Cervical length as a screening tool for preterm birth in twin pregnancies: a systematic review and critical evaluation of quality clinical practice guidelines

Objectives: Twin pregnancies are at increased risk of preterm birth (PTB) compared to singletons. Evaluation of cervical length (CL) represents the optimal tool to screen PTB in singleton. Conversely, there is less evidence on the use of CL in twins. Our aim was to evaluate the methodological quality and clinical heterogeneity of clinical practice guidelines (CPGs) on the CL application in twins using AGREE II methodology.Methods: MEDLINE, Scopus, and websites of the main scientific societies were examined. The following aspects were evaluated: diagnostic accuracy of CL, optimal gestational age at assessment and interventions in twin pregnancies with reduced CL. The quality of the published CPGs was carried out using "The Appraisal of Guidelines for REsearch and Evaluation (AGREE II)" tool. The quality of guideline was rated using a scoring system. Each considered item was evaluated by the reviewers on a seven-point scale that ranges from 1 (strongly disagree) to 7 (strongly agree). A cut-off >60 % identifies a CPGs as recommended.Results: The AGREE II standardized domain scores for the first overall assessment had a mean of 74 %. The score was more than 60 % in the 66.6 % of CPGs analyzed indicating an agreement between the reviewers on recommending the use of these CPGs. A significant heterogeneity was found; there was no specific recommendation on CL assessment in about half of the published CPGs. There was also significant heterogeneity on the CL cut-off to prompt intervention.Conclusions: Despite the fact that the AGREE II analysis showed that the majority of the included guidelines are of good quality, there was a significant heterogeneity among CPGs as regard as the indication, timing, and cut-off of CL in twins as well as in the indication of interventions.