Case Report: Uterine Fibroid Surgery Triggers aHUS in Woman

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by Steve Bryson, PhD |

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Uterine fibroid surgery triggered atypical hemolytic uremic syndrome (aHUS) in a woman without disease-related genetic defects, a case study reported.

Clinicians should investigate conditions such as aHUS after major gynecologic surgery accompanied by kidney impairment and abnormal lab tests indicating red blood cell damage to prevent irreversible kidney disease, even though the disease is rare, its authors recommended.

The study, “Atypical hemolytic uremic syndrome after myomectomy: A case report,” was published in Case Reports in Women’s Health.

Thrombotic microangiopathy (TMA) is a group of conditions marked by widespread blood clot formation in small blood vessels, leading to the destruction of red blood cells — a process referred to as hemolytic anemia — and organ damage.

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8 Cases of aHUS Linked to Underlying, Complement-activating Conditions

aHUS is a rare form of TMA caused by the uncontrolled activation of the complement pathway — a part of the immune system that helps defend the body from invaders — resulting in the formation of tiny blood clots, hemolytic anemia, and kidney impairment.

Mutations in genes that encode proteins that control the complement pathway may predispose a person to develop aHUS, but that does not mean the disease will occur. A complement-activating event may trigger the onset of the disease in people with or without mutations. Possible trigger events include pregnancy, infection, exposure to certain medications, and surgery.

Researchers at Weill Cornell Medicine, New York described the case of a 42-year-old woman who developed aHUS following a myomectomy to remove uterine fibroids, or noncancerous growths in the uterus.

Before surgery, her level of hemoglobin — the protein in red blood cells that carries oxygen throughout the body — was slightly under the normal range (11.2 g/dL; normal range: 11.6–15.0 g/dL), and lab tests showed no abnormalities in kidney or liver function. The surgery successfully removed at least 10 fibroids.

During surgery, however, her urine output decreased and it stopped five hours after the procedure. While lab tests showed an expected drop in hemoglobin due to surgical blood loss, she had abnormally low platelet levels and acute kidney injury, as determined by high levels of creatinine, a marker for kidney dysfunction.

The next day, although the woman’s urine output improved, her hemoglobin did not rise as expected, and her platelet counts and kidney function worsened. CT scans of blood vessels showed no indication of bleeding and a kidney ultrasound showed no blockages.

More tests revealed she had very low levels of haptoglobin, a sign of hemolysis, along with high levels of LDH, a marker of tissue damage. She also had elevated reticulocytes (immature red blood cells), indicative of anemia, and red blood cell fragments. These findings raised the suspicion for TMA.

Two days after surgery, the woman began daily plasma exchange due to the risk of thrombotic thrombocytopenic purpura (TTP), a form of TMA also marked by blood clots forming in small blood vessels. This treatment improved her kidney function and urine output.

The woman remained stable with normal levels of markers for blood clot formation and no signs of bleeding and, after five days, her platelet counts improved. At the same time, tests showed she had normal activity levels of ADAMST13, an enzyme involved in blood clotting whose levels are abnormally low in TTP. These results suggested aHUS.

By day six, her platelet counts improved further and creatinine normalized, but markers for hemolysis, including LDH and haptoglobin, continued to get worse, which was “concerning for ongoing hemolysis,” the researchers noted.

A punch biopsy of normal-appearing skin tested positive for the complement protein C5b-9 in blood vessels of the dermis and other subcutaneous tissues, consistent with a diagnosis of aHUS. Notably, genetic testing found no complement-related mutations.

The woman was started on the approved aHUS therapy Soliris (eculizumab) 12 days after surgery. She was discharged from the hospital on day 14 with stable hemoglobin and platelet counts, improved hemolysis markers, and normal kidney function. At least six months later, she was doing well with biweekly Soliris treatment.

“While two reports have described the development of aHUS following myomectomy, our case demonstrates very quick recognition of complement-mediated TMA,” the researchers wrote. “This patient is the first to our knowledge to have extensive complement deposition confirmed on tissue biopsy to support the diagnosis of surgery-induced aHUS.”

“While extremely rare, TMA should be suspected in patients after myomectomy and other major gynecologic surgery with [acute kidney injury] and laboratory abnormalities demonstrating hemolysis, as early diagnosis and treatment can prevent irreversible renal injury and death,” the researchers wrote.