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1 pissn eissn Kim YM and Chung JH: Cause of Abdominal Ultrasound Diagnostic Errors in Children with Acute Appendicitis J Korean Assoc Pediatr Surg Vol. 22, No. 2, December Original Article 소아급성충수염에서복부초음파진단오류의원인 김유미, 정재희 가톨릭대학교의과대학여의도성모병원외과학교실 Cause of Abdominal Ultrasound Diagnostic Errors in Children with Acute Appendicitis Yoo Mi Kim, Jae Hee Chung Department of Surgery, Yeouido St. Mary s Hospital, School of Medicine, The Catholic University of Korea, Seoul, Korea Purpose: The use of CT as a diagnostic tool in pediatric acute appendicitis is increasing because of its high sensitivity and specificity. However, due to both the serious concerns about radiation of CT and the convenience and reasonable cost of ultrasound (US) examination, US has value on the initial diagnosis of acute appendicitis despite of the lower sensitivity in children. The purpose of this study was to examine the factors that affect the rate of false negative diagnosis of the ultrasound from the patients who received laparoscopic appendectomy. Methods: The pediatric appendectomy cases from 2002 to 2013 in Yeouido St. Mary s Hospital have been reviewed through the medical records. We included patients who underwent an initial screening by ultrasound examination. Results: Among 181 patients, 156 patients were the sono-positive group and 25 patients were sono-negative group. There is no significant difference in ages, genders, physical examination findings and white blood cell count between the two groups. But, the degree of inflammation of appendicitis (simple, 58.3% vs. 32.0%; complicated, 41.7% vs. 68.0%) and the appendix position (antececal, 85.0% vs. 12.0%; retrocecal, 13.7% vs. 44.0%; pelvic, 1.3% vs. 44.0%) were significantly different between the two groups (sono-positive group vs. sono-negative group; p<0.05). Conclusion: The position of the appendix may act as a factor that causes an error in the diagnostic ultrasound, especially, in the retrocecal type and the pelvic type with the higher risk of necrosis or perforation. Keywords: Appendicitis, Ultrasonography, Diagnostic errors 서론급성충수염은약 7% 의유병률을가지는가장흔한복부응급질환이다 [1]. 정확한원인은알수없지만분석, 림프양증식증등으로인한내강폐색이원인이되어발생하며, 남자및 10대연령에서가장호발한다 [2]. 소아에서급성충수염의진단이어려운이유는증상이비특이적이며환아가통증에대해정확한표현을못하는경우도많고, 수술을필요로하지않고보존적으로도치료가되는다른질환도급성충수염과비슷한증상을나타내기때문이다. 오진율은문헌에따라 6.9% 에서 27.6% 까지보고하고있다 [3-5]. 오진에의해급성충수염수술이지연되면충수의천공이발생하기쉽고, 결국복막염및복강내농양, 패혈증, 장폐색등의합병증이발생하여입원기간이길어지며그로인한의료비용의상승이일어나고, 문헌에따라서 3.5 배에서 10배까지도사망률이증가한다고보고하고있다 [2]. 오진율및천공률이나이가어릴수록빈도가증가하여 1세이하에서는 100% 까지도증가한다 [2]. 따라서급성충수염은조기의정확한진단이중요하며, 주로임상적증상, 혈액검사및영상을이용한검사등을진단에종합적으로사용한다. 