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John Clarke

Gastroenterologist, Motility specialist

Clinical Associate Professor, Medicine - Gastroenterology & Hepatology

Bio: Dr. John Clarke recently joined the Gastroenterology & Hepatology Division at Stanford University as Director of the Esophageal Program. He previously spent 17 years in Baltimore, including 9 years on the faculty at Johns Hopkins University where he was an Associate Professor and at various times Director of Esophageal Motility, Director of Gastrointestinal Motility, Clinical Director of the Johns Hopkins Center for Neurogastroenterology, and Clinical Director of the Gastroenterology & Hepatology Division at Johns Hopkins Bayview Medical Center.

His career has combined research, education and clinical care. His clinical areas of expertise include achalasia, dysphagia, eosinophilic esophagitis, esophageal dysmotility, gastroesophageal reflux disease, gastroparesis, GI-manifestations of scleroderma and GI dysmotility. While at Johns Hopkins University, he was inducted into The Miller-Coulson Academy for Clinical Excellence, an institutional honor society for master clinicians at the time limited to 50 members across the entire university.

From an education standpoint, he has lectured in over a dozen countries, authored over 25 textbook chapters and serves on the educational affairs committee of the American College of Gastroenterology. He has also won several major teaching awards, including The Johns Hopkins University Alumni Association Award for Excellence in Teaching, given to one faculty member per year in the entire School of Medicine.

His research has focused on optimization and characterization of diagnostic studies to evaluate motility disorders, as well the relationship between therapeutic endoscopic techniques and treatment of motility disorders. He was an investigator on the NIH Gastroparesis Consortium and is also a former recipient of the AGA Don Castell Award.

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Summary
Clinical Trials
Reviews

4.8 out of 5

171 Patient Ratings
52 Patient Comments

Digestive Health Center in Redwood City

420 Broadway Street, Pavilion D, 2nd Floor
Redwood City , CA 94063
Phone: 650-736-5555

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Esophagus Center

420 Broadway Street, Pavilion D, 2nd Floor
Redwood City , CA 94063
Phone: 650-736-5555

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Amyloid Center

300 Pasteur Drive
2nd Floor, Room A260
Stanford , CA 94305
Phone: 650-725-6186

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Summary
Clinical Trials
Reviews

Practice Areas

Esophageal manometry
Esophageal Manometry
Esophageal motility disorders including spasm
Esophagogastroduodenoscopy (EGD)
Gastric Electrical Stimulation
Gastric Pacemaker
Gastrostomy (Feeding) Tube
Motility Disorders
Non-cardiac chest pain
Other endoscopic procedures
Paraesophageal Hernias
Sigmoidoscopy
Small bowel manometry
Upper GI endoscopy

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Professional Education

Board Certification: Gastroenterology, American Board of Internal Medicine (2007)
Fellowship: Johns Hopkins University Dept of Gastroenterology (2007) MD
Board Certification: Internal Medicine, American Board of Internal Medicine (2002)
Residency: Johns Hopkins Hospital Internal Medicine Residency (2002) MD
Medical Education: Columbia University College of Physicians and Surgeons (1999) NY

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Honors & Awards

Award for Excellence in Teaching, John Hopkins University Alumni Association (2015)

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Administrative Appointments

Director, Esophageal Program, Stanford Medicine (2016 - Present)

