Ida Sabelis recalls being excited and nervous, but not particularly horny. It was a Saturday morning and she’d traveled with her boyfriend three hours from Amsterdam to a city called Groningen, up in the northern, marshy end of the Netherlands. And there she was making small talk in the MRI lab of a hospital with three male scientists when she suddenly had a thought.
“I realised I was the only woman in the room,” she recalls, and describes a pang of exasperation. “It was like, of course I’m the only woman in a study about women’s bodies!”
Ida had agreed to participate in the project partly as a favour, but mostly because she was a passionate anthropologist who’d spent her youth campaigning for women’s rights. And while the room’s asymmetrical gender balance annoyed her, it also got her moving, and she clapped a hand over her boyfriend’s back. “So!” she announced, “shall we get on with it then?”
The three scientists jumped to attention, along with her boyfriend Jupp, who hurried off to the bathroom to pee. One of the scientists removed the retractable steel tray from the MRI, then Ida and Jupp undressed and clambered in naked. Originally Jupp was supposed to lay on top of Ida, missionary-style, but Ida baulked at the idea. “It’s a position that for me produces hardly any arousal,” she explained. “Anyway, Jupp would have been too heavy in that tiny tube.” And so they wriggled around into a spooning position, ass to groin.
The three male researchers headed into the MRI operator’s booth to watch through a thick plate of glass. “Can you hear us?” asked one of them through an intercom wired into the bowels of the MRI. “Yes,” came Ida’s reply, followed by giggling from Jupp. “Ready when you are.”
A year earlier, in the autumn of 1991, Ida had received a phone call from her best friend’s partner, a guy named Menko Victor “Pek” van Andel. Ida and Pek had always gotten along, but Ida considered Pek a bit of an eccentric, so she took the call with raised eyebrows.
Over the phone Pek explained he had an idea for a very special and highly original piece of “body art.” That is, he wanted to create an image of the female reproductive tract during coitus, using a magnetic resonance imagery machine, commonly known as an MRI machine. Like X-rays, these machines allow doctors to see inside human bodies without surgery—but no one, according to Pek, had ever used one to see inside the female body during intercourse. “It’s never been done!” he repeated over the line. “Never!”
Ida was sceptical but intrigued. Pek might have been eccentric, but he also had a degree in medical research and had co-invented an artificial cornea. He had the connections to source an MRI machine, but more importantly, the academic gravitas to ensure the project wouldn’t become porn. And so after some consideration, and a long conversation with Jupp, she agreed.
Pek was correct when he said no one had used an MRI to examine female internal sexual organs, but others had certainly tried using their imaginations. The most famous early example was Leonardo da Vinci, who sometime between 1492 and 1494 sketched an illustration of a man pushing his erection into a semi-transparent vagina. The woman’s body and face don’t appear in the drawing, only her reproductive tract, which appeared as an undeviating cylinder leading between her legs directly to the base of her spine.
This sketch was created around 500 years ago, but we’ve stuck by its basic shape ever since. Nearly all diagrams found on tampon boxes and in sex-ed books depict the vagina as a straight tunnel. Penises aren’t forced to bend around corners, or conform to the female form in any way. They just go in straight and come straight out, as da Vinci had assumed. But no one had ever actually fact-checked his sketch with an MRI, so no one knew if da Vinci was correct.
Back in the lab, Ida and Jupp’s bodies were completely enveloped by the MRI scanner with only their feet protruding. Jupp was understandably worried he wouldn’t get an erection, but Ida wiggled an arm around to find that wasn’t a problem. Then they squirmed into place and, as Ida describes, “it became pleasantly warm in the tube and we truly succeeded in enjoying each other in a familiar way.”
From time to time an instruction would crackle through the intercom and they’d both burst into laughter. "The erection is fully visible, including the root," someone would say from the control room. “Hold that pose.” And then trying not to laugh Jupp and Ida would try to lay completely still, Jupp inside Ida, as the MRI machine clanged around them.
We won’t go into a complete description of an MRI’s operation. Suffice to say, they’re essentially large plastic boxes filled with metal coils. The machine’s opening runs down the coils’ centre axis, which are spasmodically magnetised with an electrical current, causing the coils to shiver and thump. An MRI machine making a scan is like a box full of charged hula-hoops jumping around and clanging together, making it probably the loudest piece of medical equipment in existence. And Ida and Jupp made love in the midst of all that noise, pausing intermiddly to hold a pose—while Jupp tried to hold his erection—until finally after about 45 minutes they were told to “finish up.” And they did.
Afterwards they were withdrawn from the machine, naked and sweaty “like buns from an oven.” Ida and Jupp then dressed and hurried to the control room to see the images they’d created.
