
Locations
Doctors Office: This is where you go for
regular check-ups and consultations.
Endoscopy Center: This is where you go
for medical procedures, including
colonoscopies, ultrasounds, studies, and more.
Lancaster
Doctors Office: This is where you go for
regular check-ups and consultations.
Endoscopy Center: This is where you go
for medical procedures, including
colonoscopies, ultrasounds, studies, and more.
MidAtlantic Endoscopy 1
Doctors Office: This is where you go for
regular check-ups and consultations.
Endoscopy Center: This is where you go
for medical procedures, including
colonoscopies, ultrasounds, studies, and more.
MidAtlantic Endoscopy 2
Meet Mark H. Johnston, MD, FACP, FACG, AGAF
Dr. Johnston earned his MD at Hahnemann University. He completed his Residency at Naval Medical Center Portsmouth and his Fellowship in Gastroenterology at National Naval Medical Center, Bethesda, MD.
He is former Chief of Gastroenterology at the National Naval Medical Center, Bethesda, MD, and retired as a Navy Captain in 2005. He has treated numerous members of Congress, the Supreme Court and White House.
Dr. Johnston is board certified in Internal Medicine and Gastroenterology and is a Fellow of the American College of Physicians, American College of Gastroenterology and Fellow of the American Gastroenterological Association.
He has been practicing gastroenterology in Lancaster County since 2005.
He is the author of numerous publications and is internationally known for his expertise in esophageal disease. He has several U.S. Patents for his invention of CryoSpray Ablation Therapy. This technique uses a spray of liquid nitrogen to treat cancerous and precancerous conditions of the esophagus including Barrett’s Esophagus and esophageal cancer. He has spoken nationally and internationally in his areas of research: GERD, Barrett’s Esophagus and esophageal cancer.
He has privileges at Penn Medicine Lancaster General Hospital.
He and his wife live in Lancaster. They have three children; two sons who are active-duty medical officers in the Navy and a daughter who is a Physician Assistant. In his free time, he enjoys spending time with his family, the outdoors, hiking and sailing. He has led and served in over 30 medical mission trips to Kenya, China and Albania.
Medical Education
Hahnemann University
Residency
Portsmouth Naval Medical Center
Fellowship
National Naval Medical Center
Patient Forms
- RGI Historial Medico Del Paciente ( 688 KB)
- RGI Medical History Form ( 167 KB)
- RGI Release Of Info Form ( 66 KB)
Prep Instructions for Procedures
- Colonoscopy Preparation Instructions, Standard Split Prep ( 133 KB)
- Upper Endoscopy (EGD), Endoscopic Ultrasound (EUS) or ERCP Preparation ( 58 KB)
- Alta Endoscopia (EGD) o ERCP Preparación ( 185 KB)
- Bowel Prep with Prepopik ( 82 KB)
- Capsule Endoscopy Preparation ( 55 KB)
- Flexible Sigmoidoscopy Preparation Instructions ( 52 KB)
- Español Instrucciones de Dosis Dividida—Prepopik Preparación ( 307 KB)
- Miralax/Gatorade Colonoscopy Preparation—2 Day Prep ( 53 KB)
- Español Preparación De Colonoscopia Miralax Dosis Dividida ( 199 KB)
- Español Preparación de Miralax (2) Dos Dias para la Colonoscopia ( 152 KB)
- Español Preparación Para Flexible Sigmoidoscopy ( 182 KB)
- Español Preparación Para Una Capsular Endoscopia ( 271 KB)