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1 Korean J Gastroenterol Vol. 65 No. 2, pissn eissn ORIGINAL ARTICLE 우측대장에서대장내시경후굴에의한추가적인폴립발견율 김흥업, 부선진, 나수영, 송현주 제주대학교의학전문대학원내과학교실 Additional Polyp Detection Rate Using Colonoscopic Retroflexion in Right Colon Heung Up Kim, Sun-Jin Boo, Soo-Young Na and Hyun Joo Song Department of Internal Medicine, Jeju National University School of Medicine, Jeju, Korea Background/Aims: There have been several studies showing that retroflexion (RF) in the right colon (RC) could reduce the polyp miss rate of proximal colon during colonoscopy. This study was conducted to evaluate the additional benefit of RF technique in the RC. Methods: Patients who underwent colonoscopy from May 2008 to April 2011 were enrolled in the study. Data were obtained by retrospectively reviewing the medical records. RF was attempted in every patients undergoing colonoscopy since May 2008 except in cases of small RC vault, co-morbidity, severe diverticulosis, failed RF despite two trials, complaints of severe abdominal pain, or time burden. At first, RC was examined under direct vision. It was then examined by RF to detect missed polyps during the initial observation. Finally, the RC was re-examined with direct view. Results: The cumulative RF success rate in the RC was 78.84% (1,805 of 2,319). The RF success rate increased with the number of cases (50% at 160 cases, 70% at 400 cases, and reached near 90% over 1,000 cases). Few polyps (4.88%) were detected only with RF and the additional adenoma detection rate was 3.32%. The additional polyp/adenoma detection rates were higher in the old age group (p<0.01). There were no RF associated perforation or severe complication. Conclusions: Using RF examination, additional 4.88% of polyps could be detected in the RC. This technique could be a useful and safe method to detect hidden polyp during colonoscopy. (Korean J Gastroenterol 2015;65:90-98) Key Words: Ascending colon; Colonic polyps; Colorectal neoplasms; Diagnostic errors; Retroflexion 서론 국내에서대장암은남자에서두번째, 여자에서세번째로많이발생하며 2011년현재연평균 5.6% 의증가율을보이는주요한암이다. 1 대장암이전구단계인선종을거쳐암으로진행한다는것은잘알려진사실이고, 이를조기에발견하기위해내시경을통한선별검사가시작되었는데, 과거일부에서는 S자결장경도사용했지만절반이상의환자에서원위대장에선종이없이근위대장에만선종이발견되어, 실질적인대장암의선별검사로대장내시경의중요성이부각되었다. 2 대장암선별검사후대장암사망률이감소하는것은잘알려져있으나발생부위별로나누어보았을때선별검사후좌측대장암발생률, 3 유병률, 4 사망률은 4-6 모두감소하였으나우측대장에서는뚜렷하지않았다. 대장내시경선별검사에서발견되지못하고간과된폴립에의해중간암이발견될독립적예측인자로고령, 대장게실, 우측대장암, 비전문가에의한시술, 일부에서는여성등을들수있으며, 7,8 그빈도는 2-6% 이고우측대장에가장많았다. 