Patterns of colonic transit were assessed by a simple radioisotopic technique using 3.7 MBq of orally administered [111In]DTPA in 16 control subjects and 37 patients with intractable constipation. Normal subjects showed rapid diffuse spread of isotope through the colon resulting in low activity in all regions of interest (ROI). Activity was lost to feces at 24 hr and was virtually complete by 72 hr (median 94%, range 71-100%). Five constipated patients showed normal transit. Those with colonic inertia (N = 26) showed a significantly slowed geometric center of isotope compared to controls (P < 0.001), falling below the normal range at 48 hr. Percentage activity curves showed the major site of isotope hold-up to be in the transverse colon and splenic flexure. Other constipated patients (N = 6) showed late delay of the geometric center of isotope and accumulation of activity in the descending and rectosigmoid colon, compared to controls, at 96 hr. Oral [111In]DTPA colonic scintigraphy is a useful clinical test in the investigation of constipation.

Global and regional assessment of colonic transit by scintigraphy failed to discriminate between patients with STC with or without coexistent RED. Thus, RED is not associated with a specific pattern of transit delay and scintigraphy alone cannot predict the presence or absence of RED, knowledge of which is important for management.

This study demonstrates that differences in colonic transit exist between subgroups of patients with STC. These might be explained by differences in duration of symptoms or differences in aetiology.

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