Colonoscopy clinicians in Irvine, California

CMS lists 40 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 Irvine, California (details below).

Colonoscopy volume

Clinician	Colonoscopies billed	Percentile rank
Roxanne Lim, MD	578	99%
Philip Chen, MD	505	99%
Fang Yu, MD	488	99%
David Kaufman, DO	401	98%
Shahrooz Bemanian, MD	255	94%
Kumaravel Perumalsamy, MD	243	93%
Paul Lee, MD	232	92%
Lance Uradomo, MD	188	87%
David Choi, DO	183	86%
Victor Yu	181	86%
You-Jen Chou, MD	173	85%
Matthew Oman, MD	169	84%
Heba Ashraf, MD	140	77%
Bret Namihas, MD	132	75%
James Lin, MD	102	65%
Poneh Rahimi, MD	77	54%
Ardalan Babaknia, MD	63	46%
Caroline Hwang, MD	60	45%
Herbert Lee, MD	55	42%
Jim Amerian, MD	48	38%
Omeed Alipour, MD	47	37%
Rashmi Kumar, MD	46	36%
Seper Dezfoli, MD	34	29%
Bashar Sharma, MD	28	25%
Jun Ichi Ohara, MD	27	24%
Jacques Van Dam, MD	24	22%
Danh Dan, MD	1-10	13% or below
Shireena Desai, MD	1-10	13% or below
Syeda Husain, MD	1-10	13% or below
Robert Kung, MD	1-10	13% or below
Brian Lee, MD	1-10	13% or below
Kelvin Nguyen, MD	1-10	13% or below
Henry Niho, MD	1-10	13% or below
Jeffrey Niizawa, MD	1-10	13% or below
Jeffrey Rauch, MD	1-10	13% or below
Victoria Sheen, MD	1-10	13% or below
Khoi Tran, MD	1-10	13% or below
James Wang, MD	1-10	13% or below
Yuki Young, MD	1-10	13% or below
Selena Zhou, 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).