Castell point

If you’ve ever stood at the bedside trying to figure out whether the spleen is enlarged—without an ultrasound in sight—Castell’s point is the skill you need in your hands. It’s quick, elegant, and surprisingly underappreciated. Let’s walk through its history, the technique, and what the evidence actually says.

The Eponym and Its Origins

Castell’s point is named after Donald O. Castell, an American gastroenterologist who published the key description in 1967 in the Annals of Internal Medicine. His paper, “The Spleen Percussion Sign,” was a straightforward clinical study evaluating a single percussion point as a rapid bedside screen for splenomegaly.

Castell’s insight was refreshingly practical: instead of attempting to outline the entire spleen by percussion—a notoriously unreliable exercise—why not focus on one reproducible spot and ask a single yes-or-no question?

Anatomy Behind the Technique

To understand Castell’s point, picture the lowest intercostal space in the left anterior axillary line—typically the 8th or 9th intercostal space. In a healthy adult, this area sits over the left lung base and the gastric air bubble. Because air-filled structures produce tympany on percussion, this space should sound tympanitic in the normal state.

When the spleen enlarges, it descends and rotates anteriorly, displacing the air-containing stomach and bowel. The result: the same percussion point now produces dullness instead of tympany.

That simple shift—tympany to dullness—is the entire diagnostic signal of a positive Castell’s sign.

How to Perform the Examination

The technique is straightforward, but a few details matter:

1. Position the patient supine, with the left arm raised above the head to open the intercostal spaces.

2. Locate the lowest intercostal space in the left anterior axillary line. This is typically the 8th or 9th space.

3. Percuss lightly over this point first while the patient breathes normally.

4. Then ask the patient to take a deep inspiration and hold it briefly, and percuss again.

Interpretation:

∙ Negative (normal): Tympany in both phases → spleen is unlikely to be enlarged.

∙ Positive (abnormal): Dullness on full inspiration (or dullness in both phases) → raises suspicion for splenomegaly.

The reason to percuss during inspiration is that a borderline-enlarged spleen may only produce dullness when it descends further with the diaphragm.

What the Evidence Says

Castell’s original study reported a sensitivity of 82% for detecting splenomegaly confirmed by other methods. That’s a respectable number for a bedside test requiring no equipment.

Later studies added important nuance. A widely cited 1993 paper by Grover and colleagues in JAMA compared multiple percussion and palpation techniques for splenomegaly. Their key finding: when Castell’s point percussion was tympanitic in both phases of respiration, splenomegaly was effectively ruled out—a strong negative predictive value in low-prevalence settings.

Conversely, dullness alone had a more modest positive predictive value, meaning a positive Castell’s sign should prompt further evaluation rather than confirm the diagnosis outright.

The practical takeaway: Castell’s point is most useful as a rule-out tool. If it’s tympanitic throughout, you can reassure yourself (and your patient) that significant splenomegaly is unlikely.

Castell’s Point vs. Traube’s Space

You may already know Traube’s space—that crescent-shaped area over the left lower chest where tympany normally reflects the gastric air bubble. The two techniques are complementary, not interchangeable.

Both are affected by the patient’s last meal—a full stomach reduces tympany and can produce false-positive dullness. Ideally, examine on an empty or near-empty stomach.

Clinical Pearls

∙ A positive Castell’s sign in both phases (not just on inspiration) is more specific for splenomegaly than dullness on inspiration alone.

∙ Pleural effusion on the left is a major confounder—it produces dullness at this location regardless of splenic size.

∙ In obesity, both Castell’s point and Traube’s space percussion become less reliable; ultrasound is the pragmatic fallback.

∙ The sign adds the most value in the emergency or general medicine context, where you need a rapid, equipment-free screen—think infectious mononucleosis, portal hypertension, hematologic malignancy.

∙ Always combine percussion findings with palpation. A palpable spleen is already at least twice the normal size; percussion can detect earlier enlargement.

Why It Still Matters

In an era of point-of-care ultrasound, one might ask whether Castell’s point has become obsolete. The answer is no—for several reasons.

First, bedside ultrasound is not universally available, and clinical skills remain essential in resource-limited settings. Second, learning percussion trains the examiner’s hands and ears in ways that carry over to the entire physical exam. Third, when the history raises the possibility of splenomegaly—fever plus fatigue in a young patient, a new diagnosis of lymphoma, unexplained thrombocytopenia—having a rapid, reliable screening tool at your fingertips saves time and builds diagnostic momentum.

Donald Castell gave us a small but durable gift in 1967: one point, one question, one answer. Tympany or dullness. It’s still worth knowing.

Recommended Video

Stanford Medicine 25 – Spleen Examination

https://med.stanford.edu/stanfordmedicine25/the25/spleen.html

Reference

Castell DO. The spleen percussion sign: a useful diagnostic technique. Ann Intern Med. 1967;67:1265–1267. doi:10.7326/0003-4819-67-6-1265