Liver fibrosis occurs when long-term or repetitive injury or inflammation causes excessive amounts of scar tissue to accumulate in the organ. Most types of chronic liver disease can lead to fibrosis.
Unlike healthy liver cells, scar cells cannot repair or otherwise function. As a result of this, fibrosis can reduce the overall function of the liver and affect the organ’s ability to regenerate.
Fibrosis scar tissue can also block or limit blood flow within the liver. This can starve and eventually kill healthy liver cells, creating more scar tissue in the process. Treatment tends to clear infections, make lifestyle changes, and take certain medications. This can often reverse the damage of mild to moderate liver fibrosis.
If the inflammation continues, possibly because a person has not received treatment, the liver fibrosis can develop into more serious liver conditions.
If a doctor thinks someone has liver fibrosis, she will carefully collect a small tissue sample or biopsy from the liver using a large needle. A pathologist, who is a doctor who specializes in finding the root cause of the disease, will examine the sample under a microscope. They do this to assess the extent and type of damage.
Determining the degree of fibrosis is difficult because pathologists only have a small sample to work with. Other doctors can also evaluate the same sample in different ways. Healthcare providers can use various scales to define the stages of fibrosis. These include the Metavir, Ishak, and Batts-Ludwig scales. These and similar scoring systems take into account the effect fibrosis has had on the portal vein, which distributes blood from the intestines to the liver. Many scales also measure the extent of fibrosis and the location or number of septa, which are fibrous bands of tissue in the biopsy sample.
The Metavir scoring system assesses the progression of fibrosis on a scale from A0 to A3:
- A0: no activity
- A1: mild activity
- A2: moderate activity
- A3: severe activity
The Metavir system also scores the level of fibrosis from F0 to F3:
- F0: absence of fibrosis.
- F1: portal fibrosis without septa
- F2: portal fibrosis with rare septa.
- F3: numerous septa but without cirrhosis.
- F4: cirrhosis
Cirrhosis is scar tissue that builds up in the liver. This can occur due to uncontrolled fibrosis. The most advanced type of fibrosis someone can have before developing cirrhosis, according to the Metavir system, is stage A3F3. The Ishak fibrosis scoring system is more complex, typically running from 0 to 6:
- 0: an absence of fibrosis
- 1: an expansion of some areas of the portal, possibly with short, fibrous septa
- 2: an expansion of most areas of the portal, possibly with short, fibrous septa
- 3: an expansion of portal areas with sporadic portal-to-portal bridges
- 4: an expansion of the portal areas with a significant bridge from portal to portal
- and from portal to central
- 5: significant bridge from portal to portal and from portal to central with sporadic nodules
- 6: probable or definite cirrhosis
Using the Ishak scale, the most advanced stage of fibrosis a person can have before developing cirrhosis is stage 5. The Batts-Ludwig scale, common in the United States, is slightly simpler. This scale goes from 0 to 4:
- 0: lack of fibrosis
- 1: portal fibrosis
- 2: rare portal-to-portal septa
- 3: fibrous septa
- 4: definite or probable cirrhosis
Using the Batts-Ludwig scale, the most advanced stage of fibrosis a person can have before developing cirrhosis is stage 3.
People with fibrosis usually don’t know they have it. This is because it rarely causes obvious symptoms. However, within the liver, fibrosis can:
- Reduce overall function, including blood purification, energy storage, and infection clearance.
- Limit the organ’s ability to regenerate.
- Restrict blood flow within the organ.
People generally begin to experience symptoms when fibrosis progresses to cirrhosis. These initial symptoms may vary, but some of the common indicators of early cirrhosis include:
- A little appetite.
- Feeling weak
- Unexplained exhaustion
- Unexplained weight loss
- Nausea and vomiting
- Discomfort or mild pain in the upper right part of the abdomen.
Some common signs of more advanced cirrhosis include:
- A tendency to bruise or bleed easily.
- Edema or fluid retention in the lower legs, ankles, or feet.
- Jaundice, which is a yellowing of the skin and eyes.
- Ascites or abdominal swelling from a buildup of fluid.
- Skin itch.
- Increased sensitivity to medications and their side effects.
- Problems with certain cognitive functions, such as memory, concentration, or sleep.
- A darkening of the urine.
The best way to treat liver fibrosis is to address the root cause. Successful treatment of the cause of early to moderate liver fibrosis can reverse most, if not all, of the damage fibrosis has caused.
Almost all chronic liver conditions eventually lead to fibrosis, as each condition causes long-lasting inflammation in the liver. This inflammation can lead to the formation of scar tissue, which is fibrous.
The most common causes of liver fibrosis in the United States are:
- Chronic alcohol abuse.
- Viral hepatitis C or B.
- Nonalcoholic fatty liver disease (NAFLD)
- Nonalcoholic steatohepatitis (NASH), a subtype of NAFLD
- NAFLD and NASH tend to develop in people with excess weight, diabetes or prediabetes, and high levels of fat and cholesterol circulating in the blood.
- Doctors refer to the latter condition as metabolic syndrome.