Ultrasonographic prevalence and proposed morphologic classification of bilobed gallbladder in cats

Abstract

Objectives Morphologic anomalies of the feline gallbladder (GB) have been previously reported in the literature. These morphologic variants are frequently encountered on routine abdominal ultrasound examination. The aim of this study was to provide an ultrasonographic classification system of these variants and document the overall incidence in the feline population. Methods A prospective, descriptive study was undertaken; cats that had an abdominal ultrasound examination that included at least one sagittal and transverse plane image of the GB were included. GB shape was evaluated and categorized based on a classification scheme of morphologic variants modified from the human literature. Septated (S), bilobed (B1, B2, B3), duplex (D) and complex (C) categories were described. Results Of 516 cats included in the study, 389 had normal GB morphology, while 127 had anomalous GB morphology. The overall incidence rate of anomalous GB morphology was 24.61%. When examined by morphologic type, the septated (S) morphology had an incidence of 9.69%. A bilobed (B) morphology was the most commonly observed classification; incidence was 14.35% within our population; incidence of B1, B2 and B3 subtypes were 2.91%, 6.98% and 4.46%, respectively. Duplex GBs only made up 0.39% of the total population. The incidence of complex (C) morphologies was 0.19%. Conclusions and relevance The incidence of GB morphologic anomalies was higher in our population than previously reported. Identification of these anomalies on routine ultrasound evaluation is common; numerous different morphologies can be identified and a standardized classification scheme is proposed. Complete evaluation of morphology can be challenging, particularly with regard to cystic duct anatomy. Clinical significance is uncertain and future studies are warranted to determine the relationship between morphologic variants and hepatobiliary disease.

Double cholecystectomy of duplex gallbladder associated with chronic cholecystitis in a cat

“…The Persian breed is slightly overrepresented in the group with abnormal gallbladder morphology. Spain et al (2021) reported an incidence of congenital gallbladder anomalies in 6/10 Persian cats compared to the population's overall incidence of 24.6%. In addition, 63% of the anomalous morphology group were male (Spain et al, 2021).…”

“…A duplex gallbladder having two cystic ducts is a rare presentation of congenital gallbladder anomaly in cats (Spain et al., 2021 ), with only two other symptomatic cases of duplex gallbladder in cats reported in the scientific literature (Moores & Gregory, 2007 ; Woods et al., 2012 ). The first case was a duplex gallbladder associated with choledocholithiasis, cholecystitis, gallbladder rupture and septic peritonitis in a domestic shorthair cat.…”

“…(2021) reported an incidence of congenital gallbladder anomalies in 6/10 Persian cats compared to the population's overall incidence of 24.6%. In addition, 63% of the anomalous morphology group were male (Spain et al., 2021 ). The cat in the present case was a female Persian cat.…”

“…Morphological anomalies of the gallbladder are more commonly seen in cats than other domestic animals and humans, with incidence levels of 12.3% and 24.6% previously reported (Boyden, 1926;Spain et al, 2021). Congenital variants in gallbladder morphology can be classified into septated, bilobed, duplex and complex.…”

“…Congenital variants in gallbladder morphology can be classified into septated, bilobed, duplex and complex. A bilobed gallbladder was the most observed abnormality, whereas a duplex gallbladder made up only 1.6% of the reported anatomical gallbladder anomalies (Spain et al., 2021 ). There is no evidence to show that the presence of an anatomical anomaly in itself is associated with a higher risk of biliary disease in cats.…”