Definition of Biliary Sludge
Biliary sludge is mixture of microscopic particles that have precipitate from bile. Biliary sludge was first observed when ultrasonography (ultra sound) was invented in the 1970s. Its composition varies, but cholesterol monohydrate crystals, calcium bilirubinate, and other calcium salts are the most common components.
Biliary sludge is like microscopic gallstones, although it is not define at what size a sludge particle becomes a gallstone. A gallstone is defined as a particle with a diameter larger than 2mm that cannot be crushed between the fingers. Smaller particles (less then 2mm) are defined as components of sludge. What actually defines biliary sludge is whether there are any symptoms because the treatment is the same as for gallstones.
The name is not universally accepted; other terms include microlithiasis, microcrystalline disease, pseudolithiasis, and biliary sand.
Formation of Biliary Sludge
The formation of biliary sludge is a dynamic process and is reversible. Composed of cholesterol crystals, calcium bilirubinate granules, and mucin glycoprotein suspended in bile. It also contains a large proportion of undefined residue and protein-lipid complexes. Calcium bilirubinate granules are almost invariably present, and bilirubin is usually found in its unconjugated, least soluble form. (Bilirubin is excreted by the liver mainly in its diglucuronide form). Also the enzyme B-glucuronidase (probably originated in the biliary epithelium), which deconjugate bilirubin, is increased in chronic low-grade biliary infection.
The theory is put forward that gallstones can not form from clear bile without the intermediate microprecipitates. Thus it is generally thought that sludge is a necessary precursor to gallstones.
Sludge formation not only depends upon the chemical composition of bile but also depends on the physical-chemical interactions of the liver caused by lifestyle factors, abnormalities of gallbladder mucosal function, and poor performance of the gallbladder. It has been postulated that a change in bile composition or obstruction, or both, stimulates gallbladder epithelial cells to secrete excess mucus and promotes stasis, with subsequent precipitation of cholesterol crystals and calcium bilirubinate in the gallbladder lumen.
Who is a risk from Biliary Sludge?
Studies and research have shown that a number of specific categories of people are at risk. However, biliary sludge has been associated with certain other factors including rapid weight loss and fasting although it most commonly occurs in individuals with no identifiable reason. The following people are specifically at risk from forming biliary sludge:
- Pregnant women
- People with prolonged fasting after gastrointestinal tract surgery or acute trauma
- People who are fed through a tube into a vein, called total parenteral nutrition (TPN)
- People who have undergone a of a bone marrow, liver or other solid organ transplant
- Patients with infection who receive ceftriaxone sodium.
- Patients treated with the drug octreotide to help control diarrhea and other symptoms of abdominal illness
In all these people studies have shown that there is a change in bile composition coupled with gallbladder stasis but once the people get well, the sludge usually disappear and only a small minority of persons with sludge go on to form gallstones.
Outcome of Biliary Sludge
The most common symptom of biliary sludge, when it causes symptoms, is pain in the abdomen sometimes associated with nausea and vomiting. This occurs when the particles obstruct the ducts leading from the gallbladder to the intestine (duodenum).
Simplistically there are three clinical outcomes of sludge:
- Complete resolution – the sludge just disappears such as after pregnancy.
- The sludge disappears and returns cyclically. It has been found in studies that half the people who suffer with abdominal pain found it disappeared over 3-year period
- Gallstone formation - A small proportion, about 1 in 10 of people with sludge develop biliary colic, and a smaller percentage develops other complications, such as pancreatitis, acalculous, colecystitis and cholangitis.
It has also been noted that 31% of people with nonalcoholic pancreatitis have sludge but this does not mean that people with biliary sludge automatically are at risk with pancreatitis.
Biliary sludge can be detected with ultrasound of the abdomen or by directly examining bile contents under a microscope (bile microscopy).
The term biliary sludge refers to a characteristic ultrasound picture of movable, low-amplitude echoes that layer in the most dependent part of the gallbladder. Other material in the gallbladder, including blood, necrotic debris, multiple small gallstones, or pus, can also have a similar appearance of sludge. Sludge is detectable in 55% of cases by normal abdominal ultrasound. A special type of ultrasound that is inserted through the mouth into the stomach and duodenum called an endoscopic ultrasonography can detect 96% of cases.
Direct microscopic examination of the contents of the gallbladder allows the chemical composition of sludge to be defined. Bile microscopy is considered the gold standard for diagnosis of sludge and can detect sludge in 88 to 100% of cases with little uncertainty. A sample of bile sediment is examined under light or polarizing microscope. Cholesterol monohydrate crystals appear as rhomboid plates and calcium bilirubinate granules appear as brownish or reddish-brown clumps. More than two crystals per 100x field or more than four crystals per sample indicate that biliary sludge is present. The density of particles is no indication of the type or severity of a condition.
Oral bile acid dissolution by ursodeoxycholic acid - can dissolve biliary sludge in 3 months, although the number and size of their gallstones don’t change. The recurrence rate of sludge is not known, but in gallstones cases they recur in up to 50% of people.
Shock-wave lithotripsy - People who are receiving shock-wave lithotripsy for gallstones can develop biliary sludge which may have been induced by the treatment.
Surgery - Surgeons will undoubtedly recommend having the gallbladder removed (cholecystectomy) as the definitive therapy if people develop symptoms or complications.
Liver flushing – Biliary cleansing using liver flush protocol together with lifestyle changes is the alternative choice to medical intervention.
There are no proven medical methods for the prevention of sludge formation and people with a high risk of developing biliary sludge are only be monitored by their doctors. Specific measures to prevent sludge are not practical or cost-effective in the general population.
However, sludge is often found incidentally on ultrasound examinations, but if people don’t have any symptoms it is recommended that they are monitored. If people have moderate to severe symptoms it should be monitored more closely initially, but it must be remembered that about one in three people will not have another episode and the sludge will disappear and not return. It may be necessary to monitor the condition for one to two, even three years, as the number of episodes may be few and far between and in time within a three year period may disappear. If the condition is severe, frequent and persisted attempts should be made to eliminate it.
Ursodeoxycholic Acid - decreases cholesterol secretion into bile and prolongs crystal nucleation time. In people who loose weight rapidly it decreased the incidence of gallstones by 50-100%. In people with idiopathic pancreatitis and sludge, ongoing maintenance therapy with ursodeoxycholic acid prevented recurrence of sludge and pancreatitis.
- Cholecystokinin was used to prevent the development of sludge in people whom have gallbladder stasis is an underlying cause of sludge. In one study, no individual receiving daily intravenous infusion of cholecystokinin developed sludge but 62% of a placebo group did.
- Adopting a healthy lifestyle rich in foods that stimulate biliary activity Exercise to lift the metabolism, avoiding stress and medication can help return the biliary function to its equilibrium. Liver flushing can help expel stale bile, sludge, cell debris, infection and stones from the biliary system and reverse stasis.
Biliary sludge is a latent cause of trouble and if left unattended can lead to more serious problems
Four separate studies or different duration 5 to 38 months showed that biliary sludge with symptoms disappeared in about 70% of cases.
The largest study monitored 96 people with biliary sludge and the following observations made:
- The sludge disappeared in 18%.
- Disappeared only to reappear in 60%.
- Evolved into gallstones in 8%.
- Proportion who had their gallbladder removed 13%.
The people that had their gallbladder removed one half had gallstones and one half had only sludge.