Man coughs up blood clot shaped like lung tree, doctors ‘astonished'

Familiar with the phrase "cough up a lung"? It's not actually possible, but one man stunned doctors when he coughed up a blood clot in the shape of one.

Researchers published the shocking findings in the New England Journal of Medicine recently. In the report, they shared the story of a 36-year-old man admitted to an intensive-care unit with aggressive end-stage heart failure.


The patient’s heart was immediately connected to a pump designed to help blood flow through the body, co-author Georg Wieselthaler described in the assessment. However, the machine can cause coagulation, so they used heparin, a blood thinner medication, to prevent them from forming.

The heparin created another issue though. Thicker blood is needed to prevent blood vessels from developing tiny tears that can cause internal bleeding. Unfortunately, that is exactly what happened to the patient.

Blood leaked from his pulmonary network into his right lung then into his bronchial tree. He began coughing up smaller clots and eventually coughed up a large, oddly shaped, folded one. When doctors unfurled the glob, it was in the exact shape of the right bronchial tree.

"We were astonished," Wieselthaler told The Atlantic. "It's a curiosity you can't imagine—I mean, this is very, very, very rare."

Few similar cases have been documented, including a 34-year-old woman who coughed up a large piece of membrane in the 1920s and a 25-year-old pregnant woman who hacked up a smaller bronchial tree cast in 2005.

So why don’t the casts break apart?

As for Wieselthaler’s patient, he believes the answer is related to fibrinogen, a protein in the blood plasma that causes cell fragments to form a mass. The patient’s infection and heart failure possibly led to a very high concentration of fibrinogen, which made his blood rubbery and capable of staying intact as he coughed.

“Because it was so large, he was able to generate enough force from an entire right side of his thorax to push this up and out,” co-author Gavitt Woodard added. If the pieces were smaller, she said, “he might not have been able to generate the force.”

Although the patient felt immediately better after the clot was out of his system, he died about a week later from complications of heart failure.

Despite the grim ending, the doctors wanted to show a part of the human body. Woodard said, "recognizing the beautiful anatomy of the human body is the main point of it."