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Gastroenterology, Hepatology and Nutrition Fellowship


View from Denver's City ParkThe University of Colorado School of Medicine (CU SOM) offers a three-year fellowship training program in the field of Pediatric Gastroenterology, Hepatology and Nutrition. The Program is run by the Section of Gastroenterology, Hepatology and Nutrition in the Department of Pediatrics at the CU SOM at the Children's Hospital Colorado. Dr. Cara L. Mack is the Director of the Fellowship Training Program. The Program has been continuously fully accredited in Pediatric Gastroenterology by the Residency Review Committee of ACGME since the specialty was first recognized by ACGME in December 1994 and is accredited through 2018 as part of the New Accreditation System (NAS). To better meet the needs of applicants, our pediatric gastroenterology fellowship training program participates in the National Resident Match Program (NRMP) and the Electronic Residency Application Service (ERAS) program for fellowship applicants.


The first year of fellowship is dedicated to acquiring clinical proficiency in both inpatient and outpatient aspects of Pediatric GI/Hepatology/Nutrition. The clinical activities of the first year are based at Children's Hospital Colorado, a 304-bed facility, which is the major teaching hospital for the Department of Pediatrics of the CU SOM. Children's Colorado is also the pediatric home to the NIH-supported Colorado Clinical and Translational Sciences Institute, housing the Pediatric Clinical Translational Research Center that is available to fellows and faculty to assist with performance of clinical investigations. The GI/Hepatology/Nutrition service consults on, or is the primary attending physician for, 800-900 inpatients per year and sees over 14,000 outpatient visits per year. Over a one-year period, the GI/Hepatology/Nutrition Section performs over 4,000 procedures, including approximately 1,600 upper gastrointestinal endoscopies, 600 colonoscopies and flexible sigmoidoscopies, 100 liver biopsies, 20 small bowel biopsies and other gastrointestinal procedures (motility studies, breath hydrogen analyses, ERCP, esophageal pH studies, esophageal impedance, video capsule endoscopy, etc).


Inpatient Training

The three first-year fellows rotate between the Inpatient Service, Consult Service, and Outpatient /Procedure Service. While on the Inpatient GI Consult Service, the fellow performs all in-hospital consultations and supervises the care of all patients admitted to either the GI or the Liver service, under the supervision and mentorship of the attending GI or Liver physician. Emphasis is placed on physical diagnosis, developing an accurate differential diagnosis, learning the methods of evaluating and treating the child and assessing the family's needs (family-centered care). Diagnostic procedures required by these patients are performed by the fellow under the supervision of the GI or Liver attending physician. The fellow will be exposed to the full range of GI, liver, pancreatic, and nutritional problems, including acute and chronic diarrhea and colitis, vomiting disorders, esophageal and intestinal motility disorders, failure-to-thrive and nutritional problems, allergic GI diseases, inflammatory bowel disease, functional GI diseases, chronic constipation and abdominal pain, short gut syndrome, parenteral and enteral nutrition management, acute and chronic hepatitis, a variety of metabolic and genetic liver diseases, neonatal cholestasis, acute and chronic liver failure, chronic cholestatic disorders, bile duct and gall bladder disorders, acute and chronic pancreatitis, GI problems of the immunosuppressed or immunodeficient patient, and others. The fellow will learn to perform and interpret the full gamut of GI diagnostic and interventional procedures, including upper gastrointestinal endoscopy, colonoscopy and sigmoidoscopy, capsule endoscopy, polypectomy, esophageal variceal endosclerosis and ligation, esophageal pH and pH/impedence testing, duodenal intubation, paracentesis, percutaneous liver biopsy, diagnostic paracentesis, endoscopic retrograde cholangiopancreatography, pneumatic and non-pneumatic dilatation of strictures, removal of GI tract foreign bodies and percutaneous endoscopic gastrostomy tube placement. The Inpatient and Consult services range from 10-20 patients each. The Liver attending, Liver Center Team, dietitian, social worker, pharmacist and nutritional support nurse are all part of the Inpatient Liver Care Team.