8 이러한중간암은시술자관련요인이나구조적인원인으로발생할수있는데, 좌측보다는우측대장에서 3배나더호발하는경향이있고, 대장폴립은 Received November 2, Revised December 15, Accepted December 16, CC This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright Korean Society of Gastroenterology. 교신저자 : 김흥업, , 제주시아란 13길 15, 제주대학교병원소화기내과 Correspondence to: Heung Up Kim, Department of Internal Medicine, Jeju National University Hospital, 15 Aran 13-gil, Jeju , Korea. Tel: , Fax: , Kimhup@jejunu.ac.kr Financial support: This study was supported by clinical research grant of Jeju National University Hospital. Conflict of interest: None. Korean J Gastroenterol, Vol. 65 No. 2, February

2 Kim HU, et al. Retroflexion Polyps in the Right Colon 91 크기와관계없이편평형에서암이동반되었을가능성이더높은데, 9 전구단계의선종도우측대장에서는작고편평한모양으로잘발견되지않는특성이있으며, 10,11 편평하여잘발견되기힘든톱날폴립 / 선종도주로우측대장에호발하므로, 우측대장을검사할때더욱신중한검사가요구된다 우측대장관찰시폴립간과율을낮추기위한일환으로사각지역을최소화하기위한다양한시도들이있는데, 그중내시경선단을후굴하여검사하는방법이있으나천공의가능성때문에일부폴립절제술에서만시도해야한다는보고가있었다. 15 제1저자는이논문을바탕으로우측대장의폴립절제시내시경선단의후굴을시도해보다가이러한검사기법이비교적안전하고숨어있는폴립을발견하는데도움이된다는것을알게되어적응증을조금씩넓혀왔고그결과를보고하려고한다. 대상및방법 1. 대상과대장내시경종류 2008년 5월부터 2011년 4월까지제주대학교병원내시경실에서한명의내시경의가시행한결과를후향적으로분석하였다. 사용한내시경기종은 Olympus CF-Q240AI, CF-Q260AI, CF-H260AI (Olympus, Tokyo, Japan) 으로모두중간길이의대장내시경이었다. 대상자의역학적자료, 진단또는치료내시경, 폴립의수, 조직소견은의무기록을후향적으로분석하여얻었다. 내시경선단이맹장과말단회장까지도달한경우만대상에포함시켰고, 장정결도는따로분석하지않았으나대변이너무많아검사가제대로이루어지지못한경우는대상에포함시키지않았다. 진정처치유무는포함시키지않았고다만 2010년초반까지는내시경을위한진정처치를거의하지않아진정없이검사한경우가대부분이었다. 진단된폴립을추후다시폴립절제한경우는중복을피하기위하여두가지검사의결과를통합하여치료내시경으로처리후결과를정리하였다. 이연구는제주대학교병원연구윤리위원회로부터승인을받아진행하였다 (JNUH IRB file number ). 2. 검사방법 Fig. 1. The fluoroscopic X-ray shows retroflexed tip of colonoscope in the right colon. 우측대장은맹장과상행결장으로국한하였다. 내시경당시검사방법을일관성있게진행하였고모든대상자에서대장내시경을삽입하여맹장과말단회장부까지삽입이성공하면상행결장의이물질을제거한후우측대장전반을직시하에서관찰하였다. 이때선단에캡은부착하지않았고내시경선단으로횡행주름을눌러가며폴립을확인하였다. 그다음공기를충분히넣어대장내강을확장시킨다음내시경선단을가급적맹장부까지위치시키고서서히후굴하였는데 (Fig. 1), 후굴의방법은내시경조절장치를최대한상방향굴절과좌방향굴절하면서내시경을좌방향으로비틀어회전시켰다. 16 후 Fig. 2. The grade of retroflexion in the right colon. (A) Grade 1, less than two haustral folds are seen. (B) Grade 2, 3-4 haustral folds are seen. (C) Grade 3, more than five haustral folds are seen as full circumference and straight lumen. Vol. 65 No. 2, February 2015

