The sitzmark test is commonly used to assess colonic motility. The basis of the test is to determine whether colonic transit is normal or abnormal. This is determined by the persistence of markers (>6/24) five days after ingestion. If >19/24 have been expelled, transit is generally normal. If markers remain, it indicates disturbed colonic transit. If most markers are found in the rectosigmoid, it suggests obstructive defecation. If markers are found throughout the colon, it is consistent with colonic inertia OR obstructive defecation. If the test is normal, you're done. If the test is abnormal, it does not need to be performed repeatedly, nor is there documented utility in taking x-rays every day until all the markers are gone. If the test is abnormal, it suggests significant impairment in colonic transit which should be further clarified by other studies to exclude pseudoobstruction syndromes (which can be paraneoplastic and have vomiting associated), obstructive defecation syndromes and (always) mecahnical obstruction if it's not been done.No one should have surgery performed based solely on the results of a sitzmark study.