While on the Outpatient/Procedures Rotation, the fellow attends four half-day clinics including urgent outpatient clinics, and multidisciplinary subspecialty clinics such as Liver Clinic, the Gastrointestinal Eosinophilic Disease Program, Intestinal Failure, IBD Referral Clinic, CF Clinic and Adolescent Obesity Clinics. The fellows are exposed to the full range of outpatient GI/ liver Nutrition disorders, and learn the appropriate and cost-effective evaluation and management of these infants and children. During the Outpatient Procedures Rotation, the fellow attends four half-day procedure block times under the direction of the attending pediatric gastroenterologist assigned to the block. Each fellow participates in a dedicated continuity clinic which begins during the second month of the first year continuing throughout their training. Fellows provide continuing care for patients evaluated in the inpatient and/or outpatient setting in this clinic. The fellows are involved in the outpatient management of home care for some of the 100-120 infants and children with complex parenteral and enteral nutritional support, including many with cystic fibrosis.

The CU SOM and Children's Hospital Colorado have an active pediatric liver transplantation program. The Pediatric Liver Center, under the medical direction of Dr. Shikha Sundaram and the surgical direction of Dr. Frederick (Fritz) Karrer of the Department of Surgery, is actively involved in the evaluation of potential candidates for transplantation, peritransplant care, and post-transplant follow-up of all children. The Pediatric Liver Center is the regional referral center for the evaluation and care of children with acute and chronic hepatobiliary diseases. Six Pediatric Hepatologists within the Section provide consultation and ongoing care for these children. Fellows participate in the evaluation and care of children with liver disorders and those receiving liver transplantation under the direction of the Liver Transplant/Hepatology attending physician.

First-year fellows have a four-week rotation without any inpatient or outpatient clinical responsibilities for a series of electives. During this time the fellows rotate in pathology and radiology.


During the first year fellow four-week elective rotation, the fellows participate in the Exploring Research Opportunities Rotation during the afternoon. Working with the Program Director and Section Chief, a research plan for the fellow’s second and third years will be developed. By the end of their first year, the fellow presents his or her research plans to the Scholarship Oversight Committee for advice and approval. This Oversight Committee will systematically monitor the fellow's progress during the next two years, assuring appropriate progress and success of the fellow.

The second and third years of training are primarily devoted to research training (clinical, translational, or basic research) which will be carried out in the laboratories and facilities of the CU SOM and Children's Colorado. Responsibilities on the inpatient services are minimized during years 2 and 3 in order to provide about 80% protected time for research training. During the first year of fellowship, the fellow will meet with each of the Pediatric Gastroenterology/Hepatology/Nutrition faculty and other appropriate researchers at CU SOM, and, in conjunction with the Director of Fellowship Training and the Section Chief, will choose a mentor and a field of study. The Department of Pediatrics at CU SOM has a formal core educational program in Ethics, Professionalism, Statistics, Evidence-Based Medicine and Quality Improvement for all fellows that begins in the first year of fellowship. For fellows who elect to pursue Clinical and Translational Research, we encourage completion of a Masters in Clinical Sciences through the Clinical Sciences Program. There is a core curriculum on research ethics led by CCTSI for fellows. Basic research trainees are encouraged to participate in appropriate didactic course work as well as mentored laboratory research.  Research opportunities are numerous, under the mentorship of one of the Pediatric GI/ Hepatology/Nutrition faculty or another mentor of the School of Medicine.

The GI/Hepatology/Nutrition Fellowship is an NIH-funded training program in pediatric gastroenterology, hepatology and nutrition, and works closely with the NIH-supported Mucosal Inflammation Program and Clinical Nutrition Research Unit at CU SOM. In these Centers, there is a large number of NIH-supported investigators studying basic and clinical areas. In addition, the Colorado Clinical and Translational Sciences Institute at CU SOM, in conjunction with the Clinical Translational Research Center at Children's Colorado, provides training in clinical and translational research, and provides assistance with study design, biostatistics, bioinformatics, research nursing, and financial and scientific support for clinical investigation. The Pediatric GI T32 Training Program, first awarded by NIDDK in 2005 and renewed in 2010, is directed by Ronald J. Sokol, MD, Chief of the Section of Pediatric Gastroenterology, Hepatology and Nutrition at CU SOM. During the second and third years of training, the fellow continues to attend one half-day continuity clinic per week, the teaching conferences of the Section, and rotate on the inpatient service for 2-4 weeks per year. The GI/Hepatology/Nutrition Section is also an active Clinical Center in 7 national research consortia studying childhood liver and gastrointestinal diseases, bringing many clinical research opportunities for fellows.

