Cholecystectomy, the surgical removal of the gallbladder, is among the most frequently performed abdominal operations in the United States, with around three-quarters of a million procedures carried out each year [1, 2]. Its prevalence is largely due to the high incidence of gallstone disease and its associated complications, which are the primary indications for the surgery [2, 3]. The advent of laparoscopic techniques has revolutionized cholecystectomy, offering a minimally invasive approach that has become the standard of care. Despite the recognized safety and efficacy of laparoscopic cholecystectomy, its widespread practice inevitably leads to a spectrum of postoperative complications [2,3,4].

Timely and accurate identification of post-cholecystectomy complications is crucial, as it can significantly influence patient outcomes, reducing the morbidity associated with delayed diagnosis and treatment [5, 6]. Imaging is an indispensable tool providing a non-invasive means of differentiating between normal postoperative anatomy and pathology. Based on the indication, ultrasound and computed tomography (CT) are the primary imaging modalities used to evaluate postsurgical complications. CT is essential for the diagnosis of vascular complications. Magnetic resonance cholangiopancreatography (MRCP) is the imaging modality of choice for evaluating the biliary tree. Bile leak can be diagnosed on a radionuclide scan or on magnetic resonance imaging using hepatobiliary-specific contrast agents [7, 8].

This review article provides an overview of the common indications for cholecystectomy and the surgical anatomy underpinning the procedure. It describes the nuances of the surgical technique, with particular attention to the identification of anatomical variants that may predispose patients to complications. These variants play a pivotal role in the complexity and outcome of the surgical procedure. Additionally, we discuss the role of imaging in the postoperative setting, its utility in identifying complications, and the importance of distinguishing between normal postsurgical changes and complications.

Common indications for cholecystectomy

Symptomatic gallstone disease is the most common indication for cholecystectomy. Other indications include acute cholecystitis, chronic cholecystitis, choledocholithiasis, gallstone pancreatitis, gall bladder polyps and masses, and biliary dyskinesia [9, 10].

Relevant surgical anatomy and surgical technique

The Calot's triangle (hepatocystic triangle) serves as an anatomical landmark during cholecystectomy. It is an imaginary triangle bordered on the left side by the common hepatic duct, inferiorly by the cystic duct, and superiorly by the inferior liver surface (Fig. 1). It contains the right hepatic artery and its branch, the cystic artery (Fig. 1), along with connective tissue and the cystic lymph node of Lund (the first lymph node of the gallbladder) [11]. Dissection in the hepatocystic triangle is performed to obtain the 'critical view of safety'. Misidentifying the normal anatomy and failing to recognize anatomical variants of significance can lead to surgical complications [12]. It is imperative to ensure that only two structures enter the gallbladder: the cystic duct and the cystic artery [3, 12]. The cystic artery and the cystic duct are ligated, and then the gallbladder is removed [3]. Intraoperative cholangiogram may be routinely performed by some surgeons [3]. Others may use it as a problem-solving tool if biliary anatomy is uncertain or there is suspicion of biliary injury or for evaluating possible choledocholithiasis [3, 12].

Fig. 1

Surgical landmarks for cholecystectomy: Calot’s triangle bounded superiorly by the inferior surface of the liver, inferiorly by the cystic duct (CD), and on the left side by the bile duct (CBD & CHD). Important contents of the Calot’s triangle include the Right hepatic artery (RHA) and the cystic artery (CA), a branch of the right hepatic artery. The cystic artery is identified and ligated during surgery to prevent hemorrhage

