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Colonoscopy clinicians in Anaheim, California

CMS lists 43 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 Anaheim, California (details below).

Colonoscopy volume

Clinician Colonoscopies billed Percentile rank
Ashokkumar Amin, MD 184 87%
Jason Yip, MD 172 85%
Syam Gaddam, MD 133 75%
Bret Namihas, MD 130 75%
Sajen Mathews, MD 121 72%
Thomas Konturek, MD 115 70%
Ravindra Alapati, MD 106 66%
Joshua Beirne, MD 93 61%
Tahmina Haq, MD 70 50%
Ambika Bali, MD 69 49%
Ki-Yoon Kim, MD 60 44%
Amit Bhanvadia, MD 59 44%
Leo Leer, MD 50 38%
Dick Yip, MD 46 36%
Kevin Kuettel, MD 41 32%
Brian Riff, MD 39 31%
Kavita Singh, MD 38 30%
Ikponmwosa Enofe, MD 21 20%
Kathy Akashi, MD 1-10 13% or below
Walid Ayoub, MD 1-10 13% or below
Danh Dan, MD 1-10 13% or below
Shireena Desai, MD 1-10 13% or below
Erica Duh, MD 1-10 13% or below
Theodore Durbin, MD 1-10 13% or below
Bassem Elgohary, MD 1-10 13% or below
Andrew Giap, MD 1-10 13% or below
Syeda Husain, MD 1-10 13% or below
Robert Kung, MD 1-10 13% or below
Kelvin Nguyen, MD 1-10 13% or below
William 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
Dennis Riff, MD 1-10 13% or below
Jenny Risman, MD 1-10 13% or below
Victoria Sheen, MD 1-10 13% or below
Bijal Surti, MD 1-10 13% or below
Derek Tang, MD 1-10 13% or below
Doan Trang Tran, MD 1-10 13% or below
James Wang, MD 1-10 13% or below
Rex 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.

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.

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).