Physician Profile
Elmer Y. Chang, M.D.
Unclaimed ProfileAbout Dr. Chang
Based in Mission Viejo, CA, Elmer Y. Chang, M.D. is listed in the NPI registry under gastroenterology. Elmer graduated from Northwestern University Feinberg Medical School in 1998. Medicare claims data shows Elmer provided 1,259 services to 1,099 patients. The services billed most often include established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more, biopsy of large bowel using a flexible endoscope, and established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more.
Summarised automatically from public NPI registry and CMS Medicare data. Not written or reviewed by this provider. Claim this profile to replace it — free, and no identity document with a practice or institutional email.
Education & Training
Specialty
Credentials & Licensing
License numbers are what the provider reported to NPPES when the NPI was issued or updated. NPPES does not verify licensure; confirm current standing with the state licensing board.
Medicare information
Exactly as CMS reports it (National Downloadable File, Opt-Out Affidavits, Order & Referring). Not an insurance directory; confirm coverage with the office.
Contact Information
- (949) 364-5090
- Email not available
Practice Locations
27871 MEDICAL CENTER RD SUITE 200
Mission Viejo, CA 92691
Conditions Commonly Evaluated or Treated
Within Gastroenterology generally. Availability varies by clinician, training and location — this profile has not been claimed, so nothing here is a personal claim by the provider.
Conditions
Most searched conditions
- Acid reflux
- Celiac disease
- Crohn's disease
- Hemorrhoids
- IBS
- Swallowing difficulties
- Ulcerative colitis
Biliary and pancreas
- Acute pancreatitis
- Gallstones
- Pancreatic cysts
- Primary sclerosing cholangitis
Colon and anorectal
- Anal fissure
- Colon cancer
- Colon polyps
- Lower gastrointestinal bleeding
Esophagus and swallowing
- Barrett's esophagus
- Eosinophilic esophagitis
- Esophageal stricture
- Esophagitis
Functional bowel and motility
- Chronic diarrhea
- Fecal incontinence
- Small intestinal bacterial overgrowth
Liver
- Ascites
- Autoimmune hepatitis
- Cirrhosis
- Fatty liver disease
- Hemochromatosis
- Hepatitis B
- Hepatitis C
- Portal hypertension
Stomach and duodenum
- Functional dyspepsia
- Gastritis
- Gastroparesis
- H. pylori infection
- Peptic ulcer disease
Bowel & Colon
- Diverticulitis
Digestive Symptoms
- Constipation
Gallbladder & Bile Ducts
- Blocked Bile Duct
Procedures & services
Most searched procedures
- Colonoscopy
- Endoscopy
- Gallbladder removal
- Hernia repair
- Liver biopsy
Lower endoscopy
- Colon polyp removal
- Endoscopic control of gastrointestinal bleeding
- Flexible sigmoidoscopy
Upper endoscopy
- Endoscopic submucosal dissection
- Esophageal dilation
Capsule and physiology testing
- Anorectal manometry
- Capsule endoscopy
- Esophageal manometry
Diagnostic Testing
- 24-Hour Acid Reflux Test
- EUS-Guided Fine Needle Biopsy
- H. Pylori Breath Test
- SIBO Breath Test
Liver procedures
- Esophageal variceal banding
- Liver elastography
- Paracentesis
Treatments
- Stool Transplant
Procedures Most Often Billed to Medicare
1,259 services · 1,099 patients · 12 distinct codes
| Procedure | Type | Code | Services | Compared with peers |
|---|---|---|---|---|
| Biopsy of large bowel using a flexible endoscope | Procedure | 45380 |
192 | More than most peers in Gastroenterology |
| Biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope | Procedure | 43239 |
149 | More often than most peers in Gastroenterology |
| Removal of polyps or growths of large bowel using an endoscope with mechanical snare | Procedure | 45385 |
130 | More often than most peers in Gastroenterology |
| Balloon dilation of esophagus, stomach, and/or upper small bowel using a flexible endoscope, less than 3.0 cm | Procedure | 43249 |
64 | More than most peers in Gastroenterology |
| Removal of polyps or growths of esophagus, stomach, and/or upper small bowel using an endoscope with mechanical snare | Procedure | 43251 |
51 | More than most peers in Gastroenterology |
