Pediatr Surg Int DOI 10.1007/s00383-015-3758-0
ORIGINAL ARTICLE
Surgeon-performed ultrasound: accurate, reproducible, and more efficient Deidre L. Wyrick1 • Samuel D. Smith1 • Jeffrey M. Burford1 • Melvin S. Dassinger1
Accepted: 5 August 2015 Ó Springer-Verlag Berlin Heidelberg 2015
Abstract Purpose A study previously performed at our institution demonstrated that surgeon-performed ultrasound (SPUS) was accurate compared to radiology department ultrasound (RDUS) when evaluating children with suspected appendicitis. The purpose of this study was to determine if these results were reproducible and if SPUS decreased time to definitive diagnosis. Methods A surgery resident performed examinations and ultrasounds on children with suspected appendicitis. Final diagnosis was confirmed by pathology. Results were compared to RDUS and combined with the previous study for a final comparison with RDUS. Mean time to diagnosis was recorded. Data were analyzed using Fisher exact and Student’s t test. Results Fifty-eight patients underwent SPUS, of these 35 had RDUS. The accuracy of SPUS alone was 93 % (54/58) and RDUS accuracy was 94 % (33/35) (p = 1). When SPUS was combined with clinical examination accuracy increased to 95 % (55/58). When results were combined with the previous study, overall accuracy of SPUS was 90 % (101/112) compared to overall RDUS accuracy of 89 % (50/56). Mean time to diagnosis for RDUS was 135 min (n = 35), whereas mean time to diagnosis for SPUS was 30 min (n = 58; p = 0.0001). Conclusion SPUS is accurate and reproducible in evaluating children with suspected appendicitis. SPUS potentially decreases time to definitive therapy and emergency department wait times.
Keywords Appendicitis Ultrasound Surgeon-performed ultrasound SPUS
& Deidre L. Wyrick
[email protected]
After Institutional Review Board approval (#111415), patients with suspected appendicitis had a history, physical exam, and US performed by a single surgery resident. The resident sonographer was notified of all cases of suspected appendicitis and patients/families were approached for
1
Department of Pediatric Surgery, University of Arkansas for Medical Sciences, Arkansas Children’s Hospital, 1 Children’s Way, Slot 837, Little Rock, AR 72202, USA
Background Acute appendicitis remains one of the most common pediatric conditions treated by surgeons. Over the last several years, there has been a transition away from computed tomography (CT) for the diagnosis of appendicitis and many pediatric facilities now use ultrasound as their initial imaging modality [1, 2]. Similarly, there has been a push by the American College of Surgeons, the Accreditation Council for Graduate Medical Education, and the American Board of Surgery for surgical trainees and surgeons to be exposed to the use of ultrasonography [3–5]. Our institution has been cognizant of this shift and has advocated the use of surgeon-performed ultrasound. We have previously published our data on SPUS for the diagnosis of pyloric stenosis and acute appendicitis [6–9]. Our previous appendicitis study demonstrated that SPUS was accurate in diagnosing appendicitis; however, all of the ultrasounds were done by one surgery resident. The aim of this paper is to investigate if SPUS for the diagnosis of appendicitis is reproducible and to investigate if SPUS reduces the time to definitive diagnosis.
Methods
123
Pediatr Surg Int
The final diagnosis made by the research resident was compared to radiology studies, operative findings, final pathology or discharge diagnosis for those who were observed. Ultrasound technicians performed radiology department ultrasounds. All ultrasound images are read or verified by pediatric radiology attendings. The radiology department was blinded to the surgery resident’s ultrasound findings. Sensitivity, specificity, positive and negative predictive value, and accuracy were calculated for ultrasound alone and for clinical diagnosis plus ultrasound. The cohort from this study was then combined with the results from the study previously done at our institution and a final comparison was done. Finally, mean time to diagnosis for both radiology department and surgeon-performed ultrasound was documented. For RDUS, mean time to diagnosis was defined as time from order entry to radiologist read. For SPUS, mean to diagnosis was defined as time from initiation of consult until completion of history, physical exam, and ultrasound. Data were analyzed using Fisher exact and Student’s t test.