압박초음파방법이 1986년 Received: June 13, 2016, Revised: September 12, 2016, Accepted: October 11, 2016 Correspondence: Jae Hee Chung, Department of Surgery, Yeouido St. Mary s Hospital, School of Medicine, The Catholic University of Korea, ro, Yeongdeungpo-gu, Seoul 07345, Korea. Tel: , Fax: , jhjung@catholic.ac.kr Copyright 2016 Korean Association of Pediatric Surgeons. All right reserved. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Journal of Korean Association of Pediatric Surgeons 33

2 J Korean Assoc Pediatr Surg 2016;22(2):33-37 Puylaert [6] 에의해처음기술된이후로빠르게전세계적으로널리사용되어왔다. 최근에는초음파정확도에한계가있어, 컴퓨터단층촬영 (CT) 이나자기공명영상 (MRI) 등정확도높은진단방법들이소아급성충수염진단에초기검사로사용이늘어나고있다 [7,8]. 그러나 CT의방사선조사에대한우려와 MRI 의고비용의단점들이있는반면, 복부초음파의이용편리성및합리적인비용등의장점을고려할때초음파검사가여전히소아급성충수염의초기진단방법으로유용한가치를가지고있음은부인할수없다. 초음파의진단적한계를극복할수있는다른보완적방법에대한연구가진행되고있고, 이를통해초음파검사를소아의급성충수염의초기진단방법으로적극적으로사용해야한다고주장하고있다 [1]. 초음파검사는특이도가높아급성충수염을확진하는데는유용하나민감도가비교적낮아질환을확실히배제할수는없다 [7,9]. 어떠한경우가초음파검사의정확도를떨어지게하는지를알아보는것도이러한한계점을극복하는데에중요할것으로생각된다. 이에이번연구에서는본원에서수술로충수염을진단받았던환자중에서초음파검사의진단위음성률에영향을주는요인들을살펴보고자하였다. 대상및방법 2002년부터 2013년까지여의도성모병원에서급성충수염으로진단되어수술받은만 15 세이하의환자중초음파를초기검사로시행한환자들을선별하여의무기록을검토하였다. 환자의나이, 성별, 신체검진소견, 백혈구수치, 충수염의정도, 충수의위치, 초음파소견, 진단점수제점수, 초음파검사이외의진단을위해시행되었던검사등을조사하여비교하였다. 충수염의정도는단순형과복잡형으로나누었고단순형은화농충수염, 복잡형은괴저성충수염, 천공성충수염및충수주위농양을포함시켰다. 충수위치는맹장의앞쪽과옆쪽에위치하는것은전맹장형, 맹장의뒤쪽에위치하는것은후맹장형, 맹장의대부분이골반입구아래로들어가면서골반강내에위치하는것을골반강형으로나누었다. 소아충수염지수 (pediatric appendicitis score) 는 2002 년 Samuel [10] 이고안한것을사용하였다. 모든수술은복강경하충수절제술로시행되었다. 통계분석은 PASW Statistics 18.0 (IBM Co., Armonk, NY, USA) 을이용하여카이제곱검정과 t test 검정을이용하였으며, p값은 0.05 미만일때유의성이있는것으로하였다. 본연구는여의도성모병원기관연구윤리위원회의승인을얻었다 (SC16RISI0051). 결과 2002 년부터 2013 년까지수술및병리소견상급성충수염으로진단된환자중신체검사및검사실검사만으로수술을결정한환자, 초기검사로 CT를시행하였던환자, 초음파를초기검사로시행했으나의무기록상에서검사결과를확인할수없었던환자를제외하고, 연구대상이된초음파를초기검사로시행한환자수는총 181 명이었다. 이중충수염진단양성군은 156명, 진단음성군은 25명으로, 위음성률은 13.8% 였다. 초음파진단양성군및진단음성군의평균나이는각각 9.1 세, 10.5 세로유의한차이는없었으며, 양군모두남자에서호발하였다. 또한압통, 반동성압통, 근긴장등의신체검진소견, 백혈구수치도두군간차이가없었다 (Table 1). 충수염의정도에따라분류하여신체검진소견을비교하였을때도두군간차이가없었다. 그러나충수위치및충수염의염증정도에서는두군간에유의한차이가있었는데, 충수위치는전맹장형 (antececal type) 은진단양성군에서높았고 (85.0% vs. 12.0%), 후맹장형 (retrocecal type, 13.7% vs. 44.0%) 과골반강형 (pelvic cavity type, 1.3% vs. 44.0%) 은진단음성군에서유의하게높았다 (p<0.001). 충수염의염증정도에서, 화농성충수염의빈도는진단양성군에서높았고 (58.3% vs. 32.0%), 복잡성충수염은진단음성군에서유의하게높았다 (41.7% vs. 68.0%, p=0.014; Table 1). Table 1. Characteristics of Patients Who Received Appendectomy with Acute Appendicitis (n=181) Variable Sono-positive group (n=156) Sono-negative group (n=25) p-value Age (yr) 9.1± ± Sex Male 85 (54.5) 13 (52.0) Female 71 (45.5) 12 (48.0) WBC count (10 9 /L) 15.3± ± Seg. neutrophil counts (%) 80.6± ± Physical exam. on RLQ Positive