Contrast ultrasonography of the normal small bowel

Abstract

In basal conditions, the small bowel loops cannot be properly visualized by means of real-time ultrasound (US). Aims of this study were: 1. to assess whether an isosmolar solution containing a nondigestable, nonabsorbable and nonfermentable hydrophilic macro molecule, such as polyethylene glycol (PEG), can be profitably used as a contrast agent to visualize the entire small intestine with US (small intestine contrast ultrasonography, SICUS); and 2. to define the normal US values of wall thickness and luminal diameter of the jejunum, ileum and terminal ileum. Real-time ultrasonography was performed in 10 healthy volunteers with 4- and 5-MHz linear-array transducers in basal fasting conditions and after ingestion of an isosmolar PEG solution. In basal fasting conditions, only a few segments of jejunum and/or ileum could be visualized in some of the investigated subjects. After ingestion of the contrast solution, the entire small bowel could be visualized in any single subject. A contrast sonography of the entire small bowel could be satisfactorly performed with 200 mL–820 mL of contrast solution in a time period that did not exceed 65 min. Luminal diameter at the level of the jejunum (19 ± 2.3 mm) and proximal ileum (18 ± 1.8 mm) was significantly greater ( p < 0.01) than at the level of distal ileum (16.4 ± 2.8 mm). Wall thickness was greater at the level of the terminal ileum (2 ± 0.4 mm) than of the jejunum (1.6 ± 0.5 mm) but the difference did not reach statistical significance. Details such as valvulae conniventes and multilayered structure of the wall could be recognized. In conclusion, after the ingestion of an isosmolar PEG electrolyte balanced solution, it is possible to visualize with ultrasonography the entire small intestine and to measure wall thickness and luminal diameter of the jejunum, the ileum and the terminal ileum. Such a noninvasive, inexpensive method can be used to investigate the morphological aspects of the small bowel.