Findings: chest radiographs show an obvious elevation of the right hemidiaphragm, with blunting of the posterior costophrenic angle (B, arrow). There is also a small ovoid opacity in the right lower lung (A, arrow) and laminar atelectasis at the right lung base.

Abdominal CT shows widespread ascitis, which is mass-like in the right subphrenic space (A, arrows). There is a small pleural effusion. The density of the ovoid lung lesion (B,C arrows) is similar to that of the masses in the subphrenic space.

Final diagnosis: ovarian carcinoma with pseudomyxoma peritonei and pulmonary metastases.

This case is presented to discuss the causes of elevated hemidiaphragm. Unilateral diaphragmatic elevation is not an uncommon finding, but in most cases, it is not clinically relevant. Nonetheless, it is sometimes a sign of a serious condition, as in the case shown.

In healthy individuals, the right hemidiaphragm is about 2cm higher than the left. Small differences in height should not cause concern, but obvious asymmetry deserves investigation.

The main causes of unilateral diaphragmatic elevation are:

1. Diseases of neighboring organs (chest and abdomen)
2. Diaphragmatic pathology (paralysis and eventration)
3. False elevations (subpulmonic fluid and hernias)

A common cause of diaphragmatic elevation is disease in neighboring organs.
The diaphragm is a frontier organ between the chest and the abdomen, and diseases in these anatomic areas may affect the position of the diaphragm. Any upper abdominal process (abscess, visceromegaly) may elevate the corresponding hemidiaphragm (Fig. 3). Similarly, any process causing a loss of lung volume (atelectasis, surgery), may pull the hemidiaphragm upward (Fig. 4).

Fig. 3 (aboove): elevated left hemidiaphragm secondary to marked splenomegaly. Notice the medial displacement of the gastric fornix (A, arrow) and the uniform opacity of the left upper quadrant. Abdominal film confirms the splenomegaly (B, arrows). Diagnosis: lymphoma.

Fig. 4 (above): elevation of hemidiaphragm due to loss of lung volume. Case A shows signs of LUL collapse (A, arrows). Case B corresponds to a RUL lobectomy. Post-surgical metallic sutures (B, arrows) may be overlooked if they are not carefully sought out.

Time for a test. Pre-op radiographs of a 27-year-old male undergoing urethral surgery. What would your diagnosis be?

1. Subpulmonic fluid
2. Diaphragmatic hernia
3. Diaphragmatic paralysis
4. None of the above

Findings: Chest radiographs show an irregular elevated right hemidiaphragm, with obliteration of the costophrenic angle. Patient had ruptured his urethra in a motorcycle accident and additionally had a torn diaphragm with herniation of the liver, which was overlooked in this film.

Patient remained asymptomatic, and three years later the hernia is more obvious. Note the hepatic flexure of colon (A, arrow) marking the inferior border of the liver. Unenhanced CT at that time shows a large rent in the diaphragm (B, arrows), with most of the liver herniated into the chest.

Final diagnosis: traumatic diaphragmatic hernia, surgically proven.

Traumatic diaphragmatic hernias may be overlooked during the initial evaluation following trauma, being superseded by the most important pathology. The herniated viscera interpose between the diaphragm and the undersurface of the lung, simulating an elevated diaphragm. A history of significant trauma should alert us to perform a CT to exclude hernia (Fig. 8).

Fig. 8 (above): 45-year-old asymptomatic male with previous history of trauma. Chest radiograph shows elevation of right hemidiaphragm. CT confirms the rent (B, arrow) and shows herniation of most of the liver.

Multislice CT is the technique of choice for studying diaphragmatic hernias. Barium is a safe and accurate method for detecting bowel hernias by demonstrating the narrow areas where the bowel crosses the rent (‘kissing beaks’ sign). Unfortunately, nobody uses barium any more. Had to dig up an old case to show the sign (Fig. 9).

Fig. 9 (above): marked elevation of left hemidiaphragm secondary to gastric hernia. Barium swallow shows the ‘kissing beaks’ sign which marks the location of the rent (B, arrows).

Fatty diaphragmatic hernias are common in elderly patients, and usually appear as localised diaphragmatic lumps. Occasionally, they may be large and simulate an elevated hemidiaphragm (Fig. 10).

Fig. 10 (above): elevated left hemidiaphragm with fuzzy border in a 74-year-old man (A, arrow). Coronal CT shows a large opening with herniation of fat and retroperitoneal vessels (B, arrows). Notice how the decubitus position increases the herniation.

Subpulmonic effusion is the most common cause of false diaphragmatic elevation. Pleural fluid collects between the diaphragm and the lung, simulating an elevated hemidiaphragm (Figs. 11 and 12).

Fig. 11 (above): chest radiograph (A) shows the classic signs of subpulmonic effusion: a dense and elevated hemidiaphragm. A shallow costophrenic sulcus is not seen in this case. Compare with radiograph after resolution of fluid (B).

TIP: in my experience, the lateral film is very helpful in the diagnosis of subpulmonic effusion. When the signs are not very evident in the PA film (Fig. 12a), there is always obliteration of the posterior costophrenic sulcus (12b, arrow). CT shows a significant amount of free fluid in the right pleural space. US study is easier than a lateral decubitus film to confirm the presence of fluid.

When other causes are excluded, we have to consider eventration or diaphragmatic paralysis. In eventration, the muscle is replaced by fibrous tissue. Paralysis may be due to any process that affects the phrenic nerve, such as a tumor or surgery (Fig. 13), although in most cases, the cause is not found.

Fig. 13 (above): chest radiographs before and after surgery for thoracic aneurysm. Post-op film shows elevation of left hemidiaphragm secondary to phrenic nerve injury.

Eventration/paralysis are not uncommon in elderly people, but such findings are usually irrelevant. Comparison with previous films helps to determine whether the condition is stable.

Fig. 14 (above): a 76-year-old patient with eventration/paralysis of left hemidiaphragm. Coronal CT shows an intact left hemidiaphragm (B, arrows) that is markedly atrophic when compared to the right.

Follow Dr. Pepe’s advice:

• The main causes of unilateral diaphragmatic elevation are paralysis/eventration, abdominal processes, loss of lung volume, and false elevations.
• The most common cause of false elevation is subpulmonic fluid
• When there is a significant history of trauma, rule out diaphragmatic herniation.
• Diaphragmatic eventration or paralysis are relatively frequent in elderly persons, but these findings are usually not significant.