DT 146/148 (98.6) 24/25 (96.0) Positive RT 104/148 (70.3) 19/25 (76.0) Positive MG 48/104 (46.2) 10/25 (40.0) Appendicitis type Simple 91/156 (58.3) 8/25 (32.0) Complicated 65/156 (41.7) 17/25 (68.0) Appendix location <0.001 Antececal 130/153 (85.0) 3/25 (12.0) Retrocecal 21/153 (13.7) 11/25 (44.0) Pelvic 2/153 (1.3) 11/25 (44.0) Values are presented as mean±sd or n (%). Seg., segmented; exam., examination; RLQ, right lower quadrant; DT, direct tenderness; RT, rebound tenderness; MG, muscle guarding. 34 Journal of Korean Association of Pediatric Surgeons

3 Kim YM and Chung JH: Cause of Abdominal Ultrasound Diagnostic Errors in Children with Acute Appendicitis Table 2. Characteristics of Patients with Negative Ultrasonographic Finding (n=25) Variable No. (%) of patients Ultrasonography findings No visualized appendix 18 (72.0) Normal appendix 7 (28.0) Fluid collection Yes 7 (28.0) No 18 (72.0) Pediatric appendicitis score 5 5 (20.0) (20.0) 8 15 (60.0) Time to operation from admission (hr) (68.0) >24 8 (32.0) Other imaging study No 12 (48.0) Repeat ultrasonography 2 (8.0) CT 11 (44.0) 초음파진단음성군의특징을살펴보면, 초음파소견상 18 예 (72.0%) 에서충수를찾을수없었고, 7예 (28.0%) 에서정상충수를관찰할수있었다. 그러나정상충수를보였던경우에한예만충수의끝까지관찰하지못하였음을기술하였고나머지는이에대한기술이없었다. 복수는 7예 (28.0%) 에서보였고나머지 18예 (72.0%) 에서는관찰되지않았다. 초음파진단음성군에서수술은 17예 (68.0%) 에서내원당일시행되었고 8예 (32.0%) 에서 24시간이후에시행되었다. 수술전다른진단적검사를추가적으로시행하지않은경우가 12 예 (48.0%) 였고, 초음파를다음날다시시행한경우가 2예 (8.0%), 복부 CT를당일또는다음날시행한경우가 11예 (44.0%) 에서있었다. 진단적검사를추가적으로시행하지않은 12예의경우는진단점수제를시행하여 10점만점에 8 점이상인경우에속하는경우로임상적증상을판단근거로삼았던경우였다 (Table 2). 고찰 급성충수염의진단에있어복부초음파는문헌에따라다르기는하지만, 민감도 78%-88% 와특이도 83%-94% 를가지고있다 [8]. 저자들이 2004년 59명의환자를대상으로전향적으로진단점수제와초음파검사를이용한급성충수염진단정확도에대한연구를시행하였고, 이때초음파의민감도는 77%, 특이도는 91% 였으며, 음성개복률은 3% (2/59) 였다 [11]. 이번연구에서는후향적인연구이지만 86.2% 의민감도와 13.8% 의위음성률을보여, 문헌들의보고와다르지않았다. 초음파검사의단점은특이도에비하여낮은민감도 를보이고, 검사자의숙련도에따라검사의정확도에영향을줄수있으며, 특히정규근무시간후에는더욱이용의제약이있을수있다는것이다. 본연구에서도이러한인자가영향을줄수있지만안타깝게도후향적연구이기때문에검사자및판독자를정확히알수없었고기록에의존할수밖에없었다. 그러나본병원에는숙련된소아방사선과전문의가상주하고있기때문에, 정규근무시간, 즉오후 5시이내에시행된검사는숙련된소아방사선과전문의의검수를받고판독되었다. 초음파진단음성군 25예중 7예 (28.0%) 가정규근무시간이후에시행되었다. 이러한초음파의단점과언제든지이용가능하고진단정확도가높아 95% 이상의민감도와특이도를가지는복부 CT의장점때문에최근에는소아에서도복부 CT 를내원하여처음시행하는검사로이용하는경우가많다. 그러나복부 CT의큰단점은소아에서방사선조사의위험과이로인한암발생에대한우려이다. 15세이하의소아에서방사선조사에의해발생하는악성질환으로부터사망하는추정위험도는약 0.07%-0.10% 정도이고, 나이가어릴때노출될수록더욱빈도가늘어나며, 소아에서 2번이상의 CT 를찍었을때백혈병과뇌종양이발생할확률이 3배로증가한다고한다 [12,13]. 이는소아에서는성장을위한조직세포들의세포분열이활발하기때문에방사선영향을좀더쉽게받게되기때문이다. 방사선조사를피하기위해최근복부 MRI 를소아에서시행하고있으며, 거의 100% 에가까운민감도와특이도를보고하고있다 [8]. 그러나우리나라와같이충수절제술이포괄수가제로지급되는의료체계에서는이런고가의검사는특수한상황이아니면, 현실적으로불가능한상황이다. 따라서소아에서충수염을진단하는데있어처음시행되는검사로초음파검사의필요성과중요성이다시강조되어야하며, 초음파검사의약점을보완하는방안을찾는데주력해야한다. 이러한목적에서본연구를시행하게되었으며, 어떤경우에위음성결과를보이는지파악함으로써이를보완하고자하였다. 