Rex D K
Department of Medicine, Indiana University School of Medicine, Indianapolis.
Am J Gastroenterol. 1995 Mar;90(3):353-65.
Colonoscopy for bleeding indications (positive fecal occult blood test, emergent or nonemergent rectal bleeding, melena with a negative upper endoscopy and iron deficiency anemia) has a substantial yield for cancers (1 per 9 to 13 colonoscopies), although slide rehydration of fecal occult blood tests decreases the yield (1 per 45 colonoscopies). Prospective studies indicate that nonbleeding colonic symptoms have a substantially lower yield for cancer than bleeding symptoms (1 per 109 colonoscopies). Patients with indications for screening colonoscopy with a relatively high yield of cancer are those with Lynch syndrome (1 per 39 colonoscopies) and males more than 60 yr old (1 per 64 colonoscopies). Perioperative colonoscopy in persons undergoing colorectal cancer resection has a high yield for synchronous cancer (2-3%). An initial examination in persons with long-standing ulcerative colitis has a high yield for cancer (12%). Surveillance colonoscopy after cancer resection has an intermediate yield for anastomotic cancer (1 per 74 procedures) and metachronous cancers (1 per 82 colonoscopies), although this number may overestimate the yield of metachronous cancer. Postpolypectomy surveillance and ulcerative colitis surveillance colonoscopy have relatively low yields for cancer (1 per 317 and 360 colonoscopies, respectively). However, postpolypectomy surveillance colonoscopy, in combination with initial clearing colonoscopy, has been proven to be almost entirely effective in preventing colorectal cancer death. Further, cancer yields for postpolypectomy surveillance should improve with implementation of new surveillance guidelines, with little or no impact on mortality. The effectiveness of ulcerative colitis surveillance is less certain. Referral of patients with low-grade dysplasia for colectomy would improve the value and effectiveness of surveillance colonoscopy in ulcerative colitis. Adenoma yields at colonoscopy are relatively independent of indication, as evidenced by the high yield of adenomas in screening colonoscopy studies. Demographic factors, including increasing age and male gender, are important predictors of adenomas at initial colonoscopy. Age, male gender, and multiple and large adenomas at initial examination are predictors of adenomas at subsequent postpolypectomy surveillance. Persons with ureterosigmoidostomies can be screened by interval flexible sigmoidoscopy and do not require screening colonoscopy. A history of breast cancer does not predict an improved yield of colonoscopic screening compared to average-risk persons.
因出血指征（粪便潜血试验阳性、急诊或非急诊直肠出血、上消化道内镜检查阴性的黑便以及缺铁性贫血）而行结肠镜检查时，发现癌症的几率较高（每9至13次结肠镜检查发现1例癌症），不过粪便潜血试验的玻片复水会降低这一几率（每45次结肠镜检查发现1例癌症）。前瞻性研究表明，非出血性结肠症状发现癌症的几率远低于出血性症状（每109次结肠镜检查发现1例癌症）。癌症发现几率相对较高的结肠镜筛查指征患者包括林奇综合征患者（每39次结肠镜检查发现1例癌症）以及60岁以上男性（每64次结肠镜检查发现1例癌症）。接受结直肠癌切除术患者的围手术期结肠镜检查发现同时性癌症的几率较高（2 - 3%）。对长期溃疡性结肠炎患者进行初次检查发现癌症的几率较高（12%）。癌症切除术后的监测性结肠镜检查发现吻合口癌（每74例手术发现1例）和异时性癌（每82次结肠镜检查发现1例）的几率中等，不过这一数字可能高估了异时性癌的发现几率。息肉切除术后监测性结肠镜检查和溃疡性结肠炎监测性结肠镜检查发现癌症的几率相对较低（分别为每317次和360次结肠镜检查发现1例）。然而，息肉切除术后监测性结肠镜检查与初次清洁结肠镜检查相结合已被证明几乎能完全有效预防结直肠癌死亡。此外，随着新监测指南的实施，息肉切除术后监测性结肠镜检查发现癌症的几率应会提高，且对死亡率影响很小或无影响。溃疡性结肠炎监测的有效性尚不确定。将低级别发育异常患者转诊进行结肠切除术将提高溃疡性结肠炎监测性结肠镜检查的价值和有效性。结肠镜检查时腺瘤的发现几率相对独立于指征，这在结肠镜筛查研究中腺瘤的高发现几率中得到了体现。人口统计学因素，包括年龄增长和男性性别，是初次结肠镜检查时腺瘤的重要预测因素。年龄、男性性别以及初次检查时多个和大的腺瘤是息肉切除术后后续监测时腺瘤的预测因素。输尿管乙状结肠吻合术患者可通过定期柔性乙状结肠镜检查进行筛查，无需进行结肠镜检查。与平均风险人群相比，乳腺癌病史并不能预测结肠镜筛查的发现几率会提高。
