Case report describes aHUS diagnosis of pregnant woman
22-year-old in 2nd trimester went to hospital with headache
Researchers in Mexico described the series of events that led to a diagnosis of atypical hemolytic uremic syndrome (aHUS) in a 22-year-old pregnant woman.
The case highlights the need for vigilance, as well as prompt diagnosis and treatment, they said. The report, “Pregnancy-associated atypical hemolytic uremic syndrome. Case report,” was published in the Journal of Obstetrics and Gynaecology Research.
aHUS belongs to a group of disorders called thrombotic microangiopathies, or TMAs. These disorders are marked by the formation of blood clots inside small blood vessels that can damage internal organs, especially the kidneys. Patients typically show signs of red blood cell destruction and have low platelet counts as well.
In most cases, aHUS is associated with mutations in genes that regulate the complement cascade, resulting in its abnormal activation. The complement system comprises a set of proteins that are part of the body’s immune defenses.
aHUS rare during pregnancy
Mutations alone are usually not enough to cause aHUS to develop. Generally, an event trigger, such as an infection or pregnancy, is necessary to induce the onset of the disease. In the case of pregnancy, most reports of aHUS occur during the postpartum period, the time following birth.
The woman in the case report was in the 26th week of her second pregnancy when she went to a hospital with a generalized, throbbing headache. Her attending physician prescribed aspirin and paracetamol, which partially relieved her symptoms.
However, one day later, she developed a fever. Her doctor prescribed the antibiotic cephalexin, but it had no effect. Her urine output was reduced, and she had petechiae — tiny spots of blood — on the palms of her hands and inner thighs.
Tests showed she had low blood pressure and tachycardia, or a fast and abnormal heart rhythm. Blood work revealed the presence of mild anemia, a severely low platelet count, and protein in her urine. Additional signs of liver and kidney damage were also detected.
The woman was transferred to another hospital. She was drowsy on arrival and was admitted to the obstetric intensive care unit, where she received treatment with a vasopressor, a type of medication used to increase blood pressure. An ultrasound indicated the baby’s growth was being restricted.
Due to suspicion of TMA, she received dexamethasone every 12 hours, but two days later she had vaginal bleeding and her platelet count dropped even further. Eventually, she had a spontaneous abortion.
aHUS diagnosis confirmed after blood tests
Additional blood tests revealed the presence of red blood cell fragments (schistocytes). Activity levels of the enzyme ADAMTS13, typically very low in a type of TMA called thrombotic thrombocytopenic purpura, were at 67%. She was negative for Shiga toxin, a compound that can indicate the presence of typical HUS when detected.
Overall, these signs confirmed the diagnosis of aHUS. She was then prescribed six plasmapheresis and six hemodialysis sessions. Her platelet counts improved following the plasma exchange sessions, but her kidney dysfunction remained.
On the eighth day of her hospital stay, she tested positive for methicillin-resistant Staphylococcus aureus (MRSA), a bacteria that is resistant to many of the antibiotics usually used to treat ordinary staph infections. She also had a urinary tract infection.
She received intravenous (into-the-vein) antibiotic treatment with vancomycin for MRSA, along with a seven-day course of the broad spectrum antibiotic imipenem.
By day 14, she was diagnosed with severe inflammation of the inner lining of the large intestine caused by the Clostridioides difficile bacterium. She received treatment with oral and intravenous vancomycin for eight days.
By day 18, treatment with Soliris (eculizumab) was initiated. After the first dose, her levels of kidney dysfunction markers started to drop and she no longer required hemodialysis.
She was discharged after 97 days in the hospital. A follow-up consultation confirmed she had mild to moderate chronic kidney disease, but treatment halted its progression and prevented the need for a kidney transplant.
“aHUS remains a rare disorder, with clinical features overlapping with other pregnancy-related conditions causing diagnostic delays,” the researchers wrote. “Early diagnosis and early treatment are extremely important for the prognosis, posing a genuine challenge for physicians.”
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