Which of the following is a contributing factor to gastrointestinal toxicity in the first 2-3 weeks after stem cell transplant?

• A. Chemotherapy and total body irradiation
• B. Vaccination side effects
• C. Dehydration only
• D. Exercise-induced gastritis

Answer: (A)

The main factor driving GI toxicity in the first 2–3 weeks after stem cell transplant is the conditioning regimen used before transplant—high-dose chemotherapy with or without total body irradiation. This powerful treatment damages rapidly dividing cells, including the GI mucosa, leading to mucositis and breakdown of the GI barrier. That mucosal injury causes symptoms like nausea, vomiting, diarrhea, and abdominal pain right during the early post-transplant phase as engraftment has not yet occurred to repair the lining.

Vaccination side effects aren’t a primary cause in this early period because vaccines are typically not a driving factor during profound immunosuppression, and they’re not responsible for the acute mucosal injury seen with conditioning. Dehydration can worsen symptoms but doesn’t initiate the GI toxicity itself, and exercise-induced gastritis isn’t relevant to the transplant process. The conditioning-related mucosal injury best explains the GI toxicity observed in the first weeks.