Thickening of the gallbladder wall, usually considered >3 mm, is a non-specific sign of various conditions.
Gallbladder wall thickening can be caused by inflammatory, benign, and malignant etiologies. Pseudothickening caused by the normal postprandial state of the contracted gallbladder is also extremely common 5. Thus, for all non-emergent exams, a fasting period of 6-12 hours (fewer or none in children) is advised to achieve maximal gallbladder distension.
For the causes of focal and diffuse gallbladder wall thickening, see the respective articles:
As the gallbladder was a low-hanging fruit for the first, rudimentary B-mode US scanners, normal limits of the gallbladder wall thickness (3 mm) were established early on 1. Some later studies recommended a minimally modified cut off value of 3.5 mm 2,3. Nevertheless, most modern guidelines adopted the more easily memorized 3 mm value as the threshold not just for US, but for CT/MRI as well 4-6.
Evaluation of the gallbladder wall is ideally carried out using a curvilinear US probe and subcostal scanning approach. Depending on the situation, patient anatomy, and the variabilities of the best acoustic window a supine or left lateral decubitus position can both be used. Most commonly the measurement is made on the long axis view of the gallbladder. The posterior gallbladder wall thickness can usually be measured less reliably due to e.g. adjacent bowel loops, gallstones, or layered dense bile. Hence the measurement is best carried out on the anterior wall where it abuts the liver, resulting in better intrinsic contrast 4.
If US findings are equivocal, or the gallbladder cannot be reliably visualized, CT is the most commonly used second line imaging technique. Use of intravenous contrast is often warranted to increase the contrast between the normally thin (<3 mm), rim-enhancing gallbladder wall and adjacent tissues 5.
MRI is not routinely used for the evaluation of gallbladder but can be valuable for problem-solving if US/CT exams yield inconclusive results. Use of sequences with narrow slice thickness and minimal gap between sections are recommended. The normal gallbladder wall is less than 3 mm thick, shows low intensity on T2 and intermediate on T1 weighted sequences, and enhances homogeneously after the administration of intravenous contrast 6.
- 1. Ultrasound of gallbladder wall thickening and its relation to cholecystitis. (2012) American Journal of Roentgenology. 132 (4): 581-5. doi:10.2214/ajr.132.4.581 - Pubmed
- 2. M. Imhof, J. Raunest, Ch. Ohmann, H. -D. Röher. Acute acalculous cholecystitis complicating trauma: A prospective sonographic study. (1992) World Journal of Surgery. 16 (6): 1160. doi:10.1007/BF02067089 - Pubmed
- 3. Antonio Pinto, Alfonso Reginelli, Lucio Cagini, Francesco Coppolino, Antonio Amato Stabile Ianora, Renata Bracale, Melchiore Giganti, Luigia Romano. Accuracy of ultrasonography in the diagnosis of acute calculous cholecystitis: review of the literature. (2013) Critical Ultrasound Journal. 5 (1): 1. doi:10.1186/2036-7902-5-S1-S11 - Pubmed
- 4. ACEP Emergency Ultrasound Imaging Criteria Compendium. October 2014 Revised edition. https://www.acep.org/patient-care/policy-statements/Emergency-Ultrasound-Imaging-Criteria-Compendium/
- 5. Gabriel J. Runner, Michael T. Corwin, Bettina Siewert, Ronald L. Eisenberg. Gallbladder Wall Thickening. (2013) American Journal of Roentgenology. 202 (1): W1-W12. doi:10.2214/AJR.12.10386 - Pubmed
- 6. Onofrio A. Catalano, Dushyant V. Sahani, Sanjeeva P. Kalva, Matthew S. Cushing, Peter F. Hahn, Jeffrey J. Brown, Robert R. Edelman. MR Imaging of the Gallbladder: A Pictorial Essay. (2008) RadioGraphics. 28 (1): 135-55; quiz 324. doi:10.1148/rg.281065183 - Pubmed