Problem: The presence of interleukin-18 (IL-18) in serum and pre-ovulatory follicular fluid (FF) and its possible correlation to in-vitro fertilization/embryo transfer (IVF/ET) outcome and ovarian hyperstimulation syndrome (OHSS) development.
Method of study: A prospective study was carried out. Assays for serum and pooled pre-ovulatory FF levels of IL-18 were performed on 30 patients who underwent oocyte retrieval for IVF/ET.
Results: Mean serum and FF levels of IL-18 were 370.4 +/- 224 and 228.9 +/- 208 pg/mL, respectively (r = 0.77, P < 0.0001). Levels of FF IL-18 were comparable between the two ovaries (right = 221 +/- 166.8 pg/mL, left = 237 +/- 171.9 pg/mL; r = 0.7550, P = 0.49). A positive correlation was found between IL-18 FF levels and number of retrieved oocytes (r = 0.45; P = 0.019). In three patients (10%) who developed OHSS, the mean serum level of IL-18 at day of ovum pickup was significantly higher compared with patients without OHSS (620 +/- 196 pg/mL versus 345 +/- 251 pg/mL, respectively, P = 0.04).
Conclusions: Both pre-ovulatory FF and serum levels of IL-18 correlate with the number of retrieved oocytes. The serum IL-18 level at day of ovum pickup may predict consequent development of OHSS. Further investigations are warranted to determine the role of IL-18 in the folliculogenesis and OHSS pathogenesis.