Variants of significance in biliary and arterial anatomy

It is crucial to recognize variants in the biliary anatomy to avoid injury to the biliary system during the surgery. The Hartman's pouch, an anatomical variant, is a bulge that may be present in the neck of the gallbladder. If prominent, it can obscure the visualization of the cystic duct and the Calot's triangle [12]. Small bile ducts arising from the right lobe of the liver, the subvesical ducts (Ducts of Luschka), can drain into the extrahepatic bile ducts or into the gallbladder [13] (Fig. 2b). Accessory or aberrant bile ducts may drain into the right hepatic duct in the Calot's triangle (Fig. 2b). An aberrant bile duct is the only pathway of biliary drainage of the portion of the liver that it drains, while an accessory duct represents a duct providing an additional path for biliary drainage [14]. Significant variants in the anatomy of the cystic duct include low parallel insertion of the cystic duct into the common hepatic duct and a spiral configuration of the cystic duct traversing posterior to the common hepatic duct before its insertion on the left side of the common duct. Drainage of the cystic duct into the right hepatic duct (Fig. 2c), duplication of the cystic duct, short course of the cystic duct, or congenitally absent cystic duct are other rare variants of significance [11, 12, 15]. Accessory ducts seen during cholecystectomy generally drain the right lobe (Fig. 2b). They typically traverse the Calot’s triangle and drain into the common hepatic duct inferior to the confluence of the right and the left hepatic ducts. Rarely, the cystic duct may drain into an accessory duct [12] (Fig. 2d). The right posterior duct, a sectoral duct draining segments VI and VII, which commonly unites with the right anterior hepatic duct to form the right hepatic duct, may aberrantly drain into the common hepatic duct or the cystic duct [12, 14] (Fig. 2e and f). MRCP may help in the preoperative diagnosis of some of these abnormalities, while CT and ultrasound are not particularly helpful in diagnosing biliary anatomical variants.

Fig. 2

Common variants of the biliary tree in relation to cholecystectomy. a Normal biliary anatomy b Subvesical ducts of Luschka, accessory bile ducts, or aberrant bile ducts can drain into the extrahepatic biliary tree. c and d The cystic duct can drain into the right hepatic duct or into an accessory bile duct. e and f The right-sided bile ducts, especially the right posterior duct, can drain into the cystic duct or into the common duct. CBD: Common bile duct. RHD Right hepatic duct, LHD Left hepatic duct, CHD Common hepatic duct, CD Cystic duct

Significant variants in the arterial vasculature include a replaced or accessory right hepatic artery originating from the superior mesenteric artery (10–22%) or common hepatic artery originating from the abdominal aorta (2%), which can have a variant course in the Calot’s triangle. If there is a tortuous course of the right hepatic artery in the Calot’s triangle, known as ‘Moynihan’s hump’, the right hepatic artery may be mistaken for a cystic artery. Occasionally, two cystic arteries may be present [11, 12]. Rarely, the cystic artery may arise from arteries other than the right hepatic artery [12].

Other factors predisposing to surgical complications

In addition to the anatomical variants discussed above, impaired visualization and difficult dissection increase the risk of developing surgical complications. Inflammatory changes and adhesions/fibrosis in the surgical bed can obscure the anatomy, causing difficulty in surgery [16]. Obesity can lead to difficult dissection and impaired identification of anatomical landmarks and variants [2, 12]. Underlying liver disease can increase the risk of operative blood loss [17, 18].

Surgical approaches and types of cholecystectomy

Cholecystectomy was traditionally performed via an open approach. Laparoscopic cholecystectomy, introduced in the 1980s, is the current standard and preferred method of cholecystectomy for symptomatic gallbladder stones due to the advantages of lower morbidity, faster recovery, less pain, and better cosmetic results when compared to open cholecystectomy. Laparoscopic cholecystectomy may be converted into an open procedure in 4 to 8% of the cases. Typically, a conversion to an open surgical approach is utilized in more challenging procedures where surgical landmarks are not clearly identifiable due to inflammation/scarring, anatomical variants requiring further clarity, or intraoperative complications necessitating an open procedure [2]. Robotic cholecystectomy is becoming increasingly popular. It has a similar rate of postsurgical complications when compared to the laparoscopic route. Its advantages include three-dimensional visualization and a lower conversion rate into an open procedure. The disadvantages include increased cost of the procedure and longer surgery time [19, 20].

During a cholecystectomy, the entire gallbladder is typically removed, termed as total cholecystectomy. However, if challenges arise during surgery that prevent the safe removal of the entire organ, a subtotal cholecystectomy may be performed. Types of subtotal cholecystectomy include subtotal fenestrating cholecystectomy and subtotal reconstituting cholecystectomy. In subtotal fenestrating cholecystectomy, a part of the gallbladder wall adherent to the liver is not removed, and the exposed mucosal surface is ablated, followed by ligation of the cystic duct. As a result, there is no residual gallbladder lumen, and it is not associated with an increased risk of cholecystolithiasis. However, there is an increased risk of developing a bile leak. In subtotal reconstituting cholecystectomy, the residual gallbladder is sutured to form a lumen, which is continuous with the cystic duct (Fig. 3). As there is a residual gallbladder lumen, potentially cholelithiasis and cholecystitis can occur [8, 21]. The spectrum of complications that can occur post-total cholecystectomy can also develop post-subtotal cholecystectomy.

