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.
Fasciolopsis
"Fasciolopsis buski" is commonly called the giant intestinal fluke, because it is an exceptionally large parasitic fluke, and the largest known to parasitise humans. Its size is variable and a mature specimen might be as little as 2 cm long, but the body may grow to a length of 7.5 cm and a width of 2.5 cm. It is a common parasite of humans and pigs and is most prevalent in Southern and Southeastern Asia. It is a member of the family Fasciolidae in the order Plagiorchiida. The Echinostomida are members of the class Trematoda, the flukes. The fluke differs from most species that parasitise large mammals, in that they inhabit the gut rather than the liver as "Fasciola" species do. "Fasciolopsis buski" generally occupies the upper region of the small intestine, but in heavy infestations can also be found in the stomach and lower regions of the intestine. "Fasciolopsis buski" is the cause of the pathological condition fasciolopsiasis.