下段の図９〜図１２で上行結腸（A）は拡張し，下行結腸（D）は虚脱しているので，両者間で閉塞していることを示唆する．図８の１から肛門側へ追跡すると図１０の１３で閉塞する．図５〜図８の↑は，強い造影効果を受けないので典型的な腫瘍性病変ではないが，閉塞部位の先端部での壁肥厚を示し原因疾患であろう．大腸ファイバー検査で横行結腸癌が確認され（図A：△），経肛門的に減圧し（図B：▲），1週間後に根治的手術を施行した．参考症例と下記文献でも示されているように，右側大腸癌による閉塞でも経肛門的減圧が可能である．

参考症例（横行結腸癌）：62歳女性．2週間前に上腹部痛が出現し食欲が低下した．近医にて腹部エコーと上部内視鏡検査を施行されたが原因を特定されないため紹介来院した．熱はなく，腹部はやや膨満し，15cm大の弾性硬の腫瘤を触知した．
図５〜図８で下行結腸（D）は虚脱し，上行結腸（A）は液状内容物で拡張しているので，その肛門側での閉塞を疑い図４の1から追跡すると，図６の8で閉塞する．図４から壁肥厚が始まり（↑），図７〜図１０で不整な，強い造影効果を受ける腫瘤となり（↑），横行結腸癌による閉塞と診断する．図１０〜図１２の△はリンパ節転移巣であろう．大腸ファイバー検査で上記所見が確認され，経肛門的に減圧し（図C：▲），1週間後に根治手術を施行した．

文献考察：横行結腸癌，右側結腸閉塞でも経肛門的減圧が可能
Am J Gastroenterol. 2005 Dec;100(12):2765-70.
Acute colorectal obstruction treated by means of transanal drainage tube: effectiveness before surgery and stenting.
Horiuchi A, Nakayama Y, Tanaka N, Kajiyama M, Fujii H, Yokoyama T, Hayashi K.

OBJECTIVES: The aim of this study was to clarify the usefulness of the management of acute colorectal obstruction using a transanal drainage tube before surgery or stenting. METHODS: Fifty-four patients (34 males and 20 females, aged 46-94 yr, mean = 69.7) treated between May 1998 and March 2004 for acute colorectal obstruction were identified in a colorectal obstruction database, and their clinical and radiological features were reviewed. Based on abdominal computed tomography findings, urgent colonoscopy was performed. Subsequently, endoscopic decompression using a Dennis Colorectal Tube (DCT) was attempted. RESULTS: Endoscopic decompression using the DCT was technically successful in 52 of 54 patients (96.3%). The site of obstruction was the cecum in 4, the ascending colon in 2, the transverse colon in 7, the descending colon in 11, the sigmoid colon in 18, and the rectum in 12. The etiology of obstruction was primary colorectal carcinoma in 45, non-colonic metastatic carcinoma in 4, postoperative obstruction in 4, and retrograde intussusception in 1. Following adequate cleansing of the colon, 44 patients underwent a one-stage surgery after 7+/- 3 days (SD; range, 4-10 days). Stenting was successfully used as the final palliative treatment in 4. The use of the DCT alone relieved postoperative stenosis (3 patients) and retrograde intussusception (Prognosis in patients with obstructing colorectal carcinoma. Am J Surg 1982;143:742-7). During these treatments, perforation occurred in one patient with postoperative stenosis of the cecum. CONCLUSIONS: Management of acute colorectal obstruction using the DCT was found to be effective and safe, irrespective of the site or etiology of the obstruction. Therefore, this procedure should be considered as a primary method for decompression of the obstructed colon before considering surgery or stenting.PMID: 16393233