In 1920 the Chicago obstetrician Joseph Bolivar DeLee, in a paper titled “The Prophylactic Forceps Operation,” urged physicians to cut the perineum of laboring women as a routine to spare them the worse damage of a ragged spontaneous tear — and the gap between that protective promise and the eventual evidence is the entire case. By the late twentieth century the operation DeLee reasoned his way into was one of the most common surgical procedures performed on American women, done on the order of a third of all vaginal deliveries (60.9% in 1979) and on a clear majority of first-time mothers, almost none told there was no trial behind it.
The justification was intuitive: a clean, controlled incision must heal better than a jagged laceration, and a pre-emptive cut must protect the pelvic floor against future prolapse and incontinence. The intuition was wrong in the most consequential way. When the procedure was finally tested against the comparator it had skipped for decades — selective use, cutting only on indication — the routine cut did not prevent severe trauma. A midline episiotomy extended the wound straight toward the anal sphincter and rectum, so the prophylactic incision was itself causally linked to the third- and fourth-degree tears it was meant to forestall.
The reckoning was slow because the practice was entrenched, not because the data were ambiguous. A 1983 interpretive review of more than 350 sources spanning 1860 to 1980 found no defensible evidence for routine use; the 1993 Argentine Episiotomy Trial, a randomized study of 2,606 women, showed routine use conferred no benefit and more harm; and the 2005 AHRQ-commissioned systematic review in JAMA closed the question, finding routine episiotomy improved no immediate outcome and prevented no incontinence or prolapse. In April 2006 the American College of Obstetricians and Gynecologists issued Practice Bulletin No. 71, recommending the routine be restricted. The procedure was not banned — it retains narrow, evidence-based indications — but its eighty-year career as a default was abandoned. It stands as obstetrics’ cleanest case of a plausible, near-universal intervention adopted on reasoning and reversed only by the trial that should have come first.
For roughly the first three-quarters of the twentieth century, tonsillectomy was the most frequently performed operation in the United States — a near-compulsory rite of childhood scheduled on the order of a million-plus times a year for sore throats, “mouth breathing,” poor appetite, and the vague proposition that a child would simply be healthier without tonsils; the gap between that universal promise and the evidence is the entire case, because the operation was never shown to deliver the broad benefits claimed, killed a measurable number of the children it was sold to protect, and for a period in the 1940s demonstrably raised the risk of paralytic polio. At its 1959 peak roughly 1.4 million tonsillectomies were performed annually in the U.S., the overwhelming majority on children, and by mid-century an estimated 30 percent of American children had lost their tonsils — many to surgeons who, examined honestly, could not say why.
The procedure rode the “focal infection” theory: the early-twentieth-century belief that lurking pockets of chronic infection in the tonsils seeded disease throughout the body and were best excised pre-emptively. On that theory the indication became, in practice, the mere possession of tonsils. The surrogate that justified the knife was not a measured health outcome but a clinical impression — the tonsils “looked enlarged” — and impressions, it turned out, were nearly random. In 1934 the American Child Health Association sent 1,000 New York schoolchildren through successive examinations and found 61 percent had already been tonsillectomized; of the remaining 39 percent, physicians recommended surgery for all but 65, then for nearly half of those who had just been cleared, and again for nearly half of that residue — a recursive demonstration that the indication lived in the examiner, not the child.
The disconfirming evidence accumulated for forty years before the practice yielded. James Alison Glover’s 1938 study showed English tonsillectomy rates varying by an order of magnitude between districts with no relation to disease — the founding observation of “unwarranted variation,” still called the Glover phenomenon. From 1942 onward, epidemiologists documented that children tonsillectomized shortly before exposure to poliovirus suffered the deadly bulbar form at multiples of the background rate. And in 1984 the first rigorous randomized trial, by Jack Paradise in the New England Journal of Medicine, found a real but narrow benefit only for the most severely and frequently infected children — a tiny slice of those who had been operated on for decades. The operation was not banned. It was restricted, its indications tightened, its volume cut by more than half, retired from routine use by evidence that arrived long after the harm.