Dr. Diehl is a board-certified and fellowship-trained gastroenterologist. His clinical interests include endoscopic ultrasound, endoscopic retrograde cholangiopancreatography (ERCP) and innovative advanced therapeutic endoscopy. Dr. Diehl obtained his medical degree from the University of California, Los Angeles. He completed his residency at Harbor-UCLA Medical Center and his fellowships in gastroenterology at the University of California, San Francisco Medical Center and the University of California, Los Angeles Medical Center. Dr. Diehl is certified by the American Board of Internal Medicine. In his free time, Dr. Diehl enjoys spending time with his family and exercising, particularly swimming. He also has an appreciation for old cars. Dr. Diehl is rated as a Distinguished provider by MediFind in the treatment of Achalasia. His top areas of expertise are Barrett Esophagus, Gallbladder Disease, Watermelon Stomach, Endoscopy, and Gallbladder Removal.

Anthony T. Petrick, MD, FACS, FASMBS, is a board-certified general surgeon specializing in esophageal and bariatric surgery. Dr. Petrick performs a number of advanced and specialized surgical procedures including advanced endoscopy, revisional bariatric surgery, laparoscopic gastric band (or “lap band”), gastric bypass, biliopancreatic diversion with duodenal switch and gastric sleeve. He also treats people for various conditions affecting the stomach and gastrointestinal (GI) system, including hiatal and paraesophageal hernia, achalasia and acid reflux (GERD).|Board-certified in general surgery, Dr. Petrick earned his medical degree from Georgetown University in Washington, D.C. He completed general surgery residency at Georgetown University Medical Center in Washington, D.C. He then completed a fellowships in Surgical Oncology at and Beth Israel Deaconess Medical Center in Boston and in Bariatric and Foregut surgery at the University of Pittsburgh Medical Center.|For the past 18 years, Dr. Petrick served as program director for the Geisinger bariatric and foregut surgical fellowship. He now serves as associate program director, acting as a mentor to bariatric surgery fellows. Dr. Petrick has a strong commitment to research in bariatric and foregut surgery and has authored more than 100 articles. Currently, he serves as chief quality officer for inpatient services at Geisinger and Director of the Division of Bariatric and Foregut surgery.|Dr. Petrick is an active member of the Society of Gastrointestinal and Endoscopic Surgeons and a fellow of the American College of Surgeons and American Society of Metabolic and Bariatric Surgeons. He chairs to Data and Quality Committee for the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program and also serves as an editorial board member for the journal Surgical and Obesity-Related Diseases and a columnist for Bariatric Times.|In his free time, Dr. Petrick serves on the board of education at St. Joseph School in Danville. He also coaches the Susquehanna Valley Stampede varsity and junior varsity ice hockey teams.|Clinical Focus: Bariatric Surgery|If you’re a provider who’d like to refer a patient, call our 24/7 referral line at 800-332-8901 or visit www.emr-link.com. Dr. Petrick is rated as an Experienced provider by MediFind in the treatment of Achalasia. His top areas of expertise are Obesity, Hiatal Hernia, Hernia, Gastric Bypass, and Endoscopy.

David M. Parker, MD, FACS, FASMBS, is a board-certified general surgeon specializing in bariatric surgery for both adolescents and adults. Dr. Parker performs several advanced and specialized surgical procedures, including gastric bypass, biliopancreatic diversion with duodenal switch, revisional bariatric surgery, laparoscopic gastric band (or “lap band”) and gastric sleeve. He also provides care for various conditions affecting the stomach and gastrointestinal (GI) system, including hiatal hernia, paraesophageal hernia, achalasia and acid reflux.|He has a clinical interest in minimally invasive laparoscopic and robotic surgery.|Board-certified in general surgery, Dr. Parker earned his medical degree from West Virginia University in Morgantown. He completed a general surgery residency at the Dwight D. Eisenhower Army Medical Center in Fort Gordon, GA, followed by a fellowship in bariatric and foregut surgery at Geisinger Medical Center in Danville.|While in medical school, he received the Presidential Award for Excellence in Scholarship. During his fellowship, he received the SAGES Award for best fellow presentation.|Dr. Parker serves as program director for the Geisinger bariatric and foregut surgical fellowship. He has a strong commitment to research in bariatric and foregut surgery and has authored more than 24 published articles.|He is an active member of the Society of Gastrointestinal and Endoscopic Surgeons and a fellow of the American College of Surgeons and American Society of Metabolic and Bariatric Surgeons.|Dr. Parker has served in the United States Army and continues to serve as a lieutenant colonel in the United States Army Reserve. He is also a football enthusiast, rooting for the West Virginia Mountaineers in his free time. Dr. Parker is rated as an Experienced provider by MediFind in the treatment of Achalasia. His top areas of expertise are Hiatal Hernia, Hernia, Obesity, Gastric Bypass, and Endoscopy.

