Unusual cause of gas complicating a biloma, postcholecystectomy

Abstract

A 50-year-old man presented to the emergency department with abdominal pain, vomiting and fever. He had been admitted 6 months ago with acute cholecystitis when he underwent endoscopic retrograde cholangiopancreatography (ERCP) to remove ductal gallstones. Elective cholecystectomy was performed 3 days prior to the current admission. CT demonstrated a fluid and gas containing collection in the gallbladder fossa, biliary gas and free intra-abdominal gas. ERCP revealed a retained common bile duct gallstone and leakage from the cystic duct remnant. We postulate that the gas within the collection originated from intrahepatic gas post-ERCP or from a gas forming organism. The free intra-abdominal gas originated from the collection rather than an intraoperative bowel injury. This complicated case highlights an unusual appearance of a common complication. It demonstrates the importance of discussion with the clinical team to ensure that an accurate diagnosis is made and the correct treatment is provided.

Background

A cholecystectomy is a surgical procedure to remove the gallbladder which is commonly performed laparoscopically. During this procedure, the surgeon will assess the bile ducts to identify retained stones, although stones in the proximal common bile duct (CBD) are not easily identified. A retained stone will prevent drainage of bile from the liver into the duodenum, thereby increasing pressure within the bile ducts. This pressure backlog can cause bile to leak from the surgically clipped cystic duct into the gallbladder fossa causing a ‘biloma’.

The presence of an accessory cystic duct can also cause a biloma. This additional cystic duct may not be identified at surgery and therefore can remain unclipped and become a source of bile leakage.

Endoscopic retrograde cholangiopancreatography (ERCP) involves placing an endoscope into the duodenum and performing a sphincterotomy to pass a special catheter into the biliary tree. Contrast is passed through the catheter and images of the biliary tree (occlusion cholangiogram) are acquired using X-rays. An ERCP identifies abnormalities of the biliary tree including the presence of stones. Sphincterotomy leaves a permanent defect at the ampulla of Vater allowing gas to pass from the small bowel into the biliary tree.

We report a case where the sequelae of ERCP (biliary gas) and cholecystectomy (biloma) were seen at the same time, giving rise to an unusual CT appearance of a common complication postcholecystectomy. The recognition of these imaging appearances as a complication of cholecystectomy was important in avoiding a misdiagnosis and unnecessary treatment or surgery.

Case presentation

A 50-year-old man was admitted to the emergency department (ED) with sudden-onset right-sided abdominal pain, vomiting and swinging high-grade fever. He had a medical history of gallstones, hiatus hernia, irritable bowel syndrome and fibromyalgia.

He had previously been admitted to hospital 6 months ago with acute cholecystitis. During the admission, he underwent ERCP and had a gallstone removed from the CBD. Over the course of the following 5 months, he represented twice to the ED with abdominal pain requiring opiate analgesia.

Three days prior his current admission, he had undergone a laparoscopic cholecystectomy and reduction of an umbilical hernia.

Investigations

On admission, blood tests revealed a C reactive protein of 197 mg/L indicating the presence of an underlying inflammatory process. Alkaline phosphatase (ALP) (427 IU/L) and bilirubin (85 μmol/L) were both elevated suggesting cholestasis.

A CT scan performed on the same day showed a fluid and gas containing collection in the gallbladder fossa, free intrabiliary gas and a few locules of free intra-abdominal gas in the upper abdomen (see figures 1–3).

Figure 1.

High density surgical clips adjacent to the gallbladder fossa indicates that the patient has had a cholecystectomy (arrows). A 5×4×4 cm mixed gas and fluid-filled collection is centred on the gallbladder fossa with marked surrounding mesenteric inflammatory fat stranding (arrowheads).

Figure 2.

The biloma conforms to the shape of the recently removed gallbladder (arrowheads) and could easily be mistaken for gallbladder or also a loop of bowel containing faeculent material.

Figure 3.

A few tiny locules of free gas in the intrahepatic bile ducts of the left lobe of the liver, as a result of ERCP with sphincterotomy (arrows). There are additional locules of free intra-abdominal gas overlying the liver anterolaterally (arrowheads). ERCP, endoscopic retrograde cholangiopancreatography.

An ERCP performed 8 days later revealed two stones in the CBD (see figure 4). An occlusion cholangiogram performed at the same time demonstrated a small leak from the cystic duct remnant (see figures 5 and 6).

Figure 4.

Repeat ERCP and occlusion cholangiogram demonstrates two rounded filling defects within the CBD, which were two retained gallstones (arrows). CBD, common bile duct; ERCP, endoscopic retrograde cholangiopancreatography.

Figure 5.

Occlusion cholangiogram showing a small leak of contrast from the cystic duct remnant (arrows).

Figure 6.

Occlusion cholangiogram again showing a small leak of contrast from the cystic duct remnant (arrow).

A gallbladder fossa drain was inserted under CT guidance and pus aspirated. This pus sample grew Escherichia coli and Clostridium perfringens.

Differential diagnosis

Given the recent cholecystectomy, the gallbladder fossa fluid collection most likely represented a biloma. This was confirmed at subsequent ERCP which demonstrated bile leakage from the cystic duct remnant. However, the presence of gas within the gallbladder fossa collection was unusual.

The patient had previously had a sphincterotomy from a prior ERCP procedure which had resulted in a direct connection between the duodenum and biliary tree. This was confirmed by the presence of intrahepatic biliary gas on the CT scan. The fluid from the gallbladder fossa grew C. perfringens (a recognised gas forming organism). Therefore, the gas in the gallbladder collection may have originated from the duodenum (due to sphincterotomy) or alternatively formed by a gas forming organism within the gallbladder collection.