3 92 김흥업등. 우측대장후굴폴립 굴을시행하지않았던경우는심각한질환이있거나전신상태가좋지않은경우, 후굴시도중환자가심한통증을호소하는경우, 단축이제대로되지않은경우, 우측대장내강이좁은경우, 맹장과상행결장에게실이많은경우, 점막의염증상태가심한경우, 환자의협조가좋지않은경우, 2회의시도에서성공하지못한경우, 시간적여유가없는경우등이었다. 후굴이이루어지면대장에고여있는액체를흡인하면서근위부에서서서히원위부까지관찰하고간만곡부에다다랐을때중지하였다. 간만곡부근처에서는다시이물질을제거하고관찰하였고, 반전상태의관찰이끝나면내시경을가능한한우측대장의근위부로밀어넣고상하-좌우조정간을서서히풀면서천천히굴곡을해제하였다. 이때환자가긴장을하고있으면긴장이풀릴때까지공기를주입하면서기다렸다가서서히굴곡을해제하였고, 그다음내시경선단을맹장까지재삽입하여다시맹장과상행결장을확인하였다. 이렇게 3단계로상행결장을확인했는데, 각단계별로최소 2장의사진을남기는것을원칙으로하였고이사진을토대로이후후굴의정도를평가하였다. 후굴의정도는 3가지단계로평가하였는데, 1단계는 1-2개의전주상의횡행주름만관찰되는경우로대략대장내시경의굴곡부가상행결장의중위부나원위부에, 선단이원위부에위 치한경우로했고, 2단계는전체둘레가관찰되는횡행주름이 3-4개일경우로선단이중위부에위치한경우로했으며, 3단계는 5개이상의횡행주름이완전한상태에서일직선상으로관찰되는경우로하였다 (Fig. 2). 또한상행결장을대략 Fig. 3. The learning curve of retroflexion (RF) of colonoscope in right colon. The RF success rates improved with increasing number of cases. The RF success rate was 50% at the point of 160 cases. At 400 cases, the rate improved to 70%, and then reached 90% after 1,000 cases. Fig. 4. A case of advanced colon cancer detected by retroflexion of colonoscope in the proximal portion of remnant colon. The patient was 69-year-old female who underwent right hemicolectomy for colon cancer one year ago. (A) The lesion could not be detected by direct vision. (B) During retroflexion, about 1 cm sized IIa+IIc lesion was clearly detected. After rescue surgery, the lesion confirmed to be well differentiated adenocarcinoma with proper muscle invasion. The Korean Journal of Gastroenterology

4 Kim HU, et al. Retroflexion Polyps in the Right Colon 93 적으로 3등분하여근위부, 중위부, 원위부로나누었다. 내시경후굴법의숙련도는매 100예마다후굴성공률을계산하여구하였다 (Fig. 3). 후굴상태에서만확인이가능한폴립을후굴폴립 (retroflexion polyp) 이라고정의하고결과지에따로기재하였으며, 첫번째단계에서발견되지않고후굴상태에서처음발견되었다가이후세번째직시하검사에서다시관찰가능한폴립은대상에서제외하였다. 대장을수술한예에서도똑같이적용하되아전대장절제술은대상에서제외하였고, 우반대장절제술을받은경우에는회장-대장문합부에서간방향으로주행하다가꺾어지는형태상의간만곡부까지를우측대장으로간주하여검사하였다 (Fig. 4). 폴립의조직학적분류는과형성폴립, 고분화선종, 저분화선종, 선암으로구분하였고, 톱날폴립은아직조직학적분류기준이정립되지않은것을감안하여분화도에따라선종으로분류하였다. 3. 통계대상자의특성에서후굴에성공한군과그렇지않은군을비교할때연령의비교에는독립표본 t-test를사용하였고성별, 진단및치료내시경의구분을비교할때는카이제곱검정을사용하였으며, p<0.05인경우유의하다고판단하였다. 후굴성공예를대상으로남녀별, 연령군별로성별또는평균연령의차이, 후굴의정도, 후굴폴립의크기를비교할때에는독립표본 t-test를사용하였고, 반전의정도, 후굴폴립의개수, 위치, 조직비교에는카이제곱검정을사용하였으며, p<0.05인경우유의하다고판단하였다. 또한변수의성격은후굴의정도와폴립의위치, 그리고조직의종류에서는순위척도를사용하였다. 후굴폴립의발견위치에따라후굴폴립의개수, 조직을비교할때는카이제곱검정과일원분산분석을사용했고 p<0.05인경우유의하다고판정하였다. 결과 1. 우측대장에서후굴성공요인총 2,319명이선정되었고시술자의평균맹장까지삽입시간은 5.16±3.44분이었다. 조직생검수기코드로계산한대략적인전체폴립발견율은 62.6% 였으며, 실제우측대장에국한된폴립발견율은전체대장내시경의 23.20% (538명) 였다. 평균연령은 57.84±12.84세, 남자가 1,451명 (62.57%), 여자가 868명 (37.43%) 이었다 (Table 1). 이중우측대장에서후굴에성공한경우가 1,805명으로 77.84% 의성공률을보였고, 남자에서는 1,124명 (77.46%), 여자는 681명 (78.46%) 으로성비에따른후굴의성공률차이는없었다 (p=0.58). 성공한군과실패한군의연령은각각 57.03±12.67세와 60.68±13.06 세로성공한군의연령이낮았다 (p<0.01). 맹장까지삽입시간은후굴성공군에서는 4.86±2.93분, 실패군에서는 6.84±5.19 분으로통계적으로매우유의하게성공군에서삽입시간이짧았다 (p<0.01). 