Gastroparesis was the defining motility disorder that attracted me to the field of Neurogastroenterology and Motility. My career has been committed to better understanding this disease and other motility disorders in hopes that this will lead to better and more treatment options for our patients. My research and clinical work related to gastrointestinal motility disorders has led to collaborations with other specialties/conditions that affect GI motility and function such as ME/CFS, Myotonic dystrophy, Autonomic dysfunction, Migraines, Cystic fibrosis, Sjogren's disease and Scleroderma.

Clinical Focus

  • Gastroenterology
  • Esophageal Dysphagia
  • Gastroparesis
  • Dyspepsia
  • Intestinal Pseudoobstruction
  • Irritable Bowel Syndrome
  • Constipation
  • Motility

Academic Appointments

Administrative Appointments

  • Director, GI Motility and Neurogastroenterology, Division of Gastroenterology (2008 - Present)

Professional Education

  • Board Certification: Gastroenterology, American Board of Internal Medicine (2005)
  • Fellowship:California Pacific Medical Center (2005) CA
  • Residency:California Pacific Medical Center (2002) CA
  • Medical Education:UCLA School of Medicine (1999) CA
  • MD, UCLA School of Medicine (1999)

Research & Scholarship

Current Research and Scholarly Interests

My research interests focus on disorder of gastrointestinal motility. Specifically, those related to nausea and vomiting with or without gastroparesis, reflux and swallowing disorders, and irritable bowel syndrome. My research focuses on understanding and characterizing the abnormal motility pattern(s) that are associated with these symptoms.

Clinical Trials

  • Study to Evaluate Switching From Regimens Consisting of a Ritonavir-boosted Protease Inhibitor Plus Emtricitabine/Tenofovir Fixed-Dose Combination to the Elvitegravir/Cobicistat/Emtricitabine/Tenofovir DF Single-Tablet Regimen in Virologically Suppressed, HIV-1 Infected Patients Not Recruiting

    This study will evaluate the non-inferiority of Stribild® (elvitegravir/cobicistat/ emtricitabine/tenofovir disoproxil fumarate (E/C/F/TDF)) single-tablet regimen (STR) relative to regimens consisting of a protease inhibitor (PI) boosted with ritonavir (RTV) plus Truvada® (FTC/TDF) fixed-dose combination in maintaining HIV-1 RNA < 50 copies/mL at Week 48 in virologically suppressed, HIV-1 infected adults. This study will also evaluate the safety, tolerability, and efficacy of the two regimens through 96 weeks of treatment.

    Stanford is currently not accepting patients for this trial. For more information, please contact Debbie Slamowitz, 7232804.

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  • Impact of KUVAN® on Gastric Relaxation in Women With Diabetic Gastroparesis. Not Recruiting

    Kuvan® (sapropterin dihydrochloride) for Improving Gastric Accommodation in Women with Diabetic Gastroparesis (KIGA-DG)

    Stanford is currently not accepting patients for this trial. For more information, please contact Nighat j Ullah, 650-721-7216.

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  • Aprepitant for the Relief of Nausea in Patients With Chronic Nausea and Vomiting of Presumed Gastric Origin Trial Recruiting

    The principal objective of this multicenter, randomized, placebo-controlled trial is to evaluate whether 4 weeks of treatment with aprepitant will improve nausea as compared with placebo in patients with symptoms of chronic nausea and vomiting of presumed gastric origin.

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  • Continuous Glucose Monitoring and Insulin Pump Therapy in Diabetic Gastroparesis Not Recruiting

    A pilot study to assess the safety, feasibility, and potential (uncontrolled) efficacy of continuous glucose monitoring (CGMS) in conjunction with an insulin pump to improve glycemic control for treatment of type 1 and type 2 diabetic patients with gastroparesis

    Stanford is currently not accepting patients for this trial.

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  • Gastroparesis Registry 2 Recruiting

    To expand a registry of patients for the study of the epidemiology, etiology, and degree of morbidity associated with gastroparesis.

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  • Clinical Management With SPM System and Validation of the SPM 5 Hour Cutoff in Patients With Symptoms of Gastroparesis Recruiting

    This protocol is designed to validate use of the SPM for diagnosis of delayed gastric emptying in patients with symptoms of gastroparesis and assess impact of a SmartPill study on patient management in the gastroparetic populations. Patients with symptoms of gastroparesis will be recruited. Patients will undergo concurrent gastric scintigraphy and SPM testing to determine the presence or absence of delayed gastric emptying based on predetermined diagnostic cutoffs for each technique.

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2016-17 Courses


All Publications

  • Clinical Presentation and Pathophysiology of Gastroparesis GASTROENTEROLOGY CLINICS OF NORTH AMERICA Nguyen, L. A., Snape, W. J. 2015; 44 (1): 21-?


    Gastroparesis is a heterogeneous disorder defined by delay in gastric emptying. Symptoms of gastroparesis are nonspecific, including nausea, vomiting, early satiety, bloating, and/or abdominal pain. Normal gastric motor function and sensory function depend on a complex coordination between the enteric and central nervous system. This article discusses the pathophysiology of delayed gastric emptying and the symptoms of gastroparesis, including antropyloroduodenal dysmotility, impaired gastric accommodation, visceral hypersensitivity, and autonomic dysfunction. The underlying pathophysiology of gastroparesis is complex and multifactorial. The article discusses how a combination of these factors leads to symptoms of gastroparesis.

