She is hoping that a new treatment being offered to infertile couples at a nearby in-vitro fertilisation clinic will answer her prayers.
"I am trying not to get too excited because I have been let down so many times, but it seems to give us a chance," she says. "I would cut off my right leg to have a baby."
The new treatment, which will help thousands of couples affected by male infertility, skilfully combines two recent advances in one approach. It is unusual, but delightfully equitable, because it means minimally invasive treatment for both partners.
Known as surgical sperm retrieval, it is suitable for men who produce sperm, but whose sperm cannot get from their testes into their semen. This can be due either to a naturally occurring blockage in part of the male reproductive tract, or congenital absence of the vas deferens, the longest part of the tract. The problem occurs in about 1 to 2 per cent of all infertile couples, who number about 1.5 million. Other candidates are men who want to become fathers again but who have had failed vasectomy reversals - men such as David.
The surgeon begins by extracting sperm from the infertile man's epididymis (a short, coiled tube connecting the testes to the vas deferens, where sperm usually mature), or his testes, by inserting a fine needle under local anaesthetic and drawing them with suction. The procedures are known as percutaneous epididymal sperm extraction (Pesa) or testicular sperm extraction (Tese).
While this is being done, the man's sedated partner is having her eggs removed by needle aspiration under ultra-sound guidance through her vagina, as if for in-vitro fertilisation. However, instead of just combining the man's sperm with his partner's eggs in a petri dish - standard IVF procedure - they are put together in a more effective way.
Having selected the healthiest-looking sperm, the embryologist, an essential member of any assisted conception team, injects one into each of the woman's eggs, under another new procedure known as intracytoplasmic sperm injection (ICSI).
Neither technique is new (doctors started retrieving sperm from testes as far back as 1984), but combining the two has only recently become feasible at a handful of hospitals in London and the South-east. The ICSI technique has already proved highly successful in treating men with few or dysfunctional sperm, and is now being used to help men who have no sperm in their semen at all.
"It has transformed the situation for these men," said Anthony Hirsh, a consultant andrologist at Whipps Cross Hospital, Essex, and Harley Street, who was one of the first to carry out the procedure.
"Under the old system when we were using conventional IVF procedure, the pregnancy rate was only 2 to 4 per cent. But using ICSI, the chance of egg fertilisation is 50 per cent and the chance of a pregnancy is about 20 per cent per treatment cycle.
"Also, before ICSI, we had to remove about a million sperm from the epididymis by microsurgery, so the operation took up to four hours and involved a general anaesthetic. With ICSI, we only need about 10,000 sperm from which to select the best, so it takes about five minutes under local anaesthetic. ICSI has changed the whole ball game, so to speak," he says.
David and Sandra are hoping to have the operation within the next two months at the Midland Fertility Services clinic in Aldridge, north of Birmingham, where Mr Hirsh is teaching staff how to perform it. They are one of four couples currently awaiting treatment. In all four cases, the men have had vasectomies after already having had one family. In two of them, the woman also has fertility problems.
Peter Bromwich, the clinic's medical director, says: "We would like to offer the service because it gives a chance of parenthood to a group of men whose best hope, up to now, has been to use donor semen. ICSI offers an almost equal chance of conceiving a baby.
"The main problem for many couples will be the cost. At the moment, we are bringing Tony Hirsh up from London to carry out the procedure, but when our own programme is up and running, we will be using two teams of staff - one for the man and one for the woman."
Costs are bound to be high because of the complexity of the treatment. It is unlikely to be less than pounds 3,500 and could be more, since couples having ICSI alone are charged pounds 2,000. It will not be the treatment of first choice for many men whose semen does not contain sperm. Those men who have blocked sperm ducts as a result of infection or after a previous unsuccessful operation often obtain a good result from corrective surgery, while almost half of those whose blockages are the result of vasectomy will achieve fertility by having a reversal operation. However, it is thought particularly useful for those men born without a vas deferens, who, up until now, had no chance of fathering a child.
Although the procedure to remove the sperm is relatively straightforward, is usually done under local anaesthetic and allows the man to go back to work the next day, problems arise when the embryologist has to find the sperm among the extracted material. The procedure is relatively simple when the material is extracted from the epididymis because sperm mature in this tube, and even a few drops of liquid from it usually contain thousands of sperm.
If the fertility doctor has to extract material from the testis itself (because the epididymis is damaged by scar tissue, blocked or absent), it is much harder. The testis consists of coiled micro-tubules, not much thicker than a human hair, in which sperm are manufactured. When a sample is removed, the doctor has lumps of solid glandular tissue, containing relatively few sperm.
"We have got our eyes trained to see movement," said Bert Stewart, the Midland Fertility Service's deputy scientific director and embryologist. "Sperm, at this point in their development, tend to be immobile. To find something sperm-shaped that is not moving is hard."
David and Sandra will be relying on Dr Stewart's expert eyesight. Sandra says if it does not work, they will go back to donor insemination, but the advantage of the method is that the baby will be genetically David's child as well as hers. "This new treatment is a bonus," she adds.
n Names of patients have been changed.Reuse content