linguistic:paraphrasing, quality:correction, structural:scholar_edition
Size

The length of the small intestine can vary greatly, from as short as 3 metres (10 feet) to as long as 10.5 m (34 + 1 ⁄ 2 ft), also depending on the measuring technique used. The typical length in a living person is 3–5 m (10– 16 + 1 ⁄ 2 ft). The length depends both on how tall the person is and how the length is measured. Taller people generally have a longer small intestine and measurements are generally longer after death and when the bowel is empty.

It is approximately 1.5 centimetres (5 ⁄ 8 inch) in diameter in newborns after 35 weeks of gestational age, and 2.5–3 cm (1– 1 + 1 ⁄ 8 in) 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 metres (320 sq ft).