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Publications

Preliminary pneumoperitoneum facilitates transgastric access into the peritoneal cavity for natural orifice transluminal endoscopic surgery: A pilot study in a live porcine model
Ko, C.-W., Shin, E. J., Buscaglia, J. M., Clarke, J. O., Magno, P., Giday, S. A., … Kantsevoy, S. V. (2007). Preliminary pneumoperitoneum facilitates transgastric access into the peritoneal cavity for natural orifice transluminal endoscopic surgery: A pilot study in a live porcine model. ENDOSCOPY, 39(10), 849–53.
D-1- and D-2-like dopamine receptors are co-localized on the presynaptic varicosities of striatal and nucleus accumbens neurons in vitro
Wong, A. C., Shetreat, M. E., Clarke, J. O., & Rayport, S. (1999). D-1- and D-2-like dopamine receptors are co-localized on the presynaptic varicosities of striatal and nucleus accumbens neurons in vitro. NEUROSCIENCE, 89(1), 221–233.
Is blood the ideal submucosal cushioning agent? A comparative study in a porcine model
Giday, S. A., Magno, P., Buscaglia, J. M., Canto, M. I., Ko, C.-W., Shin, E. J., … Kantsevoy, S. V. (2006). Is blood the ideal submucosal cushioning agent? A comparative study in a porcine model. ENDOSCOPY, 38(12), 1230–1234.
Nausea and vomiting in gastroparesis: similarities and differences in idiopathic and diabetic gastroparesis. Parkman, H. P., Hallinan, E. K., Hasler, W. L., Farrugia, G., Koch, K. L., Calles, J., … HAMILTON, F. (2016). Nausea and vomiting in gastroparesis: similarities and differences in idiopathic and diabetic gastroparesis. Neurogastroenterology and Motility .
Clinical and pH study characteristics in reflux patients with and without ineffective oesophageal motility (IEM). Triadafilopoulos, G., Tandon, A., Shetler, K. P., & Clarke, J. (2016). Clinical and pH study characteristics in reflux patients with and without ineffective oesophageal motility (IEM). BMJ Open Gastroenterology, 3(1).
Pyloric Therapies for Gastroparesis. Ahuja, N. K., & Clarke, J. O. (2017). Pyloric Therapies for Gastroparesis. Current Treatment Options in Gastroenterology.
The Role of Impedance Planimetry in the Evaluation of Esophageal Disorders. Ahuja, N. K., & Clarke, J. O. (2017). The Role of Impedance Planimetry in the Evaluation of Esophageal Disorders. Current Gastroenterology Reports, 19(2), 7-?
Three-Dimensional Anorectal Manometry Enhances Diagnostic Gain by Detecting Sphincter Defects and Puborectalis Pressure. Raja, S., Okeke, F. C., Stein, E. M., Dhalla, S., Nandwani, M., Lynch, K. L., … Clarke, J. O. (2017). Three-Dimensional Anorectal Manometry Enhances Diagnostic Gain by Detecting Sphincter Defects and Puborectalis Pressure. Digestive Diseases and Sciences.
What is the clinical significance of esophagogastric junction outflow obstruction? evaluation of 60 patients at a tertiary referral center. Okeke, F. C., Raja, S., Lynch, K. L., Dhalla, S., Nandwani, M., Stein, E. M., … Clarke, J. O. (2017). What is the clinical significance of esophagogastric junction outflow obstruction? evaluation of 60 patients at a tertiary referral center. Neurogastroenterology and Motility , 29(6).
Esophageal distensibility measurement: impact on clinical management and procedure length. Ahuja, N. K., Agnihotri, A., Lynch, K. L., Hoo-Fatt, D., Onyimba, F., McKnight, M., … Clarke, J. O. (2017). Esophageal distensibility measurement: impact on clinical management and procedure length. Diseases of the Esophagus , 30(8), 1–8.
The Changing Impact of Gastroesophageal Reflux Disease in Clinical Practice: An Updated Study Akst, L. M., Haque, O. J., Clarke, J. O., Hillel, A. T., Best, S. R. A., & Altman, K. W. (2017). The Changing Impact of Gastroesophageal Reflux Disease in Clinical Practice: An Updated Study. ANNALS OF OTOLOGY RHINOLOGY AND LARYNGOLOGY, 126(3), 229–35.
Early satiety and postprandial fullness in gastroparesis correlate with gastroparesis severity, gastric emptying, and water load testing Parkman, H. P., Hallinan, E. K., Hasler, W. L., Farrugia, G., Koch, K. L., Nguyen, L., … HAMILTON, F. (2017). Early satiety and postprandial fullness in gastroparesis correlate with gastroparesis severity, gastric emptying, and water load testing. NEUROGASTROENTEROLOGY AND MOTILITY, 29(4).
Learning Curve for PerOral Endoscopic Myotomy Deciphered: a Comprehensive Analysis Using Two Different Methodologies El Zein, M. H., Kumbhari, V., Saxena, P., Kamal, A., Ngamruengphong, S., Besharati, S., … Khashab, M. (2015). Learning Curve for PerOral Endoscopic Myotomy Deciphered: a Comprehensive Analysis Using Two Different Methodologies. GASTROINTESTINAL ENDOSCOPY, 81(5), AB167–AB167.
Intraoperative measurement of esophagogastric junction cross-sectional area by impedance planimetry correlates with clinical outcomes of peroral endoscopic myotomy for achalasia: a multicenter study Ngamruengphong, S., von Rahden, B. H. A., Filser, J., Tyberg, A., Desai, A., Sharaiha, R. Z., … Khashab, M. A. (2016). Intraoperative measurement of esophagogastric junction cross-sectional area by impedance planimetry correlates with clinical outcomes of peroral endoscopic myotomy for achalasia: a multicenter study. SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES, 30(7), 2886–94.
