Your treatment may be cancelled for several reasons:
1. The ovaries may respond inadequately and the treatment is cancelled prior to egg retrieval.
2. Despite the presence of follicles no eggs may be retrieved. The reason for this is two-fold. The follicles may contain no eggs (empty follicle syndrome). This is seen in < 1% of the patients. The follicles may prematurely rupture prior to egg retrieval procedure. This is seen in 3-5% of the patients depending on the stimulation protocol.
3. The eggs may not fertilize. This is very rare in the microinjection era. However in approximately 2-5% of the patients no fertilization may be seen due to abnormal eggs.
4. Fertilized eggs may not cleave. This is also very rare and due to abnormal eggs.
5. Azospermic husband may not yield spermatozoa to needle aspiration or open biopsy. In this case the treatment is cancelled prior to egg retrieval.
6. No normal embryos if PGD is performed. In this case embryo transfer is not performed.