title: Diagnostic miss rate for colorectal cancer: an audit.
abstract: BACKGROUND
  Colorectal cancer (CRC) is a common cancer worldwide. While screening improves survival, avoiding delayed diagnosis in symptomatic patients is crucial. Computed tomographic colonography (CTC) or colonoscopy is recommended as first-line investigation and most societies recommend counseling patients undergoing colonoscopy about a miss rate of 5%. This audit evaluates "miss rate" of colorectal investigations, which have led to diagnostic delay in symptomatic cases in a district general hospital in the United Kingdom.
  
  
  METHODS
  This is a retrospective review of 150 consecutive CRC cases presenting between August 2010 and July 2011. Evidence of bowel investigations done in the 3 years prior to diagnosis was obtained from computerized health records. Data regarding previous bowel investigations such as colonoscopy, CTC, double contrast barium enema (DCBE), and CT abdomen/pelvis were collected.
  
  
  RESULTS
  6.7% cases were identified via screening pathway while 93% were identified through symptomatic pathway. 17% (26/150) of newly diagnosed CRC had been investigated in the preceding 3 years. Of these, 8% (12/150) had false negative results. The false negative rate for CRC diagnosis was 3.5% for colonoscopy (3/85), 6.7% for CTC (1/17), 9.4% for CT (5/53), and 26.7% for DCBE (4/15). Some patients had a missed diagnosis despite more than one diagnostic test. Time delay to diagnosis ranged from 21-456 days.
  
  
  CONCLUSIONS
  17% of patients diagnosed with CRC had been investigated in the previous 3 years. Higher miss rate of barium enema should preclude its use as a first-line modality to investigate CRC.
authors.affiliation: Department of Colorectal Surgery, Princess of Wales Hospital, Bridgend, United Kingdom (Mary Than, Jolene Witherspoon, Javed Shami).
authors.forename: Mary
authors.initials: M
authors.lastname: Than
authors.affiliation: Department of Colorectal Surgery, Princess of Wales Hospital, Bridgend, United Kingdom (Mary Than, Jolene Witherspoon, Javed Shami).
authors.forename: Jolene
authors.initials: J
authors.lastname: Witherspoon
authors.affiliation: Department of Colorectal Surgery, Princess of Wales Hospital, Bridgend, United Kingdom (Mary Than, Jolene Witherspoon, Javed Shami).
authors.forename: Javed
authors.initials: J
authors.lastname: Shami
authors.affiliation: Department of Digestive Diseases and Clinical Nutrition, Tata Memorial Hospital, India (Prachi S. Patil).
authors.forename: Prachi
authors.initials: P
authors.lastname: Patil
authors.affiliation: Division of Colorectal Surgery, Department of Surgical Oncology, Tata Memorial Hospital, India (Avanish Saklani).
authors.forename: Avanish
authors.initials: A
authors.lastname: Saklani
keywords: Keywords Investigation; colorectal cancer; miss rate