Revenue Cycle Insider

Here’s why you need more than the operative report.

Colon polyps are common findings in gastroenterology, especially during colonoscopy procedures. While the presence of a polyp might seem routine, accurately coding it is not. Understanding whether a polyp is neoplastic (meaning potentially cancerous) or non-neoplastic (typically benign) is the critical first step toward assigning the correct ICD-10-CM code.

Here’s what every new gastrointestinal (GI) coder needs to know, including pitfalls that can lead to incorrect claims.

Step 1: Don’t Code Until the Pathology Report Is Final

Watch out: Never code based on the operative note alone.

While a gastroenterologist may suggest the type of polyp during the procedure, only the pathology report provides the definitive diagnosis. This distinction is important not only for accurate diagnosis coding but also for determining the timing of surveillance colonoscopies.

Best practice: Always wait for the final pathology report before assigning a diagnosis code. It will tell you if the polyp is non-neoplastic (e.g., hyperplastic) or neoplastic (e.g., adenomatous or malignant).

Step 2: Know How to Code Non-Neoplastic Polyps

Hyperplastic polyps are typically benign and often found in the rectosigmoid region. Your coding options include:

• D12.7 (Benign neoplasm of rectosigmoid junction)
• D12.8 (Benign neoplasm of rectum)
• D12.9 (Benign neoplasm of anus and anal canal)
• K63.5 (Polyp of colon) (This code is less specific; use only if location isn’t clear or behavior isn’t specified)

Watch out: Beware of using K63.5 as your default diagnosis code. It’s less specific than codes in the D12.- (Benign neoplasm of colon, rectum, anus and anal canal) series, which better reflect the diagnosis when the location is known.

Inflammatory or pseudopolyps: These may appear in patients with inflammatory bowel disease (IBD) or ulcerative colitis. Your coding options include:

• K51.4- (Inflammatory polyps of colon) with extensions based on complications (such as K51.414 [Inflammatory polyps of colon with abscess])

Best practice: Be sure documentation supports an underlying condition like IBD or colitis when using this code.

Step 3: Code Neoplastic Polyps Accurately

Adenomatous polyps (APs) are neoplastic and carry a cancer risk, which affects follow-up and surveillance recommendations. Your coding options include:

• D12.- with a location-based 4^th character
• Z86.010 (Personal history of colon polyps) for surveillance/follow-up colonoscopy

Caution: Don’t ignore polyp subtypes in the path report. Terms like “tubular,” “villous,” or “tubulovillous” may indicate coding differences.

Villous adenomas are more likely to progress toward malignancy. Your coding options include:

• D37.4 (Neoplasm of uncertain behavior of colon) for villous adenoma or polyps not clearly benign

Use D37.4 when the pathology report doesn’t confirm benign or malignant behavior but describes features of high-risk neoplasia.

Sessile serrated lesions have the characteristics of both a hyperplastic and an adenomatous polyp. Your coding options include:

• D12.-, depending on location (e.g., D12.5 [Benign neoplasm of sigmoid colon] for descending colon)

Warning: Do not choose a hyperplastic polyp code when pathology clearly states “sessile serrated adenoma.” These are neoplastic and should be coded as such.

Step 4: Watch for Malignant Findings

When a neoplastic polyp becomes cancerous, it’s called an adenocarcinoma. Look for terms like “high-grade dysplasia” or “carcinoma in situ” in the path report. Your coding options include:

• D01.0 (Carcinoma in situ of colon)
• D01.1 (Carcinoma in situ of rectosigmoid junction)

Red flag: Be sure you don’t report a benign code (D12.-) when pathology indicates malignant transformation. Coding benign when it’s malignant can affect not just billing but treatment planning.

Final Coding Tips for New GI Coders

1. Never code based on assumption. The pathology report is your definitive source.

2. Match the code to both the type of polyp and its location. Location-specific codes are always preferred when available.

3. Use history codes (like Z86.010) for surveillance visits or follow-up colonoscopies.

4. Be cautious with combination findings. If there are multiple types of polyps in different locations, report more than one code.

5. Understand pathology terminology. Terms like “villous,” “tubular,” “sessile serrated,” and “in situ” all carry specific coding implications.

Suzanne Burmeister, BA, MPhil, Medical Writer and Editor