우측대장에서후굴과관련하여발생한천공등의심각한합병증은없었고후굴중일시적인복통, 경미한점막손상등이일부관찰되었다. 2. 우측대장에서후굴에성공한군의특성우측대장에서후굴에성공한 1,805명중남자와여자가각각 1,124명, 681명이었다 (Table 2). 평균연령은남자와여자에서각각 57.25±12.43세와 56.67±13.06세로남녀간차이는없었다 (p=0.35). 60세미만 ( 약년군 ) 과 60세이상 ( 고령군 ) 의연령군별로나누었을때약년군은 942명 (52.19%), 고령군은 862명 (47.76%) 이었고이들의평균연령은각각 47.37± 9.02세, 67.59±5.78세였다. 후굴의정도를나누어보았을때 1, 2, 3단계가각각 192명 (10.64%), 919명 (50.91%), 694명 (38.45%) 이었고성별로나누었을때남자가각각 114명 (10.14%), 549명 (48.84%), 461명 (41.01%), 여자는각각 78명 (11.45%), 370명 (54.33%), 223명 (32.75%) 으로, 남자에서우측대장의보다근위부에서후굴에 Table 1. Comparison of Retroflexion (RF) a Success and Failure Group RF success RF failure Total p-value Patient 1,805 (78.84) 514 (21.16) 2,319 Age (yr) 57.03± ± ±12.84 <0.01 Sex 0.58 Male 1,124 (77.46) 327 (22.54) 1,451 (62.57) Female 681 (78.46) 187 (21.54) 868 (37.43) Insertion time b,c (min) 4.86± ± ±3.44 <0.01 Values are presented as n (%) or mean±sd. a RF of colonoscope in the right colon; b cecal intubation time. c RF success: n=1,457, RF failure: n=258, total: n=1,715. Vol. 65 No. 2, February 2015

5 94 김흥업등. 우측대장후굴폴립 Table 2. Analysis of the Success Cases of Retroflexion (RF) in the Right Colon and RF Polyps according to Sex and Age Group Variable Total Sex Age group (yr) Male Female p-value <60 60 p-value Patient 1,805 1,124 (62.27) 681 (37.72) 942 (52.19) 862 (47.76) Age (yr) 57.03± ± ± ± ±5.78 Grade of RF a Grade (10.64) 114 (10.14) 78 (11.45) (9.87) 99 (11.48) <0.01 Grade (50.91) 549 (48.84) 370 (54.33) 452 (47.98) 467 (54.18) Grade (38.45) 461 (41.01) 223 (32.75) 397 (42.14) 297 (34.45) RF PDR b 88 (4.88) 57 (5.07) 31 (4.55) (2.76) 62 (7.19) <0.01 RF PDR by grade c Grade 1 9 (0.50) 6 (0.53) 3 (0.44) (0.53) 4 (0.46) Grade 2 43 (2.38) 25 (2.22) 18 (2.64) 8 (0.85) 35 (4.06) Grade 3 36 (1.99) 26 (2.31) 10 (1.47) 13 (1.38) 23 (2.67) Number of RF polyp d 1 83 (4.60) 55 (4.89) 28 (4.11) (2.76) 57 (6.61) (0.22) 1 (0.09) 3 (0.44) 0 4 (0.46) 3 1 (0.06) 1 (0.09) (0.12) RF ADR b 60 (3.32) 39 (3.47) 21 (3.08) (1.80) 43 (4.99) <0.01 RF ADR by grade c Grade 1 7 (0.39) 4 (0.36) 3 (0.44) (0.42) 3 (0.35) 0.07 Grade 2 26 (1.44) 15 (1.33) 11 (1.62) 4 (0.42) 22 (2.55) Grade 3 27 (1.50) 20 (1.78) 7 (1.03) 9 (0.96) 18 (2.09) Size of RF polyp e 4.5± ± ± ± ± Distal 32 (1.77) 23 (2.05) 9 (1.32) (1.17) 21 (2.44) 0.25 Mid 53 (2.94) 32 (2.85) 21 (3.08) 11 (1.17) 42 (4.87) Proximal 10 (0.55) 6 (0.53) 4 (0.59) 4 (0.42) 6 (0.70) Total 95 (5.26) 61 (5.43) 34 (4.99) 26 (2.76) 69 (8.00) Histology of RF polyp e HPP 31 (1.72) 20 (1.78) 11 (1.62) (0.96) 22 (2.25) 0.81 LGD 53 (2.94) 33 (2.94) 20 (2.94) 14 (1.49) 39 (4.52) HGD 9 (0.50) 8 (0.71) 1 (0.15) 3 (0.32) 6 (0.70) Cancer 2 (0.11) 0 2 (0.29) 0 2 (0.23) Values are presented as n (%) or mean±sd. RF polyp/adenoma, the polyp or adenoma only detected by retroflexion of colonoscope in the right colon; ADR, adenoma detection rate; PDR, polyp detection rate; HPP, hyperplastic polyp; LGD, tubular adenoma with low grade dysplasia (including sessile serrated adenoma); HGD, tubular adenoma with high grade dysplasia; Cancer, all case of adenocarcinoma. a Grade 1, less than 2 folds are seen; Grade 2, 3-4 haustral folds are seen as full circumference; Grade 3, more than 5 haustral folds are seen as full circumference and straight lumen. b Additional adenoma or polyp detection rate in right colon by retroflexion of colonoscope. c The number of RF polyp or adenoma detected in each grade of retroflexion. d The number of RF polyp detected in single person. e The number in the blank is calculated as a percentage of the number of polyps in each group. 성공한경우가유의하게많았다 (p=0.02). 연령군별로나누었을때는단계별로약년군은 93명 (9.87%), 452명 (47.98%), 397 명 (42.14%) 이었고고령군은 99명 (11.48%), 467명 (54.18%), 297명 (34.45%) 으로나이가젊은군에서우측대장의보다근위부에서후굴에성공한경우가유의하게많았다 (p<0.01). 우측대장에서후굴폴립이발견된경우는총 88명 (4.88%) 으로남자와여자가각각 57명 (5.07%), 31명 (4.55%) 으로남녀간에차이는없었고 (p=0.73), 연령군별로약년군과고령군에서각각 26명 (2.76%), 62명 (7.19%) 으로고령군에서유의하게추가적인후굴폴립이많았다 (p<0.01). 후굴정도에따 른후굴폴립발견율은남녀군에서차이가없었고 (p=0.42), 연령군별비교에서 1단계는약년군과고령군에서각각 5명 (0.53%) 과 4명 (0.46%), 2단계는 8명 (0.85%) 과 35명 (4.06%), 3 단계는 13명 (1.38%) 과 23명 (2.67%) 으로고령군에서후굴단계별로후굴폴립발견율이높았다 (p=0.046). 한명당 1개의후굴용종이발견된경우가 88명중 86명으로가장많았고 2개가 4명, 3개가 1명이었으며, 성별 (p=0.18), 연령군별 (p=0.33) 차이는없었다. 후굴선종발견율은 1,805명중 60명이발견되어 3.32% 였으며, 남녀군에서각각 39명 (3.47%), 21명 (3.08%) 으로차이 The Korean Journal of Gastroenterology

6 Kim HU, et al. Retroflexion Polyps in the Right Colon 95 Table 3. Characteristics of the Retroflexion (RF) Polyps according to Site in the Right Colon Total Distal Mid Proximal p-value Number of RF polyp Size of RF polyp (mm) 4.5± ± ± ± Histology of RF polyp HPP 31 (32.63) 11 (34.38) 19 (35.85) 1 (10.00) 0.09 LGD 53 (55.79) 14 (43.75) 30 (56.60) 9 (90.00) HGD 9 (9.47) 5 (15.63) 4 (7.55) 0 Cancer 2 (2.11) 2 (6.25) 0 0 Values are presented as n only, mean±sd, or n (%). RF polyp/adenoma, the polyp or adenoma only detected by retroflexion of colonoscope in the right colon; HPP, hyperplastic polyp; LGD, tubular adenoma with low grade dysplasia (including sessile serrated adenoma); HGD, tubular adenoma with high grade dysplasia; Cancer, all case of adenocarcinoma. 