Role of sonography in assessing complications after laparoscopic cholecystectomy.

Laparoscopic cholecystectomy, which was introduced to the arsenal of surgical procedures in the middle of the 1980s, is a common alternative for conventional cholecystectomy. Its primary advantage is less invasive character which entails shorter hospitalization and faster recovery. Nevertheless, the complications of both procedures are comparable and encompass multiple organs and tissues. The paper presents ultrasound presentation of the surgical bed after laparoscopic cholecystectomy and of complications associated with this procedure. In the first week following the surgery, the presence of up to 60 ml of fluid in the removed gallbladder bed should be considered normal in certain patients. The fluid will gradually absorb. In single cases, slight amounts of fluid are detected in the peritoneal cavity, which also should not be alarming. Carbon dioxide absorbs from the peritoneal cavity within two days. Ultrasound assessment of the surgical bed after cholecystectomy is inhibited by hemostatic material left during the surgery. Its presentation may mimic an abscess. In such cases, the decisive examination is magnetic resonance imaging but not computed tomography. On the other hand, rapidly accumulating fluid around the liver is an alarming symptom, particularly when there is inadequate blood supply or when peritoneum irritation symptoms develop. Depending on the suspected cause of the patient's deteriorating condition, it is essential to perform urgent computed tomography angiography, celiac angiography or endoscopic retrograde cholangiopancreatography or magnetic resonance cholangiopancreatography. The character of the fluid collection may be determined by its ultrasound-guided puncture. This procedure allows for aspiration of fluid and placement of a drain. Moreover, transabdominal ultrasound examination after laparoscopic cholecystectomy may contribute to the identification of: dropped stones in the right hypochondriac region, residual fragment of the gallbladder with possible concretions, undiagnosed choledocholithiasis, existing cholestasis, pseudoaneurysm of the hepatic artery, portal vein thrombosis and hematoma as well as hernias of the abdominal walls. Moreover, ultrasound examination helps to identify optimal sites in the abdominal integuments, which enables collision-free access to the peritoneal cavity.

Laparoscopic cholecystectomy has become a basic method of treating uncomplicated cholelithiasis. Open cholecystectomy is reser ved for cases in which intense in flammation is present. This particularly refers to inflammation in the Calot's triangle, to situations when there are suspicions of gangrenous cholecystitis, wall perforation and gallbladder neoplastic lesions, to cases complicated by a fistula between the gallbladder and gastrointestinal tract as well as to patients with pathological fatty deposition and with adhesions in the upper abdomen(. The diagnosis of this type of complication, apart from conventional transabdominal ultrasound (US), requires the application of other imaging techniques, such as endoscopic ultrasound, computed tomography, endoscopic retrograde cholangiopancreatography, magnetic resonance cholangiopancreatography (MRCP) or celiac/mesenteric angiography. Currently, laparoscopic cholecystectomy (LCH) is a gold standard due to shorter hospitalization and reduced unfavorable in fluence of the surger y that involves abdominal integuments. Nevertheless, the indicators of complications of both methods (open and laparoscopic) are comparable(.

The paper presents a range of changes visualized by means of US examination in the surgical bed after LCH which are irrelevant from clinical point of view and which reveal complications associated with this method.

