Small intestine
It is approximately 1.5 cm in diameter in newborns after 35 weeks of gestational age, and 2.5–3 cm (1 inch) in diameter in adults. On abdominal X-rays, the small intestine is considered to be abnormally dilated when the diameter exceeds 3 cm. On CT scans, a diameter of over 2.5 cm is considered abnormally dilated. The surface area of the human small intestinal mucosa, due to enlargement caused by folds, villi and microvilli, averages 30 square meters.
Intestine transplantation
Intestine transplantation dates back to 1959, when a team of surgeons at the University of Minnesota led by Richard C. Lillehei reported successful transplantation of the small intestine in dogs. Five years later in 1964, Ralph Deterling in Boston attempted the first human intestinal transplant, albeit unsuccessfully. For the next two decades, attempts at transplanting the small intestine in humans were met with universal failure, and patients died of technical complications, sepsis, or graft rejection. However, the discovery of the immunosuppressant ciclosporin in 1972 triggered a revolution in the field of transplant medicine. Due to this discovery, in 1988, the first successful intestinal transplant was performed in Germany by E. Deltz, followed shortly by teams in France and Canada. Intestinal transplantation was no longer an experimental procedure, but rather a life-saving therapy. In 1990, a newer immunosuppressant drug, tacrolimus, appeared on the market as a superior alternative to ciclosporin. In the two decades since, intestine transplant efforts have improved tremendously in both number and outcomes.