없었으나 (p=0.64), 연령군별로구분했을때약년군에서 17명 (1.80%), 고령군에서 43명 (4.99%) 으로고령군에서유의하게후굴선종발견율이높았다 (p<0.01). 그러나후굴정도에따라나누었을때는성별 (p=0.41), 연령군별 (p=0.07) 차이는없었다. 후굴폴립의크기는 4.5±2.4 mm로, 성별 (p=0.36), 연령군별 (p=0.90) 로차이는없었다. 발견된후굴폴립의총개수는 88명중 95개였으며, 우측대장의원위부 ( 간만곡인접부 ), 중간부, 근위부 ( 맹장인접부 ) 에서각각 32개 (1.77%), 53개 (2.94%), 10개 (0.55%) 로, 성별 (p=0.54), 연령군별 (p=0.25) 차이는없었다. 후굴폴립의조직은과형성폴립이 31개 (1.72%), 고분화선종이 53개 (2.94%), 저분화선종이 9개 (0.50%), 선암이 2개 (0.11%) 였고, 역시성별 (p=0.11), 연령군별 (p=0.81) 차이를보이지않았다 (Table 2). 3. 후굴폴립의특성발생위치에따른후굴폴립의특징을비교해보면 (Table 3), 원위부, 중위부, 근위부에각각 32개, 53개, 10개가발견되었고, 그크기는각각 5.2±2.4 mm, 4.2±2.1 mm, 4.7±2.9 mm로차이가없었다 (p=0.15). 후굴폴립의조직은과형성폴립의경우원위부, 중위부, 근위부에서각각 11개, 19개, 1 개였고, 고분화선종은 14개, 30개, 9개였으며, 저분화선종은 5개, 4개, 0개였고, 선암은 2개, 0개, 0개로분포해, 위치에따른조직의차이를보이지않았다 (p=0.09). 4. 우측대장에서내시경후굴의숙달도후굴의숙달도추이를보면증례가늘어날수록성공률도증가하여 160예까지는대략 50% 에서후굴에성공하였고 400 예에서는 70%, 1,000예이상에서는 90% 에근접하여점차향상되었다 (Fig. 3). 후굴의정도는증례에따라분포양상에큰변화가없었다. 또한같은기간우측대장에서내시경후굴에따른천공이나심각한합병증은한건도없었으며일부에서후굴시도 중일시적인통증을호소하거나점막의미란또는열상이발생한경우가있었다. 5. 후굴에의해서만관찰된선암증례이번연구중 2예에서선암이발견되었는데, 한예는상피내암이었고다른한예는근육층까지침범한선암이었다. 후자의경우엄격한의미에서상행결장은아니지만직시하에서는어떠한조작에의해서도발견되지않고오로지후굴했을경우만뚜렷하게관찰되었던증례였다 (Fig. 4). 고찰 대장내시경에서폴립을간과하는이유는크게시술자관련요인과 구조적인요인을들수있다. 구조적요인으로는병변이횡행주름의근위부나만곡부의소만측에있는경우, 편평한병변, 대장정결도가좋지않은경우등이거론되고있다. 10,20-22 대장은일자형의관강구조가아니고횡행주름과만곡등내시경검사중시야를가리는구조물이많아사각지대를줄이기위한노력이필요하다. 컴퓨터단층촬영대장조영술을이용하여대장내시경의관찰효율을알아본결과현재표준으로사용하고있는 140도표준시야각의내시경으로는전체대장내강면적의약 85% 를관찰할수있어 23 15% 에달하는사각지대를해결하는것이큰숙제로남아있다. 이를위해먼저생각할수있는것이내시경의시야각을늘리는것인데, 170 도광각으로설정했을때이론상 92% 의대장면적을관찰할수있었다. 23 일부에서는광각내시경을적용한제품이출시되고있는데, 가장대표적인것이 Full Spectrum Endoscopy (Fuse; EndoChoice Inc., Alpharetta, GA, USA) 로, 160도시야각을갖는내시경좌우측면에각각카메라를추가하여시야각을 330도까지확장하여횡행주름등에가려진병변을찾아내는데유용하다고알려져있다. 24,25 Vol. 65 No. 2, February 2015

7 96 김흥업등. 우측대장후굴폴립 시야각외에대장내시경중선종발견의구조적인문제를해결하기위한노력들이있어왔는데효과가있다고알려진것은고해상도내시경, 협대역내시경, 자가형광영상, 물-교환대장내시경, 캡-보조대장내시경, 내시경후굴법, Third Eye Retroscope (TER; Avantis Medical Systems Inc., Sunnyvale, CA, USA) 등이다. 24 물-교환 (water-exchange) 대장내시경으로선종발견율을높였다는보고가있으나일부에서는이러한이점이단순히환자의안락감을높인결과라고생각하고있고, 24 고해상도대장내시경, 협대역내시경, 자가형광영상은사각지대의해결이라기보다는직시하에서보이는점막의병변을보다잘보이게하여선종발견율을높이는것이다. 24 그러므로대장내시경검사의구조적인문제를해결하기위한현실적인대안으로는캡-보조대장내시경, 내시경후굴법, TER을꼽을수있겠다. 캡-보조대장내시경은선단에투명캡을붙여대장주름을누르면서관찰할수있다는이점이있고맹장삽입시간을단축시키는데도움이되나선종발견율의향상에대해서는일부부정적인견해를보이는서구연구자들도있고, 26 대장주름을누르는장점은있으나돌출된캡이오히려시야를방해하는단점이있다. 이론적으로반대방향에서쳐다보는후굴기법을사용한다면 98% 의대장면적을관찰할수있다고계산된바있다. 