Comprehensive analysis of efficacy and safety of peroral endoscopic myotomy performed by a gastroenterologist in the endoscopy unit: a single-center experience Khashab, M. A., El Zein, M., Kumbhari, V., Besharati, S., Ngamruengphong, S., Messallam, A., … Clarke, J. O. (2016). Comprehensive analysis of efficacy and safety of peroral endoscopic myotomy performed by a gastroenterologist in the endoscopy unit: a single-center experience. GASTROINTESTINAL ENDOSCOPY, 83(1), 117–25.
Gender is a determinative factor in the initial clinical presentation of eosinophilic esophagitis Lynch, K. L., Dhalla, S., Chedid, V., Ravich, W. J., Stein, E. M., Montgomery, E. A., … Clarke, J. O. (2016). Gender is a determinative factor in the initial clinical presentation of eosinophilic esophagitis. DISEASES OF THE ESOPHAGUS, 29(2), 174–78.
Outcomes and Factors Associated With Reduced Symptoms in Patients With Gastroparesis Pasricha, P. J., Yates, K. P., Nguyen, L., Clarke, J., Abell, T. L., Farrugia, G., … Parkman, H. P. (2015). Outcomes and Factors Associated With Reduced Symptoms in Patients With Gastroparesis. GASTROENTEROLOGY, 149(7), 1762-?
Refractory gastroparesis can be successfully managed with endoscopic transpyloric stent placement and fixation (with video) Khashab, M. A., Besharati, S., Ngamruengphong, S., Kumbhari, V., El Zein, M., Stein, E. M., … Clarke, J. O. (2015). Refractory gastroparesis can be successfully managed with endoscopic transpyloric stent placement and fixation (with video). GASTROINTESTINAL ENDOSCOPY, 82(6), 1106–9.
Comprehensive Radionuclide Esophagogastrointestinal Transit Study: Methodology, Reference Values, and Initial Clinical Experience Antoniou, A. J., Raja, S., El-Khouli, R., Mena, E., Lodge, M. A., Wahl, R. L., … Ziessman, H. A. (2015). Comprehensive Radionuclide Esophagogastrointestinal Transit Study: Methodology, Reference Values, and Initial Clinical Experience. JOURNAL OF NUCLEAR MEDICINE, 56(5), 721–27.
Small Intestinal Transit Time Is Delayed in Small Intestinal Bacterial Overgrowth Roland, B. C., Ciarleglio, M. M., Clarke, J. O., Semler, J. R., Tomakin, E., Mullin, G. E., & Pasricha, P. J. (2015). Small Intestinal Transit Time Is Delayed in Small Intestinal Bacterial Overgrowth. JOURNAL OF CLINICAL GASTROENTEROLOGY, 49(7), 571–76.
High-resolution anorectal manometry and dynamic pelvic magnetic resonance imaging are complementary technologies Jodorkovsky, D., Macura, K. J., Gearhart, S. L., Dunbar, K. B., Stein, E. M., & Clarke, J. O. (2015). High-resolution anorectal manometry and dynamic pelvic magnetic resonance imaging are complementary technologies. JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, 30(1), 71–74.
Upper Esophageal Sphincter Abnormalities Frequent Finding on High-resolution Esophageal Manometry and Associated With Poorer Treatment Response in Achalasia Chavez, Y. H., Ciarleglio, M. M., Clarke, J. O., Nandwani, M., Stein, E., & Roland, B. C. (2015). Upper Esophageal Sphincter Abnormalities Frequent Finding on High-resolution Esophageal Manometry and Associated With Poorer Treatment Response in Achalasia. JOURNAL OF CLINICAL GASTROENTEROLOGY, 49(1), 17–23.
Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Chedid, V., Dhalla, S., Clarke, J. O., Roland, B. C., Dunbar, K. B., Koh, J., … Mullin, G. E. (2014). Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Global Advances in Health and Medicine, 3(3), 16–24.
Low Ileocecal Valve Pressure Is Significantly Associated with Small Intestinal Bacterial Overgrowth (SIBO) Roland, B. C., Ciarleglio, M. M., Clarke, J. O., Semler, J. R., Tomakin, E., Mullin, G. E., & Pasricha, P. J. (2014). Low Ileocecal Valve Pressure Is Significantly Associated with Small Intestinal Bacterial Overgrowth (SIBO). DIGESTIVE DISEASES AND SCIENCES, 59(6), 1269–77.
Domperidone for delayed gastric emptying in lung transplant recipients with and without gastroesophageal reflux Lidor, A. O., Ensor, C. R., Sheer, A. J., Orens, J. B., Clarke, J. O., & McDyer, J. F. (2014). Domperidone for delayed gastric emptying in lung transplant recipients with and without gastroesophageal reflux. PROGRESS IN TRANSPLANTATION, 24(1), 27–32.
Multichannel Intraluminal Impedance-pH Testing Is Clinically Useful in the Management of Patients with Gastroesophageal Reflux Symptoms Jodorkovsky, D., Price, J. C., Kim, B., Dhalla, S., Stein, E. M., & Clarke, J. O. (2014). Multichannel Intraluminal Impedance-pH Testing Is Clinically Useful in the Management of Patients with Gastroesophageal Reflux Symptoms. DIGESTIVE DISEASES AND SCIENCES, 59(8), 1817–22.
Peroral endoscopic myotomy as a platform for the treatment of spastic esophageal disorders refractory to medical therapy (with video) Khashab, M. A., Saxena, P., Kumbhari, V., Nandwani, M., Roland, B. C., Stein, E., … Pasricha, P. J. (2014). Peroral endoscopic myotomy as a platform for the treatment of spastic esophageal disorders refractory to medical therapy (with video). GASTROINTESTINAL ENDOSCOPY, 79(1), 136–39.
Jet injection of dyed saline facilitates efficient peroral endoscopic myotomy Khashab, M. A., Messallam, A. A., Saxena, P., Kumbhari, V., Ricourt, E., Aguila, G., … Clarke, J. O. (2014). Jet injection of dyed saline facilitates efficient peroral endoscopic myotomy. ENDOSCOPY, 46(4), 298–301.