We discussed the case with the general surgical team. The patient was clinically well throughout the admission and did not have the expected clinical presentation of severe sepsis from a gas forming organism. This indicates that the gas within the gallbladder collection may have, at least in part, arisen from biliary gas due to sphincterotomy.

The CT also revealed a small volume of free intra-abdominal gas and we considered the possibility of bowel injury following recent cholecystectomy. Discussion with the clinical team and review of the clinical notes indicated an uncomplicated cholecystectomy procedure with no record of bowel injury. We, therefore, postulate that the free intra-abdominal gas originated from the gas within the gallbladder collection.

Treatment

The patient underwent radiological drainage of the collection (8 French gauge pigtail catheter) and was treated with intravenous metronidazole and gentamicin for 11 days, followed by oral ciprofloxacin and metronidazole for 7 days.

Outcome and follow-up

The patient was discharged 11 days postreadmission with oral antibiotics and had a planned follow-up appointment 1 month later at which point he was recovering well.

Discussion

A cholecystectomy is a day case surgical procedure that is commonly performed laparoscopically. Following removal of the gallbladder, the surgeon will perform an intraoperative occlusion cholangiogram to ensure no residual stones remain within the biliary system.

Complications postcholecystectomy are rare (1.7% in the first 30 days).¹ Bile leakage is the second most common complication of cholecystectomy after cystic artery injury.² It may occur due to intraoperative injury to the gallbladder or bile ducts, due to the presence of an accessory cystic duct that was not seen on imaging or at surgery, or due to leakage from the cystic duct remnant.^{3 4}

Patients with a bile leak usually present with bile in the drain 1 day after surgery, although if drains are removed early, patients can present 2–3 days postoperatively with biliary peritonitis.⁵ CT scan typically shows a fluid density collection within the gallbladder fossa but does not identify the source of the leak. Therefore, patients will undergo ERCP or percutaneous transhepatic cholangiogram to identify the source of the bile leak.⁶

In our case, the cause of the biliary leak was due to a retained gallstone within the CBD which had not been identified at surgery. This gallstone restricted the normal flow of bile into the duodenum which caused backing up of bile within the biliary tree and increased intrabiliary pressure. This increased biliary pressure caused bile to leak from the clipped remnant cystic duct.

The presence of free intra-abdominal gas on CT was an unexpected finding. During a laparoscopic procedure, carbon dioxide is used to inflate the abdomen and allow space for the surgeon to perform the required procedure. Carbon dioxide is typically absorbed by the body within 48 hours so the finding of free gas 3 days postlaparoscopic cholecystectomy was unexpected.⁷

We considered the possibility of bowel injury that may have occurred during the surgical procedure. This is a rare complication postlaparoscopic surgery and occurs in approximately 1% of cases.⁸ If perforation has occurred, it is commonly identified intraoperatively by the surgeon although occasionally it may present a few days following the procedure.⁹ In our case, the surgical team felt bowel injury was unlikely given that surgery was uneventful. Discussing the case with the general surgeons was key to explaining the findings on CT and ensuring that the patient received the correct treatment.

Patient’s perspective.

I’d been having these issues for at least 2 years. Eventually though I was sent to Bournemouth and had a different ultrasound camera that goes inside (endoscopic). This one found stones where the other test hadn’t been able to. I had the ERCP really quickly within a couple of weeks. I had issues after that with inflammation in my liver and my gallbladder and it affected my colon, I was really ill. They said they’d send me home until everything recovered and advised me to lose weight, which happened to coincide with the COVID-19 lockdown. They rang me in 8 weeks' time and gave me a video call and I said to the doctor that I didn’t really want an operation as I’d had no problems at all and had had issues with healthcare in the past. He said it’s a long wait so he’d put me on the list and I could take my time and always change my mind. Then 4 days later, I had a really painful flare up. Then I was getting one every few weeks, then every day, and they were getting more severe. My liver tests started getting worse and I became jaundiced. So at that point I didn’t really have a choice and had to proceed with the operation. My doctor was really good and managed to get me an operation within a month. My friend who works in theatres told me that it’s not common to have stones left behind after the operation. He said they normally do a scan at the end of the procedure, but the surgeon said she didn’t do it because I’d had an ERCP and they put stents in and cut something so I shouldn’t have trapped stones anymore. She was fairly confident that my issues were all gallbladder related as it was so inflamed when they took it out. She said that because of all the liver issues that I’d had, and they have to put a tracer in to look for the stones, she didn’t want to put me through the added risk. She said that even if she had done that during the surgery, they couldn’t remove the stones then, they would have had to do a separate ERCP. She did say that things might have been quicker, but I would still have had to have gone through what I went through. It was reassuring to have that conversation with the surgeon but frustrating that I couldn’t get hold of her as she had gone on holiday for 4 weeks! My biggest problem in the hospital has been with trying to get pain relief on time, because the processes are wrong. Most of the problems I have experienced have been because of a breakdown in communication.

Learning points.

• Biloma is one of the most common complications postcholecystectomy but its appearance on imaging can be variable.

• Patients with gallstone disease can often undergo multiple procedures which can complicate the appearances of imaging and may cause confusion.

• In order to avoid misdiagnosis, it is important that radiologists are aware of any previous interventional or surgical procedures and interpretation of these studies often requires close liaison with the clinical team.