Feasibility, Safety, and Potential Efficacy of Fecal Microbiota Transplantation (FMT) for Gastrointestinal Dysfunction in Children Following Hematopoietic Cell Transplant (HCT).

Eligibility Criteria

• * Age \< 22 years old.
• * Received an allogeneic HCT greater than or equal to 30 days prior to enrollment
• * Diagnosed with one of the following conditions:
• 1. Steroid-resistant gut a GvHD (defined as GI symptoms that do not improve within 5 days after initial steroid therapy, \>/= 1mg/kg of prednisolone) OR
• 2. Steroid-dependent gut a GvHD (defined as the presence of a response to methylprednisolone 2 mg/kg/day but relapsing when an attempt was made to taper steroid treatment).
• 3. Current or prolonged GI dysfunction following HCT, defined as having diarrhea or loose stools \>/= 4 weeks with at least one of the following:
• 1. Requiring NG or G-tube feeds
• 2. Requiring TPN or IVF for more than 4 weeks
• 3. Diagnosis of gastroparesis by GI specialist documented in the medical record
• * Willing and able to provide informed assent/consent
• * Cytomegalovirus (CMV) or Epstein Barr Virus (EBV) IgG negative at the time of consent
• * Female participant who is pregnant or nursing
• * History of previous FMT
• * Intra-abdominal surgery within 4 weeks of enrollment
• * At increased risk for peritonitis: presence of intra-abdominal devices (G-or GJ-tubes are acceptable), receiving peritoneal dialysis, or ascites
• * Concurrent abdominal radiation therapy
• * Any acute or chronic illness/condition as well as medication that in the opinion of the investigator puts the subject at greater risk from FMT or may confound the study results.