Through-the-scope transpyloric stent placement improves symptoms and gastric emptying in patients with gastroparesis Clarke, J. O., Sharaiha, R. Z., Valeshabad, A. K., Lee, L. A., Kalloo, A. N., & Khashab, M. A. (2013). Through-the-scope transpyloric stent placement improves symptoms and gastric emptying in patients with gastroparesis. ENDOSCOPY, 45, E189–E190.
Biofeedback Therapy for Defecatory Dysfunction "Real Life" Experience Jodorkovsky, D., Dunbar, K. B., Gearhart, S. L., Stein, E. M., & Clarke, J. O. (2013). Biofeedback Therapy for Defecatory Dysfunction "Real Life" Experience. JOURNAL OF CLINICAL GASTROENTEROLOGY, 47(3), 252–55.
The Relationship Between Depressive Symptoms and Voice Handicap Index Scores in Laryngopharyngeal Reflux Elam, J. C., Ishman, S. L., Dunbar, K. B., Clarke, J. O., & Gourin, C. G. (2010). The Relationship Between Depressive Symptoms and Voice Handicap Index Scores in Laryngopharyngeal Reflux. LARYNGOSCOPE, 120(9), 1900–1903.
Enhanced diagnostic yield with prolonged small bowel transit time during capsule endoscopy. Buscaglia, J. M., Kapoor, S., Clarke, J. O., Bucobo, J. C., Giday, S. A., Magno, P., … Mullin, G. E. (2008). Enhanced diagnostic yield with prolonged small bowel transit time during capsule endoscopy. International Journal of Medical Sciences, 5(6), 303–8.
Multi-Organ RNA-Sequencing of Patients with Systemic Sclerosis (SSc) Finds That Intrinsic Subsets Are Conserved across Organ Systems Mehta, B. K., Franks, J., Cai, G., Toledo, D., Wood, T. A., Archambault, K. A., … Whitfield, M. L. (2017). Multi-Organ RNA-Sequencing of Patients with Systemic Sclerosis (SSc) Finds That Intrinsic Subsets Are Conserved across Organ Systems. ARTHRITIS & RHEUMATOLOGY, 69.
Aprepitant Has Mixed Effects on Nausea and Reduces Other Symptoms in Patients With Gastroparesis and Related Disorders Pasricha, P. J., Yates, K. P., Sarosiek, I., McCallum, R. W., Abell, T. L., Koch, K. L., … Parkman, H. P. (2018). Aprepitant Has Mixed Effects on Nausea and Reduces Other Symptoms in Patients With Gastroparesis and Related Disorders. GASTROENTEROLOGY, 154(1), 65-+.
Baclofen and gastroesophageal reflux disease: seeing the forest through the trees. Clarke, J. O., Fernandez-Becker, N. Q., Regalia, K. A., & Triadafilopoulos, G. (2018). Baclofen and gastroesophageal reflux disease: seeing the forest through the trees. Clinical and Translational Gastroenterology, 9(3), 137.
Advances in the diagnosis and classification of gastric and intestinal motility disorders Keller, J., Bassotti, G., Clarke, J., Dinning, P., Fox, M., Grover, M., … Camilleri, M. (2018). Advances in the diagnosis and classification of gastric and intestinal motility disorders. NATURE REVIEWS GASTROENTEROLOGY & HEPATOLOGY, 15(5), 291–308.
The Effect of Race in Patients with Achalasia Diagnosed With High-Resolution Esophageal Manometry Chedid, V., Rosenblatt, E., Gandhi, K. (K., Dhalla, S., Nandwani, M. C., Stein, E. M., & Clarke, J. O. (2018). The Effect of Race in Patients with Achalasia Diagnosed With High-Resolution Esophageal Manometry. AMERICAN JOURNAL OF THE MEDICAL SCIENCES, 355(2), 126–31.
A Positive Correlation Between Gastric and Esophageal Dysmotility Suggests Common Causality. Zikos, T. A., Clarke, J. O., Triadafilopoulos, G., Regalia, K. A., Sonu, I. S., Fernandez-Becker, N. Q., … Nguyen, L. A. (2018). A Positive Correlation Between Gastric and Esophageal Dysmotility Suggests Common Causality. Digestive Diseases and Sciences.
REFRACTORY GASTROPARESIS: GASTRIC PERORAL ENDOSCOPIC MYOTOMY (G-POEM) VS. INTRAPYLORIC BOTULINUM TOXIN INJECTION Parsa, N., Yang, J., Gutierrez, O. I. B., Moran, R., Sanaei, O., Fayad, L., … Khashab, M. A. (2018). REFRACTORY GASTROPARESIS: GASTRIC PERORAL ENDOSCOPIC MYOTOMY (G-POEM) VS. INTRAPYLORIC BOTULINUM TOXIN INJECTION. GASTROINTESTINAL ENDOSCOPY, 87(6), AB241–AB242.
Use of Esophageal pH Monitoring to Minimize Proton-Pump Inhibitor Utilization in Patients with Gastroesophageal Reflux Symptoms. Triadafilopoulos, G., Zikos, T., Regalia, K., Sonu, I., Fernandez-Becker, N. Q., Nguyen, L., … Clarke, J. O. (2018). Use of Esophageal pH Monitoring to Minimize Proton-Pump Inhibitor Utilization in Patients with Gastroesophageal Reflux Symptoms. Digestive Diseases and Sciences.
Nonerosive reflux disease: clinical concepts. Gyawali, C. P., Azagury, D. E., Chan, W. W., Chandramohan, S. M., Clarke, J. O., de Bortoli, N., … Wu, J. (2018). Nonerosive reflux disease: clinical concepts. Annals of the New York Academy of Sciences.
Indications and interpretation of esophageal function testing. Gyawali, C. P., de Bortoli, N., Clarke, J., Marinelli, C., Tolone, S., Roman, S., & Savarino, E. (2018). Indications and interpretation of esophageal function testing. Annals of the New York Academy of Sciences.
Pyridostigmine for the treatment of gastrointestinal symptoms in systemic sclerosis. Ahuja, N. K., Mische, L., Clarke, J. O., Wigley, F. M., & McMahan, Z. H. (2018). Pyridostigmine for the treatment of gastrointestinal symptoms in systemic sclerosis. Seminars in Arthritis and Rheumatism.
Patients with symptoms of delayed gastric emptying have a high prevalence of oesophageal dysmotility, irrespective of scintigraphic evidence of gastroparesis. Triadafilopoulos, G., Nguyen, L., & Clarke, J. O. (2017). Patients with symptoms of delayed gastric emptying have a high prevalence of oesophageal dysmotility, irrespective of scintigraphic evidence of gastroparesis. BMJ Open Gastroenterology, 4(1), e000169.
