['To assess the effectiveness of outpatient treatment of Ovarian Hyperstimulation Syndrome associated with ascites.', 'Forty-eight patients diagnosed with ovarian hyperstimulation and ascites from 2,246 consecutive in vitro fertilization cycles were retrospectively studied. Patients were treated with outpatient transvaginal culdocentesis and rehydration with intravenous crystalloids and albumin every 1-3 days until resolution of symptoms or hospitalization was required. Outcomes measured included incidences of hospitalization, pregnancy outcomes, cycle characteristics, and oocyte donors versus nondonors comparisons.', 'No complications occurred from outpatient treatments, and 91.6% of patients avoided hospitalization. The pregnancy rate in patients undergoing transfer was 84.7%, and the spontaneous loss rate was 16%. Overall, the estradiol on day of hCG was 4331 pg/mL (range 2,211-8,167), ascites removed was 1910 cm3 (122-4,000), and number of outpatient treatments was 3.4 (1-14). Nondonors averaged more outpatient treatments than donors (3.97 vs. 1.85), but similar rates of hospitalization (3/35 vs. 1/13).'] Does aggressive outpatient treatment of ovarian hyperstimulation syndrome with ascites using transvaginal culdocentesis and intravenous albumin minimize hospitalization?