23 TER은선종발견율을 11-16% 향상시켰는데, 27,28 이기구의문제는흡입구를통해삽입하므로고여있는물을흡인하기곤란하고, 다른검사를위해서는이기구를빼고필요한기구를삽입해야하므로검사시간이길어져특히폴립절제시불편할수있으며, 일회용으로경제적인부담이생긴다는것이다. 27,28 또후굴경의해상도가떨어지는것도문제이고실제현장에서는시간적, 경제적인면이고려되어야하므로 TER이나 Fuse 등의장비를바로도입하기는어려울것으로생각된다. 이러한관점에서본다면현실적으로는대장내시경후굴법이매력적이다. 위내시경에서는저부를관찰하기위해대부분의경우후굴법을사용하나대장의경우는관강이좁아일상적으로사용하기힘들다. 주로직장에서치상선을관찰할때많이사용하며유용성논란에도불구하고대체적으로시행할것을권고하는상황이다 직장에서대장내시경의후굴이가능한이유는직장의관강이크기때문인데, 맹장을포함한우측대장도관강의크기가커대장내시경의후굴이가능하다. 대장내시경의후굴은부가적인기구를사용하지않기때문에시간적, 경제적인비용이추가로들지않으면서이론적으로 TER과유사한효과를기대할수있다. 우측대장의선종발견율이후굴에의한검사에도향상되지않는다는초기보고가있었고 33 후굴에의한대장천공의문제점이제시되었으나, 15 간만곡부의내측면등직시하에서관찰이어려운부분을해결하기위해후굴에대한연구가지 속되었는데, 16 이후연구에서는폴립의완전절제에도움이되고 15,34 추가적인폴립과선종 (5.80%, 4.40%) 을발견할수있는방법이라고소개되고있다. 16 방법론에서도과거이론적으로후굴이용이한소아대장내시경을사용하였으나, 35 최근연구에서는대부분성인용대장내시경을사용하였고, 오히려성인용이소아용대장내시경보다후굴성공률이높았다 (p=0.045). 16 저자들은 2008년부터후굴방법을적용하기시작했는데, 처음부터적극적으로시행하지못했던이유는천공발생에대한불안감때문이며이것이후굴숙련도가느리게상승한주원인이었다 (Fig. 3). 우측대장에서후굴하여원위부로검사를진행하다보면횡행결장까지순조롭게진행되는경우도있지만단축이잘된경우에서는오히려간만곡부가위분문부처럼접히고좁아져있는경우를많이보았기에, 상행결장부터횡행결장까지를일괄하여후굴검사를하기는힘들었다. 우측대장에서후굴에성공한군과실패한군을나누었을때성공한군의연령이실패한군의연령보다약 3세가량낮았는데 (p<0.01), 이는아마도고령자의경우전신상태가좋지않고동반질환이있어무리하게후굴을시도하지않았기때문으로생각된다 (Table 1). 특히후굴성공군이실패군보다맹장삽입시간이짧았는데 (p<0.01), 이는삽입이용이한군에서후굴성공률이더높다는것을의미한다. 내시경후굴에성공한군을성별, 연령군별로나누었을때남자 (p=0.02), 약년군 (p<0.01) 일수록보다근위부에서후굴이성공한경우가많았다. 이는여자의경우조금더민감하여맹장측에서후굴할때불편감이나통증을더많이호소하고단축이덜된경우가많으며, 고령인경우전신상태를고려하여과감하게시도하지못한것이원인으로생각된다. 성별, 연령군별로발견된후굴폴립의동시발견빈도, 발견위치, 조직분포는차이가나지않았다. 다만후굴의정도를분석했을때성별차이는없었지만연령군별로나눌때고령군에서간만곡부근처에서만성공한예가많아 (p<0.01), 고령군에서는후굴성공률도낮고완전하게하기도힘든것으로나타났다. 후굴폴립의발견율은 4.88% 로, 성별차이는없었으나 (p=0.73) 약년군과고령군에서각각 2.76%, 7.19% 로고령군에서후굴폴립의발견율이높았는데 (p<0.01), 이는고령군에서폴립이더많으므로사각지역폴립또한같은빈도로많았던것으로생각된다. 그러므로고령에서후굴이힘들다하더라도시도를해볼가치가있다. 고령, 남자, 감시내시경상황, 직시하검사에서폴립이발견되었을경우후굴에의한검사에서추가적인폴립이발견될독립적인예측인자라하였으나, 16 이번연구에서는성별에따른차이를발견할수없었고연령별차이만발견할수있었다. 이번연구에서성별차이가없었던이유에대해서는추후다시검증해볼필요가있다고생각한다. 우측대장에서후굴에 The Korean Journal of Gastroenterology

8 Kim HU, et al. Retroflexion Polyps in the Right Colon 97 의한추가적인폴립발견율 4.88% 와추가적인선종발견율 3.32% 는기존에알려진 5.8% 와 4.4% 에 16 비해크게다르지않은결과를보여주었다. 중간암발생률이우측대장에서가장많다는점을고려하면, 8 우측대장에서후굴등의보다적극적인방법으로폴립의간과를방지하는것이필요하며최소한후굴에의해추가적으로발견된선종만큼의중간암발생은감소할것으로기대한다. 이번연구의단점은단일내시경의에의한후향적연구라는점, 그리고 3단계의완벽한우측대장의후굴관찰이이루어진경우가적었다는점을들수있다. 3단계의완벽한후굴성공이 40% 로낮은것처럼보이지만, 이는기존서구의결과와유사한성적이었으므로 33 우측대장의전체를후굴로보지못한것이이번연구에국한된것으로만볼수없고, 후굴의숙달도를후굴의정도로나누어보았을때 (Fig. 3) 3단계의가장완벽한후굴이시간이갈수록증가하기보다는각단계별로일정비율로나타나고있어구조적인문제도있을것으로생각된다. 또한후굴방법은우반대장절제술후감시내시경을할때유용하게사용할수있을것이라생각된다. 이번연구에등록된한증례에서도직시하에서는관찰되지않았으나, 후굴에의해서 1 cm 크기의융기함몰성선암병변이관찰되어수술적치료를받았다 (Fig. 4). 