Postoperative site soon after LCH

In 1991, Kang et al. ( demonstrated that 1–60 ml of fluid (mean 4 ml) is found in the postoperative bed after LCH in 53% of cases. Previous data had indicated that this sign occur red in 12–24% of cases. In t he majorit y of these patients(, the fluid was anechoic or hy poechoic (fig. 1). Merely 30% presented high echogenicity, which was explained by the presence of fresh blood, omentum or mesenter y. Eleven out of 106 patient s (10.4%) also presented slight amounts of free fluid in the peritoneal or pleural cavities. Moreover, Bersani and Lallemand(, monitored the image of free fluid in the surgical bed after LCH on the 3rd, 5th, 7th and 9th days following the surgery and agreed that it absorbed within 2– 4 days. McAlister( reported similar observations. The above -mentioned authors( and Müller et al. ( believe that performing routine US examination in the first days following the surgery is unjustified because it is characterized by low sensitivity (8%) and burdened with a large number of false positive results, which leads to prolonged hospital stay. Other authors report higher sensitivity of US examination after LCH(. Therefore, it may be assumed that US examination is justified when there are suspicions of complications manifested by inadequate blood supply or symptoms of peritoneal irritation, such as: injury to the bile ducts, acute bleeding and bile leak to the peritoneal cavity. Such complications develop in 3 – 4% of patients af ter laparoscopic surger y(. US examination does not allow for a reliable dif ferentiation of the character of free fluid (hematoma, collection of bile or abscess). The image in this technique is concealed by gas but whereas carbon dioxide absorbs quickly – within two days(, air may persist several days longer (fig. 2). Moreover, the image is made complicated by the hemostatic material retained after LCH, which resembles an abscess. In such cases, magnetic resonance imaging is helpful since the hemostatic material saturated with blood brea kdown products generates low signal in T2-weighted images(. When doubts persist concerning the character of the fluid collection in the LCH bed, ultrasound-guided puncture may be performed for diagnostic or therapeutic purposes (evacuation, drain insertion)(.

Fig. 1

One day following laparoscopic cholecystectomy. A slight amount of fluid can be seen in the gallbladder bed indicated by distance markers

Fig. 2

One day following laparoscopic cholecystectomy. Gas in the peritoneum (arrows) prohibits the assessment of the surgical bed. L – liver

A constant image in patients after LCH which should not arouse suspicions is a set of intense reflections with a subsequent comet tail artefact (fig. 3) in the porta hepatis – it corresponds to metal clips. Gradually, following several weeks or months after the surger y, a hyperechoic scar band with the width of several to over a dozen millimeters will appear in the gallbladder bed (fig. 4). In some cases the surgical bed is occupied by the duodenal bulb, frequently filled with gas, which conceals US presentation of the common bile duct. Sometimes the duodenal bulb is filled with fluid that mimics a fluid cistern (fig. 5). In this case, visualization of peristalsis in this “lesion” or appearance of other contents will be a decisive sign (fig. 6). Some researchers, soon after LCH, observe slight dilatation of the common bile duct without a detectable obstacle(. Another finding is a thin duct with the length f rom several to 30 mm (fig. 7), which corresponds to a fragment of or to the whole cystic duct which is seldom entirely removed during LCH(. A diagnostic problem in surgical bed assessment is posed by the gallbladder bed in which a pathomorphologist detected low-grade gallbladder carcinoma. In such cases, some surgeons deem it necessary to perform wedge resection of the liver encompassing segments IV and V adhering to the gallbladder fossa. Others decide to merely observe the surgical bed in imaging examinations (fig. 8). The early detection of relapse in positron emission tomography – computed tomography (PET/TK) is feasible only after 6 weeks from the surgery when inflammatory reaction subsides and when tissues are healed(. In US examinations, the lesions are diagnosed with delay – when they in filtrate the liver, when foca l met a st a ses in it s pa renchy ma develop or when enlarged lymph nodes appear in the porta hepatis.

Fig. 3

One year following laparoscopic cholecystectomy. In the gallbladder bed, in two views, a metal surgical clip can be seen (arrows)

Fig. 4

Eight months following laparoscopic cholecystectomy. In the gallbladder bulb, in two views, a hyperechoic band can be seen (arrows)

Fig. 5

After laparoscopic cholecystectomy. In two views, fluid in the duodenal bulb occupies the site of the removed gallbladder mimicking a pathological collection (arrow)

Fig. 6

Duodenal bulb changing its content over time (arrows) in the gallbladder bed

Fig. 7

Four-centimeter-long fragment of the gallbladder retained after laparoscopic cholecystectomy

Fig. 8

Gallbladder bed is occupied by hyperechoic tissue, 12 mm thick (arrows). Histological examination of the gallbladder specimen after its removal revealed the features of cellular atypia

Complications of LCH

Complications after laparoscopic cholecystectomy do not occur less frequently than after conventional laparotomy(. They may be generally divided into:

gallbladder and bile ducts injuries;

vascular injuries;

injuries to the liver and other organs;

injuries to the abdominal wall.

