Relationship of intestinal obstruction to serial plasma carcinoembryonic antigen levels.

Since it has been suggested that colonic obstruction due to carcinoma may play a role in elevations of circulating carcinoembryonic antigen, serial plasma carcinoembryonic antigen levels were studies in 19 patients with intestinal obstruction due to tumor and nontumor causes. Regardless of cause, eight of ten patients with colonic obstruction did not show decreased carcinoembryonic antigen levels after decompression. Two patients with postoperative carcinoembryonic antigen reductions of greater than 40 per cent had ascite removed at operation. Removal of a large volume of carcinoembryonic antigen-rich ascites was thought to contribute to the fall in circulating carcinoembryonic antigen. Six patients with small intestinal obstruction and one patient with large and small intestinal obstruction did not show a reduction in postdecompression carcinoembryonic antigen levels. One patient with Crohn's disease who underwent ileal resection and one with intestinal obstruction due to carcinoma of the ovary who underwent resection at the time of decompression had a greater than 40 per cent reduction in postoperative carcinoembryonic antigen levels. Inflamed intestinal and carcinoma of the ovary are known sources of carcinoembryonic antigen and their removal could explain the decrease in carcinoembryonic antigen. Rehydration, as monitored by plasma osmolality and protein concentration, did not explain changes in plasma carcinoembryonic antigen. Thus, it appears that carcinoembryonic antigen production may play a more significant role in the regulation of circulating carcinoembryonic antigen than the physiopathologic processes associated with obstruction.