Empty Follicle Syndrome (EFS)

Definition - What does Empty Follicle Syndrome (EFS) mean?

Empty follicle syndrome (EFS) occurs when no eggs are collected during egg retrieval even though lab values and ultrasound indicate the presence of many mature follicles in women undergoing in vitro fertilization (IVF). The exact mechanism of this uncommon phenomenon is unknown although once EFS occurs the risk of reoccurrence increases significantly, decreasing the probability of successful IVF treatment.

FertilitySmarts explains Empty Follicle Syndrome (EFS)

EFS occurs in 0.2–7% of IVF treatment rounds with its cause likely being multifactorial. Maternal age is a risk factor for EFS with older women experiencing EFS at a higher rate. Premature ovarian failure or low ovarian reserve may also increase the risk of EFS.

EFS may also occur if the injection medication used to mature the eggs (trigger shot) in IVF is mistimed. If the injection is administered too early before egg retrieval it is possible for the eggs to have already ovulated and left the follicles.

Once EFS has occurred, the risk of recurrence in subsequent IVF cycles is 20%. This risk increases as the age of the patient increases, with a risk of recurrence of <10% in patients over 35 years, 24% for those between 35 and 39 years, and 57% for those over 40 years of age.

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