Leadership Team

The legacy and collaboration of our leadership sets us apart. This team has dedicated their careers to creating the best organization where providers can thrive.

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Mark Gilreath
Chief Executive Officer

Mark Gilreath brings more than 27 years of operational leadership, innovation, and GI experience to United Digestive’s executive team. As former operating partner for Frazier Healthcare Partners, he facilitated the formation of United Digestive in 2018.

In 2008, Mark founded EndoChoice Inc. (NYSE: GI) and served as its CEO from the company’s inception until the company was acquired by Boston Scientific in 2016. EndoChoice focuses on the R&D and commercialization of a diverse portfolio of medical technologies and services for physicians in gastrointestinal (GI) endoscopy. The Company was recognized six consecutive years by Inc. Magazine as one of the fastest growing companies in America. Mark led the company from his basement in 2008 to an IPO on the New York Stock Exchange, with more than 500 employees.

Before founding EndoChoice, Mark served on the executive committee at Given Imaging (NASDAQ: GIVN) as President of The Americas and Chief Marketing Officer. During his eight years at Given Imaging, the company launched the PillCam Video Capsule and was transformed from a pre-revenue startup to a NASDAQ company approaching $200 million in revenue. The Company was acquired by Covidien (now Medtronic).

Prior to joining Given Imaging, Mark served in a variety of leadership roles at PENTAX Medical during 7 years of rapid growth. He began his career serving in the U.S. military in Naval Intelligence during Operation Desert Storm.

Mark has served on the boards of several public and private companies, and non-profit organizations. In 2013, he was selected as Business Person of the Year in Metro Atlanta, and he is an active member of YPO’s Southern 7 Chapter. Mark holds a B.Sc. in finance from Winthrop University and an MBA from the Fuqua School of Business at Duke University.

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Neal C. Patel, MD

Embracing the dyad leadership model which partners physician and business leaders, Dr. Patel serves as President of United Digestive. Prior to assuming the role, Dr. Patel first served as Vice President of Clinical Development, followed by the position of Chief Strategy Officer. He is currently a partner physician and also serves as a member of the physician executive committee for Atlanta Gastroenterology Associates. Dr. Patel represents United Digestive on a national level as a board member of the Digestive Health Provider Association (DHPA) and as a member of the American College of Gastroenterology’s Practice Management Committee.

Dr. Patel graduated magna cum laude and was a Presidential Scholar with a degree in Banking and Finance at the University of Georgia. He then graduated cum laude from the Morehouse School of Medicine, where he received the prestigious Academic Achievement Merit Scholarship. Dr. Patel later completed his internal medicine residency and gastroenterology and hepatology fellowship with the Mayo Clinic School of Graduate Education. While there, he was named Assistant Professor of Medicine. He currently holds academic appointments with both Emory University School of Medicine and Morehouse School of Medicine.

Dr. Patel has leveraged his background in finance coupled with strong clinical experience to widely present and publish on the future of gastroenterology and private equity partnerships. In addition, he has published numerous clinical studies in peer-reviewed journals and co-authored several book chapters, including a chapter in the highly regarded Sleisenger and Fordtran’s Gastrointestinal and Liver Disease.

John Suh MD MPH

John Suh, MD, MPH
Chief Medical Officer

Prior to serving as chief medical officer at United Digestive, Dr. John Suh held various leadership roles within the organization and affiliated practice, Atlanta Gastroenterology Associates. He served as a member of United Digestive’s inaugural physician executive committee, on the organization’s  endoscopy governing body, and continues to serve as medical director for the organization’s Advanced Center for GI Therapeutics. In addition, he is a former board member of the Digestive Health Provider Association, an organization comprised of independent GI practices from across the nation.

After completing his undergraduate degree at Johns Hopkins University in Baltimore, Dr. Suh received a master’s degree in health policy and management at Emory University’s Rollins School of Public Health in Atlanta. During graduate school, he served as a research assistant at the Centers for Disease Control in special pathogens. He then worked as an intern for the Institute for Diversity in Health Management and as a consultant for Healthcare Microsystems.

