Gallbladder Polyps

The gallbladder

The gallbladder is a pear-shaped organ underneath your liver and behind the lower ribs in the right upper abdomen. It stores bile, concentrates it and releases it when we eat. Bile is a digestive juice produced by the liver. The gallbladder is connected to the liver and intestine through a thin tube called the common bile duct (CBD). The CBD carries bile from the liver and gallbladder to the intestine.

The polyp

Polyps are an abnormal growth of cells and tissues. They look like small, flat bumps or tiny mushroom-like stalks on the inner lining of the gallbladder wall, projecting into the gallbladder lumen.

Gallbladder polyps are relatively common. They are reportedly present in 5% of the population. 3%–7% of the abdominal ultrasound will detect a gallbladder polyp.

Most of the gallbladder polyps are benign (non-cancerous). Some larger polyps could be malignant (cancerous) or have the potential to become malignant.

Causes and risk factors for the formation of gallbladder polyp

The risk factors for gallbladder polyp include:

• High cholesterol or salts in bile
• Gallstones
• Familial polyposis
• Gardner syndrome
• Peutz-Jeghers syndrome
• Hepatitis B

Classification (types) of gallbladder polyps

Gallbladder polyps are classified into pseudopolyps and true polyps.

Pseudopolyps

The majority (95%) of polyps in the gallbladder are pseudopolyps. They do not have any risk of cancer and generally do not require treatment.

The types of pseudopolyps include:

• Cholesterol polyps: These are the most common polyps of the gallbladder, accounting for 60%–70% of all polyps. These polyps are the deposition of fat and cholesterol in the cells of the inner lining of the gallbladder. They are typically multiple.
• Adenomyomatosis: These make up the next largest group (25% of all polyps). There is a growth of the inner lining that invaginates into the crevices of a thickened muscularis forming so-called Rokitansky-Aschoff sinuses. Cholesterol crystals precipitate in bile trapped in Rokitansky-Aschoff sinuses.
• Inflammatory polyps: These are around 10% of all polyps. They form secondary to gallstones and chronic inflammation.

True polyps

These constitute approximately 5% of all polyps.

• Adenoma: They are usually benign (non-cancerous). They account for 4%–7% of all gallbladder polyps.
• Adenocarcinoma; Gallbladder cancer: 15-25% of gallbladder cancer will present as gallbladder polyp.

Rarely, leiomyomas, lipomas, neurofibromas, and neuroendocrine tumours, metastases and lymphoma may present as polypoid gallbladder lesions. Sometimes adherent gallstones and gallbladder sludge may be immobile and mimic gallbladder polyps.

Symptoms of gallbladder polyps

Most patients with gallbladder polyp do not have any symptoms. The polyp is diagnosed when tests are done for some other illness or on a routine check-up. They can be seen on ultrasound, CT scan, MRI or PET-CT.

Occasionally, they cause symptoms and these include

• Abdominal pain
• Abdominal discomfort
• Food intolerance
• Bloating
• Nausea

Complications of gallbladder polyp

The most dreaded complication of gallbladder polyp is cancer. Gallbladder cancer is an aggressive disease. Cure and survival are reduced in advanced stages. Since some of the polyps can be cancer or turn into cancer, they should be distinguished diligently.

They can cause swelling of the gallbladder (cholecystitis) obstructing the cystic duct. They can also cause cholangitis (infection of the bile duct) or pancreatitis (swelling of the pancreas) when fragments of polyp pass into the bile duct.

Diagnosis of gallbladder polyp

Diagnosis means identifying a disease. Following tests will help us make the diagnosis of gallbladder polyp and find the type.

Physical history and examination: Understanding symptoms and checking for signs by a physician are basics of arriving at a diagnosis.

Blood tests: Complete blood count measures the distinct cells in the blood. Besides, liver and kidney function tests assess the function of these organs.

Ultrasound (USG): An ultrasound scan uses high-frequency sound waves to create an image of the inside of the body. This is a basic test to see the liver, gallbladder and bile ducts. Most gallbladder polyps are identified on USG. This is also the main modality for following up these polyps when required.

Endoscopic ultrasound (EUS): It is an ultrasound of the gallbladder from inside. This test can be useful in distinguishing the type of polyp.

Computed tomography (CT) scan: CT Scanner acquires images of the inside of our body with the help of x-ray beams. These images are then computer-processed, giving an accurate representation. Contrast injected into the blood enhances these images. A CT scan is more helpful in staging the disease when a cancerous polyp is identified.

Magnetic resonance imaging (MRI): Instead of x-rays, it uses radio waves, and strong magnetic fields.