Fig. 3

A 35-year-old female with subtotal reconstituting cholecystectomy (arrow) for symptomatic cholelithiasis. Complete cholecystectomy could not be performed as a critical view of safety could not be obtained during the surgery due to morbid obesity

Percutaneous cholecystostomy is a non-surgical alternative in patients who are at high risk for perioperative complications and can be performed as a stop-gap or as a definitive procedure. It is performed under imaging guidance and can utilize ultrasound, CT, and fluoroscopy, either individually or in combination. The gallbladder can be entered via either transhepatic or transperitoneal approaches. Common complications include catheter dislodgment, bile peritonitis, hemobilia, and gallbladder perforation [22, 23]. Endoscopic procedures may also be used to drain the gallbladder. Endoscopic transpapillary drainage of the gallbladder is a well-established procedure. Endoscopic ultrasound-guided transmural gallbladder drainage via the stomach or the duodenum using a lumen-apposing metal stent is also gaining popularity [22, 24, 25].

Imaging modalities in the evaluation of postsurgical complications

Various imaging modalities can be used to evaluate postsurgical complications and should be tailored as per the indication. Ultrasound and Computed Tomography (CT) are the first imaging lines, depending upon the indication. Ultrasound is useful in assessing liver pathology, postsurgical collections, and evaluation for intrahepatic biliary dilatation. CT ​ provides excellent spatial resolution with fast acquisition time. It accurately depicts foci of air and calcifications. A single-phase CT study is typically performed in the portal venous phase after intravenous contrast administration. A multiphase CT study must be performed if there is suspicion of active bleeding. Magnetic resonance imaging (MRI) provides excellent soft tissue resolution, and magnetic resonance cholangiopancreatography (MRCP) is ideal for imaging the biliary tree and evaluating choledocholithiasis. MRI using hepatobiliary contrast helps diagnose bile leaks. MRI is limited by the long duration of examination and dependence on breath-holding and is suboptimal for the evaluation of air and calcifications. Hepatobiliary scintigraphy in the form of a hepatobiliary iminodiacetic acid (HIDA) scan can also help confirm a bile leak. A SPECT-CT study provides a better anatomical overview of the bile leak when compared to the planar HIDA scan and can be helpful in problem-solving. A percutaneous transhepatic cholangiogram (PTC) or an endoscopic retrograde cholangiopancreatography (ERCP) may be performed as a part of diagnostic work-up and interventional management of bile leaks. Angiography may be required to evaluate and manage vascular complications [8, 15, 26, 27].

Expected postsurgical changes

Small fluid collections can be seen in the gallbladder fossa and in the abdominal cavity (Fig. 4a). These collections can represent simple fluid or small postsurgical seromas or hematomas. If the collection has blood products within, it can show a high signal on the noncontrast T1-weighted image (Fig. 4 b and c). Although there is no specific timeframe that can be used to differentiate expected versus pathological collections, large collections and progressive increases in the size of the postsurgical collections should raise a concern for pathological collections, while expected postsurgical collections will stay stable or show progressive interval decrease in size [26]. Fat stranding can be seen in the region of the gallbladder fossa and at the incision site in the anterior abdominal wall [27]. Reactive inflammatory changes may be seen in the liver adjacent to the gallbladder fossa (Fig. 4d). Contrast-enhanced CT and MRI will demonstrate hyperenhancement when compared to the rest of the liver parenchyma.

Fig. 4

Expected changes post cholecystectomy. a A 27-year-old with abdominal pain post cholecystectomy. An axial CT image showing trace collection (black arrow) and fat stranding in the gallbladder fossa (white arrow), which are expected postsurgical changes. b and c A 75-year-old female with small postsurgical hematoma post-cholecystectomy. b Axial T2 and c Axial precontrast T1W images demonstrate a T2 hyperintense collection that contains intrinsic T1 signal suggestive of blood products (arrow). d A 72-year-old post-recent cholecystectomy. Axial T1W post-contrast image shows reactive hyperemia in the adjacent liver (black arrows). Expected trace collection and fat stranding in the gallbladder fossa (white arrow).

