Gastroenterology Fellowship

Program Overview

The Pediatric Gastroenterology Fellowship Program at the Nemours Children’s Hospital, Delaware, in affiliation with Sidney Kimmel Medical College at Thomas Jefferson University (TJU), trains physicians in advanced skills in pediatric gastroenterology. Our 3-year program provides comprehensive specialty training in gastroenterology (GI), hepatology and nutrition.

You’ll learn to diagnose and treat children with acute and chronic diseases of the digestive system and nutritional disorders, as well as gain broad-based research experience in basic or clinical sciences. The program is accredited by the Accreditation Council for Graduate Medical Education (ACGME) in accordance with the guidelines of the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition.


Our Fellowship Program

The Nemours Gastroenterology Fellowship Program provides stimulating clinical training in gastroenterology, hepatology and nutrition and exposure to liver transplantation. Our dynamic group of faculty clinicians and researchers are committed to helping you attain a quality education. Our fellows attend weekly educational sessions in addition to monthly pathology, radiology and physiology conferences and combined surgical rounds. Fellows also present and attend topic oriented journal clubs through out the year.

You’ll have opportunities to learn the indications, risks, benefits and techniques of performing procedures such as upper endoscopy, colonoscopy, percutaneous liver biopsy, capsule endoscopy, esophageal dilatation, percutaneous endoscopic gastrostomy tube insertions, variceal banding, pH/impedance probes and motility studies at our state-of-the-art pediatric GI endoscopy suite. You’ll learn to teach and mentor residents and medical students. You will conduct your own clinical or basic science research project under the supervision of one of our faculty members.

Training Overview

Our GI fellowship program will provide training in both the inpatient and outpatient setting. Rotations include the GI inpatient service, the GI inpatient consultation service, the GI outpatient service as well as research and elective rotations. Fellows also attend their own continuity clinic a half day per week in which they will follow their own patients throughout the 3 years of fellowship. In-hospital electives include pediatric surgery, pathology and radiology. We also have an active liver transplantation program and our fellows do a month’s rotation on the liver transplant service.

Our fellows participate in and gain exposure to in-hospital committees and quality improvement projects. On a wider scope, our fellows participate in the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition fellows’ conferences in addition to other national and international meetings.

Valuable Clinical Experience

You’ll also gain valuable experience participating in the care of children who are followed in our specialty clinics such as those that focus on patients with inflammatory bowel disease (IBD), celiac disease and bowel dysfunction. Fellows will also attend liver clinic during their outpatient rotation. On their inpatient rotations, our fellows learn the intricacies of providing total parenteral nutrition as well as the management of complications that may result from this type of nutritional support.

During the on-call component, you’ll have experiences that improve several aspects of your competency-based training, including patient care, knowledge, interpersonal communications, professionalism, systems-based practice and others. You’ll work directly with emergency department staff and referring physicians doing urgent patient evaluations and other important activities.

Proficiency in GI Diagnostics and Procedures

During your training you’ll become proficient in a wide range of specialized GI diagnostic and therapeutic procedures, such as:

  • Diagnostic EGD (and biopsy)
  • Diagnostic colonoscopy (and biopsy)
  • Flexible sigmoidoscopy (and biopsy)
  • Ileoscopy via ileostomy (and biopsy)
  • Polypectomy
  • Hemostasis in GI bleeding
  • Variceal band ligation, sclerotherapy, heater probe, argon plasma coagulation
  • Percutaneous endoscopic gastrostomy
  • Liver biopsy
  • Dilation of esophageal strictures
  • Foreign body retrieval
  • Capsule endoscopy
  • Esophageal pH-multichannel impedance
  • Breath hydrogen testing
  • Pancreatic stimulation

During your second and third years, you’ll be able to choose electives that add to your knowledge in such GI-related disciplines as transplantation, pathology, radiology and surgery.

Research Support and Resources

As an integral part of your fellowship experience, you’ll receive thorough training in research as it relates to the fields of gastroenterology, hepatology and nutrition. The research component will focus primarily on scholarly activities during the first year and either basic science research or clinical projects during the second and third years.

Scholarly Activities

Training in the scholarly experience begins in the first year of the fellowship and continues throughout your training. You’ll develop the full range of requisite skills for research, from project design to completion and presentation to our scholarship oversight committee, in accordance with American Board of Pediatrics certification requirements.

GI Research Lab

Our state-of-the-art GI Research Lab, located on the campus of Nemours Children’s Hospital, Delaware support fellow research activities. This one of kind program provides a designated research team to assist fellow research activities. The team works with fellows and their clinical mentors to support their research projects including bench work, funding core lab service, initial study designing, data analyzing and methods writing for publication.