enrollment. Patients were enrolled concurrently during the study period. All patients were initially evaluated by physicians in the emergency department and imaging studies were performed according to the appendicitis protocol devised at our institution. At our institution, all children with suspected appendicitis and a BMI B35 kg/m2 are sent for ultrasound. All patients in which the pediatric surgery department was consulted for rule-out appendicitis were eligible for enrollment, regardless of perforation status. The decision to consult the pediatric surgery department was at the discretion of the attending caring for the child. The surgery department is called at the discretion of the ED staff. A single surgery resident who had attended a basic ultrasound course evaluated all patients enrolled in the study. In addition to the basic ultrasound course, the resident had experience using ultrasound from performing clinical duties. Examples of these duties include using US for trauma exams, central venous line placement, peripheral intravenous line placement, and breast core needle biopsies. The surgeon ultrasound was performed using a Sonosite M-Turbo (Bothell, WA, USA) US with a 13-6 MHz linear transducer using a technique previously described by our institution. The US was performed using a graded compression technique with emphasis at the point of maximal tenderness. If the appendix was not found at this location, the entire right lower quadrant was scanned in both the longitudinal and transverse directions [9]. Signs of appendicitis included a non-compressible blind-ending tubular structure with a diameter of [6 mm. Periappendiceal fluid, appendicolith, hyperemia, and fluid collections were considered secondary signs of appendicitis [10–12]. A history, physical exam, and SPUS was performed on all patients. The research sonographer was blinded to all radiology imaging results and to the plan of the surgical team. Two diagnoses were documented: the first was based solely on US findings and the second was based on the complete clinical picture, including the history, physical exam, and US. The surgical attending of record made the final decision regarding further imaging, admission to the hospital for observation or appendectomy.
Results Fifty-eight patients were evaluated by the research resident and included for analysis. The mean age of patients evaluated was 9.6 years (range 9 months–20 years). Thirty-two (55 %) of the patients were male and 26 (45 %) were female. Fifty-seven patients had formal radiology imaging. Thirty-five (61 %) had a RDUS and the remainder had a CT scan. Thirty-nine patients underwent appendectomy and of these three patients had pathology negative for appendicitis. Results are summarized in Table 1. The accuracy of SPUS alone was 93 % (54/58) compared with RDUS accuracy of 94 % (33/35) (p = 1). When examining SPUS alone, there were 4 false-negative exams during the study period and 0 false-positive exams. The four incorrect ultrasounds were exam numbers 5, 15, 24, and 39. Three of these ultrasounds (5, 15, and 24) were in the first half of the study to yield a first half accuracy of 90 % (26/29). The
Table 1 Comparison of results
No. of patients
SPUS
SPUS ? clinical examination
RDUS
Combined study SPUS
Combined study SPUS ? clinical examination
Combined study RDUS
58
58
35
112
112
56
Sensitivity
27/31 (87 %)
29/31 (94 %)
14/14 (100 %)
50/60 (83 %)
56/60 (93 %)
17/20 (85 %)
Specificity Positive predictive value
27/27 (100 %) 27/27 (100 %)
26/27 (96 %) 29/30 (97 %)
19/21 (90 %) 14/16 (88 %)
51/52 (98 %) 50/51 (98 %)
47/52 (90 %) 56/61 (92 %)
33/36 (92 %) 17/20 (85 %)
Negative predictive value
27/31 (87 %)
26/28 (93 %)
19/19 (100 %)
51/61 (84 %)
47/51 (92 %)
33/36 (92 %)
Accuracy
54/58 (93 %)
55/58 (95 %)
33/35 (94 %)
101/112 (90 %)
103/112 (92 %)
50/56 (89 %)
123
Pediatr Surg Int
final incorrect ultrasound occurred in the second half of the study to yield a second half accuracy of 97 % (28/29). When examining the four false negatives for SPUS alone, the first had a BMI of 35 kg/m2, the second had BMI of 32 kg/m2, the third had a retrocecal appendix that was not seen, and the fourth had a non-retrocecal appendix that was not seen. In the first three cases, the patient had a CT scan positive for appendicitis. In the final case, the appendix was seen on radiology US. When SPUS was combined with clinical exam, the accuracy of SPUS increased to 95 % (55/58) with a sensitivity of 94 % (29/31) and specificity of 96 % (26/27). The two false negatives for SPUS plus clinical exam are described above and include the patient with a BMI of 32 kg/m2 and the patient with the retrocecal appendix. In the lone false positive for SPUS plus clinical exam the appendix was not seen, however, the patient had a history and physical exam consistent with acute appendicitis. At operation, he was noted to have an inflamed terminal ileum and was subsequently diagnosed with Crohn’s disease. When combined with the results of a study previously performed at our institution, overall SPUS accuracy was 90 % (101/112) and overall RDUS accuracy was 89 % (50/ 56). Between the two studies, the accuracy of RDUS improved from 81 % (17/21) to 94 % (33/35). SPUS accuracy also increased from 87 % (47/54) to 93 % (54/58) [9] (Table 1). Finally, the mean time to diagnosis for radiology department ultrasound was 135 min (n = 58) compared to 30 min (n = 58; p = 0.0001) for SPUS.
