To the editor:
The hemolytic uremic syndrome (HUS) is an acute and potentially fatal form of thrombotic microangiopathy, with an incidence of 17.2 new cases/per million population/year. Seven percent of the cases are associated to oral contraceptive treatment, pregnancy and puerperium. Puerperium-related cases have the worst prognosis, as renal replacement treatment is often required.1 The plasmapheresis is elective, as it is the only therapy, that has shown to improve the survival by 80%-90%2,3 and the prognosis of the renal involvement.
We present a 20 year-old Caucasian woman in her first pregnancy that underwent a cesarean at 41st week because the delivery did not progress. The baby was a healthy male. On the 10th day after the delivery she was evaluated because of lumbar and hypogastric pain and fever of 38.5 ºC. Blood parameters were: urea 224.6 mg/dL, creatinine 6.46 mg/dL, albumin 2.9 g/dL, hemoglobin 5.9 g/dL, 16% of schistocytes in peripheral blood, haptoglobin undetectable, LDH 4.162 U/L, and platelet count 104 x 109/L. The urinalysis showed proteinuria 20 g/24-hours with normal sediment. D-dimers determination was 16.381 mcg/L and for this reason an MRI without contrast was performed that ruled out renal vein thrombosis. The gynecologic exam showed placental remnants in the uterus, she was diagnosed with endometriosis and a uterine scraping was performed.
Sixty-two to seventy-four percent of pregnancy-related HUS cases occur at the end of the pregnancy. Differential diagnosis should be made with hypertensive conditions of the pregnancy, which produce symptoms that do not last more than 3 days after the delivery. Persistent or worsening symptoms beyond the third day of the puerperium decrease the probability of spontaneous recovery and strength the indication of plasmapheresis.5 The reported patient was on the tenth day after the delivery, and daily plasmapheresis was initiated, which had to be discontinued, first because of allergy to infused plasma and definitively because of acute pulmonary edema that prompted mechanical ventilation.
The patient had severe hypertension, which required five drugs to be controlled. The reason could be found in the pathological study of the renal biopsy that revealed lesions typical of thrombotic microangiopathy, with severe vascular involvement, including intimal proliferation and hyperplasia, presence of glomeruloid bodies and several glomerular changes. It is known that patients with HUS and arterial involvement (with no prodromes such as bloody diarrhea), as in the present case, have a worse prognosis than those who only have glomerular involvement (and prodromal bloody diarrhea).6
Despite appropriate treatment renal function was not recovered and the patient required chronic hemodialysis. The risk of recurrence in further pregnancies is high, and chronic renal failure is the most important consequence, which happens in 25% of the cases.
The pathophysiological hypothesis is a deficiency of the ADAMTS13 proteinase, which degrades the serum polymers of von Willebrand factor, due to the high levels of estrogens during the pregnancy, particularly at weeks 36-40.8,9 Anyway we cannot rule out that the endometriosis could be an infectious cause of HUS in this patient.
This case illustrates the difficulty to manage HUS in the puerperium, especially regarding the differential diagnosis and management.
