Castell's sign

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Castell's sign^[1] is a medical sign assessed to evaluate splenomegaly and typically part of an abdominal examination. It is an alternative physical examination maneuver to Traube's sign.

It involves percussion in the lowest intercostal space on the left, with the patient in inspiration and expiration. If inspiration causes the tone to shift from tympanic to dull, it suggests splenomegaly, which may not be palpable (sensitivity and specificity of approximately 80%).^[2]

Splenomegaly, although associated with numerous diseases, remains one of the more elusive physical exam findings in the abdomen. Conditions such as infectious mononucleosis, thalassemia, and cirrhotic liver disease may all involve splenomegaly and as a result, the search for a reliable sign associated with this condition has been sought for generations. Currently, several such signs of splenomegaly exist, all of whose utility has been debated in medical literature. The presence or absence of splenomegaly, however, can be reliably appreciated on physical exam use Castell’s sign in conjunction with other clinical information, increasing the positive predictive value of the test. When used in a decision-making rubric, Castell’s sign becomes a valuable part of deciding whether to pursue further imaging.

Castell’s method involves first placing the patient in the supine position. With the patient in full inspiration and then full expiration, percuss the area of the lowest intercostal space (eighth or ninth) in the left anterior axillary line. If the note changes from resonant on full expiration to dull of full inspiration, the sign is regarded as positive. The resonant note heard upon full expiration is likely due to the air-filled stomach or splenic flexure of the colon. When the patient inspires, the spleen moves inferiorly along the posterolateral abdominal wall. If the spleen is enlarged enough that the inferior pole reaches the eighth or ninth intercostals space, a dull percussion note will be appreciated, indicating splenomegaly.

Donald O. Castell first described his sign in the 1967 paper, “The Spleen Percussion Sign” published in Annals of Internal Medicine.^[1] Castell, a George Washington Medical School graduate, is also a Navy-trained gastroenterologist. While stationed at the Great Lakes naval base in northern Illinois, Castell studied 20 male patients, 10 of whom had a positive percussion [Castell’s] sign and 10 patient controls with negative percussion signs. The spleen of each patient was then quantitatively measured using cromium-labeled erythrocytes and radioisotope photoscan of the spleen. Castell showed those patients in the control group had a mean spleen size of 75cm2 with a range of 57cm2 to 75cm2, while those who had a positive percussion sign had a mean spleen size of 93cm2 with a range of 77cm2 to 120cm2. Castell concluded that his technique of spleen percussion was thus useful in identifying “slight to moderate degrees of splenic enlargement” and as a result, a “valuable diagnostic technique.”

Some limitations, however, were also reported by Castell in his original paper. First the presence of gross splenomegaly or profuse fluid in the stomach or colon may lead to the absence of a resonant percussion note on full expiration. Also, later articles have criticized the maneuver’s reliability as befalling to more obese individuals and the amount of time the patient is post-prandial.

1993 JAMA study, however, found that Castell’s sign was the most sensitive physical exam maneuver for detecting splenomegaly (82% where P<0.05) when comparing palpation, Nixon’s sign (another percussion sign), and Traube’s space percussion.^[2] In addition, the examiner can increase the positive predictive value by utilizing this maneuver in nonobese patients who are more than two hours post-prandial. In asymptomatic patients where there is a low clinical suspicion for splenomegaly, however, physical examination alone is likely inadequate for a definitive determination due to the overall low sensitivity of the examination. Similar to many other findings in medicine, Castell’s sign must be combined with clinical findings to rule in splenomegaly. Grover et al, for example, recommends a greater than 10% preexamination clinical suspicion of splenic enlargement to effectively rule in the diagnosis of splenomegaly with physical exam. To rule out an enlarged spleen, however, follow-up imaging is probably necessary.

Given the paucity of physical exam findings to evaluate possible splenomegaly, Castell’s sign is the most sensitive of those which exist and is thus a good tool to teach in an advanced-type physical diagnosis course. Castell’s has been shown to be superior in sensitivity to other spleen percussion signs as well as palpation, which is not likely useful due to the extreme enlargement necessary to feel the spleen below the costal margin. Castell’s sign is thus, in the appropriate clinical scenario, an important part of the abdominal physical exam.^[3]

[edit] Reference

1. ^ ^{a b} Castell DO. The spleen percussion sign. A useful diagnostic technique. Ann Intern Med. 1967 Dec;67(6):1265-7. PMID 6061941.
2. ^ ^{a b} Grover S, Barkun A, Sackett D (1993). "The rational clinical examination. Does this patient have splenomegaly?". JAMA 270 (18): 2218-21. PMID 8411607. 
3. ^ Barkun et al. Splenic enlargement and Traube’s space: how useful is percussion? Am J Med. 1989 Nov 87(5): 562-6. PMID: 2683766.