본연구의결과를살펴보면초음파진단양성군및진단음성군의평균나이, 성별, 신체검진소견및백혈구수치모두두군간차이가없었다. 그러나충수위치및충수염의염증정도에서는두군간에유의한차이가있었는데, 충수위치가후맹장형이거나골반강형일때초음파의위음성률이높았고, 진단이지연되어진단음성군에서복잡성충수염의빈도가높았다. 2015년 Cohen 등 [9] 은복벽의두께와낮은통증점수가통계적으로위음성률과관계가있다고보고하고있다. 또한, 충수가보이지않을때음성예측도는 86.36% 이고, 보이지않는충수와백혈구수치가 7,500개 /μl 이하, 또는 11,000개 /μl 이하인소견이함께있을때음성예측도는각각 98.86%, 96.99% 까지상승된다고보고하였다. 본연구에 Journal of Korean Association of Pediatric Surgeons 35

4 J Korean Assoc Pediatr Surg 2016;22(2):33-37 서는초음파진단음성군의특징을살펴보면, 초음파소견상 18예 (72.0%) 에서충수를찾을수없었고, 7예 (28.0%) 에서정상충수를관찰할수있었다. 진단음성군에서백혈구수치가 11,000개 /μl 이하인예는 3예밖에되지않고그중 1예에서만 7,500개 /μl 이하였으며평균치는 15,500개 /μl 였다. 정상충수를관찰한 7예에서도충수의끝까지관찰하지못함을언급한경우는 2예가있었고, 나머지는언급이없었다. 2016년 Partain 등 [14] 은충수염이의심되는소아에서초음파의소견이애매할때충수를관찰하는것이외의이차적소견으로주변장의충혈, 복강내농양같은액체고임, 복수, 충수분석이나타날때충수염이아닌경우와비교하여유의하게충수염일가능성이높다고보고하였다. 그러나이러한소견은전체충수염환자중에최고 20% (8.1%-20.3%) 환자에서만나타나기때문에 [14], 이러한소견이없다고하더라도충수염을배제할수는없다. 본연구에서도복강내복수가고였던경우는 7예 (28.0%) 밖에안되고, 18 예 (72.0%) 에서는없었다. 저자들의연구에서진단음성군에서진단양성군에비해유의한차이를보였던것은충수위치와충수염의형태였는데, 문헌들에서보면충수돌기가후맹장형으로있을때는진단이어려워천공되는경우가많다고보고되고있지만 [15,16] 충수돌기의끝이골반강내로들어가있는경우에대해서는보고가거의없다. 그러나본연구에서는골반강형이진단음성군에서후맹장형과같은빈도를보이고있으며, 11 예중 9예에서복잡형이었고, 후맹장형에서는 11 예중 6예에서복잡형이어서, 골반강형에서도천공이된후에발견되는경우가많아보인다. 수술시기는초음파진단음성군에서입원시부터 24시간내에 17 예 (68.0%) 에서시행하였는데, 이렇게초음파로진단이어려웠음에도조기에수술을시행할수있었던것은임상적지표를바탕으로한진단점수제를바탕으로하여 8점이상에서는초음파의소견과관계없이수술을바로시행하였거나지체없이 CT 검사를진행하여충수염을진단하고수술한까닭으로생각된다. 그러나진단점수제만을이용하여수술을결정하는것은한계가있는데, 이는저자들의이전보고에서진단점수제의민감도는 100% 였으나특이도가 30% 밖에되지않아진단정확도는 72% 에불과했기때문이다 [11]. 문헌들에서도충수염의조기진단을위한초음파검사에추가되는임상적지표들과필요에따라복부 CT의적용을이야기하고있지만 [5,7,17] 저자들은일찍이 2002 년부터 Samuel [10] 의진단점수제와초음파검사를사용하였는데, 기준을보면, 5점이하에서는초음파소견과관계없이추적관찰하였고, 6점에서 7점사이에서는초음파소견에따라수술을결정하고, 8점이상에서는초음파소견과관계없이수술하였다. 1년간전향적으로 59명을대상으로시행하여 94.9% 의진단정확도를보고한바있었다 [11]. 이후로데이터를수집하지는않았지만임상에지속적으로적용해오고있었다. 그러나때에따라이프로토콜이지켜지지않고, 점수가 8점이상이었던 3예에서불필요한 CT 를시행하였고, 7 점이하였던 8명에서빠른진단을위해내원당일또는 2일째에 CT를시행하였다. 결론적으로, 충수염에서충수의위치는초음파의진단적오류를일으키는인자로작용할수있으며, 주로후맹장형및골반강형이이에해당하고, 괴사나천공의위험도가높아진다. 소아충수염에서초기진단검사로초음파를적극시행하며, 이의단점을보완하기위해진단점수제등을활용하여조기진단하고수술을결정하며, 필요에따라복부 CT를시행함으로써, 무분별한방사선조사로부터환자들을보호하는것이필요할것으로생각된다. CONFLICTS OF INTEREST No potential conflict of interest relevant to this article was reported. REFERENCES 1. Mostbeck G, Adam EJ, Nielsen MB, Claudon M, Clevert D, Nicolau C, et al. How to diagnose acute appendicitis: ultrasound first. Insights Imaging 2016;7: van den Bogaard VA, Euser SM, van der Ploeg T, de Korte N, Sanders DG, de Winter D, et al. Diagnosing perforated appendicitis in pediatric patients: a new model. J Pediatr Surg 2016;51: Galai T, Beloosesky OZ, Scolnik D, Rimon A, Glatstein M. Misdiagnosis of acute appendicitis in children attending the emergency