Amniocentesis before cerclage in asymptomatic women with mid-trimester short cervix: time to consider?

The efficacy of cervical cerclage (CC) in case of asymptomatic mid-trimester short cervix, or the ultrasound finding of a cervical length<25 mm within 24 weeks of gestation, has been documented in women with a previous history of preterm birth (PTB). Conversely, no robust evidence supports the role of CC in prolonging pregnancy and improving maternal-neonatal outcomes in pregnant patients with mid-trimester sonographically short cervix and no prior history of PTB. However, the limited effect of CC in this population may be partially explained by the lack of pre-procedure diagnosis of underlying intra-amniotic inflammation and/or infection (IAI/IAI-I) that could undermine the beneficial effect of mechanical continence exerted by CC. Performing an amniocentesis in mid-trimester short cervix and analysing the amniotic fluid for inflammatory markers (i.e. IL-6 and MMP-8) and/or the presence of pathogens in the amniotic cavity by standard culture, digital PCR, or more recently, third generation sequencing techniques, may offer the opportunity of a differential diagnosis between mechanical versus inflammatory cervical insufficiency. In this review, we explore the available literature on intra-amniotic inflammation/infection in mid-trimester short cervix and discuss the potential role of analysing amniotic fluid by amniocentesis before CC, to improve the selection of patients who may benefit from cerclage or alternative management strategies, including antibiotics in selected cases of IAI/IAI-I. An individualized approach to maternal-fetal care in this context may represent a promising strategy to cervical insufficiency and potentially improve the efficacy of therapeutic options to prevent PTB.