Traube's space

Traube's (semilunar) space is an anatomic region of some clinical importance. It's a crescent-shaped space, encompassed by the lower edge of the left lung, the anterior border of the spleen, the left costal margin and the inferior margin of the left lobe of the liver. Thus, its surface markings are respectively the left sixth rib, the left anterior axillary line, and the left costal margin.

Percussion for splenomegaly
The normal human spleen measures about 125 millimeters in length, and splenomegaly is an important clinical sign. There are 2 possibilities to evaluate splenomegaly in the clinical examination: percussion and palpation. Percussion can be done in this space.

Underneath Traube's space lies the stomach, which produces a tympanic sound on percussion (medicine). If percussion over Traube's space produces a dull tone, this indicates splenomegaly. Assessing this may be more difficult in obese patients.

In 1993, a systematic review by the Rational Clinical Examination found that percussion over Traube's space yields :
 * sensitivity = 62%
 * specificity = 72%

Specificity may be higher if the patient has not eaten in the last two hours.

Eponym
It is named for Ludwig Traube, although it was first described by his pupil in 1868. Another method was described by Donald O. Castell in 1967 (Castell's sign).