Raised diaphragm seen by chance on a chest X-ray
A chest X-ray or CT done for something else may say that one hemidiaphragm is raised, elevated or high, or may use the word eventration. This means one side of the diaphragm, the dome-shaped muscle under the lungs, sits higher than expected. It is often found by chance and many people have no symptoms. (LeCompte 2025)(Laghi 2021) This page covers what the report means, how common it is and when another test is suggested, not treatment.
What the report words mean
- Hemidiaphragm. One half, right or left, of the diaphragm. (Laghi 2021)
- Normal height. The right side normally sits a little higher than the left because the liver lies under it, on average less than 2 cm. (LeCompte 2025) In adults with normal lung function, the height of the dome varied from person to person and was linked to age, weight and chest size. (Suwatanapongched 2003)
- Raised or elevated hemidiaphragm. One side sits higher than expected. It describes how the X-ray looks, not the cause. (Laghi 2021)
- Eventration. Part or all of one side is raised but still fully attached, with no hole in it. Part of the muscle is replaced by a thin sheet. The type present from birth usually raises only the front inner part of the right side. (Laghi 2021)(LeCompte 2025)
- Paralysis or weakness. The nerve that works the diaphragm (the phrenic nerve) is not working, so that side does not move down well when you breathe in. This can also make that side look raised. (Laghi 2021)(Qureshi 2009)
- Hernia is different. In a diaphragm hernia there is a gap in the muscle that belly contents can pass through. In eventration the muscle stays in one piece. (Laghi 2021) See hiatal hernia seen by chance.
How common it is
Older reports describe eventration as rare, under 1%. A 2025 study measured 196 two-view chest X-rays taken before surgery and counted eventration when one side was more than 2.5 cm higher. (LeCompte 2025)
| Group | People | Share |
|---|---|---|
| Women | 80 | 21.3% |
| Men | 116 | 25.0% |
| All (average age 55) | 196 | 23.5% |
Source: (LeCompte 2025) The authors suggest the type present from birth may be a common normal variant. The sources here do not give clear numbers by age group.
Common harmless causes and other causes
- Normal variation. The right side being a little higher is normal, and the height of the diaphragm varies between people. (LeCompte 2025)(Suwatanapongched 2003)
- Eventration from birth. Usually found by chance and often causes no symptoms. (LeCompte 2025)
- Things in the chest or belly. A raised side can also come from a small collapsed lung area (atelectasis), pneumonia, lung scarring, earlier lung surgery, fluid, or something below the diaphragm pushing it up. (Laghi 2021)(LeCompte 2025) See atelectasis and fluid around the lung.
- A weak or paralysed side. In 36 people seen at one specialist centre, the causes were earlier surgery (36%), a tumour (19%), no cause found (17%), an injury (14%), polio (8%) and a virus (6%). The left side was affected in 64%. (Elefteriades 2008)
When a repeat X-ray or another test is suggested
- The X-ray alone cannot tell. In 42 people who had a nerve test, a raised side on the X-ray matched a weak side only about 1 time in 3. When neither side was raised, a weak diaphragm was unlikely. Two radiologists reading the same X-rays agreed only moderately. (Chetta 2005)
- Earlier X-rays. One review notes that when both sides are raised, the change can be hard to see without earlier chest X-rays to compare. (Laghi 2021)
- Tests of movement. When a weak diaphragm is suspected, an ultrasound, a sniff test (an X-ray video while you sniff), CT or MRI can show how each side moves. (Laghi 2021)(Qureshi 2009)
- Symptoms. Breathlessness, especially when lying flat, can point to a weak diaphragm. (Qureshi 2009) Symptoms are usually more marked when both sides are affected, and the outlook is good when only one side is affected. (Qureshi 2009)
- Otherwise. Whether you need another X-ray or test depends on how the X-ray looks, your symptoms and the rest of the report. Your doctor decides.
- Worry is real. See after an abnormal screening result.
The NHS says to call 999 or go to A&E (your local emergency number elsewhere) if you have severe difficulty breathing, your chest feels tight or heavy, your lips or skin turn very pale, blue or grey, or you feel suddenly confused. It says to see a GP if your shortness of breath gets worse with normal activities or when you lie down. (NHS)
Other things a chest X-ray may show
The same X-ray may mention other findings, each with its own page: an enlarged heart, a small collapsed lung area, fluid around the lung and pleural plaques.
Who it applies to
Adults told that a chest X-ray or CT done for something else shows a raised diaphragm or eventration. Babies and children, people who have just had chest, neck or heart surgery or an injury, and people being seen for a nerve or muscle condition are outside this page.
Routine age-based screening
A diaphragm finding on an X-ray does not replace the routine screenings for your age. See screenings by age and gender.
Where they differ:
- How common eventration is. Older reports say under 1%; a 2025 X-ray study found about 1 in 4 adults. The 2025 authors note that posture, breathing and body shape can change the measured height. (LeCompte 2025)
- What a raised side suggests. One review says a raised side suggests a weak phrenic nerve but is not specific. (Laghi 2021) A study comparing X-rays with nerve tests found a raised side alone is of little value for finding paralysis. (Chetta 2005)
- Symptoms. A review says most one-sided cases need no treatment. (Qureshi 2009) In people referred to a specialist centre, 78% had symptoms. (Elefteriades 2008) People found by chance and people sent to a specialist are different groups.
Your doctor decides what your result means for you.
Questions people ask
Is one side of the diaphragm normally higher?
Yes. The right side normally sits a little higher than the left because the liver lies under it. On average the gap is under 2 cm, and the normal height varies with age, weight and chest size. (LeCompte 2025) (Suwatanapongched 2003)
What is eventration of the diaphragm?
Eventration means part or all of one side of the diaphragm sits higher than usual while staying fully attached, with no hole in it. Part of the muscle is replaced by a thin sheet. It can be present from birth or come later, often after an injury to the nerve that works the diaphragm. (Laghi 2021) (LeCompte 2025)
How common is a raised diaphragm?
Older reports put eventration at under 1%. A 2025 study of 196 chest X-rays taken before surgery found it in 23.5% of adults, 21.3% of women and 25.0% of men. (LeCompte 2025)
Does a raised diaphragm on an X-ray mean it is paralysed?
Not on its own. In a study of 42 people, a raised side on the X-ray matched a weak side on a nerve test only about 1 time in 3. When neither side was raised, a weak diaphragm was unlikely. (Chetta 2005) (Laghi 2021)
Why might I be offered another test?
A raised side can have several causes, such as a small collapsed lung area, fluid, an infection or a weak diaphragm. When symptoms or the rest of the report suggest one of these, tests such as an ultrasound or a sniff test can show how the diaphragm moves. Your doctor decides what your result means for you. (Laghi 2021) (Qureshi 2009)