Gallbladder and bile ducts injuries after LCH

Gallbladder wall tears during its separation from the liver is a frequent complication (20% of LCH), particularly when there are inflammatory infiltration of the wall and adhesions in this region. In 8% of cases, it is accompanied by spillage of stones to the peritoneal cavity(, which carries the risk of abscess formation. The risk of abscess development is estimated at 2.3% when the stones have been retrieved but it rises to 7% when the concretions are retained( (fig. 9). The dropped stones should be sought for in the gallbladder bed, under the right liver lobe or in the Morison's pouch (figs. 10–12). Sometimes, they may be detected in the region of the navel. One should remember, however, that such concretions may be found in each region of the peritoneal cavity or in multiple locations. The method of choice in their identification is computed tomography(. The difficulties associated with removing the gallbladder may also result in leaving the cystic duct or even the proximal part of the gallbladder which may contain stones (fig. 13). Even if there are no stones in the retained fragment of the gallbladder, such a situation will favor their formation and persisting inflammation. The most effective method for finding retained fragments of the gallbladder is MRCP(.

Fig. 9

Three months after laparoscopic cholecystectomy. In two views, an abscess with slight biliary concretions (arrows) can be seen under the liver

Fig. 10

Several biliary concretions (arrows) can be seen in the gallbladder bed

Fig. 12

Five years after laparoscopic cholecystectomy. A single biliary concretion (arrow) is seen in the hepatorenal recess. L – liver

Fig. 13

Gallbladder stump syndrome. Slight biliary concretions (arrows) are seen in the fragment of the gallbladder retained after laparoscopic cholecystectomy

Seven days after laparoscopic cholecystectomy. Under the liver (L), there are several biliary concretions submerged in fluid content (arrows)

Bile duct injuries constitute relatively frequent complications of laparoscopic procedures. Their frequency is estimated at 0.6 – 4%(. On the one hand, they may result from: cutting, severing, burning or locking with a clip the common bile duct or accessor y hepatic bile duct, usually the right one( (fig. 14). On the other, they may be caused by inadequate closing of the cystic duct or sliding surgical clip( (fig. 15), which, however, rarely results in the formation of stones in the bile ducts(. The presence of stones in the bile ducts identified after LCH may result from the failure to detect them prior to the procedure or from their movement to the common bile duct when the gallbladder was being separated from the liver. Their formation in the intrahepatic bile ducts after t he surger y is a ra re phenomenon. Therefore, cer tain operators recommend the performance of intraoperative cholangiography in order to explain the anatomic situation prior to removing the gallbladder and to avoid undesirable effects of LCH. Others, however, are against routine application of this method( or propose laparoscopic ultrasound examination instead(. The collection of bile ( biloma), which may develop af ter LCH, can be identified by means of various methods. In such cases ultrasound exa mination revea ls fluid collection which enlarges when the bile leak is active (fig. 16). The gold standard is endoscopic retrograde cholangiopancreatography since it allows for specifying the site of bile leak and enables biliar y stenting in the treatment of this complication(. Moreover, the site of bile leak and the character of the content may also be identified by: hepatobiliar y scintigraphy, percutaneous transhepatic cholangiography and MRCP. CT cholangiography is less usef ul(. The incidence of biloma after LCH is estimated at 0.2–2%(. It is usually a consequence of an ineffective closure of the cystic duct, liver damage or failure to identify the accessory bile duct, so-called, duct of Luschka or subvesical bile duct(. In anatomic examinations, this duct was detected in 3% of persons and in imaging examinations – in 4% of persons. It is difficult to detect because its width is slight (average 2 mm). It is localized mainly in the right liver lobe, travels adjacent and parallel to the gallbladder fossa and thus, it is susceptible to damage during the removal of the gallbladder. It may be visualized with the use of intravenous cholangiography, endoscopic retrograde cholangiopancreatography or MRCP. Occasionally, it can be visualized in ultrasound examination, usually in patients with biliary hypertension (fig. 17). The injury to the duct of Luschka leads to bile leak in the first week following LCH.

