The question of whether a bullet can move within the body after being shot is common, often fueled by dramatic portrayals. While a bullet typically comes to rest upon impact, a retained bullet can sometimes shift from its initial lodged position. This phenomenon can have significant medical implications.
How Bullets Lodge in the Body
When a bullet strikes the body, its kinetic energy dissipates as it interacts with tissues, bone, and organs. This energy transfer creates a pathway of destruction, forming a “permanent cavity” where tissue is crushed and torn. The bullet’s type, velocity, and the tissues it encounters influence whether it passes through the body or becomes lodged. Higher-velocity bullets or those designed to deform, like hollow points, tend to transfer more energy and are more likely to remain within the body. If a bullet retains sufficient energy, it may exit; otherwise, it will come to rest, often becoming encased in fibrous scar tissue over time.
Mechanisms of Bullet Migration
Once lodged, a bullet’s movement can occur through several mechanisms. Gravity plays a role, particularly for bullets in areas like the lung or abdomen, where their density is greater than the surrounding tissue. Everyday body movements and muscle contractions can also cause minor shifts. For example, muscle contractions, such as those in the limbs or torso, can exert subtle forces on an encapsulated bullet, potentially dislodging it or causing it to migrate along paths of least resistance.
Bullets can also enter and travel within vascular pathways, a phenomenon known as bullet embolism. This rare event occurs when a bullet enters a blood vessel and is carried by blood flow to a distant location, potentially reaching the heart or pulmonary arteries. Documented cases include bullets migrating from a leg to the heart or even to the brain through the circulatory system. In the brain, the pulsation of cerebrospinal fluid (CSF) can facilitate bullet movement, particularly if the bullet enters the ventricular system. Over longer periods, changes in surrounding tissue, such as atrophy or resorption, might also contribute to a bullet’s gradual shift.
Consequences of Bullet Movement
When a retained bullet moves, it can lead to various medical complications. The most immediate concern is potential damage to new tissues or organs if the bullet migrates into a critical area. For instance, a bullet shifting near nerves can cause pain, discomfort, or nerve impingement. If the bullet moves to an area with bacteria, or creates new tissue damage, it can increase the risk of infection.
Vascular complications are another significant risk, especially if the bullet enters or irritates a major blood vessel, potentially leading to bleeding or the formation of blood clots. In rare instances, a bullet fragment can act as an embolus, traveling through the bloodstream and obstructing blood flow to vital organs. This can cause ischemia or be life-threatening. Such embolization can manifest with symptoms like sudden pain or lack of blood flow to an extremity.
Medical Decisions for Retained Bullets
Medical professionals carefully weigh the risks and benefits when deciding whether to remove a retained bullet. Often, if a bullet is not causing immediate harm and is in a non-critical area, it may be left in place. This decision is based on the understanding that surgical removal can sometimes cause more tissue damage, bleeding, or infection than leaving the bullet undisturbed.
However, there are specific situations where removal is considered if the bullet is causing symptoms, impinging on nerves, or located in a joint, the cerebrospinal fluid, or a blood vessel due to the risk of lead toxicity or migration. Ongoing monitoring through imaging studies is important for patients with retained bullets to detect any signs of migration or developing complications. The management of retained bullets is individualized, focusing on patient stability and potential future problems.