Castell's sign

Castell's sign is a clinical diagnostic technique used in the assessment of splenomegaly and potentially other abdominal organ enlargements. It was named after Dr. Don Antonio Castell, an American physician who described this method in the mid-20th century. The sign is particularly useful in detecting an enlarged spleen by percussing the lowest intercostal space in the left anterior axillary line.

Procedure

The examination is performed with the patient lying down (supine). The physician percusses the lowest intercostal space in the left anterior axillary line. Initially, this is done while the patient is taking a deep breath. Normally, this area would resonate with a tympanic sound due to the presence of lung tissue. However, if the spleen is enlarged, it displaces the lung upwards and occupies the space where tympany was expected, resulting in a dull sound upon percussion. This change in percussion note from tympany to dullness on inspiration is considered a positive Castell's sign, suggesting splenomegaly.

Clinical Significance

Castell's sign is a non-invasive, simple, and cost-effective method for detecting splenomegaly. It is particularly useful in settings where advanced imaging techniques such as ultrasound or computed tomography (CT) scans are not readily available. While it is a helpful diagnostic tool, it is important to note that a negative Castell's sign does not rule out splenomegaly. The sensitivity and specificity of this sign can vary, and its diagnostic accuracy is not absolute. Therefore, it should be used in conjunction with other clinical findings and diagnostic tests.

Differential Diagnosis

In the context of a positive Castell's sign, differential diagnosis may include various conditions that lead to splenomegaly, such as:

• Infectious mononucleosis
• Leukemia
• Lymphoma
• Hemolytic anemia
• Liver cirrhosis
• Portal hypertension

Limitations

The main limitation of Castell's sign is its variability in sensitivity and specificity. Factors such as the patient's body habitus, the presence of gas in the colon, or a massively enlarged spleen that extends beyond the left anterior axillary line can affect the outcome of the test. Additionally, other conditions that may cause displacement or enlargement of organs in the left upper quadrant can potentially lead to false-positive results.

Conclusion

Castell's sign remains a valuable clinical tool for the initial assessment of splenomegaly, especially in resource-limited settings. However, its limitations necessitate the use of additional diagnostic methods for confirmation. As with any clinical sign, Castell's sign should be interpreted within the context of the entire clinical picture.