Relating gastric scintigraphy and symptoms to motility capsule transit and pressure findings in suspected gastroparesis. Hasler, W. L., May, K. P., Wilson, L. A., Van Natta, M., Parkman, H. P., Pasricha, P. J., … Hamilton, F. A. (2018). Relating gastric scintigraphy and symptoms to motility capsule transit and pressure findings in suspected gastroparesis. Neurogastroenterology and Motility : the Official Journal of the European Gastrointestinal Motility Society, 30(2).
Learning curve for peroral endoscopic myotomy El Zein, M., Kumbhari, V., Ngamruengphong, S., Carson, K. A., Stein, E., Tieu, A., … Khashab, M. A. (2016). Learning curve for peroral endoscopic myotomy. ENDOSCOPY INTERNATIONAL OPEN, 4(5), E577–E582.
Upper Esophageal Sphincter Abnormalities Are Strongly Predictive of Treatment Response in Patients with Achalasia Mathews, S., Chavez, Y., Ciarleglio, M., Clarke, J., Stein, E., & Roland, B. C. (2013). Upper Esophageal Sphincter Abnormalities Are Strongly Predictive of Treatment Response in Patients with Achalasia. AMERICAN JOURNAL OF GASTROENTEROLOGY, 108, S1–S2.
The Added Diagnostic Value of Liquid Gastric Emptying Compared with Solid Emptying Alone Ziessman, H. A., Chander, A., Clarke, J. O., Ramos, A., & Wahl, R. L. (2009). The Added Diagnostic Value of Liquid Gastric Emptying Compared with Solid Emptying Alone. JOURNAL OF NUCLEAR MEDICINE, 50(5), 726–31.
Endoscopic retrograde cholangiopancreatography, but not esophagogastroduodenoscopy or colonoscopy, significantly increases portal venous pressure: direct portal pressure measurements through endoscopic ultrasound-guided cannulation Buscaglia, J. M., Shin, E. J., Clarke, J. O., Giday, S. A., Ko, C. W., Thuluvath, P. J., … Kantsevoy, S. V. (2008). Endoscopic retrograde cholangiopancreatography, but not esophagogastroduodenoscopy or colonoscopy, significantly increases portal venous pressure: direct portal pressure measurements through endoscopic ultrasound-guided cannulation. ENDOSCOPY, 40(8), 670–74.
EUS-guided submucosal implantation of a radiopaque marker: a simple and effective procedure to facilitate subsequent surgical and radiation therapy Magno, P., Giday, S. A., Gabrielson, K. L., Shin, E. J., Clarke, J. O., Ko, C.-W., … Kantsevoy, S. V. (2008). EUS-guided submucosal implantation of a radiopaque marker: a simple and effective procedure to facilitate subsequent surgical and radiation therapy. GASTROINTESTINAL ENDOSCOPY, 67(7), 1147–52.
Severity of post-ERCP pancreatitis directly proportional to the invasiveness of endoscopic intervention: a pilot study in a canine model Buscaglia, J. M., Simons, B. W., Prosser, B. J., Ruben, D. S., Giday, S. A., Magno, P., … Jagannath, S. B. (2008). Severity of post-ERCP pancreatitis directly proportional to the invasiveness of endoscopic intervention: a pilot study in a canine model. ENDOSCOPY, 40(6), 506–12.
How good is capsule endoscopy for detection of periampullary lesions? Results of a tertiary-referral center Clarke, J. O., Giday, S. A., Magno, P., Shin, E. J., Buscaglia, J. M., Jagannath, S. B., & Mullin, G. E. (2008). How good is capsule endoscopy for detection of periampullary lesions? Results of a tertiary-referral center. GASTROINTESTINAL ENDOSCOPY, 68(2), 267–72.
Performance characteristics of the suspected blood indicator feature in capsule endoscopy according to indication for study Buscaglia, J. M., Giday, S. A., Kantsevoy, S. V., Clarke, J. O., Magno, P., Yong, E., & Mullin, G. E. (2008). Performance characteristics of the suspected blood indicator feature in capsule endoscopy according to indication for study. CLINICAL GASTROENTEROLOGY AND HEPATOLOGY, 6(3), 298–301.
EUS-guided portal vein catheterization: a promising novel approach for portal angiography and portal vein pressure measurements Giday, S. A., Clarke, J. O., Buscaglia, J. M., Shin, E. J., Ko, C.-W., Magno, P., & Kantsevoy, S. V. (2008). EUS-guided portal vein catheterization: a promising novel approach for portal angiography and portal vein pressure measurements. GASTROINTESTINAL ENDOSCOPY, 67(2), 338–42.
Classifying esophageal motility by pressure topography characteristics: A study of 400 patients and 75 controls Pandolfino, J. E., Ghosh, S. K., Rice, J., Clarke, J. O., Kwiatek, M. A., & Kahrilas, P. J. (2008). Classifying esophageal motility by pressure topography characteristics: A study of 400 patients and 75 controls. AMERICAN JOURNAL OF GASTROENTEROLOGY, 103(1), 27–37.
EUS-guided portal vein carbon dioxide angiography: a pilot study in a porcine model Giday, S. A., Ko, C.-W., Clarke, J. O., Shin, E. J., Magno, P., Jagannath, S. B., … Kantsevoy, S. V. (2007). EUS-guided portal vein carbon dioxide angiography: a pilot study in a porcine model. GASTROINTESTINAL ENDOSCOPY, 66(4), 814–19.
Comparative study of endoscopic clips: duration of attachment at the site of clip application Shin, E. J., Ko, C.-W., Magno, P., Giday, S. A., Clarke, J. O., Buscaglia, J. M., … Kantsevoy, S. V. (2007). Comparative study of endoscopic clips: duration of attachment at the site of clip application. GASTROINTESTINAL ENDOSCOPY, 66(4), 757–61.
