Late-onset ovarian hyperstimulation syndrome developing during ovarian stimulation in an ectopic pregnancy: a case report

Ovarian hyperstimulation syndrome is normally induced by ovarian stimulation drugs. Severe cases of ovarian hyperstimulation syndrome involve complications such as renal failure and thrombosis. Evidence has recently been developed for a method to prevent ovarian hyperstimulation syndrome. Most cases of ovarian hyperstimulation syndrome are of an early-onset type, which occurs shortly after injection of human chorionic gonadotropin. However, late-onset ovarian hyperstimulation syndrome, which occurs in a pregnancy cycle, also requires caution. We report our experience in treating a woman who was transported to our hospital with a severe case of ovarian hyperstimulation syndrome occurring during ovarian stimulation and who was determined to have an ectopic pregnancy. Assisted reproductive technology was planned for a 29-year-old nulligravida Japanese woman diagnosed with bilateral fallopian tube obstruction and right-sided hydrosalpinx. On day 1 of controlled ovarian stimulation, the result of her human chorionic gonadotropin urine test was negative, and her serum levels of luteinizing hormone, estradiol, and progesterone were normal. On day 11 of controlled ovarian stimulation, the levels of estradiol and progesterone had risen to 9679 pg/ml and 16 ng/ml, respectively, prompting suspension of controlled ovarian stimulation. Eleven days after controlled ovarian stimulation was suspended, the patient demonstrated ascites that did not improve despite administration of cabergoline, and she was transported to our hospital 2 days after. Late-onset ovarian hyperstimulation syndrome suggested that she was pregnant, and her serum human chorionic gonadotropin level was 27,778 IU/ml. She underwent laparoscopic bilateral salpingectomy and was diagnosed with right tubal pregnancy. In an ectopic pregnancy, human chorionic gonadotropin sometimes increases later than in an intrauterine pregnancy. In our patient's case, endogenous human chorionic gonadotropin following the start of controlled ovarian stimulation may have caused late-onset ovarian hyperstimulation syndrome. The key to early detection of similar cases may be to suspect pregnancy in the event of unexpectedly high progesterone levels during ovarian stimulation.