Zebra is the American medical slang for arriving at a surprising, often exotic, medical diagnosis when a more commonplace explanation is more likely. It is shorthand for the aphorism coined in the late 1940s by Theodore Woodward, professor at the University of Maryland School of Medicine, who instructed his medical interns: "When you hear hoofbeats behind you, don't expect to see a zebra". Since horses are common in Maryland while zebras are relatively rare, logically one could confidently guess that an animal making hoofbeats is probably a horse. By 1960, the aphorism was widely known in medical circles. As explained by Sotos, medical novices are predisposed to make rare diagnoses because of the availability heuristic and the phenomenon first enunciated in Rhetorica ad Herennium, "the striking and the novel stay longer in the mind." Thus, the aphorism is an important caution against these biases when teaching medical students to weigh medical evidence. Diagnosticians have noted, however, that "zebra"-type diagnoses must nonetheless be held in mind until the evidence conclusively rules them out: The term for an obscure and rare diagnosis in medicine is.
Examples
skin lesions in the United States are often diagnosed as loxoscelism, even in areas where Loxosceles species are rare or not present. This is a matter of concern because such misdiagnoses can delay correct diagnosis and treatment.
Usage
is considered a rare condition and its sufferers are known as medical zebras. The zebra was adopted across the world as the EDS mascot to bring the patient community together and raise awareness.
The television seriesScrubs episode "My Balancing Act", focuses on this theme, and the medical veteran Dr. Cox uses the metaphor to explain to intern John "J. D." Dorian why he should first consider a simple diagnosis. The television series House had the working titleChasing Zebras, Circling the Drain, a reference to the show's recurring theme of hunting for obscure diagnoses while a patient is in a critical condition. The title character, diagnostic expert Dr. Gregory House rejects the aphorism in his particular practice, arguing that any cases with simple solutions would have been successfully diagnosed by someone else before reaching him. The episode Zebras |"Zebras" of the television series was named after this term and cites a version of the aphorism in the teaser. Harvard Medical School and Harvard School of Dental Medicine's 2017 music video "IT'S NOT A ZEBRA!" depicts a group of first-year medical students erroneously trying to diagnose a patient with a rare and unlikely disease, when in fact she has the flu. In The Expanse 's fourth book Nemesis Games, Captain James Holden suggests Monica Stuart is ".. starting a unicorn hunt. " when summarising an unspecified joke based on the aphorism.
