What is gallbladder mucocele?
A gallbladder mucocele is a condition where the gallbladder is stretched due to the accumulation of mucus or clear watery fluid in the hollow organ. It is also known as hydrops. This condition should not be confused with a gallbladder empyema where the gallbladder is filled with pus. In a mucocele, the gallbladder is larger in size than normal due to the overdistension caused by the fluid within. When left untreated, the gallbladder can become infected, press on the stomach thereby partly blocking it and gallbladder rupture is also possible. Although a mucocele is not common, it must be suspected and monitored for in the event of gallstones. Most cases of gallbladder mucocele arise as a complication of gallstones disease, and gallstones itself are a fairly common condition.
Gallbladder Mucocele Reasons
Gallbladder Anatomy and Function
The gallbladder is a hollow sac that stores bile containing wastes and fats among other substances that need to be evacuated from the body. Normally this bile is secreted when a person eats food and digestion is occurring in the duodenum, the first part of the small intestine. Since bile has an emulsifying property, it is useful for breaking down the oils and fats in a fatty meal. By doing so, other digestive enzymes can act on the fats to break it down further and allow for the body to absorb it from the gut.
Bile is produced throughout the day. The gallbladder can store as much as 1.5 liters (about 50 fluid ounces) of bile by drawing water out of the bile in the gallbladder. This concentrates the bile but also helps to reduce the space occupied in the gallbladder. The water can be added at a later stage just before the bile empties out into the duodenum. The gallbladder has a fairly thick wall which can stretch to a very large degree thereby allowing for a large quantity of bile to be stored if necessary.
Blockage in the Gallbladder
Bile empties out of the gallbladder through the narrow duct that joins the common bile duct which leads to the duodenum. When the neck of the gallbladder and its duct (cystic duct) is blocked, bile cannot flow out. Over a prolonged period of time, the bile and its salts are gradually resorbed through the gallbladder wall. Mucus and water are secreted from the wall and accumulates within the gallbladder. This is a mucocele. Usually the fluid within the gallbladder is sterile meaning that there are no microbes like bacteria and there is also no pus. Over time the gallbladder expands and distends often close to its maximum capacity, and sometimes even beyond where it may then rupture.
Effect on Gallbladder
The overdistension of the gallbladder has a host of effects on the organ. In long term cases, the walls of the bladder become thinner and even slightly transparent. The enlarged gallbladder may press against the duodenum and hamper stomach emptying. This causes gastric outlet obstruction. Blood supply to the gallbladder is affected and an infection can set in eventually leading to gangrene of the organ. The thinner and overdistended gallbladder is weak and can rupture with serious implications. The gallbladder contents that empty into the abdominal cavity may lead to peritonititis.
Gallbladder Mucocele Causes
There are a wide range of causes of a mucocele. Most of these block the gallbladder outlet although some may arise when a person is not eating which does not stimulate the release of bile. There are other unique causes seen almost only in children and babies.
- Tumors, including polyps and cancer.
- Narrow cystic duct from birth (congenital).
- Parasites in the gallbladder or bile ducts.
- External compressions of the gallbladder neck or cystic duct by swollen lymph nodes, or tumors and enlarged organs around the gallbladder.
- Prolonged total parenteral nutrition (TPN).
- Long term use of ceftriaxone (antibiotics).
Babies and Children
- Familial Mediterranean fever
- Fibrocystic disease
- Kawasaki syndrome
- Mesenteric adenitis
- Nephrotic syndrome
- Streptococcal pharyngitis
These other conditions are less likely to cause a gallbladder mucocele but it is still a possible factor that needs to be considered.
- Enlarged liver (hepatomegaly)
- Bile duct cysts (choledochal cyst)
- Kidney mass
- Adrenal gland mass, mainly the right side.
- Mass on the ascending colon
- Parasitic cysts
- Pancreatic pseudocyst
Gallbladder Mucocele Symptoms
The symptoms of a mucocele are non-specific and many other types of gallbladder disease and conditions of related organs may present in a similar way.
- Abdominal discomfort or pain on the upper right side (RUQ) or upper middle region (epigastric).
- Nausea and vomiting.
- Palpable abdominal mass with some tenderness
- Symptoms may worsen with eating, particularly fatty meals.
Symptoms of complications
- Fever and chills – infected gallbladder and empyema
- Pain persisting for more than 6 hours – acute cholecystitis
- Jaundice – bile duct obstruction
Gallbladder Mucocele Diagnosis
The symptoms alone may not be indicative of a gallbladder mucocele. The presence of a large palpable mass extending sometimes as low as the pelvis along with a history of gallbladder disease and absence of fever and chills may raise the suspicion of a mucocele. However, further testing is usually needed to visualize the gallbladder. This includes :
- Abdominal x-ray
- Ultrasound of the abdomen
- CT scan
- HIDA scan
- Magnetic resonance cholangiopancreatography (MRCP)
- Diagnostic findings during surgery, such as clear fluid in the gallbladder and a blocked duct, confirms the diagnosis.
Gallbladder Mucocele Treatment
There is no medical treatment for a gallbladder mucocele. Medication is of little use although any underlying causes need to be treated and managed appropriately. Gallbladder obstruction, with or without a mucocele or empyema, requires surgical removal. This procedure is known as a cholecystectomy.
There are two methods by which a gallbladder can be removed.
- Open surgery where a large incision is made in the right upper portion of the abdomen and the gallbladder is then removed.
- Laparoscopic surgery where a tiny hole (keyhole) is made in the abdominal wall and a flexible tube known as a laparoscope is inserted. Minute surgical instruments are also inserted through other portals and used to locate the gallbladder and remove it.
Although laparoscopic surgery is the procedure of choice as it is minimally invasive and has fewer complications, it may not always be ideal for a very enlarged gallbladder. The choice of procedure is dependent on the individual case. Removing the gallbladder usually provides total resolution of symptoms and has an excellent outcome. However, this is dependent on whether complications had already arisen or not prior to surgery.