With the advent of advanced reproductive technologies, fertility experts debate whether male infertility should even be treated.

Urologists believe varicose veins of the scrotum are the leading cause of male infertility, though the evidence is mixed on whether surgical repair raises pregnancy rates.

Infection is a common cause of infertility in men and often can be treated with antibiotics.

The aging of a female partner’s eggs should be carefully weighed against lengthy treatments like raising sperm count.

But for a semen specimen, most men are practically ignored when couples go to fertility centers. And depending on the infertility specialist offering treatment, that is either a good thing or a bad thing.

Urologists who specialize in infertility say they can treat a man with low sperm count and increase pregnancy rates, helping patients avoid costly and invasive in vitro fertilization. Reproductive endocrinologists, on the other hand, say that most male fertility treatments have not been shown to improve pregnancy rates and put patients through unnecessary risks and expense.

It is a debate that has been raging for at least 50 years in various forms surrounding almost every aspect of male infertility and its treatments.

In 1992, for example, an advance in I.V.F. called ICSI, for intracytoplasmic sperm injection, provided fuel for the reproductive endocrinologists’ view that most men do not need fertility-enhancing treatments. In the procedure, pronounced ICK-see, a single sperm is inserted directly into an egg. ICSI revolutionized treatment for men with severely low sperm counts. Reproductive endocrinologists say that trying to improve sperm count in most men is no longer necessary, because only a few healthy sperm are needed.

“That doesn’t take into account, however, the economic burden that puts on patients to undergo advanced reproductive technologies,” said Tracy L. Rankin, program director of male reproductive health at the National Institutes of Health.

ICSI and I.V.F. are expensive, rarely covered by insurance, and require women to get hormonal injections and have invasive procedures to remove eggs and transfer embryos. Urologists also point out that ICSI, like any technique that manipulates the egg, can damage it and raise the risk of genetic abnormalities, though it is not clear why.

Furthermore, ICSI does not guarantee pregnancy, said Dr. Marc Goldstein, professor and surgeon in chief of male reproductive medicine and surgery at Weill Medical College of Cornell University in New York. Still, the percentage of I.V.F. cycles using ICSI has risen sharply, to more than 57 percent in 2004 from 11 percent in 1995. And many centers perform it, even when there is no problem in the male partner.

“If you try to treat the underlying problem, you may not need I.V.F.,” said Dr. Harry Fisch, professor of clinical urology at Columbia University and the author of “The Male Biological Clock” (Simon and Schuster, 2004).

Male problems are believed to be either solely or partly responsible in about 40 percent of all infertility cases, with the most common cause of male infertility a varicocele, or swelling of a vein in the scrotum. A varicocele appears to raise the temperature of the testes, potentially damaging the developing sperm and rendering men less fertile. Varicoceles are more than twice as common in infertile men as in the general population — 35 percent compared with 15 percent.

Yet the research on surgical repair of varicoceles to correct male infertility is limited and conflicting.

“Whenever it has been studied in a controlled fashion, it’s been shown to have no impact on pregnancy rates,” said Dr. Sherman J. Silber, a urologist and the director of the Infertility Center of St. Louis. A former proponent of the surgery, he has stopped performing it. “Most urologists who specialize in infertility have a vested interest,” he said; the surgery is all they do, and “that’s the moneymaker.”

But many urologists say that they have many patients who have conceived a baby naturally after the surgery. The existing research is flawed, they say, because it included patients who did not have true varicoceles.

Dr. Ashok Agarwal, director of the Clinical Andrology Laboratory and Reproductive Tissue Bank at the Cleveland Clinic, performed an analysis of existing evidence, weeding out poor studies. Of 396 patients who underwent surgery, 33 percent had a pregnancy, compared with 15 percent of 174 control patients. “An 18 percent improvement is not only biologically significant; it is highly significant from a clinical point of view,” Dr. Agarwal wrote in an e-mail.

For couples who want more than one child, the prospect of improving sperm count might be appealing. “If you opt for assisted reproductive technologies,” Dr. Agarwal said, “you’re back there in three or four years to have another baby.”

But raising sperm count, whether through surgery, hormone treatments or lifestyle changes, takes time, a commodity many couples do not have, said Dr. Robert A. Greene, a reproductive endocrinologist and medical director of the Sher Institute for Reproductive Medicine of Northern California. It takes about three months for sperm to mature, so it will take at least that long for any treatment to raise sperm count. In most cases, it takes at least 6 to 12 months for changes to have an impact.

“Couples put off I.V.F. for a year or two waiting for sperm count to rise, while the woman’s age increases from 34 to 36 and her eggs are getting older,” Dr. Silber said.

In women in their mid-30s and older, time is of the essence. Based on national averages, the success of one cycle of I.V.F. using a fresh embryo drops from about 37 percent in women under 35 to about 20 percent in those 38 to 40. It drops further, to about 11 percent, in women in their early 40s. Most doctors would agree that if a woman is about 38 or older, the couple should go straight to I.V.F. with ICSI rather than seeking treatments to improve sperm count.

The bottom line is that a couple is likely to hear a convincing argument for whichever procedure is being offered by the specialist they see, making the decision about treatment difficult. Doctors can rattle off study results and success rates to support either side, but the devil is in the details. The research on all male treatments is limited and weak. Studies are small, not well controlled and of limited duration.

“The latest information is that basically, we don’t know,” Dr. Rankin said. A couple’s decision, in the absence of good hard data, comes down to their individual situation, the fertility factors of each partner, their finances, their age, their comfort with advanced reproductive technologies, and how many children they want.