Currently, GI/Hepatology/Nutrition Section research is funded by more than $4 million per year in grant support including twenty NIH grants awarded to Drs. Sokol, Narkewicz, Furuta, Mack, Hoffenberg, Krebs, Liu, Suchy, Soden, de Zoeten, Sundaram and Colgan, and funding from other sources (e.g., Cystic Fibrosis Foundation, American Liver Foundation and pharmaceutical industry). A bibliography of recent publications is available on the following web page: recent publications.


The following teaching conferences play an important role in the training of fellows and housestaff:

  1. Fellows' Rounds are held on Tuesday morning, during which the fellows present interesting patients to the entire group for discussion focused on evidenced-based patient management.
  2. Morbidity and Mortality Conference is held one Tuesday morning every other month.
  3. Wednesday afternoon conference (4 p.m.) alternates weekly between GI radiology, GI pathology, research, and journal club. Second- and third-year fellows present research in progress at the research conference once a year. At 5 p.m., there is a clinical topic conference. Faculty, guest faculty, and fellows present various state-of-the-art lectures on GI/Hepatology or Nutrition topics. Fellows present 1-2 times per year. Emphasis is placed on the fellow's acquisition of skills needed to deliver effective lectures and improve their teaching skills for their future careers.
  4. Adult/Pediatric GI CPC occurs every other month, run by both the adult and pediatric GI Fellows
  5. Pediatric GI/Surgery Conference: This monthly conference is run by both the GI and Pediatric Surgery Fellows and is held at Children's Colorado on the fourth Friday morning of the month. Each fellow presents once a year on topics relevant to both GI and Surgery. Emphasis is placed on presentation and teaching skills.
  6. A joint adult and pediatric GI physiology lecture series, focusing on a review of basic GI/Hepatology physiology, is under the direction of the senior GI fellows and a faculty mentor . 
  7. There are other conferences run by the Mucosal Inflammation Program, the Center for Human Nutrition, and the Adult Gastroenterology Program, in addition to Pediatric Grand Rounds. Numerous other lectures and presentations are available across the Anschutz Medical Campus.
  8. Multidisciplinary care meetings are held by the Pediatric Liver Center, Gastrointestinal Eosinophilic Disease Program, Intestinal Failure Program and Inflammatory Bowel Disease Program.

Required Application Materials

We are registered with ERAS (The Electronic Residency Application Service). Please login to ERAS, complete the Common Application Form, and attach the following supporting documentation:

  • Current Curriculum Vitae (CV)
  • Personal Statement of 1-2 pages outlining the reasons for choosing this specialty, and the applicant’s career plans
  • At least two (2) but no more than four (4) Letters of Recommendation from physicians familiar with the applicant, one of which should be from the applicant’s residency program director
  • USMLE/ECFMG scores
  • A wallet-sized photo (this will not be distributed to interviewers or anyone participating in the selection process)


Interviews are conducted at Children's Hospital Colorado in Aurora, CO in small groups. Interviews typically occur between January and mid-April, although this is subject to change. Applicants selected for a personal interview will be contacted by the fellowship program coordinator. See Contacts below.

Travel Support for Interviews: As part of our National Institutes of Health T32 Training Grant funding, we are committed to increasing the numbers of underrepresented minorities in Pediatric Gastroenterology. To minimize barriers that may limit such candidates’ ability to interview with our program, we offer opportunities for travel support. All candidates invited to interview with our Program will be sent additional information on applying for this travel support.

Salary and Benefits

Salaries are guaranteed by CU SOM and paid at the relevant PGY level with standard dental and medical insurance benefits for the fellow and family, and disability and life insurance. Funds are available for travel to one or two medical conferences per year and for books/journals.

Night and Weekend Call

Weekend at-home call for fellows is divided among the fellows and averages every ninth weekend. Weeknight at-home call is shared by first-year fellows. Fellows are supervised by designated GI and Liver attendings.

