About Our Doctors

He completed an Internal Medicine Residency program and became certified by the American Board of Internal Medicine in 1997. He later completed a Fellowship in Gastroenterology at the University of Oklahoma Health Science Center in Oklahoma City, Oklahoma in 2006 and became board certified in gastroenterology in October 2006.

Dr. Ancha joined Waco Gastroenterology in July 2006 and his diverse training background makes him a strong member of the group. He is proficient with EGD, colonoscopy, ERCP, and wireless capsule endoscopy.

He is a member of the McLennan County Medical Association, Texas Medical Association, Texas Society for Gastroenterology and Endoscopy, and the American College of Gastroenterology. Dr. Ancha cares for patients at Hillcrest Baptist Medical Center, Providence Health Center and Waco Gastroenterology Endoscopy Center in Waco, Texas.

Dr. Ancha is the proud father of two daughters.

Dr. Boss earned his undergraduate degree from the University of Texas at Austin in 1981. His medical training was at the University of Texas Medical Branch in Galveston, where he graduated in 1989. Dr. Boss stayed in Galveston to complete an internal medicine internship and residency as well as his gastroenterology fellowship. He became board certified in internal medicine and gastroenterology in 1995 and joined Waco Gastroenterology in 1998.

Dr. Boss is married with three children. He is a member of the McLennan County Medical Society, Texas Medical Association, American College of Gastroenterology, American Gastroenterological Association, American College of Physicians, and the Texas Society for Gastroenterology and Endoscopy.

He has privileges at Hillcrest Baptist Medical Center, Providence Health Center, and Waco Gastroenterology Endoscopy Center in Waco, Texas.

Dr. Contreras earned a B.A. in Biology from the University of Texas at Austin in 1984 and went on to graduate from the University of Texas Health Science Center in San Antonio in 1988. He completed his medical training with an Internal Medicine Internship and Residency and Gastroenterology Fellowship at the University of Texas Health Science Center in Dallas, Texas from 1988-1994.

He was board certified for internal medicine in 1991 and gastroenterology in 1995. He joined Waco Gastroenterology in 1994.

Dr. Contreras is a member of the McLennan County Medical Society, Texas Medical Association, American College of Gastroenterology and American Gastroenterology Association. He has privileges at Hillcrest Baptist Medical Center, Providence Health Center, and Waco Gastroenterology Endoscopy Center in Waco, Texas.

Dr. Contreras is married and has two daughters.

Dr. Levings received her medical degree from Tulane University School of Medicine.  \

She completed her Internal Medicine residency at Virginia Commonwealth University/Medical College of Virginia in 2004. She then completed her Fellowship in Gastroenterology and Hepatology at Tulane University School of Medicine in 2007.

Dr. Levings is Board certified in Gastroenterology and has been practicing Gastroenterology since 2007.  Dr. Levings has a special interest in Colon Cancer Prevention.

She has privileges at Hillcrest Baptist Medical Center, Providence Health Center, and Waco Gastroenterology Endoscopy Center in Waco, Texas.

Dr. Hanysak attended Baylor University in Waco where he graduated with degrees in biology and philosophy in 1996. He attended medical school at the University of Texas Health Science Center in San Antonio, where he remained for his internship and residency and completed a Gastroenterology Fellowship in 2009.

He was board certified for internal medicine in 2005 and gastroenterology in 2009. Dr. Hanysak is a member of the McLennan County Medical Society, Texas Medical Association, American Society for Gastrointestinal Endoscopy, American College of Gastroenterology, and the Texas Society for Gastroenterology and Endoscopy.  

Dr. Hanysak is currently the official Gastroenterologist for Baylor Athletics.  He is also the Medical Director of Gastroenterology for Providence Ascension Hospital.

Dr. Hanysak joined Waco Gastroenterology in July 2009. In addition to his extensive training in general endoscopy, Dr. Hanysak has advanced training and experience to perform endoscopic ultrasound (EUS) and is the first physician to bring this service to Waco.

Dr. Hanysak is married and has two sons.

Dr. Hanu Ancha, obtained his Doctorate in 1995 in India. Completed training in Internal Medicine at the Mount Sinai School of Medicine, Bronx, New York in 2011. Upon completion of residency he completed a three year Fellowship in Gastroenterology at the University of Oklahoma Health Science Center in Oklahoma City, Oklahoma. After completion of fellowship he worked as an attending gastroenterologist serving the veterans at the Veterans Administration hospital in Pittsburgh. Subsequently he completed an Advanced Endoscopy Fellowship at St Luke’s Medical Center in Milwaukee, WI, in 2016.

Dr Hanu Ancha, has performed both basic science and clinical research to understand and improve digestive health and published several articles in peer reviewed journals and presented his work at both local and national meetings. He holds memberships at local and national major gastroenterology associations and also serves on several patient safety committees at the local hospitals.

Dr Hanu Ancha, is board certified in Gastroenterology and Internal Medicine. He is accomplished with EGD, diagnostic and screening colonoscopy, wireless capsule endoscopy, endoscopic removal of large polyps, ERCP and endoscopic ultrasound procedures. He provides care for his patients at Waco Gastroenterology Associates, Providence hospital and Baylor Scott and White Hillcrest Medical Center in Waco.

