Impact of cannula diameter on pregnancy outcomes after minimally invasive fetal laser surgery in the treatment of twin-to-twin transfusion syndrome: A systematic review and meta-analysis

Abstract

Introduction: Preterm prelabor rupture of membranes (PPROM) remains a major complication of fetal laser surgery in the treatment of twin-to-twin transfusion syndrome (TTTS). The aim of the study was to determine the impact of cannula size on pregnancy outcomes, with a particular focus on PPROM.

Material and methods: The protocol was developed and registered in the PROSPERO database under registration number CRD42022333630. The PubMed, Web of Science, and EMBASE databases were searched electronically on May 18, 2022, and updated on March 2, 2023, utilizing a combination of the relevant MeSH terms, keywords, and word variants for "TTTS" and "laser". Randomized controlled trials, prospective and retrospective cohorts, case-control studies, and case reports/series with more than five participants were considered eligible for inclusion. Studies reporting the cannula diameter and PPROM rate after laser surgery in the treatment of monochorionic pregnancies affected by TTTS between 16- and 26 weeks' gestation were included. Data was extracted independently, and when appropriate, a random-effects meta-analysis was undertaken to calculate pooled estimates and their confidence intervals. Heterogeneity in the effect estimates of the individual studies was calculated using the I² statistic. The primary outcome was PPROM rate. Secondary outcomes were survival rate, preterm birth, and incomplete surgery. The quality of the included studies was assessed using a modified quality in prognosis study tool.

Results: We included a total of 22 studies, consisting of 3426 patients. Only one study was scored as low quality, seven as moderate quality, and the remaining 14 as high quality. The mean PPROM rate after laser surgery treating TTTS was 22.9%, ranging from 11.6% for 9 French (Fr) to 54.0% for 12 Fr. Subsequent meta-regression for the clinically relevant PPROM rate before 34 weeks of gestation, showed increased PPROM rates for increased cannula size (p-value 0.01).

Conclusions: This systematic review confirmed PPROM as a frequent complication of fetal laser surgery, with a mean PPROM rate of 22.9%. A larger cannula diameter relates to a significant higher PPROM risk for PPROM before 34 weeks gestation. Hence, the ideal balance between optimal visualization requiring larger port diameters and shorter operation time and more complete procedures that benefit from larger diameters is crucial to reduce iatrogenic PPROM rates.

Keywords: fetal membranes; fetal therapy; fetoscopy; premature rupture.

FIGURE 1

PRISMA diagram. Presentation of the procedure of literature searching and selection with numbers of articles at each stage.

FIGURE 2

Forest plot of meta‐analysis. Pooled PPROM rate (forest plot) per subgroup according to cannula diameter are shown. The subgroups are defined as follows; <9 French (Fr) (group 1), 9 Fr (group 2), 10 Fr (group 3), 11 and 11.4 Fr (group 4) and 12 Fr (group 5). The box in the middle of the line represents the point effect estimate of this particular study. The midpoint of the box represents the point effect estimate, that is, the mean effect estimate for each study. The area of the box represents the weight given to the study. The diamond below the studies represents the overall estimate. The width of the line shows the confidence interval (CI) of the effect estimate of individual studies. The width of the diamond shows the CI for the overall effect estimate. Individual effect sizes, corresponding confidence intervals and weights, as well the overall results per group, are also given in the last three columns.

FIGURE 3

Results of meta‐regression of relationship between cannula diameter and PPROM rate before 34 weeks GA (left) and 32 and 34 weeks combined (right). In both cases, an increase has been found in PPROM rate for larger diameters, which was significant for the studies before 34 weeks GA (p‐value 0.01). The bubbles represent the included studies, where the size of bubbles indicate amount of participants per study. Different PPROM definitions (right) are color indicated.