EUS-guided angiography: a novel approach to diagnostic and therapeutic interventions in the vascular system Magno, P., Ko, C.-W., Buscaglia, J. M., Giday, S. A., Jagannath, S. B., Clarke, J. O., … Kantsevoy, S. V. (2007). EUS-guided angiography: a novel approach to diagnostic and therapeutic interventions in the vascular system. GASTROINTESTINAL ENDOSCOPY, 66(3), 587–91.
Impaired deglutitive EGJ relaxation in clinical esophageal manometry: a quantitative analysis of 400 patients and 75 controls Ghosh, S. K., Pandolfino, J. E., Rice, J., Clarke, J. O., Kwiatek, M., & Kahrilas, P. J. (2007). Impaired deglutitive EGJ relaxation in clinical esophageal manometry: a quantitative analysis of 400 patients and 75 controls. AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY, 293(4), G878–G885.
EUS-guided implantation of radiopaque marker into mediastinal and celiac lymph nodes is safe and effective Magno, P., Giday, S. A., Gabrielson, K. L., Shin, E. J., Buscaglia, J. M., Clarke, J. O., … Kantsevoy, S. V. (2007). EUS-guided implantation of radiopaque marker into mediastinal and celiac lymph nodes is safe and effective. GASTROINTESTINAL ENDOSCOPY, 66(2), 387–92.
The utility of contrast-enhanced endoscopic ultrasound in monitoring ethanol-induced pancreatic tissue ablation: a pilot study in a porcine model Giday, S. A., Magno, P., Gabrielson, K. L., Buscaglia, J. M., Canto, M. I., Ko, C. W., … Kantsevoy, S. V. (2007). The utility of contrast-enhanced endoscopic ultrasound in monitoring ethanol-induced pancreatic tissue ablation: a pilot study in a porcine model. ENDOSCOPY, 39(6), 525–29.
High-resolution manometry of the EGJ: An analysis of crural diaphragm function in GERD Pandolfino, J. E., Kim, H., Ghosh, S. K., Clarke, J. O., Zhang, Q., & Kahrilas, P. J. (2007). High-resolution manometry of the EGJ: An analysis of crural diaphragm function in GERD. AMERICAN JOURNAL OF GASTROENTEROLOGY, 102(5), 1056–63.
An endoscopically implantable device stimulates the lower esophageal sphincter on demand by remote control: a study using a canine model Clarke, J. O., Jagannath, S. B., Kalloo, A. N., Long, V. R., Beitler, D. M., & Kantsevoy, S. V. (2007). An endoscopically implantable device stimulates the lower esophageal sphincter on demand by remote control: a study using a canine model. ENDOSCOPY, 39(1), 72–76.
Clinical and manometric characteristics of patients with oesophagogastric outflow obstruction: towards a new classification. Triadafilopoulos, G., & Clarke, J. O. (2018). Clinical and manometric characteristics of patients with oesophagogastric outflow obstruction: towards a new classification. BMJ Open Gastroenterology, 5(1), e000210.
Incorporating Advanced Practice Providers into Gastroenterology Practice. Nandwani, M. C., & Clarke, J. O. (2018). Incorporating Advanced Practice Providers into Gastroenterology Practice. Clinical Gastroenterology and Hepatology : the Official Clinical Practice Journal of the American Gastroenterological Association.
Gastrointestinal Involvement in Systemic Sclerosis An Update Miller, J. B., Gandhi, N., Clarke, J., & McMahan, Z. (2018). Gastrointestinal Involvement in Systemic Sclerosis An Update. JCR-JOURNAL OF CLINICAL RHEUMATOLOGY, 24(6), 328–37.
Multi-Organ RNA-Sequencing of Patients with Systemic Sclerosis (SSc) Finds That Intrinsic Subsets Are Conserved across Organ Systems Mehta, B. K., Franks, J., Wang, Y., Cai, G., Toledo, D. M., Wood, T. A., … Whitfield, M. L. (2018). Multi-Organ RNA-Sequencing of Patients with Systemic Sclerosis (SSc) Finds That Intrinsic Subsets Are Conserved across Organ Systems. ARTHRITIS & RHEUMATOLOGY, 70.
Identification of Risk Factors for Gastric Antral Vascular Ectasia (GAVE) Among Systemic Sclerosis Patients Serling-Boyd, N., Li, S., Fiorentino, D., Becker, L., Fernandez-Becker, N., Clarke, J., & Chung, L. (2018). Identification of Risk Factors for Gastric Antral Vascular Ectasia (GAVE) Among Systemic Sclerosis Patients. ARTHRITIS & RHEUMATOLOGY, 70.
Helping Patients with Gastroparesis. Onyimba, F. U., & Clarke, J. O. (2019). Helping Patients with Gastroparesis. The Medical Clinics of North America, 103(1), 71–87.
Abdominal Pain in Patients with Gastroparesis: Associations with Gastroparesis Symptoms, Etiology of Gastroparesis, Gastric Emptying, Somatization, and Quality of Life. Parkman, H. P., Wilson, L. A., Hasler, W. L., McCallum, R. W., Sarosiek, I., Koch, K. L., … Pasricha, P. J. (2019). Abdominal Pain in Patients with Gastroparesis: Associations with Gastroparesis Symptoms, Etiology of Gastroparesis, Gastric Emptying, Somatization, and Quality of Life. Digestive Diseases and Sciences.
High Prevalence of Slow Transit Constipation in Patients With Gastroparesis. Zikos, T. A., Kamal, A. N., Neshatian, L., Triadafilopoulos, G., Clarke, J. O., Nandwani, M., & Nguyen, L. A. (2019). High Prevalence of Slow Transit Constipation in Patients With Gastroparesis. Journal of Neurogastroenterology and Motility.
Under Pressure: Do Volume-Based Measurements Define Rectal Hyposensitivity in Clinical Practice? Kamal, A. N., Garcia, P., & Clarke, J. O. (2019). Under Pressure: Do Volume-Based Measurements Define Rectal Hyposensitivity in Clinical Practice? Digestive Diseases and Sciences.

