Colonoscopy Coding Guideline
- Medycoding Expert
- Mar 7
- 5 min read
Last Updated on 07 March 2026
What is colonoscopy ?
Colonoscopy is the visualization of the colon. The scope is inserted from anus or stoma (Artificial Opening) and passed upto Cecum.
What is Sigmoidoscopy ?
Sigmooidoscopy is the visualization of the sigmoid colon. The scope is inserted from anus and passed upto Splenic Flexure.
What is Splenic Flexure and Hepatic Flexure ?
Hepatic Flexure
The hepatic flexure is the point where the ascending colon finishes and the transverse colon begins.
It is located on the right upper side of the abdomen, close to the Liver.
Because it lies near the liver, it is called hepatic (hepatic = related to the liver).
Another name: Right colic flexure.
Splenic Flexure
The splenic flexure is the point where the transverse colon ends and the descending colon begins.
It is located on the left upper side of the abdomen, near the Spleen.
Because it is close to the spleen, it is called splenic.
Another name: Left colic flexure.
Difference between diagnostic and Therapeutic Colonoscopy
The patient reason for visit is some symptom or diagnosis, the physician insert the scope and examine the colon and there is no any surgical intervention like biopsy, injection etc. Such colonoscopy is called as diagnostic colonoscopy.
The patient reason for visit is some symptom or diagnosis, the physician insert the scope and examine the colon and there is some surgical intervention like biopsy, injection etc. Such colonoscopy is called as therapeutic colonoscopy.
What is Screening colonoscopy ?
The physician came without any sign and symptom , such colonosocpy is known as Screening colonoscopy. The colonosocpy is like routine examination and perform because of patient old age or family history of colon cancer, polyps etc.
The ICD for screening colonoscopy is
Z12.11: Encounter for screening for malignant neoplasm of colon
Z12.12: Encounter for screening for malignant neoplasm of rectum
Note : For screening colonoscopy , the Primary diagnosis always shoulde be Z12.11 or Z12.12 and other finding and impression will be Secondary diagnosis.
What is Surveillance Colonoscopy ?
A surveillance colonoscopy is done to check the colon again after a patient previously had colon polyps removed.
The doctor is checking to see:
If new polyps have grown
If old polyps have come back
Even though the patient had polyps before, this type of visit is still considered a screening.
So it is coded with:
Z12.11 – Encounter for screening for malignant neoplasm of colon
(This means screening for colon cancer.)
What is Follow Up Examination ?
A follow-up exam is done after a patient has already been treated for a condition, to check:
If the problem has come back
If the treatment worked
If there are any new changes
This is different from screening. A follow-up is done because there was already a known problem.
Z08:Encounter for follow-up examination after completed treatment for malignant neoplasm
Z09:Encounter for follow-up examination after completed treatment for conditions other than malignant neoplasm
Modifier 52 : Reduced Services:
Explanation : Under certain circumstances, a physician or other qualified health care professional may decide to partially reduce or eliminate a service or procedure. This decision is made based on the patient’s condition, safety concerns, or clinical judgment.
When this occurs, the provider does not change the original procedure code. Instead, they report the usual procedure code and append Modifier 52, which indicates that the service was reduced.
Modifier 53 : Discontinue services
Explanation : Sometimes, a doctor starts a surgery or diagnostic procedure, but must stop it before finishing because:
There is an unexpected complication
The patient’s health is at risk
An emergency situation occurs
In these cases, the procedure was started but not completed for the patient’s safety.
Colonoscopy Tree
Below are the scenario , that will be helpful for coding colonoscopy,
What is Incomplete Colonoscopy ?
A incomplete colonoscopy in the defined by CMS ,as inability to advance the colonoscopy to the cecum or colon-small intestine anastomois due to unforeseen circumstances.
Can sigmoid scope reach upto colon ?
Yes, if patient has shorter bowel then it can reach, so dont code for colonoscopy because the scope is sigmoidoscopy.
What is high risk and low risk ?
Medicare beneficiaries without high risk factors are eligible for screening colonoscopy every 10 years. Beneficiaries at high risk for developing colorectal cancer are eligible once every 24 months.
Medicare considers an individual at high risk for developing colorectal cancer as one who has one or more of the following:
A close relative (sibling, parent or child) who has had colorectal cancer or an adenomatous polyp.
A family history of familial adenomatous polyposis.
A family history of hereditary nonpolyposis colorectal cancer.
A personal history of adenomatous polyps.
A personal history of colorectal cancer.
Inflammatory bowel disease, including Crohn’s disease and ulcerative colitis.
When to code G0105 or G0121
Insurance should be Medicare.
Encounter for Screening.
Procedure is diagnostic (Not any Surgical intervention)
For High risk patient with above condition ,use G0105
For Low risk patient with above condition, use G0121
G0105: Colorectal cancer screening; colonoscopy on individual at high risk
G0121: Colorectal cancer screening; colonoscopy on individual not meeting criteria for high risk
When to use PT and 33 Modifier ?
PT Modifier
Insurance is Medicare
The patient came for Screening.
Biopsy or any surgical intervention performed.
PT: (Colorectal cancer screening test; converted to diagnostic test or other procedure)
33 Modifier
Insurance is Non-Medicare
The patient came for Screening.
Biopsy or any surgical intervention performed
33 : Preventive Services
Note : Positive Cologuard test encounter is considered as screening for Colonosocopy.
R19.5 additional code will go if primary condition of this symptom does not occurs.
Add KX modifier to G0105 or G0121
Requirements specified in the medical policy have been met.
CPT Code range for Colonoscopy
45378: Colonoscopy, flexible; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)
45379: Colonoscopy, flexible; with removal of foreign body(s)
45380: Colonoscopy, flexible; with biopsy, single or multiple
45381: Colonoscopy, flexible; with directed submucosal injection(s), any substance
45382: Colonoscopy, flexible; with control of bleeding, any method
45388: Colonoscopy, flexible; with ablation of tumor(s), polyp(s), or other lesion(s) (includes pre- and post-dilation and guide wire passage, when performed)
45384: Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by hot biopsy forceps
45385: Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by snare technique
45386: Colonoscopy, flexible; with transendoscopic balloon dilation
45388: Colonoscopy, flexible; with ablation of tumor(s), polyp(s), or other lesion(s) (includes pre- and post-dilation and guide wire passage, when performed)
45389: Colonoscopy, flexible; with endoscopic stent placement (includes pre- and post-dilation and guide wire passage, when performed)
45390:Colonoscopy, flexible; with endoscopic mucosal resection
45391: Colonoscopy, flexible; with endoscopic ultrasound examination limited to the rectum, sigmoid, descending, transverse, or ascending colon and cecum, and adjacent structures
45392: Colonoscopy, flexible; with transendoscopic ultrasound guided intramural or transmural fine needle aspiration/biopsy(s), includes endoscopic ultrasound examination limited to the rectum, sigmoid, descending, transverse, or ascending colon and cecum, and adjacent structures
45393: Colonoscopy, flexible; with decompression (for pathologic distention) (eg, volvulus, megacolon), including placement of decompression tube, when performed
45398: Colonoscopy, flexible; with band ligation(s) (eg, hemorrhoids)