Spontaneous reversal of portal blood flow: the case for and against its occurrence in patients with cirrhosis of the liver.

Because of its presumed serious clinical significance, we made an analysis of the evidence for and against the occurrence of spontaneous reversal of portal flow in cirrhosis of the liver. We examined the evidence obtained from manometric studies, radioactive tracer studies, radiologic studies, and actual measurements of magnitude and direction of portal blood flow. Concerning manometric studies, we introduced a physical analysis, based on first principles, which demonstrates that the occluded portal pressures cannot be used to construct a hydraulic gradient for portal flow. Similarly, we examined the weakness of the evidence derived from radioactive tracer and radiologic studies and, in the latter, the drastically opposite results reported by different investigators. Finally, we found that actual measurements of magnitude and direction of portal flow provide impressive evidence against the occurrence of spontaneous reversal of portal flow in cirrhosis. We conclude that unless new and convincing evidence is provided, it may not serve the best interests of medicine and of our patients to continue accepting spontaneous reversal of portal flow in cirrhosis as if it were a proven phenomenon.