department: the experience of a large, tertiary care pediatric hospital. Eur J Pediatr Surg 2016 Jan 8 [Epub]. s Reynolds SL. Missed appendicitis in a pediatric emergency department. Pediatr Emerg Care 1993;9: Rothrock SG, Skeoch G, Rush JJ, Johnson NE. Clinical features of misdiagnosed appendicitis in children. Ann Emerg Med 1991;20: Puylaert JB. Acute appendicitis: US evaluation using graded compression. Radiology 1986;158: Craig S, Dalton S. Diagnosing appendicitis: what works, what does not and where to from here? J Pediatr Child Health 2016;52: Duke E, Kalb B, Arif-Tiwari H, Daye ZJ, Gilbertson-Dahdal D, Keim SM, et al. A systematic review and meta-analysis of diagnostic performance of MRI for evaluation of acute appendicitis. AJR Am J Roentgenol 2016;206: Cohen B, Bowling J, Midulla P, Shlasko E, Lester N, Rosenberg H, et al. The non-diagnostic ultrasound in appendicitis: is a non-visualized appendix the same as a negative study? J Pediatr Surg 2015;50: Samuel M. Pediatric appendicitis score. J Pediatr Surg 2002;37: Journal of Korean Association of Pediatric Surgeons

5 Kim YM and Chung JH: Cause of Abdominal Ultrasound Diagnostic Errors in Children with Acute Appendicitis Chung JB, Jeon SY, Song YT. A clinical score and ultrasonography for the diagnosis of childhood acute appendicits. J Korean Assoc Pediatr Surg 2004;10: Brenner D, Elliston C, Hall E, Berdon W. Estimated risks of radiation-induced fatal cancer from pediatric CT. Am J Roentgenol 2001;176: Pearce MS, Salotti JA, Little MP, McHugh K, Lee C, Kim KP, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 2012;380: Partain KN, Patel A, Travers C, McCracken CE, Loewen J, Braithwaite K, et al. Secondary signs may improve the diagnostic accuracy of equivocal ultrasounds for suspected appendicitis in children. J Pediatr Surg 2016;51: Butler M, Servaes S, Srinivasan A, Edgar JC, Del Pozo G, Darge K. US depiction of the appendix: role of abdominal wall thickness and appendiceal location. Emerg Radiol 2011;18: Herscu G, Kong A, Russell D, Tran CL, Varela JE, Cohen A, et al. Retrocecal appendix location and perforation at presentation. Am Surg 2006;72: Yap TL, Chen Y, Low WW, Ong CC, Nah SA, Jacobsen AS, et al. A new 2-step risk-stratification clinical score for suspected appendicitis in children. J Pediatr Surg 2015;50: Journal of Korean Association of Pediatric Surgeons 37

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012임수진 Received : 2012. 11. 27 Reviewed : 2012. 12. 10 Accepted : 2012. 12. 12 A Clinical Study on Effect of Electro-acupuncture Treatment for Low Back Pain and Radicular Pain in Patients Diagnosed with Lumbar