RESUMO
BACKGROUND: Recent guidelines indicate that colonoscopy and sigmoidoscopy are both acceptable options for screening average-risk patients for colorectal cancer. Retrospective studies have found that a majority of patients with cancer proximal to the splenic flexure have a normal screening flexible sigmoidoscopy. METHODS: This was a multicenter, prospective description of colonoscopic findings and family history in consecutive patients with proximal colon cancer. RESULTS: Among 116 prospectively identified average-risk patients with cancer proximal to the splenic flexure, 40 (34.5%) had neoplasia distal to the splenic flexure. The prevalence of patients with adenomas greater than or equal to 1 cm, with only one tubular adenoma less than 1 cm, and with only hyperplastic polyps were 16.4%, 8.6%, and 6.9%, respectively. CONCLUSIONS: Most average-risk patients with cancer proximal to the splenic flexure will have a normal screening flexible sigmoidoscopy. These patients have an unexpectedly high prevalence of large distal adenomas, but the prevalence of both single small tubular adenomas and hyperplastic polyps alone is similar to that expected during screening of the general population. Clinicians and payers should continue to seek methods to improve the cost-effectiveness and availability of screening colonoscopy in average-risk persons.
Assuntos
Adenocarcinoma/patologia , Neoplasias do Colo/patologia , Pólipos do Colo/patologia , Neoplasias do Colo Sigmoide/patologia , Adenocarcinoma/epidemiologia , Adenocarcinoma/genética , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Neoplasias do Colo/epidemiologia , Neoplasias do Colo/genética , Pólipos do Colo/epidemiologia , Pólipos do Colo/genética , Colonoscopia/métodos , Feminino , Humanos , Masculino , Programas de Rastreamento/métodos , Pessoa de Meia-Idade , Prevalência , Estudos Prospectivos , Fatores de Risco , Sensibilidade e Especificidade , Distribuição por Sexo , Neoplasias do Colo Sigmoide/epidemiologia , Neoplasias do Colo Sigmoide/genética , Sigmoidoscopia/métodosRESUMO
Isotonic saline is the fluid most commonly used for treatment of asymptomatic hypotonic dehydration, but as shown in the case presented in this article, rapid increase in serum sodium may follow administration of isotonic saline, leading to the development of central pontine myelinolysis (CPM). Because the necessity of rapid correction is less, whereas the risk of CPM is greater with chronic asymptomatic hyponatremia than with acute hyponatremia, use of a half normal saline might be more appropriate than normal saline for treating certain patients with hypotonic dehydration with asymptomatic hyponatremia. The calculations indicate that half normal saline will expand the extracellular volume quite effectively, but the rate of increase in serum sodium will be considerably slower than that with normal saline.