  • Evaluation of PH Interferference and Accuracy of Pancreatic Enzyme Activity by Direct Pancreatic Function Testing. Jonathan Beri, Heidi Hagerott, Zhaoping He, Zarela Molle-Rios.


Active Research

Your second and third years will include more hands-on work in either basic science research or clinical projects. You’ll use knowledge gained in the first year to design and execute a study, from concept to completion and presentation, under the supervision of one of our faculty members.

Completed Research

  • Comparison of the gut microbiota composition in Caucasian Hispanic and Caucasian non-Hispanic children with and without obesity (David Garcia, Mathew DiGuglielmo, Zarela Molle-Rios)
  • Clinical Outcomes of Methotrexate Binary Treatment With INfliximab or Adalimumab in PracticE(COMBINE) — With Improve Care Now.
  • Personalized Research on Diet in Ulcerative Colitis and Crohn’s Disease PRODUCE — With Improve Care Now.
  • A Phase 4, Multicenter, Open-label Study of Serum Infliximab Concentrations and Efficacy and Safety of Dose Escalation in Pediatric Patients With Inflammatory Bowel Disease - “ADAPT”. PI Zarela Molle Rios.
  • Immunohistochemistry Expression of Cytokines for Diagnosing Eosinophilic Esophagitis, Proton Pump Inhibitor-Responsive Eosinophilic Esophagitis, and Gastroesophageal Reflux in Pediatric Patients. (Shaida Nasiri and Molle Rios)
  • The Role of Guanylyl Cyclase C and Its Ligands in Pediatric Obesity: A Prospective Study to Measure the Level of an Intestinal Hormone (Uroguanylin) in Response to a Meal Eaten by Adolescents to Evaluate the Effect on Appetite. (Dr. DiGuglielmo)
  • The Role of Guanylyl Cyclase C and Its Ligands in Pediatric Obesity: A Retrospective Study in Tissue Protein Expression Differences of Guanylyl Cyclase C, a Gut Enzyme, and Its Ligands Guanylin and Uroguanylin, Between Obese and Normal Weight Adolescents. (Dr. DiGuglielmo)
  • Serological Markers in Children With Celiac Disease and non-Celiac Disease: A Retrospective Study (Dr. Del Rosario and Dr. He).
  • Open-Label Safety and Efficacy Study of Reslizumab (CTX55700) for the Treatment of Pediatric Subjects With Eosinophilic Esophagitis Who Completed Study RES-5-0002 
  • Complementary and Alternative Medicine (CAM) Use in Pediatric Irritable Bowel Syndrome and Functional Dyspepsia (a pilot study).
  • Impact of Premedication With Steroids on Formation of Antibodies to Infliximab and Infusion Reactions in Pediatric Inflammatory Bowel Disease (IBD). (Dr. Gjikopulli and Dr. Molle-Rios)
  • Difference in the Frequency of Alpha-1-Antitrypsin Phenotype Between Children With Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis (NAFLD/ NASH) and Normal Population. (Dr. Maheshwari and Dr. Furuya)
  • Retrospective Analysis of the Correlation Between Fecal Calprotectin Levels and Inflammatory Bowel Disease (IBD) Activity.
  • Evaluation of Gastroesophageal Reflux by Detecting Gastric Pepsin A in Salivary Swabs: Correlating With Impedance/pH Monitoring. (Dr. Al-Atrash and Dr. Molle Rios)
  • Effect of Proactive Infliximab Concentration Monitoring on Clinical Remission in Pediatric Inflammatory Bowel Disease (IBD). (Dr Gijkopulli and Dr Molle Rios)

In Process

  • Immunohistochemistry Expression of Cytokines for Distinguishing Eosinophilic Esophagitis from Eosinophilia due to Inflammatory Bowel Disease. A Pilot Study Samantha Butzke Zarela Molle Rios.
  • Role of Oncostatin-M in Anti-TNF Refractory Inflammatory Bowel Disease (Jennifer Ezirike, Dr. Molle Rios, Dr. John Beri and Dr. He)

Clinical Trials

  • A Phase 3 Study of the Efficacy, Safety and Pharmacokinetics of Ustekinumab as Openlabel Intravenous Induction Treatment Followed by Randomized Double-blind Subcutaneous Ustekinumab Maintenance in Pediatric Participants with Moderately to Severely Active Ulcerative Colitis CNTO1275PUC3001 will enroll in 2021.
  • An Open Label Addendum to the AMAM adult study to Assess Efficacy and Safety of Mirikizumab in the Induction and Maintenance of Remission in Adolescents (15 to <18 years of age) with Moderately to Severely Active Crohn’s Disease (CD) will enroll in 2021.
  • FREE A food additive removal diet for pediatric Eosinophilic Esophagitis In collaboration with Nemours Orlando and Seattle Children’s Hospital — Enrolling patients

