Effect of short-time treatment with ursodeoxycholic acid on postprandial gallbladder bile flow in gallstone patients: a statistical-mathematical analysis of ultrasonographic data

Background: Gallstone disease is characterized by an impaired gallbladder (GB) emptying and a reduced GB turnover of bile, being the latter assessed by a mathematical analysis of UltraSonographic (US) data (1). In these patients administration of ursodeoxycholic (UDCA) acid seems to be associated to a reduced risk of bifiary pain and complications. The effect of UDCA on GB function is still matter of debate. Aim: To assess by means of statistical analysis of the US motility data, and GB bile flow with computer fluid dynamics the effect of UDCA therapy. Patients and Methods: in 3 GS patients, postprandial US assessment of GB volumes, for a study period of 90 minutes, with a time sampling of 1 minute, has been performed before and after 30 days of UDCA therapy (lOmg/Kg/die). The measured time series were successively analyzed with statistical tools and Fourier analysis. Results: The average volume of the gallbladder of patients is increased upon UDCA treatment (10.6%, 21.1%, 23.9%, respectively). The increase is statistically significant for the three patients. Indeed, a hypothesis test (a T-test) on the means of two distributions led to the conclusions that, with 95% significance, the null hypothesis of equal mean volumes pre and posttreatment must be rejected for the three patients. On the other hand, the organ motility is only slightly affected by UDCA administration, so that the characteristic GB-dimension oscillations remain essentially unaltered. In particular, the time series analysis shows that the volume oscillations have the same amplitude before and after UDCA treatment, and a Fourier analysis shows that also the characteristic frequencies (pre and post treatment) are basically unchanged. A simple geometrical reasoning proves that UDCA treatment improves the intra-GB bile turnover. Conclusions: Short-time treatment with UDCA induces an improvement of postprandial GB bile exchanges in GS patients. Application of standard statistical tests and time series analysis in the frequency domain to US GB motility data could provide additional insights into the assessment of intra-GB bile stasis, a key-event in the pathogenes is of GS disease. 1) M.Cicala et al. U l t rasound Med Blot 2001 Nov;27(11):1445-50.