View All 74 Publications

Clinical trials are research studies that evaluate a new medical approach, device, drug, or other treatment. As a Stanford Health Care patient, you may have access to the latest, advanced clinical trials.

Open trials refer to studies currently accepting participants. Closed trials are not currently enrolling, but may open in the future.

Open Trials

An Investigation of the EndoStim® Lower Esophageal Sphincter (LES) Stimulation System for the Treatment of Reflux Gastroesophageal Reflux Disease (GERD)

Functional Luminal Imaging Probe (FLIP) Topography Use in Patients With Scleroderma and Trouble Swallowing

Novel Endoluminal Clinical TreAtment of Reflux Gastroesophageal Reflux Disease (GERD)

The Patient Ratings and comments are gathered from our Patient Satisfaction Survey and displayed in their entirety.

4.8

Friendliness

4.8

Friendliness

4.8

Explanations

4.8

Explanations

4.8

Listens

4.8

Listens

4.8

Includes you in decisions

4.8

Includes you in decisions

4.8

Clear Communication

4.8

Clear Communication

4.8

Confidence in your doctor

4.8

Confidence in your doctor

4.8

Recommended to others

4.8

Recommended to others

4.4

Wait times

4.4

Wait times

SHC Patient, Jan 2019

I know that my mother is in very good hands with Dr. Clarke. He takes the time to listen to her. He asks for her opinion about other care options and is very empathetic and concerned for her health. Her health is what it is but is really helps her to deal with her issues knowing that Dr. Clarke continues to try and provide relief. He also advises of new and upcoming medications that may assist her. We are very grateful to Dr. Clarke for his care of my mother.

SHC Patient, Jan 2019

Best GI doc I've seen.

SHC Patient, Dec 2018

The doctor did NOT review my history (medical records) and I had to start again - Very unproductive.

SHC Patient, Dec 2018

Dr.John Clarke is very personable, helpful and knowledgeable. I am getting to know him more and as of now, I feel comfortble with his approaches.

SHC Patient, Dec 2018

This is when it gets GOOD!! Dr. Clarke is amazing, kind and spends a lot of time!! Dr. Alexander Podbody is amazing. He has qualities that will make him a successful doctor!!!! Both have great "beside manner."

SHC Patient, Dec 2018

The problem is a plan is created and then never executed. Also there have been a few times I have messaged using the online portal and no one responds.

SHC Patient, Nov 2018

I've never spent so much time with a gastroenterologist. Dr. Clark didn't seem to be in a rush (a common experience I've had in the past), and used the information from my esophagus biopsy (done in 2017) to inform me of another illness that I didn't know I had and that was causing a lot of my symptoms. This information and his advice have already made a difference.

SHC Patient, Oct 2018

Dr Clarke has always had a listening ear and provides a great bedside manner. his knowledge is vast, but he's also willing to admit when things are difficult. he's a wonderful doctor!

SHC Patient, Oct 2018

Dr. Clarke is a excellent doctor. He is caring and helpful.

SHC Patient, Oct 2018

Excellent.

SHC Patient, Oct 2018

Dr. Brian-Clark is fantastic, one of the finest physicians I have ever dealt with. Thank you!

SHC Patient, Oct 2018

I had a wonderful experience with him. He was very friendly and understanding and accommodating to my needs.

Patient Comments

Patients comments are gathered from our Patient Satisfaction Survey and displayed in their entirety. Patients are de-identified for confidentiality and patient privacy.

SHC Patient, Jan 2019

Best GI doc I've seen.

SHC Patient, Dec 2018

The doctor did NOT review my history (medical records) and I had to start again - Very unproductive.

SHC Patient, Dec 2018

Dr.John Clarke is very personable, helpful and knowledgeable. I am getting to know him more and as of now, I feel comfortble with his approaches.

SHC Patient, Dec 2018

The problem is a plan is created and then never executed. Also there have been a few times I have messaged using the online portal and no one responds.

SHC Patient, Nov 2018

SHC Patient, Oct 2018

Dr Clarke has always had a listening ear and provides a great bedside manner. his knowledge is vast, but he's also willing to admit when things are difficult. he's a wonderful doctor!

SHC Patient, Oct 2018

Dr. Clarke is a excellent doctor. He is caring and helpful.

SHC Patient, Oct 2018

Excellent.

SHC Patient, Oct 2018

Dr. Brian-Clark is fantastic, one of the finest physicians I have ever dealt with. Thank you!

SHC Patient, Oct 2018

I had a wonderful experience with him. He was very friendly and understanding and accommodating to my needs.

SHC Patient, Oct 2018

Dr. Clarke is patient, friendly, knowledgable and professional. THANK YOU so much Dr. Clarke.

SHC Patient, Oct 2018

This is my first visit... overall experience with doctor was good. follow ups and scheduling is pathetic with his staff.

SHC Patient, Oct 2018

Dr. Clarke epitomizes what an outstanding GI Doctor ought to be. Please keep him happy so he'll stay put.