Fig. 14

Bile duct injury. The common bile duct was damaged during laparoscopic cholecystectomy. After two repair procedures, the scar tissue proliferated in the hepatoduodenal ligament (arrows)

Fig. 15

Two days following laparoscopic cholecystectomy. On the bottom of the biliary collection (B) under the liver, surgical metal clip can be seen which slipped from the cystic duct

Fig. 16

Extensive biloma (B) after laparoscopic cholecystectomy which partially compresses the liver

Fig. 17

The duct of Luschka with the width of 2 mm (arrows) travelling parallel to the gallbladder fossa. GB – gallbladder, CHD – common hepatic duct. Patient with cholestasis resulting from carcinoma of the pancreatic head

Vascular injuries after LCH

They are a consequence of mechanical or thermal activity during LCH. This type of injury concerns 4.1% of LCH with 2.3% identified intraoperatively and 1.8% – postoperatively(. Hemorrhage usually occurs due to untight closure of the cysticartery or a cut to the right hepatic artery. In such cases, symptoms related to blood loss and low CBC parameters constitute an indication for an emergency intervention. CT angiography and celiacography or mesentericography prove useful in determining the site of damage. What is more, the two last methods additionally facilitate endovascular bleeding treatment(. Sonography makes it possible to confirm the presence of a fluid collection with echogenicity and size that change over time(. However, US examination is not capable of differentiating it from a collection of bile or an abscess. Sonography may be useful in differentiation of other vascular complications of LCH, such as a pseudoaneurysm or portal vein thrombosis. It allows for predicting the risk of bleeding from the gallbladder bed in cases when the gallbladder fossa is drained by a wide vein, usually the intermediate hepatic vein( (fig. 18). Severe complications encompass damage to the large vessels, such as superior mesenteric vein, vena cava or aorta(. Furthermore, closure of the arteries that supply the liver or occlusion of the portal vein may lead to liver necrosis of various degrees, which sometimes requires resection procedures or, occasionally, even liver transplantation(. It is worth adding that injury of the hepatic vessels frequently coexists with bile duct damage (vasculobiliary injury), which worsens the prognosis in a considerable way. In the material of Strasberg and Helton(, such a complication developed in 18% of patients after LCH.

Fig. 18

Wide intermediate hepatic vein drains the gallbladder fossa. GB – gallbladder

Injuries to other organs during LCH

This is a rare complication. Single reports present cases of early and delayed damage to the spleen, intestine and diaphragm as a result of a careless procedure(.

Disrupting the anatomic integrity of the abdominal wall

This type of complication constitutes a part of LCH procedure and carries the risk of port-site hernias. It occurs after 0.02–3.6% of procedures and sometimes may entail small intestinal obstruction(. The authors’ experience indicates that in such cases, US examination is as useful in the diagnostic process as computed tomography (fig. 19). Another rare complication related to trocar insertion is a hematoma in the abdominal wall. It develops mainly due to damage to the branches of the epigastric artery or to the artery itself( (fig. 20). US examination is useful in specifying the port sites prior to the procedure in order to enable non-collisional insertion of laparoscopic instruments to the peritoneal cavity, which prevents damage to the vessels in the abdominal wall, and in order to help avoid visceroperitoneal adhesions(.

Fig. 19

Abdominal wall hernia after laparoscopic cholecystectomy. A loop of the small intestine with gas (arrows) in the hernia sac

Fig. 20

Hematoma in the abdominal integuments (H) secondary to laparoscopic cholecystectomy

Conclusion

US examination following LCH is primarily indicated for the diagnosis of: pathological fluid collections in the gallbladder bed and around the liver, cholestasis, pseudoaneurysm, portal vein thrombosis as well as hematoma and hernia in the abdominal wall. Moreover, this method is useful in searching for dropped stones in the right hypochondriacregion and for retained gallbladder with possible stones as well as for undiagnosed choledocholithiasis. Furthermore, ultrasound enables the performance of guided punctures for diagnostic and therapeutic purposes. Sonography also allows for the specification of optimal post sites for laparoscopic instruments. It should be concluded, however, that all undesirable effects associated with LCH, apart from lesions in the abdominal wall, are best diagnosed by endoscopic ultrasound examination, just as in the diagnostics of micro-choledocholithiasis(.