Colonoscopy clinicians in Orange, California
CMS lists 36 clinicians with a primary specialty of Gastroenterology, Internal Medicine, Family Practice, or General Practice who have billed Medicare for at least one colonoscopy and practice in Orange, California (details below).
Colonoscopy volume
| Clinician | Colonoscopies billed | Percentile rank |
|---|---|---|
| Roxanne Lim, MD | 562 | 99% |
| Philip Chen, MD | 474 | 99% |
| William Karnes, MD | 260 | 94% |
| John Lee, MD | 248 | 93% |
| Suhail Salem | 206 | 89% |
| Sunhee Park, MD | 184 | 87% |
| Alaa Abousaif, MD | 148 | 79% |
| James Lee, MD | 142 | 78% |
| Jaehyun Kim, MD | 135 | 76% |
| Robert Fearn, MD | 127 | 74% |
| Jason Samarasena, MD | 126 | 73% |
| Haig Najarian, MD | 123 | 72% |
| Christopher Paiji, MD | 121 | 72% |
| Carlos Saad, MD | 119 | 71% |
| Shravani Reddy, MD | 99 | 64% |
| Christina Ling, MD | 88 | 59% |
| Ousama Alkhatib, MD | 74 | 52% |
| Ketan Shah, MD | 65 | 47% |
| Carl Albers, MD | 62 | 45% |
| Keith Martin, MD | 61 | 45% |
| Elliot Yu, MD | 61 | 45% |
| Kashyap Trivedi, MD | 60 | 44% |
| Pavan Mankal, MD | 50 | 38% |
| Lisa Hertz, MD | 46 | 36% |
| Kiran Sachdev, MD | 42 | 33% |
| Frances Dang, MD | 32 | 27% |
| Paurush Shah, MD | 31 | 26% |
| Mannat Saini, MD | 30 | 25% |
| John Martin, MD | 28 | 24% |
| Hooshang Meshkinpour, MD | 25 | 22% |
| Nimisha Parekh, MD | 25 | 22% |
| Joshua Kwon, MD | 20 | 19% |
| Harry Nguyen, DO | 17 | 17% |
| Andrew Ko, MD | 14 | 15% |
| Brian Mendoza, MD | 14 | 15% |
| Truongson Nguyen, MD | 1-10 | 13% or below |
Sorted by the number of colonoscopies billed to Medicare, highest first, not by quality or skill. CMS suppresses counts between 1 and 10 to protect patient privacy and publishes the range instead.
Reported in previous releases
CMS does not report a colonoscopy volume for these clinicians in the October 2, 2026 release. Their pages show figures from earlier releases.
- David Chapman, MD Last reported August 18, 2026
- Allen Houshiar, DO Last reported August 18, 2026
- Tat Lam, MD Last reported August 18, 2026
Understanding CMS Data
CMS's "Colonoscopy" category combines specific billing codes for colonoscopy to calculate the number of times each clinician billed Medicare for a "Colonoscopy." These include screening colonoscopy, diagnostic colonoscopy, and colonoscopy with biopsy or polyp removal. CMS's list also includes flexible sigmoidoscopy and laparoscopic appendectomy, so a clinician's count may include those procedures. CMS counts one procedure per patient per day, so a colonoscopy that included both a biopsy and a polyp removal counts once. CMS reports only procedures that clinicians billed to Original Medicare and Medicare Advantage. Therefore, CMS's procedure volume data does not include procedures that clinicians may have performed on patients who have other health care coverage (e.g., commercial insurance, self-pay, or the VA). Billing variation and coding errors can also affect CMS's data. Therefore, the number of procedures that CMS reports for a clinician may be higher or lower than the actual number of colonoscopies a clinician performed during the reporting period. Lastly, only clinicians with a primary specialty of Gastroenterology, Internal Medicine, Family Practice, or General Practice (as reported to Medicare) are presented.
Source: Centers for Medicare & Medicaid Services (October 2, 2026 release).