Enlarged spleen seen by chance on a scan

What the report means

Splenomegaly. The medical word for an enlarged spleen. It can be found on ultrasound, CT or MRI, or when a doctor feels the tummy. (StatPearls 2023)(NHS)
How it is measured. Reports usually give the length from top to bottom in centimetres or millimetres, and sometimes the volume. A common rule is up to about 12 cm normal, 12 to 20 cm enlarged and over 20 cm very enlarged (massive). (StatPearls 2023)(Juhl 2026)
No symptoms is common. An enlarged spleen does not always cause symptoms. When it does, they can include feeling full quickly after eating, discomfort behind the left ribs, tiredness from anaemia, frequent infections and easy bleeding. (NHS)
Spots in the spleen are different. A spot or lump inside the spleen has its own page: spleen lesion found by chance.

Why normal size varies with height, sex and age

Height, sex and weight. In 1,230 healthy volunteers, men and taller and heavier people had longer and larger spleens. 26% of men and 6% of women had a spleen longer than the usual 12 cm limit. The authors set upper limits by height and sex instead. (Chow 2016)
Age. In 1,041 healthy Korean adults, spleen length fell with age. Median length in men was about 10.1 cm at 18 to 29 and 9.2 cm at 60 and over; in women about 8.9 cm and 8.3 cm. Only 4.0% of men and 0.8% of women were over 12 cm in this group. (Lee 2023)
Stable over time. When 75 healthy volunteers were measured twice, spleen length changed little (median difference 0.1 cm). (Chow 2016)

Common causes

Infection or injury. The spleen can swell after an infection or injury, and it can be a temporary change during a short illness. (NHS)(StatPearls 2023)
Liver disease. Cirrhosis is one of the conditions the NHS lists. (NHS) See fatty liver seen by chance and liver function test results.
Blood conditions. Leukaemia is on the NHS list. A review also lists lymphoma, thalassaemia and sickle cell disease. (NHS)(Jerves Serrano 2024)
Other groups of causes. Inflammatory conditions such as rheumatoid arthritis, sarcoidosis or lupus; heart failure or a clot in a vein; and rare inherited conditions. (NHS)(Jerves Serrano 2024)

Which checks are usually done next

Blood tests and scans. The NHS says a blood test, CT or MRI can confirm an enlarged spleen. (NHS) A review describes the first work-up as imaging and basic blood tests, including a full blood count and liver function tests, to look for common causes first. (Jerves Serrano 2024)
Monitoring. The NHS says the spleen is not usually removed if it is just enlarged; the cause is looked for and the spleen is monitored. (NHS)
Radiology guidance. Canadian radiologists published recommendations in 2026 that cover splenomegaly found by chance, using the scan features, the person's health and risk factors to avoid follow-up that is not needed. (CAR 2026)
Lymph nodes. If the same scan mentions enlarged lymph nodes, see enlarged lymph node seen by chance on a CT scan.
Worry is real. See after an abnormal screening result.

What a large study found about size

Who was studied. 8,459 adults in Denmark and 38,607 in the UK had CT or MRI scans as part of research studies, with a median age in the early to mid 60s, and were followed for a median of 5 years. (Juhl 2026)
What it found. The 5-year chance of a blood cancer was moderately higher with a spleen length of 130 to 139 mm (or volume 400 to 499 mL) and clearly higher at 140 mm or more (or 500 mL or more). For a length of 140 mm or more, it reached 23% in Danish men and 12% in Danish women aged 70 and over. (Juhl 2026)
What the authors concluded. Checking for a cause is likely to be relevant at these larger sizes. They also noted that evidence has been lacking on when checking people with an enlarged spleen is useful. (Juhl 2026)

How it ties to your age-based checks

A scan that shows an enlarged spleen is a good moment to make sure your routine checks are up to date:

Who it applies to

Adults told that an ultrasound, CT or MRI done for another reason shows an enlarged spleen. Children, people already known to have a liver or blood condition, and a spot or lump inside the spleen are outside this page.

The NHS says a ruptured spleen is a medical emergency because it can cause life-threatening bleeding. Go straight to A&E (call 911 in the US) if you think your spleen is damaged or ruptured, for example pain behind the left ribs that is tender to touch, with dizziness and a fast heartbeat. This can happen straight away or weeks after an injury. (NHS) A swollen spleen is easier to damage in an injury, and the NHS says to avoid contact sports for a while when it is enlarged. (MedlinePlus)(NHS)

Routine age-based screening

An enlarged spleen on a scan does not replace the routine screenings for your age. See screenings by age and gender.

Where they differ:

One cut-off or many. A common rule treats any spleen over 12 cm as enlarged. (StatPearls 2023) Studies of healthy adults say the normal limit depends on height and sex (Chow 2016) and on age and body size. (Lee 2023)
How many are over 12 cm. In a German group, 26% of healthy men and 6% of women were over 12 cm (Chow 2016); in a Korean group, 4.0% of men and 0.8% of women were. (Lee 2023)
When to look further. A large population study found blood cancer risk rose mainly from about 130 to 140 mm. (Juhl 2026) Canadian radiology guidance aims to avoid follow-up that is not needed in people without symptoms. (CAR 2026)

Your doctor decides what your result means for you.

Questions people ask

What size is an enlarged spleen?

A common rule is that a normal adult spleen is up to about 12 cm long, 12 to 20 cm is enlarged and over 20 cm is very enlarged. But normal size varies: men and taller or heavier people have bigger spleens, and in one study of healthy adults 26% of men and 6% of women were over 12 cm. (StatPearls 2023) (Chow 2016)

Does the spleen get smaller with age?

In a study of 1,041 healthy Korean adults, spleen length fell with age in both sexes, from a median of about 10.1 cm in men aged 18 to 29 to 9.2 cm in men aged 60 and over. (Lee 2023)

What can make the spleen bigger?

The NHS lists an infection or injury, and conditions such as cirrhosis of the liver, leukaemia or rheumatoid arthritis. A review also lists blood, heart and circulation, inflammatory and rare inherited causes. An enlarged spleen can also be temporary during a short illness. (NHS) (Jerves Serrano 2024) (StatPearls 2023)

What checks usually come next?

The NHS says a blood test, CT or MRI can confirm an enlarged spleen. A review describes the first checks as imaging and basic blood tests, including a full blood count and liver tests. Your doctor decides which checks you need. (NHS) (Jerves Serrano 2024)

When is it an emergency?

The NHS says to go straight to A&E (call 911 in the US) if you think your spleen has ruptured or been damaged, for example pain behind the left ribs with tenderness, dizziness and a fast heartbeat, especially after a blow to the tummy. (NHS)