捐卵的安全性——一个有争议的话题

2006-10-18 00:00 来源:丁香园 作者:cplamst 译
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由美国杰斐逊城Vitae Caring基金会制作的电视广告称捐卵对女性有危险,但专家极力反驳称该广告过分夸大捐卵危险。

电视广告称捐卵对女性有危险——极富感染力的一幕

一位心烦意乱的妇女坐在床上,双手将膝抱在胸前,含泪哀叹自己当初作出的决定——向生育诊所捐卵。

“捐卵过程实在太痛苦,母亲对此很不高兴。而且,现在我又知道捐卵有可能导致肾功能衰竭、卵巢肿瘤、不育,甚至死亡。”一位捐卵的女士结结巴巴地说。接着,广告旁白告诉观众,研究早期胚胎干细胞需要数百万个卵细胞,女性将为此付出沉重的代价。

这个电视广告由杰斐逊城Vitae Caring基金会制作,是反对密苏里州干细胞研究多方运动的一部分。基金会主席Carl Landwehr称,这个电视广告是综合报道了一些捐过卵细胞的女性的真实经历。

最近几周,布告栏、电视广告、庭院告示牌以及参加教会活动后分发的小册子都在警告捐卵的危险。各种反对《修正案2》的组织称:为开展早期胚胎干细胞研究捐卵的妇女将利用,将会遭受中风、癌症和肾功能衰竭的折磨,一些人甚至会死亡。一份传单上写着:“超过35%捐过卵的人出现健康问题,许多还很严重,有些甚至会致死。”

专家驳斥该电视广告过分夸大危险——振振有辞

干细胞专家指责该电视广告过分夸大取卵手术——一项作为体外受精-胚胎移植的一部分,在美国平均每天要进行27例的手术的危险性。虽然医疗操作都需要承担风险,但专家指出,仅约1%的女性发生由超排卵药物或取卵手术导致的常见并发症,而且症状通常在两周内消失。

美国加州大学旧金山分校生殖健康及政策研究中心主任Marcelle Cedars医师称:“大约仅0.1%到0.2%接受过超排卵药物及取卵手术的女性,因并发严重问题需要接受入院治疗。对大多数捐卵女性来说,只是出现几天的胃胀气和明显的绞痛。我做了20多年的取卵手术,而我开据过止痛药的患者却是屈指可数,且都是作用不强于布洛芬的止痛药,这种疼痛不同于其他术后疼痛。而我所知道的,术后发生死亡的仅有两例,且都不是发生在美国。”

美国堪萨斯大学医学中心生殖内分泌学与体外受精计划牵头人Linda Nelson医师称:“超排卵药物和取卵手术的远期影响正在研究中。但是对捐卵、甚至多次捐卵的妇女进行长达10多年的随访并没有发现这对她们将来的生育造成影响。而且研究发现捐卵不会增加乳腺癌和卵巢癌的风险,也没有迹象表明会使绝经期提前。肾功能衰竭和血栓形成导致中风的患者几乎都是捐卵者在怀孕后服用保胎药导致病情恶化而引起。”

Cedars医师补充说:“如果捐卵者不能耐受这种不适,她们并不需要进行多次志愿捐卵。但大多数女性是乐意多次捐卵的。”Dallas卵细胞捐赠中心主任Joan Reese已经为不育夫妇配卵7年,她说:“75%的女性在身体恢复后都愿意再次捐卵。”

开展早期胚胎干细胞研究是否会增加风险——波澜再起

人卵细胞的新用途即将出现,研究人员利用卵细胞在实验室里培育成早期胚胎干细胞。卵细胞的细胞核被体细胞的细胞核所置换,这个卵细胞能够编码植入细胞核内的基因,因此它将开始像一个受精卵细胞那样进行分裂增殖。大约5天内,这个卵细胞便形成能分化为任何组织的干细胞,包括用来治疗帕金森病的脑细胞或用于治疗糖尿病的胰岛细胞。

一贯反对堕胎的Landwehr在电视广告中承认,仅少数捐卵者发生副反应。但是,他又说:“即使这种风险很小,由于捐卵的次数增加,捐卵女性的危险将随早期胚胎干细胞研究的开展而大幅度增加。”

