title: Can the colour of per-rectal bleeding estimate the risk of lower gastrointestinal bleeding caused by malignant lesion?
abstract: OBJECTIVE
  To estimate the risk of lower gastrointestinal bleeding (LGIB) caused by malignant lesion in patients presenting with per-rectal bleeding (PRB), by using visual aid as an objective measurement of PRB colour.
  
  
  METHODS
  This was a prospective observational study on patients presented with PRB to Family Medicine Specialty Clinic, who undergo flexible sigmoidoscopy (FS) or colonoscopy (CLN) from December 2012 to September 2013. Patients aged 40 years old or above, haemodynamically stable, with normal haemoglobin level were included. Patients with a history of previous colonic surgery, refused to have FS or CLN, with ophthalmologic diseases such as colour blindness were excluded. Parameters including subjective description of PRB colour, number of chosen red colour by patients, source and distance of bleeding from anal verge were recorded for analysis. Receiver operating characteristic (ROC) curve was used to identify the optimal cutoff level of colour for diagnosing colonic lesion. Diagnostic accuracy was assessed by area under the ROC curve (AUC). Accountability of this model was assessed by logistic regression.
  
  
  RESULTS
  The dark PRB colour was associated with diagnosis of tumour (p < 0.001) and advanced neoplastic polyp (p < 0.001). The light PRB colour was associated with the diagnosis of piles (p < 0.001). The performance of our model to predict tumour or advanced neoplastic polyps by colour (AUC, 0.798) had a better discriminative power than that to predict colonic lesion alone (AUC, 0.610) by ROC curve analysis.
  
  
  CONCLUSIONS
  Objective measurement of PRB colour accurately estimated the risk of LGIB caused by malignant lesion in patients presenting with PRB.
authors.affiliation: Department of Family Medicine and Primary Health Care, Kowloon West Cluster, Hospital Authority, Kowloon, China.
authors.forename: Pui-Yan
authors.initials: PY
authors.lastname: Lai
authors.affiliation: Department of Family Medicine and Primary Health Care, Kowloon West Cluster, Hospital Authority, Kowloon, China.
authors.forename: Kin-Wai
authors.initials: KW
authors.lastname: Chan
authors.affiliation: Department of Family Medicine and Primary Care, The University of Hong Kong, 3/F, Ap Lei Chau Clinic, 161 Ap Lei Chau Main Street, Ap Lei Chau, Hong Kong. carlosho@hku.hk.
authors.forename: Carlos King-Ho
authors.initials: CK
authors.lastname: Wong
authors.affiliation: Department of Surgery, Our Lady of Maryknoll Hospital, Hospital Authority, Kowloon, China.
authors.forename: William
authors.initials: W
authors.lastname: Meng
authors.affiliation: Department of Family Medicine and Primary Health Care, Kowloon West Cluster, Hospital Authority, Kowloon, China.
authors.forename: Wan
authors.initials: W
authors.lastname: Luk
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012007:Rectum; D012307:Risk Factors
keywords: Colonoscopy; Colour cards; Lower gastrointestinal bleeding; Per-rectal bleeding; Sigmoidoscopy