Positron emission tomography (PET) scan: Cancer cells take up a larger amount of glucose. Here injected radioactive glucose (18F-fluorodeoxyglucose; FDG) binds to the tumour, and the patient is scanned. The images are computer-processed and combined with CT images, giving us a CT image with bright coloured tumours. It can be sometimes useful in differentiating benign from a malignant polyp and in staging the disease when cancer is suspected.

Risk factors for cancer in gallbladder polyp

Differentiating between cancerous and noncancerous polyps is important. A noncancerous polyp can be observed, while those at risk of cancer are operated upon. One of the most important criteria for this is size.

Size of polyp

A size larger than 10 mm is the most reliable indicator of cancer in a polyp and warrants gallbladder removal surgery (cholecystectomy). A less than 10 mm polyp has a lower chance of harbouring cancer. However, in a study, 10% of cancerous gallbladder polyp were between 5 to 10 mm. Polyps that are less than 5 mm have an extremely low risk of cancer.

Other risk factors for cancer in a polyp

• Age more than 50 years
• Indian ethnicity (one guideline suggest that Indians should undergo surgery for 6-9 mm polyps)
• Primary sclerosing cholangitis (40-60% polyps in patients with PSC were malignant)
• Flat or sessile polyps
• Solitary polyps
• Thickening of the gallbladder wall (>3 mm)
• Presence of gallstones

Treatment of gallbladder polyp

Treatment of gallbladder polyps depends on the risk of cancer in the polyp. Surgical removal of all is not appropriate as the majority of the polyps are pseudopolyps with no risk of cancer.

Those who are at risk of cancer undergo surgery. These include those with polyps larger than 10 mm and other risk factors of cancer as enumerated earlier. In those with very low or no risk of cancer, the polyp is only observed with ultrasound. Those who have symptoms related to GB polyp also need surgery.

Follow-up

Polyps that are less than 10 mm can be followed up. Though there is variation in recommendations for following up these polyps. We follow the following protocol.

Less than 5 mm polyps: Ultrasound at 6 months, 1 year, 3 years and 5 years.

5-9 mm polyps: Ultrasound scans at six months and then annually.

On follow up if the polyp becomes 10 mm or increases in size by 2 mm. It should be operated.

Surgery for gallbladder polyp

Those who are at risk of harbouring or developing cancer in their polyp are operated upon. The type of surgery depends on the risk of cancer. Gallbladder removal surgery is called a cholecystectomy.

There are three types of cholecystectomy these patients will undergo depending on the possibility of cancer being present.

Simple cholecystectomy

In this only gallbladder is removed. The plane of dissection is between the gallbladder and the liver. This is done when the chances of the polyp being cancerous is minimal.

Radical (extended) cholecystectomy

This is a standard surgical procedure for gallbladder cancer. This procedure is done when we think that the polyp is cancerous. It entails the removal of the gallbladder along with the removal of its liver bed to the healthy tissue. The lymph nodes in the region are also removed.

Anticipatory extended cholecystectomy:

When the chance of polyp being cancer is equivocal. The gallbladder is removed with the liver bed and sent for a frozen section (the pathologist will examine for the presence of cancer). If cancer is present, lymph nodes are also cleared.

There are two ways surgeons do these surgeries

• Open
• Laparoscopic, or robotic

Open surgery for gallbladder polyps

In open surgery, a single long incision is made over the abdomen to do the surgery.

Laparoscopic surgery for gallbladder polyps

The laparoscopic approach uses minimally invasive techniques to do the same surgery with tiny incisions. This entails the insertion of special long thin surgical tools through these small holes. This results in faster recovery and reduced pain compared to conventional open surgery. This requires expertise. Make sure your surgeon is skilled and has done many of these operations.

Robotic surgery for gallbladder polyps

Robotic surgery combines the skill and expertise of a surgeon with the vision, precision, and flexibility of robotic technology. The robotic system features a 3D high-definition camera system for clear and enhanced vision with depth perception. It comprises a surgical console, where the surgeon sits, and robotic arms equipped with surgical instruments. The tiny wristed instruments can bend and rotate in ways the human hand cannot, allowing the surgeon to operate in tight spaces.

During robotic surgery, the surgeon makes minor cuts in the abdomen and inserts special tubes called ports. The robotic arms are connected to these ports, and the instruments mounted on these robotic arms go through the ports to do the surgery. A slender camera is also inserted through one port to show the surgeon a clear view of the inside. The surgeon controls the robotic arms from a console nearby, and an assistant helps by changing the instruments and aiding as needed.

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