事实上,目前捐赠的所有卵细胞都用于因年老、不育和以前的肿瘤放、化疗而不能产生活力卵细胞的妇女。除了卵细胞受精后要植入孩子的生育母亲的体内外,取卵的过程同体外受精-胚胎移植一样。 在这两种情况中,女性都需要服用超排卵药物促使多个卵细胞成熟。在生理条件下,女性每月有一批卵细胞发育,一般为5-30个不等(这由年龄和遗传因素决定)。但只有一个有代表性的发育成熟并在排卵期释放。超排卵药物能促进该月一起发育的其他卵细胞也发育成熟。这使得医生可以经阴道插入一根细针到卵巢,在超声引导下进入各个卵泡取卵。一般在全身麻醉下15分钟即可完成取卵手术,术后,捐赠者在恢复室留观几小时后即可回家。

据美国疾病控制与预防中心报道, 在2003年完成的体外受精-胚胎移植中,11.6%用的是捐赠的卵细胞。女性在2003年的捐卵次数从1997年的6643次上升到9859次。

美国生殖医学协会发言人Sean Tipton称:“大多数捐卵的副作用能够通过对捐卵者进行严格的健康和心理筛选而减少。目前尚不清楚研究早期胚胎干细胞需要多少人卵细胞。一旦科学家发现如何对卵细胞的遗传物质进行重新编程,他们便可以在实验室里进行卵细胞增殖。”

美国堪萨斯大学医学中心Nelson医师说:“医生也正在寻找让捐卵过程变得更加安全的方法。将来,可能不需要再使用超排卵药物,在实验室里就能将不成熟的卵细胞孵育成成熟的卵细胞。”

Safety of egg donation an area of contention
Ads claim the procedure is hazardous to women, but experts say risks are greatly exaggerated.
By KIT WAGAR
The Star’s Jefferson City correspondent

The image is powerful: A distraught woman is sitting on a bed, clutching her knees to her chest, tearfully lamenting her decision to donate eggs to a fertility clinic.

“The procedure was really painful, and my mom was upset,” the actress stammers. “Now I find out that it might cause kidney failure, ovarian tumors and sterility. Some women even die from it.”

An off-screen voice tells television viewers that research on early stem cells will require millions of human eggs. “And women will pay a terrible price,” the narrator says.

The ad, produced by the Vitae Caring Foundation in Jefferson City, is part of a multipronged campaign against Missouri’s stem-cell research initiative on the Nov. 7 ballot. The claims about egg donation have become key criticisms of the ballot measure, which would allow Missouri scientists to conduct any stem-cell research permitted under federal law.

Stem-cell experts, however, say that no one knows how many eggs will be needed for research. And experts in egg donation say opponents’ ads greatly exaggerate the risks of a procedure performed an average of 27 times a day in the United States as part of in vitro fertilization treatments.

While emphasizing that all medical procedures entail risk, experts say the most common problem stemming from fertility drugs and egg retrieval affects about 1 percent of patients — and symptoms usually go away within two weeks.

Carl Landwehr, president of the Vitae Caring Foundation, defended the TV ad as an accurate composite of some women’s experience with egg donation.

“Whether the words are spoken by the person who lived through it or by someone portraying that is not as important as the facts,” he said.

In recent weeks, billboards, television ads, yard signs and pamphlets handed out after church services have warned of the perils of egg donation. The claims, made by various groups opposed to Amendment 2, say that women will be exploited, will suffer strokes, cancer and kidney failure, and that some will die from donating eggs needed to expand research on early stem cells.

“Up to 35 percent of these women experience health consequences, many serious,” one flier says, “and some will even die.”

Experts say risks are minimal

Marcelle Cedars, a physician and director of the Center for Reproductive Health Research & Policy at the University of California-San Francisco, said that about 0.1 percent to 0.2 percent of women who have eggs removed after taking fertility drugs will have problems serious enough to warrant hospital treatment.

For the vast majority of women, the effect is a few days of bloating and significant cramps, she said.

“I’ve done this (egg retrieval) for nearly 20 years and can count on one hand the number of patients I’ve given pain medication,” Cedars said. “And then it was nothing stronger than ibuprofen. It’s not like post-operative pain.”