폴립발견의첫단계는폴립여부를인지하는것인데, 내시경선단으로주름을뒤져서숨어있는폴립을볼수있는시간은매우짧은경우도있어자칫간과하고넘어갈가능성이있다. 반면후굴의방법은대장주름의근위면에숨은폴립을충분히인지할수있는시간적인여유를주고사각지역이줄었다는자신감을줄수있다. 1개의후굴폴립을발견하기위해서최소 20명의대장내시경검사에서후굴을시도해야하지만후굴에숙달된경우라면가치가있다고생각되며, 향후후굴방법이폴립발견율을높일수있는합리적대안이될수있는지에대한전향적다기관연구가진행되어야할것이다. 요약 목적 : 우측대장의대장내시경검사중선단을후굴하여검사하면폴립간과율을낮춘다는보고들이있다. 이를토대로저자는 2008년 5월부터대장내시경을하는모든환자를대상으로우측대장에서후굴을시도하여숨어있는폴립을찾는시도를하였다. 이에우측대장에서후굴법이폴립발견에있어추가적인이득이있는지를알아보기위하여이번연구를진행하였다. 대상및방법 : 2008년 5월부터 2011년 4월까지 1인의내시경의에의해시행된대장내시경기록을후향적으로검토하였다. 같은기간중가능한모든예에서우측대장에서후굴을시행 하였고우측대장의직경이작거나전신상태가좋지않은경우, 동반된질환이있는경우, 우측대장게실이많은경우, 2회이상의시도에도성공하지못한경우, 심한복통을호소하거나내시경스케줄이바쁜경우는대상에서제외하였다. 처음에는직시하검사로우측대장을관찰하고다음을후굴을시도하여간과된폴립을찾으려고노력하였고마지막단계에서다시직시하검사를하였으며각단계에서적어도 2장이상의사진을기록으로남겼다. 의무기록을후향적으로분석하여성별, 연령별차이, 후굴성공여부, 후굴폴립의개수, 크기, 조직을조사하였다. 결과 : 총 2,319명중 1,805명이후굴에성공하여우측대장에서후굴의누적성공률은 78.84% 였다. 증례가늘어날수록후굴의성공률도높아져 160예에서 50%, 400예에서 70%, 그리고 1,000예이상에서는 90% 가까이도달한후점차상승했다. 이방법으로 4.88% 의추가적인폴립과 3.32% 의선종이발견되었고, 고령일수록후굴성공률과근위부후굴성공률은감소하였으나 (p<0.01) 폴립과선종은더많이발견되었다 (p<0.01). 그리고후굴과관련한천공등의중증합병증은없었다. 결론 : 우측대장에서내시경후굴에의한검사로 4.88% 의폴립, 3.32% 의선종이추가적으로발견되었다. 이기법은대장내시경검사중유용하고비교적안전한검사라고생각된다. 색인단어 : 상행결장, 대장폴립, 대장신생물, 진단오류, 후굴 REFERENCES 1. The Korea Central Cancer Registry, National Cancer Center. Annual report of cancer statistics in Korea in Sejong: Ministry of Health and Welfare, Lieberman DA, Weiss DG, Bond JH, Ahnen DJ, Garewal H, Chejfec G; Veterans Affairs Cooperative Study Group 380. Use of colonoscopy to screen asymptomatic adults for colorectal cancer. N Engl J Med 2000;343: Lakoff J, Paszat LF, Saskin R, Rabeneck L. Risk of developing proximal versus distal colorectal cancer after a negative colonoscopy: a population-based study. Clin Gastroenterol Hepatol 2008;6: ; quiz Brenner H, Hoffmeister M, Arndt V, Stegmaier C, Altenhofen L, Haug U. Protection from right- and left-sided colorectal neoplasms after colonoscopy: population-based study. J Natl Cancer Inst 2010;102: Singh H, Nugent Z, Demers AA, Kliewer EV, Mahmud SM, Bernstein CN. The reduction in colorectal cancer mortality after colonoscopy varies by site of the cancer. Gastroenterology 2010;139: Baxter NN, Goldwasser MA, Paszat LF, Saskin R, Urbach DR, Rabeneck L. Association of colonoscopy and death from colorectal cancer. Ann Intern Med 2009;150: Singh H, Nugent Z, Mahmud SM, Demers AA, Bernstein CN. Predictors of colorectal cancer after negative colonoscopy: a Vol. 65 No. 2, February 2015

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