    View details for DOI 10.1016/j.gtc.2014.11.003

    View details for Web of Science ID 000350944600005

    View details for PubMedID 25667020

  • Massive gastrointestinal dilatation in a case of hereditary hollow visceral myopathy. Digestive and liver disease Huang, R. J., Yun, C., Nguyen, L. 2013; 45 (10): 866-?

    View details for DOI 10.1016/j.dld.2013.04.005

    View details for PubMedID 23816694

  • Platelet-derived growth factor receptor a (PDGFRa)-expressing "fibroblast-like cells" in diabetic and idiopathic gastroparesis of humans NEUROGASTROENTEROLOGY AND MOTILITY Grover, M., Bernard, C. E., Pasricha, P. J., Parkman, H. P., Abell, T. L., Nguyen, L. A., Snape, W., Shen, K. R., Sarr, M., Swain, J., Kendrick, M., Gibbons, S., Ordog, T., Farrugia, G. 2012; 24 (9): 844-852


    Emerging evidence suggests that "fibroblast-like cells" (FLC) may play a role in the regulation of gastrointestinal (GI) motor function. FLC are ultrastructurally distinct from other interstitial cells, including interstitial cells of Cajal (ICC), and express small-conductance Ca(2+) -activated K(+) channels (SK3). In mice, platelet-derived growth factor receptor ? (PDGFR?) antibody has also been shown to label FLC. The aims of this study were to determine the morphology and distribution of PDGFR?-immunoreactive (ir) FLC in human gastric muscle and to determine if FLC are altered in gastroparesis, where ICC are reduced.Full thickness gastric body biopsies from five healthy subjects, 10 diabetic, and 10 idiopathic gastroparesis patients were immunolabeled using SK3 and PDGFR? staining for FLC and Kit staining for ICC. Intramuscular FLC and ICC were quantified.Intramuscular PDGFR?-ir cells had slender cell bodies and long, thin processes and were more abundant in the longitudinal compared with the circular muscle. In the region of myenteric plexus, FLC had smaller, rounder cell bodies with 3-4 processes and formed networks, often around ganglia. All SK3-ir cell structures showed complete overlap with PDGFR?-ir. FLC were in close proximity to ICC, but their cell bodies did not overlap. No differences were seen in the distribution, morphology, or overall numbers of FLC in gastroparesis patients.In conclusion, PDGFR? identifies FLC in human gastric smooth muscle. FLC were not altered in distribution or overall numbers in gastroparesis. Additional studies are required to determine their role in human GI function.

    View details for DOI 10.1111/j.1365-2982.2012.01944.x

    View details for Web of Science ID 000308089000012

    View details for PubMedID 22650155

  • Gastrointestinal Dysmotility DIGESTIVE DISEASES AND SCIENCES Nimgaonkar, A., Choi, J. W., Nguyen, L., Triadafilopoulos, G. 2012; 57 (5): 1130-1133

    View details for DOI 10.1007/s10620-011-1946-x

    View details for Web of Science ID 000303385100004

    View details for PubMedID 22038542

  • Characteristics of Patients With Chronic Unexplained Nausea and Vomiting and Normal Gastric Emptying CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Pasricha, P. J., Colvin, R., Yates, K., Hasler, W. L., Abell, T. L., Uenalp-Arida, A., Nguyen, L., Farrugia, G., Koch, K. L., Parkman, H. P., Snape, W. J., Lee, L., Tonascia, J., Hamilton, F. 2011; 9 (7): 567-U89


    Chronic nausea and vomiting with normal gastric emptying is a poorly understood syndrome; we analyzed its characteristics.We collected and analyzed data from 425 patients with chronic nausea and vomiting, enrolled at 6 centers by the Gastroparesis Clinical Research Consortium in the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Registry.Among the patients, 319 (75%) had delayed emptying, defined by the results of a standardized, low-fat meal, and 106 had normal gastric emptying. Patients with or without delayed emptying did not differ in age, sex, or race, although those with normal gastric emptying were less likely to be diabetic. Symptom severity indexes were similar between groups for nausea, retching, vomiting, stomach fullness, inability to complete a meal, feeling excessively full after meals, loss of appetite, bloating, and visibly larger stomach. There were no differences in health care utilization, quality of life indexes, depression, or trait anxiety scores. However, state anxiety scores were slightly higher among patients with delayed gastric emptying. Total gastroparesis cardinal symptom index scores were not correlated with gastric retention after 2 or 4 hours in either group. Patients with the syndrome were not adequately captured by the stand-alone criteria for the Rome III diagnoses of chronic idiopathic nausea and functional vomiting. With rare exceptions, the diagnosis remained stable after a 48-week follow-up period.Patients with nausea and vomiting with normal gastric emptying represent a significant medical problem and are, for the most part, indistinguishable from those with gastroparesis. This syndrome is not categorized in the medical literature--it might be a separate clinical entity.

    View details for DOI 10.1016/j.cgh.2011.03.003

    View details for Web of Science ID 000292467900015

    View details for PubMedID 21397732