Cedars and Linda Nelson, a physician and head of reproductive endocrinology and the in vitro fertilization program at the University of Kansas Medical Center, said the long-term effects of fertility drugs and egg donation still are being studied. But studies that have followed women for more than 10 years have found no evidence that even multiple egg donation leads to future fertility problems, they said.

Studies have found no increased risk for breast or ovarian cancer and no indication that the process hastens menopause. Cases of kidney failure and blood clots that could cause strokes almost always involve a woman undergoing the procedure to get pregnant because symptoms are worsened by drugs taken to maintain the pregnancy, they said.

Cedars knew of only two deaths after in vitro fertilization treatments. Neither was in the United States.

Nelson said major complications are very rare and usually easily treatable.

“If patients couldn’t tolerate the discomfort, they wouldn’t be volunteering to do it multiple times,” she said. “The majority are willing to do it more than once.”

Joan Reese, director of the Egg Donation Center of Dallas, has been matching infertile couples with egg donors for seven years.

She said 75 percent of the women recruited through her service become repeat donors.

Will research increase risk?

Landwehr, whose group traditionally creates ads opposing abortion, acknowledged that only a small number of egg donors suffer the side effects depicted in his television spot. But even small risks would be magnified if egg donation were ramped up to accommodate expanded stem-cell research, he said.

Virtually all eggs now donated are for women unable to produce viable eggs because of age, infertility or previous cancer treatments. The process is the same as in vitro fertilization treatments except that the eggs, after fertilization, are implanted into the birth mother.

In both cases, women are given fertility drugs to cause more than one egg to mature. Cedars said that women naturally produce a pool of eggs each month, ranging from five to 30, depending on age and genetic disposition. Only one typically matures and is released during ovulation.

Fertility drugs cause the other eggs in that month’s pool to mature. That allows a doctor to retrieve them by inserting a needle through the vagina and into the ovary. The doctor uses a sonogram to guide the needle into each follicle, typically a 15-minute procedure under general anesthetic. After a few hours in the recovery room, the donor can go home.

The U.S. Centers for Disease Control and Prevention reported that 11.6 percent of in vitro fertilization attempts in 2003 were made with donor eggs. Women donated eggs 9,859 times that year, up from 6,643 times in 1997.

But a new use of human eggs is on the horizon. Researchers use the eggs in a laboratory process to grow early stem cells. The egg’s nucleus is removed and replaced with the nucleus of a body cell.

The egg can reprogram the genes in the nucleus so they begin to divide like a fertilized egg. Within about five days, the egg has formed stem cells that have the ability to become any tissue, including brain cells to treat Parkinson’s disease or pancreatic cells to treat diabetes.

Landwehr said the number of donations — and therefore the risks to women — would rise dramatically with research on early stem cells.

Sean Tipton, spokesman for the American Society for Reproductive Medicine, which represents and sets standards for fertility clinics, said most adverse side effects of egg donation can be mitigated by rigorous health and psychological screening of potential donors.

Tipton said it’s not clear that research on early stem cells will require huge numbers of human eggs. Once scientists understand how the egg reprograms the genetic material, they can duplicate that in the lab, he said.

Nelson, the KU doctor, said doctors are seeking ways to make egg donation even safer.

“In the future, it might be possible to get eggs without fertility drugs by retrieving immature eggs and maturing them in the lab,” Nelson said.

Ads opposing Amendment 2 say:

Research on early stem cells will require millions of human eggs. Egg donors will suffer health problems ranging from kidney failure to ovarian tumors to sterility and could even die.

Experts in stem-cell research and egg donation say
:

No one knows how many human eggs will be needed for such research. The ads greatly exaggerate the risks of egg retrieval, a procedure performed an average of 27 times a day in the United States as part of in vitro fertilization treatments. Studies have found no evidence of fertility problems, increased risk for breast or ovarian cancer or that the process hastens menopause. One expert said she knew of two deaths from the procedure, but neither was in the United States.

To reach Kit Wagar, call (816) 234-4440 or send e-mail to kwagar@kcstar.com.
http://www.kansascity.com/mld/kansascity/15762292.htm


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编辑: 张靖

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