Hemostatic material (Surgicel) may be left in the surgical bed and should not be mistaken for an abscess, hematoma, or retained surgical material (Fig. 5). Surgicel can have varied imaging appearances but is most commonly seen as focal air collections within a mixed attenuation collection/mass. Surgicel, a cellulose-based product, does not have a radiodense marker, while a retained surgical sponge generally has a radiodense marker. Reviewing surgical notes and discussing with the surgeon are helpful in such diagnostic dilemmas [27, 28].

Fig. 5

A 66-year-old woman who underwent cholecystectomy for acute calculus cholecystitis, with surgicel material in the gall bladder fossa. a and b Postoperative axial and coronal CECT images showing Surgicel material in the gallbladder fossa (black arrows) and a small volume high-density collection in the gallbladder fossa, and perihepatic region suggestive of postsurgical hematomas/seromas (white arrows)

Dilatation of the intrahepatic and extrahepatic biliary system can be seen post cholecystectomy, as the biliary system serves as a reservoir for bile after gallbladder removal. The common bile duct can progressively and physiologically dilate up to 10 mm post-cholecystectomy [29]. Prexisting dilatation may be seen in the setting of a choledochal cyst, If there is dilatation of the biliary tree, especially when associated with an obstructive pattern of liver function tests, an MRCP may be performed to rule out choledocholithiasis or an underlying mass. If the MRCP does not demonstrate an obstructing cause, the differential diagnosis includes a radiologically occult mass, ampullary stenosis, and sphincter of Oddi dysfunction versus expected postsurgical changes [27, 29].

Postoperative complications

We have categorized post-cholecystectomy complications into A. Injuries to the biliary system, B. Gallstone-related complications, C. Vascular complications, D. Postoperative collections, and E. Miscellaneous complications. These complications can occur independently, sequentially, or simultaneously.

Injuries to the biliary system

Although biliary injuries are rare, with an estimated incidence of 0.4–1.5%, they are of significant concern, leading to increased morbidity and mortality, along with possible long-term sequelae [30]. These injuries occur more frequently during laparoscopic surgeries than open cholecystectomies; the incidence post-open cholecystectomy ranges from 0.1–0.5%, while the reported incidence with laparoscopic procedures is 0.5–1.5% [31, 32].

Factors contributing to these injuries include incorrect identification of biliary anatomy, failure to recognize anatomical variants, imprecise cystic or bile duct ligation, dislodgment of surgical clips, or thermal damage from cautery. These can lead to partial or complete ductal discontinuity leading to bile leak, development of biliary stricture leading to biliary obstruction, or both [33]. The sources of bile leak include leak from a peripheral duct in the gallbladder fossa (duct of Luschka), the cystic duct stump, a partial injury to the side of a hepatic duct, or a transected hepatic or common bile duct. The risk of bile leak is higher for surgeries on severely inflamed gallbladders and in patients with subtotal cholecystectomies. Biliary stricture/obstruction can be either acute or chronic. Biliary injuries may be diagnosed during the procedure, in the immediate or late postoperative periods. Prompt diagnosis generally correlates with better outcomes [30, 33]. In the early postoperative period, such injuries may result in cholangitis and intraabdominal abscesses. Long-term effects of chronic biliary obstruction include biliary strictures, intrahepatic lithiasis, secondary biliary cirrhosis, and portal hypertension [6, 34].

Various classification systems have been proposed for classifying biliary injuries during cholecystectomy. Accurate diagnosis of the type and extent of injury helps decide the appropriate management. The Bismuth and the Strasberg classifications are discussed in the present article. The Bismuth system proposed before the advent of laparoscopic cholecystectomy divides biliary injury into five types (Table 1) (Fig. 6). Types 1 to 4 are based on the location of the injury in relation to the biliary ductal system. Injury to an aberrant right hepatic duct, which may or may not be associated with a common hepatic duct injury, constitutes a type 5 injury [35]. The Strasberg Classification, which is the most widely used, applies to biliary injuries encountered during laparoscopic cholecystectomy and is divided into types A to E (Table 2) (Fig. 6) [35, 36].

Table 1 Bismuth classification of biliary injuries duri