CHD duplications are extremely rare, and the true incidence is unknown due to the condition’s asymptomatic nature [4]. The aetiology surrounding biliary tree abnormalities remains unclear. The current findings suggest a disruption in early human embryogenesis may limit the regression of primitive duct structures, although the exact cause of these anomalies is yet unknown [6].

Different variants of extrahepatic biliary tree anomalies have been encountered, typically intraoperatively at cholangiogram inciting the development of various classification systems of CBD duplications and aberrant right hepatic ducts [7, 8]. Amongst these, duplicated CBDs are the rarest which often include variations of duplicated CHDs that are always accompanied with duplicated CBDs (Fig. 4) [6]. Our case shows a duplicated CHD draining the right intrahepatic system with its counterpart draining the left and a communicating aberrant duct in between. A similar variant has been encountered only once in the literature in a 13-year-old male presenting with chronic epigastric pain and subsequent jaundice [5]. Despite the rarity of comparable variants, it is important to understand them owing to the risk of iatrogenic CBD injury [9]. The overall incidence of iatrogenic CBD injuries at LC has remained stable over the past three decades at 0.3% with current evidence suggesting that 80% of these injuries are due to a misinterpretation of biliary tree anatomy [10].

Given the rarity of this condition, diagnosis remains difficult within the preoperative stage. Although preoperative magnetic resonance cholangiopancreatography (MRCP) would have demonstrated the biliary variation prior to LC, its routine adoption in this setting is limited by its expense and availability [11]. In our institution for example, an average MRCP costs $AUD 1500 and may delay operative intervention and thus is not sustainable as a routine preoperative screening modality. Although ultrasound is both cheaper and more readily available at our institution, in this case it did not recognize the biliary variation. As such, the diagnosis of CHD duplication may have to be made intraoperatively at time of cholangiography. The routine use of IOC in all LC cases although not always necessary, may reduce rates of iatrogenic bile duct injuries by detecting various biliary tree anomalies [12]. In this case, an IOC helped confirm our intraoperative suspicion of aberrant biliary anatomy and helped outline the drainage system, prompting careful dissection of the gallbladder off the cystic plate and leaving the duplicated CHDs intact.

Consequently, this rare type of extrahepatic bile duct duplication was treated successfully and should be considered along with other encountered forms of interesting biliary tree abnormalities.