Duplication of the gallbladder refers to the bifurcation of the gallbladder primordium during the fifth or early sixth embryonic week. It is estimated to occur once in every 4000 patients. Very few documented symptomatic cases have been reported.1
Several classifications have been proposed according to anatomic or embryological development of the gallbladder. Boyden2
classified double gallbladder in bilobed gallbladder and in true duplicated gallbladder, with 2 types according to the connection of the cystic ducts. Gross3
classified double gallbladder into 6 types, designated A to F, and Harlaftis et al4
classified double gallbladder into 2 groups ()
. The case described here falls under the Boyden ductal-type, Gross B-type, and Harlaftis ductular-type classifications.
According to Boyden's classification, the 2 main types of duplications are vesica fellea divisa or bilobed gallbladder and vesica fellea duplex or true duplication, with 2 different cystic ducts. The true duplication is subclassified into the Y-shaped type (2 cystic ducts unite before entering into the common bile duct, usually the 2 gallbladders are adherent and occupy the same fossa) and the H-shaped type or ductular type (2 separate gallbladder and cystic ducts entering separately into the common bile duct). The accessory gallbladder of the ductular type may be adjacent to the normal organ in the gallbladder fossa or may be intrahepatic, subhepatic, or within the gastrohepatic ligament. The true duplication is more common and occurs due to bifurcation of the gallbladder primordium during the fifth and early sixth week of embryonic life.
The gallbladder duplication is diagnosed preoperatively in fewer than half of the cases.
Although duplication of the gallbladder may be suspected on abdominal ultrasonography for abdominal pain in the presence of 2 cystic formations in the gallbladder fossa with contraction of one or both after a meal, this diagnosis remains difficult to prove.5
Furthermore, sonography cannot adequately determine the type of duplication.5,6
Some authors have used oral cholecystography with a 60% sensitivity4
or computed tomography scanning with oral cholecystography. Although ERCP seems to be the gold-standard examination for confirming the diagnosis, the disadvantages of this approach include invasiveness and a high rate of false-negatives.7
MRCP is a noninvasive technique widely used in the evaluation of biliary tract abnormalities, including stones, anatomic variations, and preoperative drainage.8
Therefore, MRCP has become the imaging technique of choice at many institutions in the workup of patients with a biliary tract abnormality. In our case, MRCP allowed us to determine the exact type of duplication, information that is necessary prior to surgical treatment.9
The differential diagnosis of gallbladder duplication from some gallbladder diseases is often difficult. They include choledochal cyst, gallbladder diverticulum, pericholecystic fluid collection, focal adenomyomatosis, a Phrygian cap, extrinsic fibrous bands across the gallbladder, and a folded gallbladder.
The double gallbladders do not present with specific symptoms, and the incidence of disease in this gallbladder anomaly is similar to its normal variant.5
Gallstone is the commonest complication occurring in one lobe, but both lobes can be involved. There is no increase in the incidence of disease in double gallbladder, so prophylactic cholecystectomy in an asymptomatic patient is not recommended.6
But if only one gallbladder is diseased and another is normal, both should be removed because the normal gallbladder is also prone to develop the disease. It is often found incidentally during the surgery for cholelithiasis.3,5,9
In our case, the patient was symptomatic, and preoperative imaging showed a double gallbladder.
In our case, ultrasound suggested the double gallbladder. BULIDA scan also suggested a double gallbladder due to one healthy and one diseased gallbladder because of the persistent cold area adjacent to the normal gallbladder, but in the presence of both diseased gallbladders BULIDA could not detect it. MRCP was done to characterize the type of duplication, and it showed it to be the ductular type.