The detrimental role of colloidal volume substitutes in severe ovarian hyperstimulation syndrome: a case report.

Although, the mechanisms for the development of ovarian hyperstimulation syndrome (OHSS) are still not clear, the symptoms usually correlate with the levels of serum estradiol and ovarian enlargement. We report a case, where the clinical course was unusually prolonged. When menstrual bleeding had already occurred, serum estradiol was less than 10 pg/ml and the ovaries were almost normal in size, the patient developed pleural effusion and a significant alteration in blood-coagulation. This was most likely caused by an over-infusion of hydroxyethyl starch (HES) over 10 days. The pleural effusion contained high levels of HES, reaching 74% of the plasma concentration as measured by a novel method after acidic hydrolysis of HES. Carbohydrates as dextran and HES are well known to interact with the blood-coagulation system. Increase capillary permeability, typical of OHSS, leads to loss of colloidal substances into the third space, where HES is slowly degraded and osmotic pressure is high. This might prolong and aggravate the urine of OHSS.