Tuesday 30 October 2007

Oocyte Retrieval (Follicle Puncture)

The first IVF baby was born as a result of collecting an egg by laparoscopy. Patrick Steptoe had pioneered the use of the laparoscope in gynaecology - a procedure which is now used extensively but was considered in the late 1970's to be 'a dangerous procedure'. Patrick Steptoe and Robert Edwards achieved the first IVF birth on July 25th 1978, although they had achieved an ectopic pregnancy some time before that. That pregancy was the result of a single egg being collected. The photographs on the right (taken by Patrick Steptoe down the laparoscope) shows a single follicle as a shiny structure towards the bottom left of the ovary. We ocassionally have to yet resort to laparoscopic oocyte retrievals when the ovaries are not accessible with transvaginal ultrasound eg. Meyer-Rokitansky-Kustner-Hauser Syndrome.
Oocyte retrieval is performed approximately 34-36 hours after the hCG injection, immediately before each follicle releases its oocyte. Oocyte retrieval involves a short procedure (lasting 20 to 45 minutes depending on the number of follicles having reached maturity) which is performed transvaginally under ultrasound control (the same way as during the ultrasound monitoring during the stimulation phase). There is therefore no incision or scar involved since the needle is inserted in each follicle by puncturing the ovary directly through the lateral wall at the top of the vagina. Each follicle is punctured and emptied of its fluid by aspiration. The eggs are collected through the vagina under ultrasound control, using a fine needle that is passed through the vagina into the ovary. Fluid from the follicles is sucked through the needle into a test tube and is passed immediately to the adjacent laboratory where the scientist checks for eggs under the microscope. After each aspiration, the sterile test tube containing the aspirated fluid is forwarded to the IVF laboratory, which will do a microscopic search of the fuid for the presence of oocytes. Most eggs are reasonably easy to find as a jelly like mass of cells known as the cumulus surrounds them(see picture). The eggs are then placed in culture fluid (a water based salt solution with added nutrients) in special dishes and put into the incubator at body temperature. If no oocyte is identified, repeated rinsing of the follicle with some millilitres of culture medium generally permits recovery of the oocyte. Oocyte retrieval can be done under a light general anesthesia (usually Propofol) at Rotunda.
The procedure takes 15-30 minutes and most women will have one or several eggs recovered. It is rare for no eggs to be found. After OPU the woman usually remains in the recovery area for about two hours before discharge. Due to the drugs used during the procedure, driving for the next 24 hours is not advisable. Your co-ordination and perception may be impaired and insurance companies may decide not to cover claims that occur during this time. It is not unusual to have some vaginal bleeding, from where the needle passes through the vaginal wall, for the next 24 hours. Mild lower abdominal cramping for the next day or two, due to swelling of the ovaries, is also common and paracetamol can safely be used.

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