Sternal foramen (or perforated sternum) is an oval foramen present at lower one-third of the sternum. It is a relatively common anatomical variation found in 2.5% to 13.8% of individuals.^[1]

This variation is usually present at the lower one-third of the sternal body. It has an oval shape and a unique "bow tie" appearance when seen on axial computed tomography. The diameter of the sternal foramen ranges from 6 to 16 mm with an average diameter of 6.5 mm.^[2] Sometimes, the foramen can be present at the xiphod process. In extremely rare cases, the foramen is found at the manubrium.^[3]

Developmentally, sternal foramen results from the incomplete fusion of the sternal bars while they are still cartilaginous.^[4]

Although sternal foramen is asymptomatic, it may entail a risk of serious complications from blinded sternal interventions. The foramen may be misdiagnosed as sternal fracture or a gunshot wound. Awareness of sternal foramen is also crucial in acupuncture to avoid cardiac tamponade.^[5]

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  Sternal foramen on axial and sagittal CT. The "bow tie" appearance is seen on the axial view.
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  Sternal foramen and xiphoid foramen
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  Sternal foramen observed in dry skeleton
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  A 3D file showing a sternum with sternal foramen and xiphoid foramen

• Sternum
• List of anatomical variation