Dr. Suh completed his medical degree at the University of Alabama School of Medicine in Birmingham and his residency at the University of Michigan Medical Center in Ann Arbor. Following a fellowship in gastroenterology at the University of Southern California Medical Center in Los Angeles, he then completed a fellowship in advanced endoscopy at Harbor-UCLA Medical Center.

Dr. Suh is a member of the American Gastroenterological Association and the American College of Gastroenterology, and has contributed chapters to two gastroenterology textbooks. For the fifth consecutive year, he was named to Atlanta Magazine‘s ‘Top Doctors’ guide in gastroenterology – a list of top physicians in the metro area.


Edward L. Hay, Jr., MHA, FACHE
Chief Operations Officer

Edward brings more than 32 years of operations and physician practice management experience to United Digestive, including expertise in strategic planning, governance, recruiting and retention, referral management, and revenue cycle infrastructure.

Previously, Edward worked for Optum/The Advisory Board Company/Southwind for 12 years where he served in various key executive roles and provided group practice assessment and strategic planning to health systems and medical group enterprises. Most recently, he served as Senior Vice President of Operations for ProHEALTH New York, a 1,000-clinician medical group. He oversaw all practice operations, urgent care, radiology, pathology, anesthesia, ambulatory surgery center, and all centralized practice services (call center, health information management, and referral management).

Prior to his time with Optum/The Advisory Board Company/Southwind, he served as the Executive Administrator and Business Manager for the department of surgery at the Medical University of South Carolina. During his tenure, he oversaw an 80 percent growth in faculty and 41 percent growth in staff.

Edward holds a bachelor’s degree from Davidson College in Davidson, North Carolina, and a Master of Health Administration from Duke University in Durham, North Carolina. He is a fellow of the American College of Healthcare Executives, as well as an active member of the Medical Group Management Association, the South Carolina Medical Group Management Association, and the Multispecialty Group Executive Society.


Ron Fleming
Chief Financial Officer

Ron brings more than 30 years of revenue cycle management, accounting, and financial planning experience to United Digestive’s executive team, including more than 20 years serving in a Chief Financial Officer role within the healthcare industry.

Most recently, he served as the CFO for Prospira PainCare, Inc., a private equity-backed, multi-state provider of comprehensive, multidisciplinary pain management services. He previously held CFO roles with AdCare Health Systems, a long-term care provider, and Georgia Cancer Specialists, one of the Top 10 private oncology practices in the US.

Ron holds a bachelor’s degree in accounting from Ball State University, and he is a certified public accountant and certified global management accountant.

Sam Vaill
Chief Development Officer

Sam brings nearly 20 years of experience in business development, healthcare, mergers & acquisitions, private equity, and investment banking to the United Digestive executive team.

Most recently, Sam served as Chief Growth Officer for Sequel Youth & Family Services, one of the largest national providers of residential and community-based behavioral health services for children, adolescents, and adults. He oversaw various business development teams and was responsible for organic growth, mergers & acquisitions, and de novo expansion.  Sam was also responsible for helping start and set the strategy for their new Autism division.

Prior to that, Sam served as Chief Development Officer for US Acute Care Solutions, the largest physician-owned acute care provider in the country with a focus on emergency medicine and hospitalist management services. He led a team responsible for all growth-related initiatives for the organization, including mergers & acquisitions, organic growth, health system and hospital relationships, and other strategic partnerships.

Sam holds a bachelor’s degree in political science from Tufts University in Medford, Massachusetts, and an MBA from Babson College’s F.W. Olin Graduate School of Business in Wellesley, Massachusetts.

Board of Directors

A culture of collaboration and accountability starts at the top. Our board of directors is comprised of cross-functional business and clinical leaders who help guide our organization and ensure we continue to accomplish our goals.

Physician Executive Committee

With a dynamic and engaged provider base, our physician executive committee serves as the voice for their local colleagues and helps guide the clinical side of the organization. Members are elected by their peers, represent our various geographic regions, and meet regularly with United Digestive’s leadership team.

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