Saturday, November 26, 2005

Transvaginal Eggs Retrieval

You've probably read reports of South Korean cloning pioneer Hwang Woo-suk's resignation:

After more than a year of denying rumors that some eggs used in his experiment came from subordinate scientists, Hwang on Thursday acknowledged two scientists in his Seoul lab donated their own eggs for research.

He also acknowledged he had recently found out a hospital doctor paid some women for their eggs, and stepped down as director of the World Stem Cell Hub that he and international researchers announced just last month.

I haven't followed the story closely enough to comment on it. [As a general opinion, principals shouldn't donate eggs, sperm, or any type of tissue; it's best to avoid the appearance of impropriety. On the other hand, I can understand, and sympathize with, the researchers' zeal.]

In any case, I thought you might be interested to know what is involved in one of the steps of the donation process--the eggs retrieval procedure.

Here is a review of assisted reproductive technology, with some background on the types of procedures used to retrieve eggs:

The 3 basic ways to retrieve oocytes [eggs] are laparoscopically, transabdominally, or transvaginally. The laparoscopic approach was used frequently in the 1980s, especially if a GIFT* procedure was planned. The quality of ultrasonography images was still improving. Often, only the follicles that could be seen on the surface of the ovary were removed, and, if the ovary was very mobile, traction was required to support the ovary as the follicles were aspirated. Associated morbidity occurred with the procedure, which included infection and injury to the pelvic organs. General endotracheal anesthesia was usually used, and the patient's recovery often lasted 2-3 days. As the quality of ultrasonography images and culture media improved, the need for laparoscopy decreased.

The laparoscopic approach has fallen out of favor because of its associated morbidity and need for general endotracheal anesthesia. Laparoscopy is technically more difficult, especially if the ovary is very mobile.

In 1981, ultrasound-guided aspiration was first described. Initially, the transabdominal approach was used, usually with the aspirating needle going through the bladder, which, when full, provided a window of visualization for the person operating the abdominal ultrasound probe. Although still used for retrieval of oocytes from ovaries that are adhered high up in the pelvis or to the fundus [top] of the uterus, the transabdominal approach was superseded by the transvaginal approach. The first transvaginal retrieval was performed in 1984 and has now become the procedure of choice because of its ease and low morbidity.

*GIFT (gamete intrafallopian transfer): 3-4 oocytes are placed via laparoscopy into one of the fallopian tubes along with sperm.

And here is a description, with a good drawing, of the transvaginal retrieval procedure currently used for egg donations. This is a minimally invasive, outpatient procedure:

The oocyte retrieval is performed via transvaginal guidance, under ultrasound monitoring, using very thin needles (16-18 g) which reach the follicles through a simple perforation of the vaginal surface.

During this surgical procedure, the patient is kept under sedation [IV]; therefore the procedure is safe and pain-free. All the follicles found are then aspirated (together with eventual ovarian cysts which could have developed during the stimulation phase) and the fluid retrieved is immediately examined at the microscope in order to detect the egg-cells (oocytes).

As you can see from the drawing, the needle (2) is inserted through an area of the vaginal wall a bit behind the cervix, and the tip of the US probe (1) rests on the wall. The needle insertion is not painful. In fact, this part of the egg retrieval procedure is similar to a culdocentesis--a technique occasionally used to check for blood (from a ruptured ectopic) in the posterior cul-de-sac. The procedure is usually performed in the ER, without anesthesia, and with minimal discomfort to the patient.


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