Learn More About Research at Nemours

Salary & Benefits


  • PGY 4: $68,655
  • PGY 5: $71,430
  • PGY 6: $74,419
  • PGY 7: $77,078
  • PGY 8: $78,267


  • Medical
  • Dental
  • Malpractice insurance
  • Office space
  • On-call cell phone
  • Prescription drug coverage
  • Secretarial support

About Our Hospital in Delaware

The Nemours Children’s Hospital, Delaware is a multispecialty, tertiary care teaching institution located on a 300-acre estate in the scenic Brandywine Valley in Wilmington, Del.

Among the hospital’s amenities for all staff are:

  • Free parking
  • Park-like setting
  • Gym/fitness center
  • On-site child care center for children of staff

Living in Delaware Valley

Because of our location in the tri-state area of Delaware, New Jersey and Pennsylvania, we offer unique living/working opportunities. For example, you can choose to live in the downtown Philadelphia area and easily commute to our park-like hospital campus in Wilmington.

Explore Wilmington

Nemours Children’s Hospital, Delaware is located in Wilmington, Del., about 30 minutes from center city Philadelphia, and an easy drive to Baltimore, Lancaster County, Pa. (“Amish Country”), and the beaches in Atlantic City and Delaware. There is much to do in and around the city, including mansion and garden tours, museums, breweries, wineries, fine restaurants and numerous state parks.

Learn More About Delaware:

Greater Wilmington Convention and Visitors Bureau

Delaware Tourism

Delaware’s Beaches

Explore Philadelphia

Philadelphia is the sixth largest metropolitan area in the United States and offers a wealth of historical, cultural and recreational opportunities. From world-class museums to its professional sports teams to the colorful, bustling districts of South Street, Chinatown and the Italian Market, Philadelphia has something for everyone.

Learn More About the Philadelphia Area:

New Jersey Beaches

Pennsylvania Mountains

Train With Recognized Leaders

If you’re looking for a rewarding program built on academic excellence and family-centered care, Nemours Children's offers outstanding medical, surgical, pharmacy, nursing, therapy and psychology programs. Train with faculty who are respected leaders in their fields, a patient care model that stands apart and access to groundbreaking research. 

Meet Our Clinical Leadership

Zarela Molle-Rios, MD

Director, Pediatric Gastroenterology Fellowship Program

Division of Pediatric Gastroenterology, Department of Pediatrics, Nemours Children’s Hospital, Delaware

Learn More About Dr. Molle-Rios

J. Fernando del Rosario, MD

Division Chief, Division of Pediatric Gastroenterology

Department of Pediatrics, Nemours Children’s Hospital, Delaware

Learn More About Dr. del Rosario

Meet Our Program Faculty

Meet Our Participants

Current Participants 

3rd Year

  • Samantha Butzke, MD
  • Stephanie Zacharias, MD

2nd Year

  • Gabriele Meyer, MD
  • Sera Na, MD

1st Year

  • Haley Pearlstein, MD


  • 2021 Jonathan Beri, MD; Lidija Palezac, MD
  • 2020 David Garcia; Jennifer Ezirike, MD
  • 2019: Shaida Nasiri and Brittany Parlow
  • 2018: Heidi Hagerott and Sana Mansoor
  • 2017: Arieda Gjikopulli and Amaka Akalonu
  • 2016: Hadeel Al-Atrash and Vikas Uppal
  • 2015: Tara Altepeter and Anshu Maheshwar
  • 2014: Sheela Raikar
  • 2013: Jennifer Jimenez, MD
  • 2012: Erika Kutsch
  • 2011: Beth Loveridge-Lenza
  • 2010: Nikki Allmendinger and Prateek Wali
  • 2009: Alycia Leiby
  • 2008: Jeremy King

Apply Today

Application Requirements

Deadline: September 1, 2023

Training Begins: July 1, 2024

1. Submit application electronically using ERAS

2. Curriculum vitae

3. Personal statement

4. Medical school transcript

5. USMLE scores (all 3 levels)

6. Three references


We begin offering interviews to fellowship candidates in July of the year before the start of the fellowship. The actual interview process will take place roughly between August 1 and October 1 of the preceding year.

Questions About Applying?

April Aguilera
Fellowship Coordinator
(302) 651-5946

Zarela Molle-Rios, MD
Program Director
(302) 651-5928