He joined Waco Gastroenterology in July 2016 and his extensive training and experience makes him a valuable addition to Waco Gastroenterology Associates. He is married and has three children.

Dr. Rives received his medical degree from the University of Texas & Health Science Center in San Antonio, attended an Internal Medicine residency at East Tennessee State University, where he served as a peer advisor and completed fellowship at East Carolina University in Greenville, NC where he was Chief Fellow.  

Dr. Rives has a special interest in reflux disease and colon cancer prevention. Dr. Rives is currently accepting new patients and consultations.

Dr. Rives and his family are native Texans and are happy to be returning to the Lone Star State.

Dr. Bussell’s journey in medicine began right here in Waco, working nights as a phlebotomist at Baylor Scott & White Hillcrest while attending Baylor University. After graduating Magna Cum Laude with a degree in Film and Digital Media and a minor in Biochemistry, he went on to earn his medical degree from Texas A&M College of Medicine. He then completed his Internal Medicine Residency and Gastroenterology Fellowship at Baylor Scott & White in Temple, where he cared for a diverse patient population and honed advanced procedural skills.

During his residency, Dr. Bussell was honored as Intern of the Year and was inducted into the Gold Humanism Honor Society for his dedication to compassionate, patient-centered care. His research has been published in respected journals, including the American Journal of Infection Control and Baylor University Medical Center Proceedings, with topics ranging from inflammatory bowel disease to hospital-onset infections and unique clinical case studies. He has also presented at national conferences such as the American College of Gastroenterology.

Beyond his professional accomplishments, Dr. Bussell is deeply connected to the Waco community. He attended Midway ISD and earned his Eagle Scout Award through Waco’s own Troop 497. In addition to his early work at Hillcrest, he has remained engaged in service through medical mission work in Kenya, volunteering at free clinics, and participating in local service projects.

When he isn’t caring for patients, Dr. Bussell enjoys woodworking, grilling, and spending time with his wife and children.

Shamyal Khan DO
Dr. Khan grew up in North Texas and attended Austin College in Sherman, Texas where he majored in Chemistry with a minor in Anthropology. He attended the Texas College of Osteopathic Medicine and completed the Rural Scholars Program with rotations in Clifton, Texas, Crockett, Texas and Fairbanks, Alaska. 

He completed his internship and residency at Baylor Scott and White in Temple, Texas followed by a year as Chief Resident. He then completed his gastroenterology fellowship at Baylor Scott and White with a focus on advanced endoscopic procedures including endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP). 

Dr. Khan is the Medical Director of Gastroenterology for Baylor Scott & White Hillcrest Hospital.

He has a special interest in cirrhosis, pancreaticobiliary disease, and the prevention of colon cancer.  

Dr. Khan is accepting new patients and consultations.

Patrice Ihry APRN, FNP-C
Patrice earned her Associates Degree in Nursing from McLennan Community College in 2003. She then went on to earn her B.S. in Nursing from the University of Texas-El Paso in 2010 and her Masters of Science in Nursing from Texas A&M University-Corpus Christi in 2014 with a focus in Family Nurse Practitioner. She has experience in a variety of nursing practices, including post-operative care, hematology/oncology and hospice/palliative care. She has worked in a variety of settings as a Family Nurse Practitioner including skilled nursing, hospice care and the emergency room. She joined Waco Gastroenterology in the summer of 2018. Patrice resides in Lorena, Texas with her husband and two children.

Jena Mann FNP Nurse Practitioner
Jena earned her B.S. in nursing from Baylor University School of Nursing in 1997. She then went on to earn her Master of Science in Nursing from Baylor University School of Nursing in 2014. Jena has experience in upper and lower gastrointestinal disease processes and various nursing practices, including postoperative care, pediatric care, and hospice/palliative care. Additionally, Jena has extensive knowledge of liver diseases such as cirrhosis, viral hepatitis, autoimmune hepatitis, alcoholic hepatitis, and hepatitis C. She joined Waco Gastroenterology in July 2014. Jena resides in Lorena, Texas, with her husband and four children.

Nurse Practitioner Mann see patients at Waco Gastroenterology and Associates.

Call 254-537-0911 to schedule your visit and to schedule your colonoscopy screening. 45 is the new 50.

Emily Witt, MSN, APRN, FNP-C

Emily Witt, MSN, APRN, FNP-C, was raised in Mart, Texas, a small rural community just outside of Waco. Emily's deep connection to her home town laid the foundation for a career built on compassion, dedication, and service.

She began her nursing journey at McLennan Community College, earning her Associate Degree in Nursing. While working in nephrology for seven years, she continued to advance her education-earning both her Bachelor of Science in Nursing and her Master of Science in Nursing with a family nurse practitioner focus from the University of Texas at El Paso.

In 2019, Emily returned to her roots, launching her career as a family nurse practitioner at a rural clinic in Mart. For the past six years, she has cared for patients of all ages, playing a vital role in the clinic's operation, growth, and success. Her leadership and clinical expertise have made a lasting impact on the community she has long called home.

Now, Emily is excited to bring her passion for patient care to a new chapter-joining the team at Waco Gastroenterology Associates. She looks forward to embracing her connection to the Waco medical community, expanding her knowledge in gastroenterology, and continuing to serve the people of the Waco area with excellence.

When she's not caring for patients, Emily cherishes time with her two young daughters, embracing the joy of motherhood and family life.