What Is the Halo Sign?

In medicine, several different radiological phenomena are known as the “halo sign.” These involve the appearance of a distinctive ring or cloud, which may be darker or lighter than the surrounding regions, depending on what is causing it. In the skull, they may be signs of blood vessel inflammation, while in the chest, they can indicate a malignancy or another issue like a fluid buildup. Prenatal ultrasound examinations can also reveal a distinctive image known as Deuel’s halo, which is indicative of fetal death.

One common application of the halo sign is in diagnosis of temporal arteritis, an inflammation of the blood vessels in the head. Inflamed vessels can develop visible halos which may help a doctor diagnose the condition without the use of a biopsy to confirm. Chest imaging can also involve a halo sign, a ringed smudge or spot on an image like an x-ray. The halo sign indicates that something is blocking the normal transmission of x-rays, such as a malignancy or buildup of fluid.

When halo signs are identified during diagnostic workups, the doctor may recommend several steps. These can include repeat imaging or the use of a different imaging method to confirm the finding. Biopsy can provide more information about what is going on, which may be important for successful treatment. If other medical signs can lead to a diagnosis, the doctor could also move directly into treatment to resolve the issue.

Prenatal ultrasound may reveal a halo sign in the fetus. This may take the form of a distinctive ring around the skull, caused by swelling between the scalp and skull. This is an indicator of fetal death, which can be confirmed with other measures, like checking for movement and a heartbeat. There are also other signs that may be visible with x-ray or ultrasound, including the development of gas bubbles inside the fetus. Care providers follow very specific procedures when they diagnose fetal death, to be absolutely certain before moving on to treatment recommendations.

The expecting mother have several treatment options in this case; she may wait for spontaneous miscarriage or abortion, or could undergo surgery to remove the fetus before an infection has an opportunity to develop. Surgery is typically recommended to protect the mother’s health and safety, and it may be necessary in some cases. Delivery may be an option in some situations, and can be discussed with care providers if expecting mothers would prefer to labor and deliver as naturally as possible.