“When I saw them it was just like aww that’s how we fit together, says Ida. “They were beautiful! I could see my womb and then there was Jupp in a place that I knew from my own sensation, just below the cervix. There was very clear features of both our insides, including the boundary between both our bellies. It showed so much detail it made me speechless.”
One person in the room who wasn’t speechless was Pek van Andel. Looking at the scan he immediately saw that Jupp’s penis had been forced into a curved, boomerang shape. From inside Jupp’s own body, it assumed an angle of about 120 degrees, which was something Leonardo da Vinci had never drawn. And at that moment Pek knew they’d achieved something more significant than an arts project; they’d re-written around 500 years of anatomical assumptions.
However, as with a lot of art and science, both Ida and Pek immediately found themselves up against the winds of public outrage. Pek’s preliminary scans and findings were mailed to Nature, with Ida as co-author, only to be rebuffed without explanation. Then the Dutch tabloids got the story and implied that sick, helpless people had been made to wait for life-saving scans while Pek was squandering MRI equipment on frivolous sleaze. This wasn’t true, as they’d used the lab out of hours, but in any case, the hospital hurriedly backed off, which in turn denied Pek the opportunity to replicate the experiment. And that meant that a more thorough, scientific study was impossible.
“It was completely disappointing,” says Pek. “We’d found an unexplored area of research, and no one wanted to let us finish the work because they were afraid of how it would look on their resumes.”
Pek however, was not dissuaded. After deciding that a thorough study involving multiple couples was in order, he spent the next few months lobbying Groningen Hospital’s management until both the head of women's medicine and head of radiology greenlit the idea, providing it was completed in secret and no one published anything. Pek agreed, assuming he’d cross the hurdle on “publication” once he got there.
Between 1991 and 1999, eight couples and three single women had sex in the hospital’s MRI a total of 13 times. These subsequent experiments were all done in the missionary position, using volunteers above the age of 18 who were told they could quit at any moment. No one did, but as Ida points out—somewhat smuggly—none of the men were later able to complete the test without viagra.
“We were the only couple to successfully do it without viagra,” she says, proudly. “For me, the experiment was also a testimony to mine and Jupp’s happiness. I think that’s something the paper missed: how connected a couple must be to perform under those kinds of conditions.”
Finally, after eight years and three failed submissions, the British Medical Journal published their paper on the inauspicious date of December 24, 1999. The paper was titled Magnetic Resonance Imaging of Male and Female Genitals During Coitus and Female Sexual Arousal, and to this day Ida and Pek say it’s the scientific work for which they’ve both received the most citations.
“It’ll probably become my legacy,” admits Ida, who is now a Professor of Organisational Anthropology at Amsterdam’s Vrije University. “But I’m lucky. You don’t get to choose your legacy, and some people don’t get one at all.”
Aside from its observations on bent penises, the paper uncovered something else that was truly unexpected: namely, the effect sex has on the female bladder. As many women can attest, there’s something about vaginal sex that prompts the bladder to rapidly fill, as observed in every female participant over the course of the 13 experiments. And to this day scientists still aren’t sure why.
“In every final scan we could see a big, full bladder, even though most of the women went to the toilet before they went inside the MRI,” explains Pek with comical astonishment. “We think it might be evolution’s way to force women to urinate after sex. Perhaps our ancestors developed this function to avoid urinary tract infections, but that’s only a hypothesis.”
Today, Pek is retired and lives with his partner in a sprawling farmhouse in the Dutch countryside. He says he’s proud of the study, even though he says it inadvertently revealed to him a kind of cowardice inherent to scientific study. He describes how after the 1999 paper was lauded by Science magazine, everyone who’d previously wanted nothing to do with them suddenly clamoured for credit.
“People who’d actively tried to shut us down were later providing quotes to the press, or listing their participation on their resumes,” Pek clucks, shaking his head. “Success has many fathers, obviously.”
Ida says she also discovered something frustrating about human nature, which was how everyone got so hung up on sex. To this day she says her friends and family still laugh about the time she shagged her boyfriend in an MRI, even though many are tertiary-educated adults approaching retirement. In particular she finds this reaction odd around the university, where her giggly colleagues are academics working in social sciences in one of the world’s most progressive cities.
“In many ways I think we’re going backwards,” Ida says. “I grew up in a time when sex wasn’t a big deal, and we’d always go bathing naked and people seemed more open minded. Now, people just seem to be getting more and more conservative.”
Nonetheless, Ida says she’s incredibly proud of the small contribution she made towards gender equality in the science of arousal. She had no idea what she was getting herself into that morning in 1991, but she’s incredibly happy she went ahead with it. Even if the experiment was mostly run by men.