| Removal of large bowel tissue using a flexible endoscope | Procedure | 45390 |
17 | As often as other peers in Gastroenterology |
| Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more | Office visit | 99214 |
328 | More than most peers in Gastroenterology |
| Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more | Office visit | 99213 |
149 | More often than most peers in Gastroenterology |
| Moderate sedation services provided by the same physician or other qualified health care professional performing a gastrointestinal endoscopic service that sedation supports, requiring the presence of an independent trained observer to assist in the monit | Billing code | G0500 |
66 | As often as other peers in Gastroenterology |
| New patient office or other outpatient visit with moderate level of medical decision making, if using time, 45 minutes or more | Office visit | 99204 |
52 | More often than most peers in Gastroenterology |
Source: CMS Medicare public data. Shows how often procedures were billed — not quality of care or patient satisfaction.
Related providers
Connections drawn from the registry and from what providers have told us. A link here is not a referral or an endorsement.
Other gastroenterologists at this location 6
Same specialty, same street address — most likely the same department or group.
Also at this address 4
Providers at the same street address. Each files their own registry entry, so a shared practice often appears under several different names.
Other gastroenterologists in Mission Viejo 5
Same specialty, same city.
More connections — 24 related providers in 3 groups
Trained at Northwestern University Feinberg Medical School 8
Other providers in the same specialty who trained at the same institution.
Class of 1998 at Northwestern University Feinberg Medical School 8
Providers who graduated from the same medical school in the same year.
Also performs Biopsy of large bowel using a flexible endoscope 8
Providers in CA who bill this service to Medicare most often.
Common questions
What kind of doctor is Elmer Y. Chang?
Elmer Y. Chang is a gastroenterologist in Mission Viejo, CA. That is the designation recorded for this NPI in the federal registry, where it is listed as “Gastroenterology”.
NPI registry
What is Elmer Y. Chang's address?
Elmer Y. Chang is listed at 27871 Medical Center Rd Suite 200, Mission Viejo, CA 92691. Addresses come from the NPI registry and can lag a move, so confirm before travelling.
NPI registry
How can I make an appointment with Elmer Y. Chang?
The number on file is (949) 364-5090. Guide.md cannot book appointments or pass on messages — please call the office directly.
NPI registry
What is the NPI for Elmer Y. Chang?
Elmer Y. Chang's National Provider Identifier is 1912083353. It is issued by the Centers for Medicare & Medicaid Services and is unique and permanent — it does not change if they move practice.
NPI registry
Where did Elmer Y. Chang train?
Elmer Y. Chang attended Northwestern University Feinberg Medical School, graduating in 1998. This comes from the CMS National Downloadable File.
CMS public data
How much experience does Elmer Y. Chang have?
Elmer Y. Chang has 28 years experience. Calculated from a graduation year of 1998, reported in the CMS National Downloadable File.
CMS public data
What procedures does Elmer Y. Chang perform?
According to Medicare billing data, Elmer Y. Chang performs procedures including biopsy of large bowel using a flexible endoscope, biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope and removal of polyps or growths of large bowel using an endoscope with mechanical snare, alongside routine visits and testing. This reflects Medicare patients only and is billing volume, not a measure of quality.
Medicare claims
Is Elmer Y. Chang's profile verified?
Not yet. This profile is built from public federal data and has not been confirmed by Elmer Y. Chang. If this is you, claiming it is free.
Guide.md
Provider data sourced from the NPPES NPI Registry and CMS public datasets. Information is provided for reference and is not medical advice.