The “Semmelweis reflex” is from the real life experience of Dr Ignaz Philipp Semmelweis (his brief life story is included below) who is now recognized as a pioneer of antiseptic policy in medical procedures. From 1847 to 1865 he proved beyond any doubt that basic chlorine washings of hands and medical instruments in hospitals could save thousands of lives. Because germs had not yet been discovered he could prove that medical sanitation worked but not why it worked therefore even some Drs that saw it work rejected it.

The “Semmelweis reflex” refers to a problem common in the medical world. It is the automatic rejection of something different even if it’s obvious, without giving it serious thought, inspection, or experiment. It is an outright dismissal of any information that is radically out of sync with the status quo even if there is strong empirical evidence to back it up. (Some modern examples)

The “Semmelweis reflex” is often associated with "Eminence Based Medicine” where Drs gain confidence over an impressive number of years by repeating the same mistakes of other Drs. Medical professionals often do this by using medical jargon and offering obtuse opinions to perpetuate a belief system where authority has more power than valid science.

Both “Semmelweis reflex” and "Eminence Based Medicine” are involved in “Medical Myopia” where the medical world is so sure of something that they even reject overwhelming proof to the contrary from their own medical research world.

The following life story is a very condensed version of what Wiki has but matches what I’ve seen in other sources. I have added a few comments See Wikipedia Dr Semmelweis

Ignaz Philipp Semmelweis (July 1, 1818 - August 13, 1865) was a Hungarian physician called the "savior of mothers" who discovered, by 1847, that the incidence of puerperal fever, also known as childbed fever could be drastically cut by use of hand washing standards in obstetrical clinics. (Mothers and babies were dying from serious infections picked up because the Drs that delivered them didn’t wash their hands or instruments after doing autopsies on mothers or babies that had just dyed from serious infections picked up the same way)

While working at the Vienna General Hospital in Austria, Semmelweis discovered in 1847 that hand washing with chlorinated lime solutions reduced the incidence of fatal puerperal fever from about 10 percent to about 1-2 percent. During 1848 Ignaz Semmelweis widened the scope of his washing protocol to include all instruments coming in contact with patients in labor and used mortality rate time series to document his success in virtually eliminating puerperal fever from the hospital ward.

The breakthrough for Ignaz Semmelweis occurred in 1847 with the death of his friend Jakob Kolletschka from an infection contracted after his finger was accidentally punctured with a knife while performing a postmortem examination. Kolletschka's own autopsy showed a pathological situation similar to that of the women who were dying from puerperal fever. Semmelweis immediately proposed a connection between cadaveric contamination and puerperal fever. (At the time many thought that puerperal fever was a weakness in women and babies and it didn’t happen in men because they were stronger. Semmelweis realized that the pus on the knife that cut his friend had contained the disease and that puerperal fever was not a weakness in women)

Toward the end of 1847, accounts of Semmelweis's work began to spread around Europe. Semmelweis and his students wrote letters to the directors of several prominent maternity clinics; in these letters they described their recent observations. Ferdinand von Hebra, Vienna's celebrated dermatologist and the editor of a leading Austrian medical journal, announced Semmelweis's discovery in the December 1847 and April 1848 issues of his periodical. Hebra and claimed that Semmelweis's work had a practical significance comparable to that of Edward Jenner's introduction of cowpox inoculations to prevent smallpox.

In late 1848 - a British physician named Routh, who had been Semmelweis's student when the chlorine washings were initiated, wrote a lecture explaining Semmelweis's work. The lecture was presented before the Royal Medical and Surgical Society in London and was published in a prominent medical journal. A few months later, another of Semmelweis's former students, M. F. Wieger, published a similar essay in a French periodical.

Accounts of his discovery were being circulated throughout Europe. He had reason to expect that the chlorine washings would be widely adopted and that tens of thousands of lives would be saved.

At the time, diseases were attributed to many different and unrelated causes. Semmelweis' hypothesis, that there was only one cause, that all that mattered was cleanliness, was extreme at the time, and was largely ignored, rejected or ridiculed. He was dismissed from the hospital and had difficulty finding employment as a medical doctor.

His observations went against all established scientific medical opinion of the time. The theory of diseases were highly influenced by ideas of an imbalance of the basic "four humours" in the body, a theory known as dyscrasia for which the main treatment was bloodlettings.

Other more subtle factors may also have played a role. Some surgeons, for instance, were offended at the suggestion that they should wash their hands; they felt that their social status as gentlemen was inconsistent with the idea that their hands could be unclean.

Specifically, Semmelweis' claims were thought to lack scientific basis, since he could offer no acceptable explanation for his findings. Such a scientific explanation was only made possible some decades later when the germ theory of disease was developed by Louis Pasteur, Joseph Lister, and others.

On 20 May 1851 Semmelweis assumed the relatively insignificant position of unpaid, honorary head-physician of the obstetrical ward of Pest's small St. Rochus Hospital. Childbed fever was rampant at the clinic. After taking over in 1851, Semmelweis virtually eliminated the disease. During 1851-1855 only 8 patients died from childbed fever out of 933 births (0.85 percent).
He assumed that position for six years until June 1857.

