Fetus and Obstetrical (BY) ICD-10-PCS
The BY body system covers Imaging procedures on fetus and obstetrical, with 62 ICD-10-PCS codes across 2 root operations, 58 of them billable in fiscal year 2026. Each root operation defines a distinct procedural objective, and the info icons show the official definition with a preview of the codes inside.
Root Operations in This Body System 2 operations · 62 codes
| Chars 1–3 | Root Operation | Codes | Billable |
|---|---|---|---|
| BY3 | Magnetic Resonance Imaging (MRI)Computer reformatted digital display of multiplanar images developed from the capture of radio frequency signals emitted by nuclei in a body site excited within a magnetic field | 44 | 42 |
| BY4 | UltrasonographyReal time display of images of anatomy or flow information developed from the capture of reflected and attenuated high frequency sound waves | 18 | 16 |
The info icon shows the official root operation definition and previews the codes in that range.
About the BY Body System
The ICD-10-PCS root operation BY refers to Fetus and Obstetrical Imaging, which involves producing diagnostic images of the fetus or obstetrical structures. This operation is essential for monitoring fetal development and evaluating pregnancy status without invasive procedures.
Within the Imaging classification, key methods include Magnetic Resonance Imaging (MRI) and Ultrasonography. MRI (code BY3) generates detailed multiplanar images by capturing radio frequency signals from nuclei excited within a magnetic field. Ultrasonography (code BY4) uses high-frequency sound waves to create real-time images of fetal anatomy or blood flow. Both techniques provide critical, non-invasive visualization tools fundamental to obstetrical care. Accurate coding with these fetus and obstetrical imaging options ensures clear communication regarding the specific imaging technology and approach used during pregnancy management.
Questions About This Page
How many codes are in the BY body system?
The BY body system contains 62 ICD-10-PCS codes in FY 2026, organized into 2 root operations. 58 of them are billable on inpatient claims.
What is a root operation?
The root operation is the third character of every ICD-10-PCS code and names the objective of the procedure. Drainage takes fluid out, Excision cuts out a portion of a body part, and Resection removes all of one. Picking the right root operation is the central skill of PCS coding, so each one above carries its official CMS definition.
Related References
Source: CMS FY 2026 ICD-10-PCS order file and code tables, effective October 1, 2025 through September 30, 2026.