Discussion Ultrasound is increasingly being used as an extension of the physical exam and is being performed at the bedside by many different providers. Our institution has published several papers evaluating the utility and accuracy of SPUS for both hypertrophic pyloric stenosis and acute appendicitis [6–9]. This study examined whether SPUS for diagnosing acute appendicitis was reproducible and also examined if it decreased time to definitive diagnosis. As per the appendicitis protocol at our institution, the emergency department will order an US for suspected appendicitis on all patients with a BMI B35 kg/m2. Surgery consulted for US confirmed appendicitis, equivocal US (usually nonvisualization of the appendix), and also for negative studies when the ED has a high suspicion for appendicitis. In this study, combining RDUS and SPUS where the appendix was not seen 91 % (43/47) of those patients either did not have appendicitis on pathology or was discharged to home after observation and resolution of symptoms. Therefore, in our experience, a child with a
non-visualized appendix is unlikely to have appendicitis, especially if this is combined with a poor clinical picture for appendicitis. In our previous study, we showed that SPUS was equally efficacious as RDUS. Despite ultrasound being consistently described as operator dependent, we were able to show that when diagnosing acute appendicitis SPUS is reproducible. In this study, we again were able to diagnose acute appendicitis just as well as the radiology department. Approximately 2.5 years elapsed between the two study periods. As one would expect with increased exposure and number of exams performed the accuracy of the radiology department improved over this time period. Interestingly, the accuracy of SPUS performed by different research residents in each study also increased between the two studies. One possible explanation for the improvement in SPUS is that surgical residents are increasingly exposed to ultrasound and are more facile with this modality [13]. Although there are no published reports on the learning curve for diagnosing appendicitis with ultrasound, as with most physical skills, practice does improve performance. Similar to our previous study, this research resident had improved accuracy as the study progressed with three of four incorrect diagnoses coming in the first half of the study. In our experience, the learning curve of sonography is directly related to the structure being examined. We have shown that ultrasound of the pylorus can be learned with approximately five proctored exams and anecdotally ultrasound for line placement can also be learned with few proctored exams [7]. While the learning curve for appendicitis is certainly longer, we have shown that two surgical research residents were able to be accurate at this technique with between 20 and 30 exams [9]. When time to definitive diagnosis between RDUS, defined as time from US order to US read, was compared to SPUS, defined as time from notification of consult to completion of history, physical, and ultrasound, SPUS decreased time by approximately 100 min. Even though this might not make a difference clinically, it does make a difference in terms of patient satisfaction. Furthermore, decreasing time to diagnosis facilitates movement of patients out of the emergency department and frees up bed space. Compliance with ethical standards Conflict of interest of interest.
The authors declare that they have no conflict
References 1. Rao PM, Rhea JT, Noelline RA et al (1998) Effect of computed tomography of the appendix on treatment of patients and use of hospital resources. N Engl J Med 338:141–146
123
Pediatr Surg Int 2. Hagendorf BA, Clarke JR, Burd RS (2004) The optimal initial management of children with suspected appendicitis: a decision analysis. J Pediatr Surg 39:880–885 3. Grosfield JL (1996) American Board of Surgery. Bull Am Coll Surg 81:57–60 4. American College of Surgeons 79th Annual Clinical Congress (1993) Current management of blunt abdominal trauma, San Francisco, CA 5. Accreditation Council for Graduate Medical Education. http://www. acgme.org/downloads/RRC_progReq/440pr703.pdf. Accessed 1 March 2014 6. Boneti C, Mcvay MR, Kokoska ER et al (2008) Ultrasound as a diagnostic tool used by surgeons in pyloric stenosis. J Pediatr Surg 43:87–91 7. McVay MR, Copeland DR, McMahon LE et al (2009) Surgeonperformed ultrasound for diagnosis of pyloric stenosis is accurate,
123
8.
9.
10. 11. 12. 13.
reproducible and clinically valuable. J Pediatr Surg 44(1): 169–171 Copeland DR, Cosper GH, McMahon LE et al (2009) Return of the surgeon in the diagnosis of pyloric stenosis. J Pediatr Surg 44:1189–1192 Burford JM, Dassinger MS, Smith SD (2011) Surgeon-performed ultrasound as a diagnostic tool in appendicitis. J Pediatr Surg 46:1115–1120 Puylaert JB (1986) Acute appendicitis: US evaluation using graded compression. Radiology 158:355–360 Sivit CJ, Siegel MJ, Applegate KE et al (2001) When appendicitis is suspected in children. Radiographics 21:247–262 Brown MA (2008) Imaging acute appendicitis. Semin Ultrasound CT MR 29:293–307 Rozykci GS (1998) Surgeon-performed ultrasound, its use in clinical practice. Ann Surg 228:16–28
