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As the world's best athletes bid for gold at the Winter Games in Vancouver over the coming 16 days, we can be sure that every double Axel will be scrutinized and every race timed to one-thousandth of a second. But in a world obsessed with precision, one issue continues to escape neat classification and a simple solution: how to handle sexually ambiguous athletes.

Last month in Miami, the International Olympic Committee (IOC) convened the latest in a series of meetings meant to hash out the science behind medical conditions that make it difficult to determine an athlete's sex. Long a topic of debate in Olympic circles (mandatory gender testing began in the 1960s), sex ambiguity hit the headlines again last year when South African runner Caster Semenya won the women's 800-m world championship in Berlin by an astonishing two-second margin. Fellow competitors raised concerns about Semenya's masculine appearance, prompting track and field's governing body to order sex testing. The results have yet to be released, but the case focused attention on the challenges in balancing competition with an athlete's right to privacy.

At the conference in Miami, the IOC made little progress in drafting concrete guidelines to help sports federations handle athletes with what some doctors call "disorders of sex development" (DSDs). But it did recommend establishing "centers of excellence" around the world that would be equipped to treat athletes with DSDs. IOC medical commission chairman Arne Ljungqvist says the centers would offer everything from hormone therapy to surgery.

But some experts say the inherent ambiguity of DSDs makes the idea of treatment problematic. For instance, one sex development disorder, congenital adrenal hyperplasia, causes females to produce abnormal amounts of male sex hormones and is treated by administering steroids to normalize hormone levels. Panel participant Dr. Eric Vilain, professor of human genetics, pediatrics and urology at UCLA's David Geffen School of Medicine, points out that there is tremendous variation in hormone levels even in typical females, which makes determining a baseline virtually impossible. More important, Vilain says, is the ethical question of whether physicians should artificially alter hormone levels in athletes with the disorder to "level the playing field."

In the past, sports governing bodies and even the Olympics have permitted athletes with DSDs to compete. In the 1996 Atlanta Games, the last Olympics with mandatory gender-verification tests, seven females were found to have androgen insensitivity syndrome (AIS), a condition in which a person is genetically male — that is, her 23rd chromosome pair is XY — but is resistant to androgens, the male sex hormones that include testosterone. As a result, the body doesn't hear the signal to develop as a male and so develops externally as a female. All seven athletes were allowed to compete in Atlanta.

Another hurdle to a consensus on how to deal with sex ambiguity is the fact that there is very little scientific data on whether DSDs confer any real advantages to athletes. In the 2008 paper "Intersex and the Olympic Games," Robert Ritchie, a urological surgeon at Oxford University, noted, "There is no evidence that female athletes with DSD have displayed any sports-relevant physical attributes which have not been seen in biologically normal female athletes."

Indeed, sports are inherently unequal regardless of genetics, Vilain says, and any potential athletic advantages one might have because of a DSD are no different from other naturally occurring physical advantages like being taller or having more balance. So where do we draw the line?

Since discontinuing mandatory gender verification in 1999, the IOC has championed case-by-case evaluation of athletes with suspected gender disorders. The IOC, which will meet again after the Vancouver Games, is now wondering if that should change. Poorly handled cases like Semenya's suggest that the system is not working. Many athletes who agree to sex testing only learn of their medical condition from sports officials, which can be a shocking and painful way to face such an intimate revelation. María José Martínez-Patiño, who has AIS, was kicked off the Spanish national team, stripped of her titles and barred from competition in 1986 after gender-verification tests showed she was genetically male. IOC medical officials allowed her to compete in the 1992 Olympic trials in Barcelona, but the damage was done. "In the worst of moments, when I had no support from anyone, I thought I would be better off dead," she says. "It killed me that I couldn't participate in the sport and, above all, I thought I would never recover from the embarrassment."

The truth is, for a small segment of the population, even exhaustive clinical and psychological tests will never guarantee a conclusive answer about their sex. According to Vilain, it's basically impossible to come up with a "universal cutoff" to determine females from males. "That's what we're struggling with," he says. "There is no one biological parameter for sex. It's a complicated combination of parameters."

• Meg Handley / London
• The International Olympic Committee is struggling to draft guidelines on how to handle athletes with disorders of sex development. There may never be a satisfactory answer