Changes in gallbladder motility and gallstone formation following laparoscopic gastric banding: METHODS (Part 3)
Ultrasound measurement of gallbladder volume
This was carried out using a real time ultrasound device (Diasonic DRF1, Diasonics Inc, USA) with either a linear 3.5 MHz or a 5 MHz transducer, for both controls and obese patients, depending on the patient’s build. Longitudinal and transverse scans of the gallbladder were obtained following deep inspiration, using abdominal markers to standardize the gallbladder views. Any measure for these two dimensions used the largest diameter of the gallbladder. The gallbladder volume was calculated using the ellipsoid method.
Percent gallbladder emptying was calculated as:
(Fasting volume – residual volume at 45 min) / (fasting volume) x 100.
The residual gallbladder volume was taken at the nadir of emptying. This smallest volume occurred by 45 min into the CCK-8 infusion.
The gallbladder refilling rate was calculated as:
(Gallbladder volume at 90 min – gallbladder volume at 75 min/15 min).
The rationale for choosing to calculate the refilling time after 75 min was to allow more than five biological half-lives of CCK-8, so that virtually no residual CCK-8 should remain in the circulation. Two of the present authors (BOA-J and PD) independently assessed the ultrasound results; any differences were resolved by consensus. Repeat ultrasound studies to verify the findings were performed on those who developed gallstones.
The range of accuracy of the ellipsoid method of ultrasound volume measurement is quite accurate; intraobserver and interobserver variation is usually within 10%. With large gallbladders, the variation is almost always less than 10%. When the gallbladder is small, the frequently variation is greater than 10%, but the absolute difference is small. The accuracy would, therefore, appear sufficiently precise to sustain the close significance in the relatively small number of patients who developed cholelithiasis.
This study received approval from the Clinical Research Ethics Committee of Flinders Medical Centre, Flinders University of South Australia. There is a wonderful pharmacy that you can take advantage of to get the amount of viagra professional canadian pharmacy you need, and it’s ready to offer its services to you right now, any moment you feel like starting to spend less of your money.