CHESTER D ZAHN MD
NPI 1639146442
Internal Medicine - Gastroenterology in San Gabriel, CA

Q: What is Chester Zahn's NPI number?

The NPI number for Chester Zahn is 1639146442. It was assigned to this individual provider in the NPPES registry on March 1, 2006.

Q: What is Chester Zahn's specialty?

The primary specialty registered for this NPI is Internal Medicine, specializing in Gastroenterology, with taxonomy code 207RG0100X.

Q: When was this NPI record last updated?

The NPPES record for Chester Zahn was last updated on March 20, 2020. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 6 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.

Active since March 01, 2006PECOS EnrolledAccepts Medicare Assignment

40.76/100

CMS Quality Rating

1026 E LAS TUNAS DR, SAN GABRIEL, CA 91776(626) 287-7222(626) 287-1991 Get Directions Write a Review

NPPES record last updated: March 20, 2020. Verified against the NPPES registry weekly; last sync: October 18, 2026.

Record update history: Mar 20, 2020, Nov 23, 2016 (2 updates tracked since 2016).

On this page

About Chester D Zahn Md NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

CHESTER D ZAHN MD (NPI 1639146442) is an individual gastroenterology provider in San Gabriel, California, licensed in California (G69510) and active in the NPI registry since March 2006. He is enrolled in Medicare PECOS and is a graduate of Stanford University School Of Medicine (1983).

NPPES Registry Identity

NPI1639146442

Entity TypeIndividualMale

Primary Taxonomy207RG0100X

Provider Legal NameCHESTER D ZAHNCredential: MD

Location Address1026 E LAS TUNAS DRSan Gabriel, CA 91776-1633

Mailing Address1026 E Las Tunas DrSan Gabriel, CA 91776-1633 · (626) 287-7222 · Fax (626) 287-1991

Phone(626) 287-7222

Fax(626) 287-1991

Sole ProprietorYes

Medical School CMSStanford University School Of MedicineGraduated 1983

Enumeration DateMarch 1, 2006

Last NPPES UpdateMarch 20, 20202 updates tracked since enumeration

NPPES CertifiedMarch 20, 2020

✔ NPI 1639146442 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal Medicine · GastroenterologyAllopathic & Osteopathic Physicians

Taxonomy Code207RG0100X

License✔ Licensed in CA · G69510

Definition

An internist who specializes in diagnosis and treatment of diseases of the digestive organs including the stomach, bowels, liver and gallbladder. This specialist treats conditions such as abdominal pain, ulcers, diarrhea, cancer and jaundice and performs complex diagnostic and therapeutic procedures using endoscopes to visualize internal organs.

1026 E LAS TUNAS DR, San Gabriel, CA 91776

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Other Identifiers 2

OtherG69510CA · Ca Medical Board

Medicaid00G695100CA

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare and accepts Medicare assignment

Chester D Zahn Md is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.

PECOS PAC ID840393708

PECOS Enrollment IDI20070313000649

Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Medicare Billing Reassignment

Medicare enrollment records show Chester Zahn reassigns Medicare billing to 1 organization. The organization bills Medicare for the services this provider delivers there.

Zahn & Associates A Medical Corporation

Same address

Specialist

1026 E LAS TUNAS DRIVE
San Gabriel, CA 91776

Reassigned Medicare billing, California enrollment

NPI 1912059478 (626) 287-7222

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Areas of Expertise CMS Part B claims 22

Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.

Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more 99213

This is a routine visit for patients who have already been seen by the healthcare provider. During this approximately 20-29 minute appointment, your health status will be evaluated and any necessary treatments or tests will be discussed. It's a chance to address any health concerns you may have.

705 services325 patients

Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes 99222

Initial hospital inpatient care is a service where a healthcare provider spends about 50 minutes per day overseeing your care while you're admitted in the hospital. This includes reviewing your health status, planning your treatment, and ensuring your safety and comfort.

437 services397 patients

Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes 99231

Follow-up hospital inpatient care is a daily service where a healthcare professional checks on your health progress during your hospital stay. Each session typically lasts 15 minutes, involving updates on your condition and adjustments to your treatment plan, if necessary.

422 services214 patients

Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes 99232

Follow-up hospital inpatient care involves daily check-ups while you're admitted in the hospital. Typically, a healthcare provider spends about 25 minutes each day reviewing your condition, adjusting treatment if needed, and answering any questions you might have.

253 services221 patients

Biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope 43239

This procedure involves using a thin, flexible tube with a light and camera, known as an endoscope, to examine the esophagus, stomach, and upper part of the small intestine. Small tissue samples are taken for further examination to help diagnose various conditions.

164 services162 patients

New patient office or other outpatient visit with moderate level of medical decision making, if using time, 45 minutes or more 99204

This is a first-time office or outpatient visit lasting between 45-59 minutes. The healthcare provider evaluates your health, discusses your medical history, and may suggest further tests or treatments. It's an opportunity to ask questions and understand your health better.

123 services123 patients

Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more 99213

116 services113 patients

Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes 99233

Follow-up hospital inpatient care per day typically involves a 35-minute check-up by your healthcare provider. This service includes monitoring your health progress, adjusting your treatment plan if needed, and answering any questions you may have about your condition or care.

100 services90 patients

Insertion of stomach tube using a flexible endoscope 43246

This procedure involves the use of a flexible endoscope, a thin tube with a light and camera, to insert a stomach tube. It helps doctors view and access your stomach without surgery. It's typically performed under sedation to ensure comfort.

