Gallbladder mucoceles are diagnosed with increasing frequency, most likely because of better clinical awareness and easier access to ultrasound. A mucocele is a surgical disease, and sometimes a surgical emergency.
Let’s go over some recent discoveries that will improve your care of patients with mucoceles.
Phil Mayhew,* a board-certified surgeon at the University of California, Davis, studied 10 dogs with extrahepatic biliary tract obstruction. Coagulation profiles revealed that all 10 patients were hypercoagulable due to high levels of plasma d-dimers and fibrinogen levels.
Conclusion: Not all dogs with biliary obstruction need a routine injection of vitamin K. A coagulation profile should be performed before pre-treating blindly or out of habit.
Mary Lauren Mesich,** a board-certified surgeon in Minnesota, investigated the association between endocrinopathies and mucocele risk in dogs. Dogs diagnosed with hyperadrenocorticism are about 30 times more likely to develop a gallbladder mucocele than dogs without the disease.
Conclusion: Dogs with a gallbladder mucocele should be tested for concurrent hyperadrenocorticism. Diabetes mellitus and hypothyroidism did not increase the risk of mucocele.
Eric Lindquist,*** a board-certified veterinary practitioner in New Jersey, owner of www.SonoPath.com and Pennsylvania Mobile Ultrasound, launched an interesting project. He interviewed eight ultrasonographers and asked how they approach gallbladder mucoceles.
1) When is a mucocele a mucocele?
This was the first question he asked.
The consensus: An “early” or “developing” mucocele may still have most of the bile in liquid form. Only the center is starting to form a star or wagon-wheel pattern.
A “mature” mucocele has a dilated cystic duct, immobile debris and hypo- or even anechoic material around the rim. The walls are thickened and the texture can be described as coarse or heterogeneous.
Courtesy of Phil Zeltzman
Classic appearance of thick bile contained in a mucocele.
2) When to cut?
In his second question, Dr. Lindquist asked his panelists when they think the disease becomes significant enough to justify surgery.
The answers revolve around two findings: severity of blood work abnormalities (total bilirubin, alanine transferase, alkaline phosphatase and white blood cell count) as well as clinical signs.
Clinical signs typically include vomiting, anorexia, lethargy and icterus. Clinical signs associated with surgical biliary disease were further examined in an abstract**** presented at ECVIM in 2009. It showed that icterus was present in only about 25 percent of the patients who required surgery for obstructive biliary disease that included mucoceles.
Other key points in deciding whether to operate include pain in the cranial abdomen on palpation or during ultrasound, inflammation of the fat and tissues around the gallbladder; and distension of the bile duct or the gallbladder.
The situation may quickly progress to emergency surgery if there are areas of effusion around the gallbladder. These findings indicate rupture of the wall, which can very quickly progress to chemical and/or septic peritonitis.
3) A pathology continuum
The third question asked was to understand how each ultrasonographer classified the differences between an emerging mucocele, a mucocele and an inflamed mucocele with bile peritonitis.
An “emerging mucocele” is one of the first stages of the gallbladder pathology continuum. Characteristics include a sludgy appearance with some bile consolidation in the center. The overall shape of the gallbladder may not be affected at this point and there may still be normal bile around the immobile debris in the center.
The transition from an “emerging” to a full-blown mucocele is qualified by the central debris becoming stationary sediment. No free flowing bile is visible. There is dilation of both the gallbladder and its duct. The walls become thickened.
Importantly, the classic “kiwi” appearance is not required to define a mucocele. It is critical to remember that there may not be significant elevations in total bilirubin at this point.
An “inflamed mucocele with bile peritonitis” goes along with abdominal pain. Inflammation in the surrounding tissues causes a hyperechoic appearance to the mesentery, localized effusion, and possibly sludge outside of the gallbladder wall. When a mucocele has been leaking for a while, the gallbladder can appear collapsed, like a flat tire.
4) Treatment options
The final question was an opinion on treatment options. When is it appropriate to sit and watch, provide medical management or take the patient to surgery?
The answers were unanimous that “sit and watch” is never a good idea when a mucocele is suspected. Please remember that none of the panelists is a surgeon.
Medical therapy can be successful if the diagnosis is made before clinical signs and blood work abnormalities are seen. Treatment with antibiotics, ursodiol and liver supplements may reduce the chances of requiring surgery. However, the phrase “Once a bad gland, always a bad gland” should be a cautionary tale to share with owners who elect medical management.
As far as deciding when surgery is necessary, the answers were also very similar.
Clinical signs, abnormal blood work, pain and failure of medical therapy are all indications that gallbladder removal is required. Ultrasound findings include gallbladder and duct distension as well as immobile debris.
Breeds such as Shelties and cocker spaniels have a predisposition to mucoceles and should either be monitored very closely or taken immediately to surgery. Patients whose clinical signs wax and wane, or of course those who have gallbladder rupture, also benefit from aggressive and urgent surgical intervention.
Sitting on a mucocele can be a risky proposition. Rupture cannot be predicted and early surgical intervention is often the best course of action.