2.1.1 Women with endometriosis have deposits of endometrial tissue (which is normally confined to the lining of the uterus) outside the uterus. Many women are asymptomatic, but others may experience pelvic pain, dyspareunia, dysmenorrhoea or infertility.
2.1.2 In most women, endometriosis can be treated with analgesics and hormones. Women whose endometriosis does not respond may be offered minimally invasive surgery to excise or destroy the endometrial deposits, most commonly by electrocautery or laser through a laparoscope. Women with very severe symptoms may be offered more radical treatment involving hysterectomy and removal of the ovaries.
2.2.1 Laparoscopic helium plasma coagulation of endometriosis is a minimally invasive procedure used to vaporise endometrial deposits. A laparoscope is used to direct an ionised beam of helium gas at endometrial deposits to destroy them.
2.3.1 The method of evaluating symptoms following the procedure varied between studies, making comparison difficult. Across three series, symptomatic relief was achieved in 49% (39/79), 72% (179/250) and 81% (17/21) of women at 3 months' follow-up. In another case series, continuing symptoms were reported in 38% (5/13) of women at 14 months' follow-up.
2.3.2 Only one case series of 50 women, which included 9 women who presented with infertility and 15 who were both symptomatic and infertile, reported fertility outcomes: 44% (4/9) of the solely infertile group and 20% (3/15) of the women who were also symptomatic had conceived within 6 months of the procedure.
2.3.3 In one case series, none of the 250 procedures had to be converted to open surgery, and there were no re-admissions after 3 months, whereas a repeat procedure was required in 16% (5/31) of women in another case series, in which the mean period to return to normal daily activities was 12 days. There was no long-term follow-up of women beyond 6 months in published case series. For more details, refer to the 'Sources of evidence' section.
2.3.4 The Specialist Advisors noted that the procedure may cause less lateral burning than the diathermy technique, and may allow women to be treated on a day-case basis.
2.4.1 Three series recorded no side effects or complications related to the procedure in a total of 130 women. After 3 months' follow-up of 250 cases, one case series reported no major postoperative complications and no surgical complications. For more details, refer to the 'Sources of evidence' section.
2.4.2 The Specialist Advisors noted that theoretical adverse events include damage to normal tissue (as seen when other energy sources are used), bowel injury, haemorrhage, infection and, potentially, helium embolisation.