76 services74 patients

Colorectal cancer screening; colonoscopy on individual at high risk G0105

Colorectal cancer screening, specifically a colonoscopy, is a preventive measure for those at high risk. A thin, flexible tube with a camera inspects the colon to spot any abnormal growths. This test helps detect potential issues early, enhancing the effectiveness of treatment.

53 services53 patients

Destruction of polyp or growth of large bowel using a flexible endoscope 45388

This procedure involves the removal of a polyp or growth in the large bowel. A flexible endoscope, a thin tube with a camera, is inserted through the rectum to visualize and remove the growth. This helps maintain bowel health and prevent complications.

52 services52 patients

Control of bleeding of esophagus, stomach, and/or upper small bowel using a flexible endoscope 43255

This procedure involves using a flexible tube with a light, called an endoscope, to examine and treat bleeding in the esophagus, stomach, or upper small bowel. It's a safe, effective way to control bleeding and ensure your digestive health.

43 services41 patients

Diagnostic exam of esophagus, stomach, and/or upper small bowel using a flexible endoscope 43235

This procedure, known as an upper endoscopy, involves inserting a thin, flexible tube with a camera down the throat to examine the esophagus, stomach, and upper small bowel. It helps diagnose conditions like ulcers or inflammation.

31 services31 patients

Removal of polyps or growths of esophagus, stomach, and/or upper small bowel using an endoscope with mechanical snare 43251

This procedure involves the use of a thin, flexible instrument called an endoscope to visualize and remove abnormal growths, known as polyps, from the esophagus, stomach, or upper small bowel. A tool called a mechanical snare is used to safely cut and remove these growths.

30 services30 patients

Replacement of stomach stoma tube 43762

A replacement of a stomach stoma tube is a procedure where your existing tube is removed and a new one is inserted. This helps ensure the tube functions properly, allowing nutrition directly into your stomach. It's a safe, routine process done by healthcare professionals.

26 services22 patients

Initial hospital care with straightforward or low level of medical decision making, per day, if using time, at least 40 minutes 99221

Initial hospital inpatient care refers to the first day of your stay in the hospital. This service typically includes a 30-minute check-up with a healthcare professional. They'll assess your health, discuss your condition, and plan your treatment. It's part of ensuring you receive the best possible care.

24 services22 patients

Incision of pancreatic outlet using a flexible endoscope 43262

This procedure involves a small cut in the outlet of the pancreas using a flexible tube with a camera, called an endoscope. It helps doctors diagnose and treat conditions affecting the pancreas, enhancing patient comfort and recovery.

21 services21 patients

Balloon dilation of pancreatic or bile duct or sphincter using a flexible endoscope 43277

Balloon dilation is a procedure where a tiny balloon is inserted via an endoscope into your pancreatic or bile duct. The balloon is then inflated to widen the duct, improving flow and relieving blockages. It's a non-surgical, minimally invasive procedure.

20 services19 patients

Removal of stone or debris from bile or pancreatic duct using a flexible endoscope 43264

This procedure, called an endoscopic retrograde cholangiopancreatography (ERCP), involves using a flexible tube with a camera (endoscope) to locate and remove stones or debris from your bile or pancreatic duct. It's a non-surgical method to clear the ducts, enhancing your digestive health.

19 services18 patients

Repositioning of oral or nasal feeding tube in small bowel 43761

Repositioning of an oral or nasal feeding tube in the small bowel is a procedure aimed to ensure proper tube placement for optimal nutrition delivery. It involves moving the tube that provides nutrients directly to your small intestine. This routine adjustment helps maintain comfort and effectiveness.

19 services15 patients

Biopsy of large bowel using a flexible endoscope 45380

A biopsy of the large bowel using a flexible endoscope is a procedure where a thin, flexible tube with a camera is inserted through the rectum to examine the bowel. If abnormal tissue is found, a small sample is taken for further examination. This helps in diagnosing conditions like inflammation, polyps, or cancer.

15 services15 patients

Control of bleeding of upper large bowel using a flexible endoscope 45382

This procedure involves using a flexible endoscope, a thin tube with a light and camera, to view and control bleeding in the upper large bowel. Special tools can be passed through the endoscope to stop the bleeding. It's a minimally invasive way to address this issue.

12 services11 patients

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 91776 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient

$142.39 typical visit price

range $62.96 – $187.60

Typical copayment $35.59 (range $15.74 – $46.90)

Most-billed visit code 99204

Established Patient

$109.96 typical visit price

range $20.84 – $153.61

Typical copayment $27.49 (range $5.21 – $38.40)

Most-billed visit code 99214

Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Medicare Quality Performance CMS QPP · MIPS

Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.

40.76/100

MIPS Final ScoreMerit-based Incentive Payment System · CMS Quality Payment Program

Individually scored

Quality

19.94

Improvement Activities

Cost

75.96

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is Chester Zahn's NPI number?

The NPI number for Chester Zahn is 1639146442. It was assigned to this individual provider in the NPPES registry on March 1, 2006.

Where is Chester Zahn located?

Chester Zahn practices at 1026 E Las Tunas Dr, San Gabriel, CA 91776. The listed phone number is (626) 287-7222.

What is Chester Zahn's specialty?

The primary specialty registered for this NPI is Internal Medicine, specializing in Gastroenterology, with taxonomy code 207RG0100X.

Is Chester Zahn enrolled in Medicare?

Yes. Chester Zahn is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.

Which organization bills Medicare for Chester Zahn's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Chester Zahn reassigns Medicare benefits to Zahn & Associates A Medical Corporation (San Gabriel, CA). The reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Chester Zahn's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

When was this NPI record last updated?

The NPPES record for Chester Zahn was last updated on March 20, 2020. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 6 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.