Dozens of women who thought they were having a "complete mesh removal" have discovered material has been left behind, the BBC's Victoria Derbyshire programme has been told.
Some women have been left unable to walk, work or have sex after having the initial vaginal-mesh implants.
Specialist surgeons say in some cases total or partial mesh removal can be beneficial. But some women said their symptoms had become worse. One was left suicidal.
Vaginal-mesh implants remain available on the NHS in England but only when certain conditions are met. In Scotland, the use of mesh was halted in 2018.
One paitent said her surgeon had promised her a "full mesh removal", but she has now been told more than 10cm (4in) could have been left behind. She had the mesh implanted several years ago to treat urinary incontinence and said she had woken after the surgery with "chronic pain in my legs, my groin and my hips". It is believed she suffered nerve damage.
A year later – after being told by one expert a mesh removal would be unlikely to resolve her pain – she found a surgeon who told her the implant could be completely removed. She had two operations, each taking her half a year to recover from, and was told there had been a full removal. But "within a few months" the pain began to return and her health deteriorated and she found out that only 5–8cm had been removed.
"My whole world turned upside down," she said, breaking into tears.
She has since been told by a separate specialist her form of mesh was one of the most difficult to remove and could cause significant nerve damage if not removed properly. She said she had never been told this by her surgeon.
The number of women affected is unknown but the Victoria Derbyshire programme understands there are at least dozens of such cases.
The Royal College of Obstetricians and Gynaecologists said in a statement that it took "each and every complication caused by mesh very seriously". It said: "Women must be informed of all options available and the benefits and risks of each so they can make the best decision about their care."
Source: BBC News, 6 February 2020