Colonoscopy clinicians in Orange, California

CMS lists 39 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	578	99%
Philip Chen, MD	505	99%
William Karnes, MD	317	96%
John Lee, MD	273	95%
Sunhee Park, MD	266	94%
Suhail Salem	219	91%
James Lee, MD	169	84%
Alaa Abousaif, MD	162	82%
Robert Fearn, MD	158	82%
Shravani Reddy, MD	143	78%
Jaehyun Kim, MD	138	77%
Carlos Saad, MD	130	74%
Carl Albers, MD	123	72%
Christopher Paiji, MD	123	72%
Jason Samarasena, MD	123	72%
Haig Najarian, MD	121	71%
Ousama Alkhatib, MD	79	54%
Kashyap Trivedi, MD	75	52%
Elliot Yu, MD	70	50%
Ketan Shah, MD	68	49%
Keith Martin, MD	62	46%
Christina Ling, MD	58	44%
Kiran Sachdev, MD	51	39%
Lisa Hertz, MD	50	39%
Pavan Mankal, MD	46	36%
Nimisha Parekh, MD	41	33%
David Chapman, MD	40	33%
Harry Nguyen, DO	30	26%
Hooshang Meshkinpour, MD	29	25%
Andrew Ko, MD	27	24%
John Martin, MD	26	23%
Frances Dang, MD	24	22%
Mannat Saini, MD	22	21%
Paurush Shah, MD	22	21%
Joshua Kwon, MD	15	16%
Tat Lam, MD	15	16%
Brian Mendoza, MD	11	13%
Allen Houshiar, DO	1-10	13% or below
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.

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 (August 18, 2026 release).