二階外科複習08: 大腸直腸外科

Reference: 二階老趙外科學

1. 腸造廔：最常見ileostomy，位於RLQ腹直肌較高處，外翻-->避免retraction

• 永久性: end
• 暫時性: loop or divided

2. 噤便肌肉：

• 尺骨直腸肌(骨骼肌)：構成肛管直腸角度最重要的肌肉
• 內括約肌(85% resting pressure)
• 外括約肌深部 (骨骼肌)

3. 大腸生理

• 菌叢
• Bacteroides: 10^11 /ml
• E. coli: 10^9 /ml
• Layers: 上皮->lamina propria->黏膜肌層->submucosa->muscle layer->serosa
• 功能
• 吸收水分(10%)：受aldosterone影養
• 留鈉排鉀，留氯排重碳酸
• 吸收短鏈脂肪酸
• 生理性息肉(=增生，占90%)
• 正常大腸上皮4~7七天換血
• 沒有惡性傾向，大多0.5cm以下，乙狀結腸/直腸最多
• 反應性息肉(=發炎)
• 好發：IBD
• 滯留性息肉(=錯構瘤、先天性)
• 好發:PJ症候群、幼年單發性息肉、幼年多發性息肉(25%癌變)
• 症狀：阻塞、出血
• 小兒下消化道出血最常見的原因
• 腫瘤(8%): 一般人發現息肉～癌變約52~62y/o
• tubular: 發生率最高，癌變5%
• tubulovillous
• villous: 發生率最少，癌變40%
• <1cm: 癌變1%
• >2cm: 癌變50%
• Familiar polyposis syndrome
• adenomatous: 癌變100%，related to ch.5(APC gene: tumor suppression)，體顯性，發現~癌變約29~39 y/o
• polyposis coli
• Gardner's syndrome: related to 軟組織(fibroma)+骨頭(osteoma)，periampullary cancer↑
• Turcot syndrome: related to CNS tumor
  
• harmatomatous
• PJ syndrome: GI癌變風險增加(2~13%)
• Diffuse juvenile polyposis: 癌變25%
• 息肉處理：endoscopic polypectomy(有stalk超過1.5cm)、可先注射N/S墊高病灶，拿下後看margin clear/no submucosa invasion/grade I~II(well to moderate differentiation)就不用切大腸，除非很多、很大或是villous type；大腸鏡complication: 穿孔(0.2%)、出血(1%)

4. 大腸癌(平均62y/o)

• 家族遺傳性占15%，一等親罹癌則風險增3~9倍，偶發性85%


• normal-(APC,ch5)->dysplasia-(DNA hypomethylation)->early adenoma-(RAS,ch12,oncogene)->intermediate adenoma-(DCC,ch18,抑制基因)->late adenoma-(p53,ch17,抑制基因)->adenocarcinoma
•  Initiation(1st): FAP(1%，癌化100%)
•  Promotion: HNPCC(14%，癌化80%，較年輕約44y/o，right>left side，poor differentiated/signet ring type多，相同stage預後較佳，子宮內膜癌30~60%/乳癌↑/前列腺癌↑)
  
•  Malignant change(last): 需biopsy confirmation
• CT/PET 看淋巴、肝臟轉移
• EUS看深度
  
  
• TMN system
  
  
• stage I: T1~2N1M0= A+B1
• stage II: T3~4N0M0= B2+B3
• stage III: TanyN1~2M0= C1+C2+C3
• stage IV: M1= D
• 開刀
• safe margin: 2~5cm
• Pre-op: colon prepare; lavage before anastomosis or colostomy for 6~8wks(=Hartmann procedure) if emergent OP(left side)
• APR+ 永久性stomy
• LAR+ 保留直腸
• Adjuvant therapy
• chemo: oral 5-FU, levamisole(佐劑) or leukovorin
• radiation: only for rectal cancer

5. IBD

• UC 10~30%癌化
• bimodal distribution in age
• manifestation: bloody diarrhea
• evaluation of score: 體重是否下降、大便次數、心跳、血比容、發燒、ESR、albumin
• mild to moderate:  ASA
• severe: total proctocolectomy+ ileal pouch anal anastomosis if intractable, toxic megacolon
• Crohn 7%狹窄處癌化
• 女>男，年輕人較多
• 可見cobblestone
• triad: abdominal pain, diarrhea, mild obstruction
• treatment: 5-ASA--> steroid--> azathioprine
• resection of complicated segment only: fistula/abscess(25%)> toxic megacolon(19%)> obstruction(12%)> perforation(<10%)
• Toxic megacolon
• T colon> 6cm  +  systemic toxic signs(+)
• Bowel rest, give antibiotics/steroid, avoid enema, then may arrange OP

