Is Same‐Day Sonography of the Gallbladder Feasible After Intravenous Urography or Contrast‐Enhanced Computed Tomography?

OBJECTIVE: To determine whether same-day sonographic evaluation of the gallbladder is possible after the use of oral or intravenous iodinated contrast agents during intravenous urography or computed tomography. METHODS: One hundred fifty-three patients involved in this prospective study received low-osmolar or conventional contrast material. Each preparation contained 300 mg/mL iodine. Sixty-six patients received contrast agents intravenously, and 87 received them orally. Gallbladder volume was estimated sonographically, and the precontrast volume was used to calculate the volume after contraction at 30-minute intervals up to 2 hours after contrast agent administration. RESULTS: Gallbladder volume returned to precontrast values at 2 hours irrespective of the type of contrast agent or route of administration. The mean volume after contraction at 0.5 hour was 71% after intravenous contrast agent administration and 76% after oral contrast agent administration. Both changes were statistically significantly different from precontrast values (P < .01, null hypothesis) and were unaffected by the osmolarity of the contrast agent. CONCLUSIONS: Gallbladder volume was restored to precontrast values 2 hours after contrast agent administration. Thus any strategy involving simultaneous same-day sonographic or computed tomographic assessment of the gallbladder after contrast agent administration can be confidently undertaken after this period. This finding may have cost-saving implications.