Surface area of the digestive tract - revisited.

Background: According to textbooks, the human gut mucosa measures 260-300 m(2), that is, in the order of a tennis court. However, the quantitative data are incomplete and sometimes conflicting.

Objectives: To review the literature regarding the mucosal surface area of the human digestive tract; to collect morphometric data from the parts of the gut where such data are missing; and to recalculate the mucosal surface area of the intestine in man.

Methods: With focus on the intestine, we carried out morphometry by light and electron microscopy on biopsies from healthy adult volunteers or patients with endoscopically normal mucosae.

Results: Literature review of intubation or radiological methods indicates an oroanal length of ∼5 m, two-third of which refers to the small intestine. However, there is a considerable variation between individuals. The inner diameter of the small intestine averages 2.5 cm and that of the large intestine averages 4.8 cm. The mucosa of the small intestine is enlarged ∼1.6 times by the plicae circulares. Morphometric data obtained by light and electron microscopy of biopsies demonstrate that villi and microvilli together amplify the small intestinal surface area by 60-120 times. Surface amplification due to microvilli in the colon is ∼6.5 times. The mean total mucosal surface of the digestive tract interior averages ∼32 m(2), of which about 2 m(2) refers to the large intestine.

Conclusion: The total area of the human adult gut mucosa is not in the order of tennis lawn, rather is that of half a badminton court.