6. 大腸扭轉

• sigmoid(80%): elders with stool compaction
• cecum(15%): younger, cannot fix well
• 影像：inverted U shape+ bird peak colon gas on plain film
• 處理：排除peritoneal sign後，採取enema、肛管、endoscopic detorsion(成功率80%, 復發率40%)、elective operation(elective: 6~8wks後)包括right side hemicolectomy/cecopexy/ileocolostomy

7. Colon diverticulum 

• at mesenteric side (反向： Meckel's, intestinal)
• pseudodiverticulum: lacking muscle layer
• diverticulosis: no infection, no inflammation, bleeding(+)
• 最常見成人大量LGI bleeding(24hr超過1500c.c.)的原因，其次是vascular ectasia、colon cancer
• 最常見兒童大量LGI bleeding的原因則是polyp
• 檢查出血位置：monitors, on NG, endoscope, Tc99m(0.1c.c./min), tagged RBC(0.5c.c./min),  angiography(0.5~1.0c.c./min), operation
• diverticulitis: infection/inflammation(+)，暫時不做endocscope
• uncomplicated: mild(pain)/severe(SIRS)
• 輕症發作兩次--> 開刀
• 重症發作一次--> 開刀
• 48hrs內未改善的腹痛-->考慮手術
• complicated: perforation/abscess(OP最常見的原因)/fistula(膀胱陰道)/obstruction

8. Radiotherapy induced proctitis

• 常見於cervical CA,  prostate CA, bladder CA
• 劑量: 6000 cG
• 風險：老年、糖尿病
• 黏膜層(vomiting, diarrhea)-->血便(hematochesia)

9. 痔瘡

• 好發於3' 7' 11' 方位
• 以dentate line(pectinate line)分內外痔
• 內：vessel distention，出血+不痛
• 外：thrombosis，疼痛--> 48hrs內拿掉，或保守治療(軟便+高纖+溫水坐浴)
• 混合(最常見)
• 治療：
• 1~2度保守治療
• 2~3度結紮
• 3~4度hemorrhoidectomy(close有縫合, open不縫合,  circumferential黏膜層+黏膜下層整圈=Whitehead's procedure) 
• 
• 術後注意事項
• 尿滯留(疼痛導致)
• 出血

10. Anal fissure

• dentate line以下
• 6' 占90%, 12' 占10%, lateral 要懷疑Crohn's disease
• 開刀時機：慢性肛裂(1個月)，做單側lateral internal sphincterotomy(括約肌外側切開術)

11. Rectal prolapse

• 風險因子: 女>男，老>少，做過子宮切除術、長期便秘
• types of prolapse
• 假的prolapse =mucosa only= 大規模內痔
• 真的prolapse= whole layer
• 評估：sphincter tone
• normal--> resection of prolapsed part
• bad-->
• proctopexy+/- sigmoid resection(anterior resection proctopexy)
• Ripstein procedure: transabdominal proctopexy + sling
• Delorme procedure(低風險): perineal approach, mucosa proctectomy
• Altemeier procedure: perineal approach, +resection
• Thiersch procedure
  
• 術後anal tone正常：60~70%

12. Pilonidal sinus(藏毛竇)

• 年輕男生多
• 薦骨尾骨下段3cm，與肛門直腸系統無關
• 容易藏汙納垢、感染發炎，需I&D，6~8wks後excision

13. Anal carcinoma

• 分類
• dentate line以下：SCC, BCC, melanoma
• dentate line以上：small cell carcinoma, SCC
• 治療：1st line- chemoradiation(5FU+ mitomycin C+3000rad)

14. Perianal abscess (gland感染)

• 容易有fistula
• 好發位置：intersphincter(60%), transphincter(35%), suprasphincter(4%), extrasphincter(1%)
• 處理：fistulotomy、seton drainage(2~3 months, 減少括約肌傷害)
  
  
  
• Goodsall's rule 或施打methyl blue 找tract 路徑