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

Inclusion 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).

OR
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

Exclusion Criteria:

• Participant is at risk for aspiration pneumonia
• History of anaphylactic allergy to foods that are not excluded from the stool donor diet
• 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.