SHC Patient, Sep 2018

The care providers were very patient

SHC Patient, Sep 2018

Good.

SHC Patient, Aug 2018

Dr. Clarke gave me excellent care, took the time to walk me through my questions.

SHC Patient, Aug 2018

Dr. Clarke and his associate doctor really listened to all my concerns. Both doctors took their time and never rushed me. It was an extremely positive first experience.

SHC Patient, Jul 2018

excellent

SHC Patient, Jul 2018

Doctor Clarke was very kind I liked him. Most doctors I deal with are arrogant he was not.

SHC Patient, Jun 2018

Excellent provider

SHC Patient, May 2018

Based on similar Drs I have visited in the immediate area Dr Clarke is hands down the most courteous and professional Dr I have found.

SHC Patient, Apr 2018

Very good!

SHC Patient, Feb 2018

Dr. J. O. Clarke was very understanding and answered all my questions. He offered solutions that made sense and overall I felt confident that I will get better.

SHC Patient, Jan 2018

Dr. Clarke was wonderful and made me feel very comfortable.

SHC Patient, Jan 2018

These comments refer to Dr. Clarke. I was somewhat concerned that he thought my connective tissue disorder (EDS) didn't apply to internal organs, muscles and viscera--only to skin and joints. I was pleased that he took note with my concern and correction of this perception. Overall, Dr. Clarke was a very kind and knowledgable and a good listener. I wasn't expecting him to suggest P.O.E.M. and had prepped my questions for dilatation, and so afterwards, thought of questions about P.O.E.M. I should have asked...

SHC Patient, Jan 2018

Excellent service from Dr. John.

SHC Patient, Dec 2017

Both NP and doctor were very informative and helpful. Great bedside manner!

SHC Patient, Dec 2017

Dr. Clarke is a very good & caring doctor.

SHC Patient, Dec 2017

I would recommend my care provider to my family, friends or anyone that I meet.

SHC Patient, Nov 2017

Dr. Clarke is very personable responsive to my needs and issues good listener and extremely well organized with a PLAN at follow up after endo/colo.

SHC Patient, Oct 2017

Dr. Clarke is excellent. Very knowledgeable yet humble. He listens very carefully to his patients. Best GI dr. I had every have.

SHC Patient, Sep 2017

I have already recommended Dr. Clarke to others.

SHC Patient, Sep 2017

Dr. Clarke seemed to care.

SHC Patient, Aug 2017

Dr. Clarke is the best.

SHC Patient, Jul 2017

Again really liked Dr. John Clarke. He's a caring and thoughtful Doctor!

SHC Patient, Jun 2017

He communicates his expertise in a way I understand and lets me know his reasoning for his decisions.

SHC Patient, Jun 2017

Dr. Clarke is and patient. My health issues are unusual and complicated and I have really appreciated his persistence in trying to get to the bottom of the problem even though several tests have not yielded any easy answers.

SHC Patient, May 2017

O'Brien is the best GI Doc I've ever seen; and I've seen many. He's smart, keeps up on latest research, friendly, and takes the time to brainstorm options with me.

SHC Patient, May 2017

This was my first time seeing this dr. He explained things very well.

SHC Patient, Mar 2017

Has better insights than other G.I. dr.'s I have seen.

SHC Patient, Mar 2017

A most reassuring experience.

SHC Patient, Mar 2017

I find it very easy and pleasant to discuss my care with Dr. Clarke. I have great confidence in him.

SHC Patient, Mar 2017

Very caring and thoughtful.

SHC Patient, Feb 2017

Easily the best doctor I have seen. Very precise, helpful. Wish there were more such doctors. When the doctor is confident, the patient feels confident. Dr. Clarke takes the time to answer questions. I trust him.

SHC Patient, Feb 2017

So thankful to have Dr. Clarke caring for me.

SHC Patient, Feb 2017

I was very impressed that he did some research/reading about my issues prior to coming in to the room and then told me about what he had learned. Taking that extra step/time did not go unnoticed

SHC Patient, Feb 2017

Dr. Clarke is amazing! He is very thorough and open to my questions and requests. I have seen several Gastroenterologists and he has been the one to give me the most hope.

SHC Patient, Jan 2017

Dr. Clarke is awesome.

SHC Patient, Jan 2017

Dr. O'Brien reviewed my medications and determined that some were those he would prescribe, but possibly in different doses. We agreed that if my symptoms increased again, I would contact him.

SHC Patient, Jan 2017

Dr. Cooke is a caring, patient, supportive doctor.

24-hour pH monitoring

48-hour bravo pH monitoring

Ablation

Balloon Dilation

Benign Esophageal Disease

Benign Esophageal Tumors

Benign Gastric and Esophageal Disease

Botulinum Toxin for Digestive Disorders

Capsule endoscopy

Colonoscopy

Colorectal Cancer Screening

Endoscopy

Eosinophilic Esophagitis

Esophageal Disorders

Esophageal manometry

Esophageal Manometry

Esophageal motility disorders including spasm

Esophagogastroduodenoscopy (EGD)

Gastric Electrical Stimulation

Gastric Pacemaker

Gastrostomy (Feeding) Tube

Motility Disorders

Non-cardiac chest pain

Other endoscopic procedures

Paraesophageal Hernias

Sigmoidoscopy

Small bowel manometry

Upper GI endoscopy

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John Clarke

John Clarke

Gastroenterologist, Motility specialist

Digestive Health Center in Redwood City

Esophagus Center

Amyloid Center

Practice Areas

Professional Education

Honors & Awards

Administrative Appointments

Publications

Patient Comments