45378

Colonoscopy, flexible; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)

A diagnostic flexible colonoscopy is a procedure in which a physician examines the entire large intestine (colon) and the rectum using a flexible fiberoptic endoscope (colonoscope). The procedure is performed to investigate symptoms such as unexplained abdominal pain, chronic diarrhea, gastrointestinal bleeding, or to screen for colorectal cancer and polyps. The physician inserts the colonoscope through the anus and advances it through the rectum, sigmoid colon, descending colon, transverse colon, ascending colon, and finally into the cecum, often reaching the terminal ileum. During the advancement and withdrawal of the scope, the physician carefully inspects the mucosal lining for abnormalities such as ulcerations, inflammation, tumors, polyps, or areas of bleeding. Air or carbon dioxide is typically insufflated to expand the colon for better visualization. If necessary, the physician may collect specimens by brushing or washing the mucosa, which is included in this code. Note that if any tissue is removed via biopsy, snare, or other therapeutic interventions, a different code (such as 45380 for biopsy or 45385 for snare polypectomy) should be reported instead. This code represents a purely diagnostic examination where no therapeutic intervention or biopsy using forceps is performed. It is considered a separate procedure and should not be reported when a surgical colonoscopy is performed in the same session.

Clinical Indications

  • Screening for colorectal cancer in average or high-risk patients
  • Evaluation of gastrointestinal bleeding (hematochezia or melena)
  • Investigation of unexplained iron deficiency anemia
  • Assessment of chronic diarrhea or suspected inflammatory bowel disease
  • Abnormal findings on barium enema or cross-sectional imaging
  • Surveillance of previously identified colon polyps or colorectal cancer

Procedure Steps

  1. The patient is prepped with a bowel cleansing regimen prior to the procedure.
  2. Sedation or anesthesia is administered as appropriate.
  3. The patient is typically placed in the left lateral decubitus position.
  4. A digital rectal examination is performed.
  5. The lubricated colonoscope is inserted into the anus and advanced through the rectum.
  6. Under direct endoscopic visualization, the scope is advanced through the sigmoid, descending, transverse, and ascending colon.
  7. The scope reaches the cecum, identifying the appendiceal orifice and ileocecal valve, and may be advanced into the terminal ileum.
  8. Air or carbon dioxide is insufflated to distend the colon for optimal mucosal inspection.
  9. The scope is slowly withdrawn while the physician carefully examines the mucosal surface.
  10. Brushing or washing for cytology may be performed if suspicious areas are noted.
  11. The scope is completely withdrawn, and the patient is monitored in recovery.

Coding Guidelines

  • Code 45378 is used for diagnostic colonoscopy; do not use if a therapeutic procedure (e.g., biopsy, polyp removal) is performed.
  • If a biopsy is performed, use 45380.
  • If a polyp is removed by snare technique, use 45385.
  • Included in 45378 is the collection of specimen(s) by brushing or washing.
  • If the colonoscopy cannot be advanced beyond the splenic flexure, use the appropriate modifier (e.g., modifier 53 for discontinued procedure) or report as a sigmoidoscopy depending on payer rules.
  • Do not report 45378 in conjunction with therapeutic colonoscopy codes for the same session unless a distinctly different lesion is evaluated.
  • Medicare requires specific G-codes for colorectal cancer screening (e.g., G0105, G0121) instead of 45378 in certain screening scenarios.

Associated ICD-10 Codes