Split and simplify the following sentence while retaining its full meaning: In serious , but rare cases , an ovarian hyperstimulation syndrome with clearly enlarged ovaries , can go hand in hand with possible accumulation of fluid in the abdomen or thorax as well as more serious thromboembolic complications .
 Simplified version:
233 be practiced as soon as possible . In severe but rare cases , ovarian hyperstimulation syndrome with enlargement of the ovaries may be accompanied by a possible accumulation of fluid in the abdomen or thorax as well as more serious thrombosis complications .