099C4ZZDrainage of Left Mastoid Sinus, Percutaneous Endoscopic Approach
- Billable / Specific Code
099C4ZZ is a billable ICD-10-PCS procedure code for Drainage of Left Mastoid Sinus, Percutaneous Endoscopic Approach. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRGs 135, 136. The root operation Drainage involves taking or letting out fluids and/or gases from a body part. In AHRQ's Clinical Classifications Software (CCSR), this procedure falls under ENT drainage (excluding myringotomy).
Code Identity
PCS Table Breakdown
Each ICD-10-PCS code is built from seven characters, each an axis of the procedure. Hover or tap the icons for the official CMS definitions.
| Position | Designation | Value | Meaning |
|---|---|---|---|
| 1 | Section | 0 | Medical and Surgical |
| 2 | Body System | 9 | Ear, Nose, Sinus |
| 3 | Operation | 9 | Drainage |
| 4 | BodyPart | C | Mastoid Sinus, Left |
| 5 | Approach | 4 | Percutaneous Endoscopic |
| 6 | Device | Z | No Device |
| 7 | Qualifier | Z | No Qualifier |
In the ICD-10-PCS Alphabetic Index
These FY 2027 ICD-10-PCS Alphabetic Index entries lead to this code:
To code drainage of the left mastoid sinus, open the FY 2027 ICD-10-PCS Alphabetic Index at Drainage, then the subterms Sinus, Mastoid, Left. The index leads to table 099, where the approach, device and qualifier values shown in the breakdown above complete the seven-character code 099C4ZZ.
Clinical Classification (CCSR)
AHRQ groups this procedure code into these clinical categories.
Convert to ICD-9-PCS
Closest ICD-9-PCS equivalents for this code under the General Equivalence Mappings.
Code History
- 099C8ZZ — Drainage of Left Mastoid Sinus, Endo
Similar Procedure Codes
Questions About 099C4ZZ
Is 099C4ZZ a billable code?
Yes. This is a complete seven-character ICD-10-PCS code, specific enough to report Drainage of Left Mastoid Sinus, Percutaneous Endoscopic Approach on inpatient claims from October 1, 2026 through September 30, 2027.
What do the characters in 099C4ZZ mean?
The code breaks down character by character: the 1st character 0 is the Section (Medical and Surgical); the 2nd character 9 is the Body System (Ear, Nose, Sinus); the 3rd character 9 is the Operation (Drainage); the 4th character C is the BodyPart (Mastoid Sinus, Left); the 5th character 4 is the Approach (Percutaneous Endoscopic); the 6th character Z is the Device (No Device); the 7th character Z is the Qualifier (No Qualifier).
What MS-DRG does 099C4ZZ group to?
On an inpatient stay, Drainage of Left Mastoid Sinus, Percutaneous Endoscopic Approach maps to MS-DRGs 135, 136, with relative weights from 1.0615 to 2.1793. The MS-DRG sets the fixed Medicare payment for the stay.
What is the ICD-9-PCS equivalent of 099C4ZZ?
Under the General Equivalence Mappings, Drainage of Left Mastoid Sinus, Percutaneous Endoscopic Approach crosswalks to ICD-9-PCS 20.21 (Incision of mastoid) and 20.22 (Incision of petrous pyramid air cells). The mapping is approximate, so confirm it fits the documentation.
