Dosage of the trigger
Many clinicians face the risks of OHSS in women with more follicles. They deliberately pick to reduce the dosage of HCG administered as trigger shot. Doing so considerably reduces the chance of growing critical OHSS. However, a low dose of HCG (5,000 units) is in all likelihood to be insufficient to optimize the performance of meiosis, mainly when there are numerous follicles.
HCG trigger shot mistakes
In few cases when the trigger injection is given in a lower dose it does not yield eggs. This condition is called Empty follicle syndrome. Empty follicles are more common in elderly patients with poor ovarian reserve, in a flare protocol or inadequate dosage.
At times, a break in the cold chain makes the drug ineffective. If there are errors in mixing or spill during administration desired effects are not achieved. Hence, EFS phenomenon can be due to premature ovulation, low ovarian reserve, or hCG-related errors.