Strandell 1999.

Study characteristics
Methods	Parallel RCT
Participants	Country: Denmark, Iceland and Sweden Site: Multicentre trial conducted across 9 Nordic IVF sites. Participants: 204 women with hydrosalpinx were included and randomised to undergo either laparoscopic salpingectomy or no intervention prior to IVF. Age (mean ± SD): 31.8 ± 3.6 years (laparoscopic salpingectomy group) and 31.8 ± 3.7 years (no intervention group). Inclusion: presence of unilateral or bilateral hydrosalpinges as diagnosed by HSG or laparoscopy; suitability for IVF treatment; no contraindications to laparoscopy; age < 39 years at the time of randomisation. Exclusion: previous IVF treatment and the presence of cavity‐distorting uterine fibroids; male‐factor infertility requiring ICSI was accepted in centres where conventional IVF and ICSI success rates were identical. IVF protocol: although regimens varied between centres, a long protocol with GnRH‐agonist given nasally or s.c. was generally used, followed by controlled ovarian stimulation with either HMG of HP‐/rFSH. Transvaginal ultrasound‐guided oocyte retrieval ensued. Although not more than 2 embryos were routinely transferred, this was occasionally increased to 3.
Interventions	Laparoscopic unilateral or bilateral salpingectomy was performed in the intervention group, depending on whether one or two hydrosalpinges were identified. Where technical difficulties were encountered (e.g. due to extensive adhesions), a proximal ligation and distal fenestration was performed instead. While in the intervention group 2 months were advised between surgery and IVF treatment in order to allow for the wash‐out of hydrosalpingeal fluid, in the control group women underwent ART immediately following randomisation.
Outcomes	Number of collected oocytes (mean ± SD) Number of fertilised oocytes (mean ± SD) Implantation rate ‐ number of gestational sacs on ultrasound divided by the number of embryos transferred Ongoing pregnancy (pregnancy > 20 weeks) or delivery rate in first cycle per woman included, per started cycle, and per transfer cycle (n/n, %) Pregnancy rate per woman included, per started cycle and per transfer cycle (n/n, %) Clinical pregnancy rate (visible on ultrasound) per woman included, per started cycle and per transfer cycle (n/n, %) Ectopic pregnancy rate per implanted embryo and per clinical pregnancy (n/n, %) Miscarriage rate (not defined) per clinical pregnancy (n/n, %)
Notes	A subsequent analysis of cumulative data obtained from subsequent cycles in both groups was published by the trialists in 2001. Although an intention‐to‐treat analysis was performed in the follow‐up data, 24 women who had initially been assigned to the control group eventually underwent surgery after failed IVF cycles and thus their outcomes were not included in this review. The authors did not specify a trial registration number. A power calculation was performed but not followed as the sample size required (300) could not be reached within the duration of the study. The study was supported by grants from the Göteborg Medical Society, the Hjalmar Svensson Foundation and a society named "Ordensällskapet W:6".
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation performed with sealed opaque envelopes in blocks of 10 to 30.
Allocation concealment (selection bias)	Low risk	Randomisation performed with sealed opaque envelopes in blocks of 10 to 30.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding was performed.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not specified.
Incomplete outcome data (attrition bias) Intention to treat for primary outcome?	Low risk	An intention‐to‐treat analysis was performed.
Selective reporting (reporting bias)	Low risk	No suggestions of selective reporting.
Other bias	Low risk	There were no significant differences in baseline characteristics between groups apart from the rate of bilateral hydrosalpinges at inclusion, which was higher in the salpingectomy group (59% versus 41%, P = 0.02).