Fatty liver seen by chance on a scan: next steps

What the finding is

Too much fat in the liver: steatotic liver disease, formerly called fatty liver disease, means too much fat has built up in the liver. The main types are MASLD, which is not caused by heavy alcohol use and used to be called nonalcoholic fatty liver disease, and alcohol-associated liver disease. (MedlinePlus)
Common: the AASLD estimates that 25% to 30% of adults in the general population have it, and that it often goes undiagnosed. (AASLD 2023) NICE says it is usually found by chance on liver blood tests or a belly ultrasound done for another reason. (NICE NG49 research)
Stages: the NHS describes 4 stages: fat only, fat with inflammation (MASH), scarring (fibrosis) and cirrhosis. Most people only have the first stage. (NHS)

What the scan can and cannot show

Ultrasound: accurate for moderate and severe fat but less sensitive for mild fat. (AGA 2021) The AASLD says it gives only a subjective grade, misses smaller amounts of fat, especially with obesity, and is not recommended as a tool to look for fatty liver. (AASLD 2023)
CT: a 2024 review of 42 studies found a CT without contrast dye picked up 72% of fatty livers and 82% of at least moderate ones; a liver reading below about 40 to 45 Hounsfield units was a reliable sign of at least moderate fat. CT with contrast dye picked up fewer (66%). (Haghshomar 2024)
Fat is not scarring: scarring is what guidance ties most closely to future liver problems. A scan with no visible fat does not rule out inflammation or scarring, although an ultrasound can help when it shows the shape of a cirrhotic liver. (AASLD 2023)(AGA 2021) Scarring is checked with blood scores and liver stiffness scans (elastography). (EASL-EASD-EASO 2024)

If the same scan reported a spot or lump in the liver, that is a separate finding; see liver lesion found by chance.

What guidance says comes next

Look for the cause and risk factors: the AASLD says people with a fatty liver seen by chance, once other causes such as hepatitis C or alcohol are ruled out, should have a risk assessment. (AASLD 2023) The European guideline says the finding should prompt a look at the cause alongside tests for advanced scarring (strong recommendation). (EASL-EASD-EASO 2024) NICE says MASLD is more common with type 2 diabetes or metabolic syndrome. (NICE NG49)
Basic blood tests and questions: the AGA pathway lists screening for alcohol use, liver blood tests and a full blood count. (AGA 2021) See liver function test results and AUDIT-C alcohol screening.
A scarring score: the AGA, AASLD and European guideline all use the FIB-4 score from those blood results as the first step. (AGA 2021)(AASLD 2023)(EASL-EASD-EASO 2024) What the score means and the cut-offs are on fatty liver screening: the FIB-4 score.
A liver stiffness scan if needed: if the score does not rule out advanced scarring, the next step is elastography or another second test. (AGA 2021)(EASL-EASD-EASO 2024)

The AGA notes that about 11% of people with a fatty liver found by chance may be at high risk of advanced scarring, more so when liver enzymes are raised. (AGA 2021)

NHS, non-urgent advice: (NHS)

See a GP if you think you could have non-alcoholic fatty liver disease or you think you have a higher risk of getting it. Some people have symptoms such as feeling very tired, feeling generally unwell, or pain or discomfort in the tummy under the right side of the ribs.

Where they differ:

The second test. The AGA, AASLD and European guideline start with FIB-4 and move to a liver stiffness scan. (AGA 2021)(AASLD 2023)(EASL-EASD-EASO 2024) NICE NG49 uses the ELF blood test: a score of 10.51 or above means advanced scarring and a referral, and below that a retest every 3 years for adults. (NICE NG49)
The role of ultrasound. The AASLD does not recommend standard ultrasound to look for fatty liver. (AASLD 2023) The AGA says people at high risk can skip the ultrasound and go straight to risk scoring. (AGA 2021) NICE offers liver ultrasound to test some children and young people with type 2 diabetes or metabolic syndrome. (NICE NG49)
How firmly the finding is followed up. The European guideline makes a strong recommendation to test everyone with steatosis found by chance for advanced scarring. (EASL-EASD-EASO 2024) The AGA recommends evaluating them, especially those with abnormal liver tests. (AGA 2021)

Your doctor decides what your result means for you.

Questions people ask

Is a fatty liver on a scan serious?

Often not by itself. The NHS says most people only have the first stage, a build-up of fat without liver damage, and a small number go on to inflammation and scarring. The scan alone cannot tell which group you are in, which is why guidance asks for more tests. (NHS) (EASL-EASD-EASO 2024)

Can an ultrasound or CT show liver scarring?

Not reliably. The AASLD says a standard ultrasound gives only a rough grade of fat, and a scan with no visible fat does not rule out inflammation or scarring. Scarring is checked with a blood score such as FIB-4 and, if needed, a liver stiffness scan (elastography). (AASLD 2023) (EASL-EASD-EASO 2024)

What tests usually come after a fatty liver finding?

The AGA pathway lists questions about alcohol use, liver blood tests and a full blood count, then a FIB-4 score worked out from those results. A liver stiffness scan follows if the score is not low. In the UK, NICE uses the ELF blood test instead. (AGA 2021) (NICE NG49)

My liver blood tests are normal. Does the fatty liver still matter?

Guidance still asks for a fibrosis check. NICE says not to use routine liver blood tests to rule out MASLD or advanced scarring, and the AGA notes the risk is higher when the tests are raised. (NICE NG49) (AGA 2021)

Should everyone be scanned for a fatty liver?

No. Both the AASLD and the European guideline say general population screening is not advised. Checks are aimed at people with risk factors such as type 2 diabetes, or a fatty liver already seen on a scan. (AASLD 2023) (EASL-EASD-EASO 2024)