Support Staff

Support Staff in the Section includes a full-time Nutrition Support/IBD Nurse Specialist, 9 GI Nurses, 2 Liver Care Nurses, 4 GI/Hepatology Dietitians, 2 GI/Hepatology Social Workers, and 6 GI Procedures Nurses as well as Administrative Assistant staff, 2 Liver Transplant Coordinators, an IBD Nurse Coordinator and a GEDP Nurse Coordinator.


Oumou Diacko
Fellowship Program Coordinator
Department of Gastroenterology, Hepatology and Nutrition
Children's Hospital Colorado
13123 East 16th Avenue, B-290
Aurora, Colorado 80045
Tel: 720-777-2738
Fax: 720-777-7277

For additional questions, please contact:

Cara Mack, MD
Director of Fellowship Training Program
Pediatric Gastroenterology, Hepatology and Nutrition
Children's Hospital Colorado
13123 East 16th Avenue, B-290
Aurora, Colorado 80045
Tel: 720-777-6669

Gastroenterology Fellows (011) 2014.jpg 

Gastroenterology, Hepatology and Nutrition Fellows

Front Row (left-right): Gillian Noel, MD, PGY-5; Pooja Mehta, MD, PGY-5; Nathalie Nguyen, MD, PGY-4; Dania Molla Hosseini, MD, PGY-4; Kristina Leinwand, DO, PGY-4

Back Row (left-right):  Melissa Sheiko, MD, PGY-6; Shahan Fernando, MD, PGY-6; Mary Boruta, MD, PGY-6; Shelly Rustagi, MD, PGY-5


1st Year Fellows


Kristina Leinwand, DO

Residency: Phoenix Children's Hospital 
Medical School: Still University School of Osteopathic Medicine
Research Interests: TBD



Dania Molla Hosseini, MD

Residency: Children's Hospital of Los Angeles
Medical School: University of Arizona College of Medicine

Research Interests: TBD



Nathalie Nguyen, MD

Residency: UT Southwestern Children's Medical Center 
Medical School: Texas A&M College of Medicine
Research Interests: TBD


2nd Year Fellows


Pooja Mehta, MD

Residency: University of Michigan, Ann Arbor, MI (Chief Resident)

Medical School: University of Virginia School of Medicine

Research Interests: Assessment of feeding dysfunction and nutritional deficiencies in children with Eosinophilic Esophagitis as compared to children with gastroesophageal reflux disease



Gillian Noel, MD

Residency: University of Colorado/Children's Hospital Colorado, Aurora, CO
Medical School: University of Colorado Denver School of Medicine
Research Interests: Pediatric Liver Disease Transplant Hepatology



Shelly Rustagi, MD

Residency: LAC + USC Medical Center, Los Angeles, CA

Medical School: University of Missouri-Kansas City School of Medicine

Research Interests: To investigate the role of ADAM10 signaling in intestinal stem cells under normal physiological conditions and intestinal injury.



3rd Year Fellows


Mary Boruta, MD

Residency: University of North Carolina Chapel Hill School of Medicine
Medical School: University of North Carolina Chapel Hill School of Medicine
Research Interests: 1) Influence of Bacterial Colonization on Mucosal CD4+ T cell DNA Methylation and Gene Expression in a Germ Free Murine Model: This study is evaluating for changes in immune system DNA methylation caused by intestinal bacteria colonization. 2) Alterations in gastrointestinal motility and intestinal perfusion following pediatric cardiology surgery: This is a clinical project that is jointly ran by pediatric GI and cardiology assessing for the etiology behind feeding intolerance in infants after heart surgery. 3) Correlation of Nausea Profile and COMPASS 31 with diagnosis of dysautonomia on head-up tilt table testing: This is another clinical project jointly ran by pediatric GI and cardiology that assess for correlation between gastrointestinal symptoms based on surveys with symptoms and vital sign changes on tilt table testing.



Shahan Fernando, MD

Residency: Phoenix Children’s Hospital
Medical School: University of Arizona College of Medicine
Research Interests: Eosinophilic gastrointestinal diseases, specifically with regards to the role of epithelial barrier dysfunction in the pathogenesis of eosinophilic esophagitis.



Melissa Sheiko, MD

Residency: University of Colorado Pediatric Residency Program

Medical School: University of Washington School of Medicine

Research Interests: Adaptive Immunity in Hepatitis C Infection at the Maternal Fetal Interface