In primary sclerosing cholangitis (PSC), the walls of the bile ducts become inflamed, leading to scarring and hardening that narrows the bile ducts.
Because bile cannot drain properly through the ducts, it accumulates in the liver, where it damages the liver cells.
As bile accumulates, it seeps into the bloodstream. Finally, with long-term cell damage, the liver develops cirrhosis, which is a hardening or fibrosis. It can no longer function properly.
The American Liver Foundation notes that PSC is slightly more common in men than women, symptoms usually appear in people aged from 30 to 60 years.
What is primary sclerosing cholangitis?
Primary sclerosing cholangitis affects the bile ducts and the liver.
Liver cells excrete bile into tiny tubes within the liver called bile ducts. These tubes come together like the tiny veins on a leaf.
These small tubes drain the bile into the common bile duct, a larger single tube leading into the intestine. There, the bile assists digestion and gives stool its brown color.
Inflammation and scarring cause the bile ducts of patients with PSC patients to become blocked.
As a result, bile collects in the liver. Over time, it damages the liver cells and causes fibrosis or cirrhosis, which is scarring of the liver.
As cirrhosis progresses, more scar tissue will build up in the liver, which gradually becomes unable to function. The scar tissue may prevent the bile ducts from being able to drain. This can lead to an infection of the bile ducts.
Symptoms of primary sclerosing cholangitis
Most patients with early PSC have no symptoms, and it may only be noticed during a routine test. The blood test would indicate abnormally high levels of liver enzymes, and particularly alkaline phosphatase.
Symptoms occur because the bile is not being drained properly through the bile ducts the liver is impaired or starting to fail.
Bile ducts can become infected, causing chills, fever, and upper abdominal tenderness. Itching may occur when bile seeps into the bloodstream.
Finally, in the advanced stages of cirrhosis, extensive swelling can occur in the abdomen and feet.
Liver failure may occur after 10 to 15 years or longer, depending on the individual.
Causes of primary sclerosing cholangitis
The exact cause of PSC is unknown, but past studies have suggested that it could be an autoimmune condition that happens when changes occur in the way the immune system works.
When the immune system is working properly, it protects the body from infections caused by foreign invaders like bacteria and viruses.
Sometimes, however, the immune system recognizes certain body parts or organs as foreign. The body then goes to war against itself, damaging the body part it thinks is foreign.
Exactly how an autoimmune disorder leads to PSC, however, remains unclear.
PSC is often seen in patients who have inflammatory bowel disease, such as Crohn's disease and ulcerative colitis, sarcoidosis, chronic pancreatitis, and other autoimmune disorders.
Genetic factors may play a role. According to the Canadian Liver Foundation, PSC may affect several members of a family, and if one person in a family has the condition, other close relatives have a higher risk of developing it too.
Inflammatory bowel disease, and especially ulcerative colitis, have been associated with PSC. Up to 75 percent of patients with PSC also have these conditions.
It has not been linked to the viruses that cause hepatitis.
Diagnosing primary sclerosing cholangitis
A physician may suspect PSC from a patient's medical history, especially a history of inflammatory bowel disease, and from abnormal blood tests.
The diagnosis is usually made by cholangiography.
A procedure known as an endoscopic retrograde cholangiopancreatography (ERCP) combines upper gastrointestinal (GI) endoscopy and x-rays to diagnose and treat problems of the bile and pancreatic ducts.
The test is performed under sedation. A lighted, flexible endoscope is inserted through the mouth and the stomach, into the small intestine. A thin tube is placed through the scope into the bile ducts, and the dye is injected to highlight the bile ducts on the x-ray.
In patients with PSC, the bile ducts will be narrow, and they will have a beaded appearance. There will be multiple narrowings along the ducts, with areas of widening in between.
As the disease progresses, a liver biopsy is usually needed to determine how much damage has occurred. Under local anesthesia, a slender needle is inserted through the right lower chest to extract a small piece of liver for microscopic analysis.
Patients with PSC have a high chance of developing ulcerative colitis as well. Patients with both PSC and ulcerative colitis have a higher risk of developing colon cancer. For this reason, colonoscopy is important to diagnose ulcerative colitis and for early detection of cancer or precancerous conditions.
Treatment for primary sclerosing cholangitis
Treatment includes ursodiol, or ursodeoxycholic acid, a bile acid naturally produced by the liver, which has been shown to lower elevated liver enzyme numbers in people with PSC. However, it does not improve liver or overall survival. A study published in 2011 suggested that more evidence is needed about the benefits and harms of this treatment.
Surgery may be necessary to open blockages in the bile duct.
There are also medications to relieve itching, called antipruritics, bile acid sequestrants, such as cholestyramine, antibiotics to treat infections, and vitamin supplements.
Actigall is a drug that improves the composition of bile in the liver. This can reduce the amount of liver damage that occurs. If ulcerative colitis is also present, it is treated with the appropriate medicines.
If swelling occurs in the abdomen and feet, due to fluid retention from cirrhosis, this can be treated with a low-salt diet and diuretics.
Multiple immunosuppressants and antibiotics have been trialed as a way of managing of PSC, but they have not proven to change mortality. They include cyclosporine, tacrolimus, methotrexate, budesonide, and metronidazole.
In some cases, endoscopic or surgical procedures may be used to open major blockages in bile ducts.
Through an endoscope, the physician places a tiny tube with a balloon on the end into the narrowed bile duct. The balloon is inflated to expand the duct so that bile can flow through it once again. Sometimes stents of plastic tubing can be placed in the narrowed ducts to keep them open.
Often, PSC progresses to a point where liver transplantation may be necessary. Liver transplantation is now an accepted form of treatment for chronic, severe liver disease.
Advances in surgical techniques and the use of new drugs to suppress rejection have improved the success rate of transplantation. The outcome for PSC patients is excellent after liver transplant. Survival rates at transplant centers are high, with a good quality of life after recovery.