Despite the results, Semmelweis's ideas were not accepted by the other obstetricians in Budapest.

Semmelweis next instituted chlorine washings at the University of Pest maternity clinic. Once again he attained impressive results.

Semmelweis had now achieved dramatic successes at three obstetrical facilities. Even so, his ideas continued to be ridiculed and rejected both in Vienna and in Budapest.

Semmelweis's views were much more favorably received in England than on the continent, but he was more often cited than understood.

In 1856, Semmelweis' assistant József Fleishcer reported the successful results of handwashings at St. Rochus and Pest maternity institutions in the Viennese Medical Weekly. The editor remarked sarcastically that it was time people stopped being misled about the theory of chlorine washings. A popular translation into English is "it was time to stop the nonsense of hand washing with chlorine"

In his 1861 book, Semmelweis lamented the slow adoption of his ideas: "Most medical lecture halls continue to resound with lectures on epidemic childbed fever and with discourses against my theories. […] The medical literature for the last twelve years continues to swell with reports of puerperal epidemics, and in 1854 in Vienna, the birthplace of my theory, 400 maternity patients died from childbed fever. In published medical works my teachings are either ignored or attacked. The medical faculty at Würzburg awarded a prize to a monograph written in 1859 in which my teachings were rejected".

In a textbook, Carl Braun, Semmelweis's successor as assistant in the first clinic, never accepted Semmelweis' teachings.
The impact of Braun’s views is clearly visible in the rising mortality rates in the 1850s.

Beginning from 1861 Semmelweis suffered from nervous complaints. He turned every conversation to the topic of childbed fever.

A number of unfavorable foreign reviews of his 1861 book prompted Semmelweis to lash out against his critics in series of open letters written in 1861-1862. He bitterly attacked various prominent European obstetricians. The open letters were highly offensive, at times denouncing his critics as irresponsible murderers or ignoramus. The attacks undermined his professional credibility.

In mid-1865, his public behavior became irritating and embarrassing to his associates.

On 30 July 1865 Ferdinand von Hebra lured him to a Viennese insane asylum located in Lazarettgasse. Semmelweis surmised what was happening and tried to escape. He was severely beaten by several guards, secured in a straitjacket and confined to a darkened cell He died after two weeks, on 13 August 1865, aged 47, from a gangrenous wound, possibly inflicted by the beating. The autopsy revealed extensive internal injuries, the cause of death pyemia - blood poisoning. In maternity clinics this would have been called childbed fever

(In documentary I watched they indicated that when Semmelweis realized he would be locked up and never released he broke free and would not let any one or any force stop him from making it to a part of the hospital where he knew he could find pus covered medical instruments which he used to cut himself. The beating occurred as they tried to stop him. Then as they dragged him away he told them that puerperal fever was not a weakness in women but was in the pus and he told them accurately how he would die from it. He hoped that if the Drs watched him die from childbed fever after cutting himself that they would get the connection, they didn’t but he had described accurately in advance how he would die)

A few medical periodicals in Vienna and Budapest included brief announcements of Semmelweis's death. The rules of the Hungarian Association of Physicians and Natural Scientists specified that a commemorative address be delivered in honor of each member who had died in the preceding year. For Semmelweis there was no address; his death was never even mentioned

Janos Diescher was appointed Semmelweis' successor at the Pest University maternity clinic. Immediately mortality rates jumped sixfold to to six percent. But there were no inquiries and no protests; the physicians of Budapest said nothing. Almost no one - either in Vienna or in Budapest - seems to have been willing to acknowledge Semmelweis's life and work

Semmelweis' advise on chlorine washings was probably more influential than he realized himself. Many doctors, particularly in Germany, appeared quite willing to experiment with the practical handwashing measures that he proposed, but virtually everyone rejected his basic and ground-breaking theoretical innovation - that the disease had only one cause, lack of cleanliness.

On a broader scale, to a contemporary reader, Semmelweis would appear to have demonstrated glaringly evident experimental evidence, that chlorine washings reduced childbed fever. Today, it may seem absurd that his claims were rejected, precisely on the grounds of purported lack of scientific reasoning, or what today would be called a scientific proof. It is equally absurd that his unpalatable observational evidence only became palatable when quite unrelated work by Louis Pasteur in Paris some 20+ years later suddenly offered a theoretical explanation for Semmelweis' observations - the germ theory of disease.

Semmelweis is now recognized as a pioneer of antiseptic policy

Yet a legacy is the so-called Semmelweis reflex. It is not a "real" physiological reflex but a metaphor for a certain type of human behavior characterized by reflex-like rejection of new knowledge because it contradicts entrenched norms, beliefs or paradigms - named after Semmelweis whose perfectly reasonable hand-washing suggestions were ridiculed and rejected by his contemporaries.