Welcome to Our Practice

Welcome to Gastroenterology Services, LLC, Your Gastroenterologist in Oviedo, FL

Gastroenterology Services, LLC is a gastroenterology and hepatology practice that has served the Oviedo and surrounding areas for the last 10 years. Two physicians and two nurse practitioners comprise the medical staff. We provide the most up-to-date medical care to patients through a comprehensive evaluation, diagnosis and treatment of gastrointestinal and liver disorders. We pride ourselves in being a caring and empathetic team of health professionals who treat patients with compassion and respect. We also provide coverage for the Oviedo Medical Center.

We are committed to providing the best, comprehensive and up-to-date care in Oviedo and surrounding areas. Our team has been specially trained in the diagnosis and treatment of digestive and liver diseases.

Review Us
Health Grades
Health Grades
Google Reviews

Meet Our Team

  • Robert Shultz D.O.

    Robert Shultz, D.O., F.A.C.O.I., is a 1984 graduate of the Kirksville College of Osteopathic Medicine. He completed his rotating internship and internal medicine residency at Normandy Osteopathic Hospitals in St. Louis, Missouri. He completed his fellowship training in gastroenterology at the Chicago College of Osteopathic Medicine. During his fellowship training Dr. Shultz served as a visiting fellow at several prestigious medical centers including the University of Chicago, Northwestern University, Washington University, and the University of Michigan Medical Centers. Dr. Shultz is Board Certified in internal medicine and gastroenterology, and is a fellow of the American College of Osteopathic Internist.

    Read More
  • Ian Martinez M.D.

    Ian Martínez, M.D. completed his internal medicine residency and gastroenterology fellowship at Louisiana State University Health Sciences Center in New Orleans, Louisiana. After his internship in 2008, he was awarded the LSU School of Medicine Aesculapian Society Intern of the Year Ward. He was chosen for his approachability, enthusiasm, and superior quality of instruction.

    Read More
  • Amanda St. John, A.P.R.N.

    Amanda St. John is a certified Adult and Gerontological Nurse Practitioner (AGNP). She has a strong background in critical care nursing and has worked at several local hospitals as well as outpatient surgery/endoscopy. She completed her ASN degree in 2010 at Montgomery College in Maryland, where she was raised. She moved to Orlando in 2011.

    Read More
  • Michelle Calle, A.P.R.N., F.N.P-C.

    Michelle Calle is a certified Family Nurse Practitioner dedicated to providing effective, safe, and quality care to all patients across the lifespan. Her experience includes more than 10 years in healthcare ranging from progressive and critical care settings; recognized with her CCRN certification through the American Association of Critical Care Nurses in 2015. She earned her Bachelor of Science Degree in Nursing from the University of South Florida, followed by a Master of Science Degree from South University Nurse Practitioner Program with high honors; Sigma Theta Tau-International Honor Society of Nursing in January 2019.

    Read More


What Our Clients Say About Us

  • "I was expecting a lot, and I must say the whole experience exceeded all of my expectations. Highly recommended!!!!!"
  • "Highly recommended. Caring, kind, patient! Helped me a great deal."
  • "Kind and professional bedside manor. Truly cares for each of his patients and follows through."
  • "I can't say enough good things about my experience."
  • "Dr. Martinez is one of the best doctors I’ve ever visited. He took plenty of time to talk about all our concerns."
  • "Professional and caring. Helped me a great deal. Highly recommended."

Our Location

Find us on the map

Hours of Operation

Our Regular Schedule

Gastroenterology Services LLC


8:30 am-5:00 pm


8:30 am-5:00 pm


8:30 am-5:00 pm


8:30 am-5:00 pm


8:30 am-5:00 pm





COVID-19 Updates

Due to the recent COVID-19 concern, we want to assure everyone about how we sanitize our office, we follow all universal precautions.

Click here to read more.