Harshit S. Khara, MD, is an Interventional Gastroenterologist based at Geisinger Medical Center in Danville, PA.|Dr. Khara is an Associate Professor of Medicine at the Geisinger Commonwealth School of Medicine. He serves as the Director of Endoscopy; System Director of Interventional Endoscopy, Director of Endoscopic and Translational Research; Director of the Clinical Use Evaluation Committee; and System Director of Quality & Innovation. He is also the Research Director and Core faculty for the Gastroenterology Fellowship Program, as well as the Program Director for the Advanced Therapeutic Endoscopy Fellowship Program at the Center for Advanced Therapeutic Endoscopy at Geisinger, participating in the training and mentoring of advanced endoscopy and general gastroenterology fellows. Dr. Khara is also the Director of the National Pancreas Foundation Center at Geisinger.|He is involved in multi-center clinical research and quality improvement projects. Dr. Khara's clinical and research interests are in the field of interventional endoscopic ultrasound, ERCP, Barrett’s esophagus, third space endoscopy, endoscopic treatments for GERD, interventional EndoHepatology, and bariatric interventional endoscopy.|Dr. Khara earned his medical degree from Seth G.S. Medical College & K.E.M. Hospital in India then completed his Internal Medicine Residency at Drexel University College of Medicine-Saint Peter's University Hospital. He completed a Fellowship in Transplant Hepatology at the University of Nebraska Medical Center, a Fellowship in Gastroenterology at Yale University School of Medicine-Norwalk Hospital and a Fellowship in Advanced Therapeutic Endoscopy at Geisinger Medical Center.|Dr. Khara is certified in Gastroenterology by the American Board of Internal Medicine. Dr. Khara is rated as an Experienced provider by MediFind in the treatment of Achalasia. His top areas of expertise are Pancreatic Pseudocyst, Gastroesophageal Reflux Disease (GERD), Barrett Esophagus, Endoscopy, and Gastric Bypass.

Dr. Shellenberger is a board-certified and fellowship-trained gastroenterologist. His clinical interests include postgraduate medical education, esophageal motility and other GI laboratory procedures. Dr. Shellenberger earned his medical degree from the Philadelphia College of Osteopathic Medicine. He completed his residency and his fellowship in gastroenterology at Geisinger Medical Center. Dr. Shellenberger is certified by the American Board of Internal Medicine in internal medicine and gastroenterology. Dr. Shellenberger is rated as an Experienced provider by MediFind in the treatment of Achalasia. His top areas of expertise are Crohn's Disease, Angiodysplasia of the Colon, Swallowing Difficulty, Endoscopy, and Colonoscopy.

Dr. Akhtar is a board-certified and fellowship-trained gastroenterologist. His clinical interests include general gastroenterology and endoscopic retrograde cholangiopancreatography (ERCP). Dr. Akhtar attended Patna Medical College, where he received his medical degree, and completed his residency at East Carolina University. He also completed a residency and a fellowship in gastroenterology at Rutgers, the State University of New Jersey in Camden, N.J. Dr. Akhtar is certified by the American Board of Internal Medicine in gastroenterology. Dr. Akhtar is rated as an Experienced provider by MediFind in the treatment of Achalasia. His top areas of expertise are Familial Adenomatous Polyposis, Esophagitis, Turcot Syndrome, Hemorrhoidectomy, and Colonoscopy.

Jon Gabrielsen is a General Surgeon in Lewisburg, Pennsylvania. Dr. Gabrielsen is rated as a Distinguished provider by MediFind in the treatment of Achalasia. His top areas of expertise are Hiatal Hernia, Hernia, Achalasia, Gastric Bypass, and Gallbladder Removal.

Joseph Gallagher is a Gastroenterologist in Lewisburg, Pennsylvania. Dr. Gallagher is rated as an Experienced provider by MediFind in the treatment of Achalasia. His top areas of expertise are Familial Adenomatous Polyposis, Turcot Syndrome, Gardner Syndrome, Colonoscopy, and Endoscopy.