A vaginal mesh implant made by one of the world’s biggest pharmaceutical firms was launched despite the company being warned it could shrink and harden inside the body, company documents reveal.

Internal emails between executives, shared with the Guardian, show staff at Johnson & Johnson (J&J) were concerned that the plastic material the mesh was made from had the potential to turn “hard as a rock” and roll up like a “folded potato chip” inside patients.

Despite this risk, the Prolift implant was made available in 2005 and marketed for seven years. In one exchange, staff discussed how “shrinkage of the mesh may lead to pain”.

The documents are among hundreds submitted to a US court as part of a civil case brought by Suzanne Emmett, 60, from Pennsylvania. She is one of many women who allege they suffered traumatic complications after receiving the implant.

The revelations follow a global investigation into the harm caused to patients by faulty medical implants, some of which had not been tested in patients before being marketed.

The Guardian and organisations including the BBC, Le Monde and Süddeutsche Zeitung, coordinated by the International Consortium of Investigative Journalists (ICIJ), uncovered stories of faulty pacemakers, spinal implants that disintegrated and breast implants linked to a rare form of cancer.

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Emmett is suing J&J for damages, and a Philadelphia court will hear this week that she needed nine revision surgeries and has been left struggling to cope with her pain after the implant perforated her vagina. J&J is contesting the claims.

Emmett’s legal team alleges the mesh device was defective and the company was negligent in its manufacture and failed to warn doctors of all the potential dangers.

The Prolift was designed to treat pelvic organ prolapse, in which the muscles supporting the pelvic organs weaken and one or more of them press into the vagina, sometimes causing discomfort.

It was launched in the US in 2005 without approval from the Food and Drug Administration (FDA) and only obtained clearance three years later after the US regulator was alerted it was on the market.

At the time, J&J argued the implants were sufficiently similar to existing products that it believed approval was not required. The company said it could not confirm whether the implant had CE mark safety approval in Europe “due to ongoing litigation”.

Emmett was given the implant in 2007. She says that, several months later, the mesh had cut through into her vagina and since then has resurfaced more than a dozen times, with surgeons removing it piece by piece.

Her husband’s penis was scratched by the mesh during sex, which he likened to “barbed wire”. Emmett says she suffers painful bladder contractions, urge incontinence and that her sex life has been affected.

Tens of thousands of women in the UK have received mesh implants to treat prolapse, although there is no available breakdown by manufacturer. NHS data suggests as many as one in 15 women who has a vaginal mesh later requires full or partial removal of the implant.

Company documents provided to the court as part of the case show J&J was keen to position Prolift as a more effective alternative to traditional surgery, which has a recurrence rate of about 30%.

However, ahead of its launch, J&J staff also discussed the implant’s potential downsides. In a message dated May 2004, a product director at J&J’s Ethicon unit, which sold the implants, warned of the potential for the mesh to harden and fold.

The company received correspondence from surgeons raising concerns. In a 2005 message, months after the device was launched, Prof Linda Cardozo, from King’s College hospital in London, told a senior J&J manager that she found Prolift’s safety profile “quite worrying” and doctors had been given “no efficacy data to review”.

“I still have major concerns regarding the erosion rate and possible problems with [sex becoming painful],” she wrote. Cardozo said she subsequently remained unconvinced by Prolift and had not used it.

The paperwork provided to the court also included details of a study of 90 women who were given the implants between 2004 and 2006 and followed up for a year. Doctors reported an 18% failure rate, the mesh had eroded into the vagina in 9% of women and 13% had “moderate or severe vaginal retraction”, where the tissue hardens and contracts due to scarring around the implant.

The mesh implants, which are designed to be permanent, become embedded in the pelvic tissue. If the material shrinks, nerves in the tissue can be compressed, causing pain.

The court documents suggest that J&J executives liaised with US doctors behind the scenes about lobbying. One email chain discussed how to mount an offensive after the American College of Obstetricians and Gynecologists (ACOG) warned its 55,000 members in February 2007 that mesh implants should be viewed as “experimental”.

Dr Vincent Lucente, a US doctor who was paid $1.7m by the company over 12 years in travel expenses, consulting and training fees, advised J&J executives to launch a “great offence” to get the guidance changed. “I suggest a physician leader with whom you can work with be a female, well respected, with no strong industry ties,” he wrote in a 2007 email.

By September 2007, ACOG had replaced the bulletin with an updated version, without the word “experimental”, which Lucente said was down to his efforts. A J&J marketing director responded: “I am doing the happy dance! I love you man!”

ACOG said the change had been made after it received emails, letters and phone calls from members who objected to the use of the word “experimental, which these members felt did not “accurately reflect the expanding use of these surgical approaches”. Lucente did not play any role in the revision, it said.

Lucente told the Guardian he had made a single phone call to ACOG because he believed the bulletin was “factually incorrect”. “There was no lobbying; it definitely wasn’t done on behalf of Ethicon or any other industry,” he said.

The largest comparative trial of mesh and traditional surgery for prolapse, published in the Lancet in 2016, showed that for both procedures, about 30% of women still had prolapse symptoms a year later. But the trial found higher complication rates for mesh surgery, with more than one in 10 patients experiencing complications linked to the mesh implants. In 2017, the UK’s National Institute for Health and Care Excellence (Nice) guidelines recommended that mesh should no longer be used to treat prolapse.

In June 2012, Johnson & Johnson voluntarily withdrew Prolift from the market, after being ordered by the FDA to carry out further testing.

Asked about the issues raised by the documents, Johnson & Johnson declined to comment. In a statement, the company said: “We think it is inappropriate to litigate these issues in the media or for conclusions to be drawn based on references to selectively chosen documents taken out of context.”