen RD, Lambrechtsen J, Madsen PH, et al. Point-of-care ultrasonography in patients admitted with respiratory symptoms: A single-blind, randomised controlled trial. Lancet Respir Med 2014; 2(8):638-46. doi.org/10.1016/S2213-2600(14) 70135-3.
6. Elikashvili I, Tay ET, Tsung JW. The effect of point-of-care ultrasonography on emergency department length of stay and computed tomography utilisation in children with suspected appendicitis. Academic Emerg Med 2014; 21(2):163-70. doi.org/10.1111/acem.12319.
7. Guner NG, Yurumez Y, Yucel M, Alacam M, Guner ST, Ercan B. Effects of point-of-care ultrasonography on the diagnostic process of patients admitted to the emergency department with chest pain: A randomised controlled trial. J Coll Physicians Surg Pak 2020; 30(12):1262-8. doi.org/10. 29271/jcpsp.2020.12.1262 .
8. Kroger K, Kupper-Nybelen J, Moerchel C, Moysidis T, Kienitz C, Schubert I. Prevalence and economic burden of pulmonary embolism in Germany. Vasc Med 2012; 17(5):303-9. doi.org/10.1177/ 1358863X12449363 .
9. Feilchenfeld Z, Kuper A, Whitehead C. Stethoscope of the 21st century: Dominant discourses of ultrasound in medical education. Med Educ 2018; 52(12):1271-87. doi.org/10. 1111/medu.13714.
10. Cervellin G, Mora R, Ticinesi A, Meschi T, Comelli I, Catena F, Lippi G. Epidemiology and outcomes of acute abdominal pain in a large urban Emergency Department: Retrospective analysis of 5,340 cases. Ann Transl Med 2016; 4(19):362. doi.org/10.21037/atm.2016.09.10.
11. Robert G. Newcombe DGA. In: Altman D, Machin D, Bryant T GM, Ed. Statistics with Confidence: Confidence Intervals and Statistical Guidelines. 2nd edition. London: Wiley; 2000; 45-7.
12. Lindelius A, Torngren S, Sonden A, Pettersson H, Adami J. Impact of surgeon-performed ultrasound on diagnosis of abdominal pain. Emerg Med J 2008; 25(8):486-91. doi.org/10.1136/emj.2007.052142.
13. Velissaris, D, Karanikolas M, Pantzaris N, Kipourgos G, Bampalis V, Karanikola KF, et al. Acute abdominal pain assessment in the Emergency Department: The experience of a Greek University Hospital. J Clin Med Res 2017; 9(12):987-93. doi.org/10.14740/jocmr3206w.
14. Caliskan M, Coskun A, Acar A, Atak I, Kalcan S, Sisik A. Multivariate prospective evaluation of patients admitted with acute abdominal pain in emergency surgery clinics. JAEM 2010; 9:75-82.
15. Mancuso FJ, Siqueira VN, Moises VA, Gois AF, Paola AA, Carvalho AC, et al. Focused cardiac ultrasound using a pocket-size device in the emergency room. Arquivos Brasileiros De Cardiologia 2014; 103(6):530-7. doi.org/10. 5935/abc. 20140158.
16. Dhillon S, Halligan S, Goh V, Matravers P, Chambers A, Remedios D. The therapeutic impact of abdominal ultrasound in patients with acute abdominal symptoms. Clin Radiol 2012; 57(4):268-71. doi.org/10. 1053/crad.2001. 0862.
17. Wilson SP, Connolly K, Lahham S, Subeh M, Fischetti C, Chiem A, et al. Point-of-care ultrasound versus radiology department pelvic ultrasound on emergency department length of stay. World J Emerg Med 2016; 7(3):178-82. doi.org/10.5847/wjem.j.1920-8642.2016.03.003.
18. Ruger JP, Richter CJ, Spitznagel EL, Lewis LM. Analysis of costs, length of stay, and utilisation of emergency department services by frequent users: Implications for health policy. Acad Emerg Med 2004; 11(12):1311-7. doi: 10. 1197/j.aem.2004.07.008.