Kathy Harris, at 49, had known pain. She had given birth before epidurals were fashionable. She’d had a hole pushed through her navel for a tubal ligation. And she had broken a tibia eight years earlier, the last time she’d been skiing. But the agony that brought her to the hospital’s emergency department was different. It made her think of death and want it.

Nonetheless, she managed a bit of humor when I met her, four days after the worst of her ordeal. I am a gynecologic surgeon, and when I asked her to describe her pain during that time, she gave me a look that said there are some things a male doctor will never understand. “Ever been stabbed in the vagina?” she asked. “I felt the point go through and come out my left groin.”

The sudden pain had knocked her to her knees, and she’d lain on her kitchen floor, leaning on her elbows and staring at the vomit running off her hands, thinking how undignified she was and not giving a damn.

Her husband picked her up off the ceramic tiles and put her on the sofa until the paramedics came. He had been as gentle as he could be, but he looked sheepish when she told me how he’d stumbled on the rug and dropped her onto the cushions. She held herself still while the ambulance crew swung her onto the gurney, the gurney bumped down the steps, and the ambulance pulled away. She hadn’t flinched, because flinching only made the knifing pain worse. As the ambulance rounded corners and stopped and started and jolted its way to the hospital, she could focus on nothing but the awful sensations. She was suddenly a connoisseur of pain.

Inside, the staff made quite a fuss over Mrs. Harris. The resident who saw her first was struck by the way she jumped and cried out not when he pushed down on her belly but when he released the pressure. He called in the attending physician for the emergency department, who remarked about the same thing, as did the gynecology resident, the radiologist who did her ultrasound scan, and the gynecology attending physician. That sort of pain, called rebound tenderness, is a sign of inflammation around a ruptured or dying organ. Thirty years ago that sign would have led a patient straight to the operating room. But pain is a nonspecific symptom, and rebound tenderness is a crude, unquantifiable finding. Doctors often under­value these signs, preferring to focus instead on the precision of laboratory values and the hard images of scans.

Mrs. Harris’s scan revealed that her left ovary was at least three times the normal size. It filled her left pelvis. The ultrasound images were mottled, showing lakes of liquid among solid tissue. Many things can cause that picture. Ovarian cancer, which has nonspecific symptoms that mimic many conditions, is the worst of them. But ovarian cancer is usually insidious, painful only when a growing tumor ruptures the ovary. Another possibility is a benign tumor of fibrous tissue, enlarged by pregnancy or hormonal disorders. Or the cause can be ovarian torsion, the twisting of an ovary around its stalk, the source of its blood supply. All the findings —sudden onset, severe pain, a tender mass, and extreme rebound tenderness—pointed to ovarian torsion.

Yet the ultrasound images hinted at something different. Ultra­sound scanners image organs by emitting ultrahigh frequency waves that are reflected back to the probe at different frequencies depending on the speed of blood flow in the organ (the Doppler effect). The results showed that blood was flowing in the ovary, and medical dogma says that the pain of ovarian torsion arises when the ovary dies, deprived of oxygen by a twist that cuts off its vascular supply. Given that interpretation, Mrs. Harris didn’t go to surgery, despite the ominous rebound tenderness. Instead she received narcotics and intravenous fluids, and within a few hours she began to feel better; her pain subsided and her nausea passed. Except for a lump the size of a cantaloupe against her left hip—revealed in the ultrasound—she felt good, and she was discharged with a follow-up appointment to investigate the lump.

It was during her follow-up visit that I learned all the details of Mrs. Harris’s case. Now, although her pain had ebbed to a dull ache, the ovarian mass was still present. As a gynecologic surgeon, my job was to find out if the lump in the ovary was cancerous and, if it was, to cut it out. The lump was not the only worrisome sign. Her blood showed a higher than normal amount of CA-125, a protein produced by cells that line body cavities and by the cancers derived from them, especially ovarian cancer.

We operated the following week to find out what was going on. I made a vertical incision in her abdomen, which would allow access to other organs if necessary. What I found was a dead ovary, its vascular stalk twisted like an old rope. Instead of having the white color and hard texture of a normal ovary, Mrs. Harris’s ovary was a spongy, blue-black mass, filled with old clot and already attached by scar tissue to the pelvic wall. There was no sign of cancer. We removed the mass, then stitched up the five-inch incision. Mrs. Harris was home in two days and back to work in a month. The pathology report showed no evidence of cancer.

How and why ovarian torsion develops is unclear. It is unusual but not rare, accounting for roughly 3 percent of gyne­cologic emergencies. In humans the male and female gonads originate early in prenatal development from cells near the kidneys, but they migrate—in males to the scrotum, in females to the pelvis. The ovaries are loosely tethered to the spine by their elongated blood supply, and ligaments connect them to the uterus. Interruption of those ligaments, through either hysterectomy or tubal ligation, as in Mrs. Harris’s case, appears to make a woman more vulnerable to ovarian torsion. Changes within the ovary can also play a role. Ovaries with torsion are often found to have cysts in them, and a large cyst may unbalance an ovary, causing it to twist around its stalk.

Once the twist occurs, blood cannot drain out of the ovary through its veins, yet arterial blood, which flows at a higher pressure, continues to pour in. If a woman has surgery at this point, the ovary can be untwisted and saved; this can be done laparoscopically, and the ovary can be held in place by stitches to prevent torsion from happening again. Unless the twist is undone soon after it occurs, however, the ovary becomes so swollen with blood that it cannot accept any more. The ovary dies. One result is intense pain, from the ovary itself and from the surrounding pelvic lining, which grows inflamed from the decay of the dying organ. That peritoneal inflammation can cause buildup of fluids in the abdomen and release of CA-125, even in the absence of cancer. Eventually the nerves of the ovary die, the inflammation subsides, and the pain wanes. In Mrs. Harris’s case, the ultrasound images had shown blood flow, so the doctors had drawn the conclusion that the ovary was alive. More likely what they were seeing was blood still flowing shortly after the torsion occurred.

At her postoperative visit, Mrs. Harris was free of pain, but her sense of humor persisted: As she went through the door leaning on the arm of her still-sheepish husband, she reminded him that torsion also occurs in testicles.

Stewart Massad is a professor of gynecologic medicine at Washington University in St. Louis. The cases described in Vital Signs are real, but names and other details have been changed.