Abstract
BackgroundAbnormal placental cord insertion (PCI) includes marginal cord insertion (MCI) and velamentous cord insertion (VCI). VCI has been shown to be associated with adverse pregnancy outcomes. This systematic review and meta-analysis aims to determine the association of abnormal PCI and adverse pregnancy outcomes.MethodsEmbase, Medline, CINAHL, Scopus, Web of Science, ClinicalTrials.gov, and Cochrane Databases were searched in December 2016 (from inception to December 2016). The reference lists of eligible studies were scrutinized to identify further studies. Potentially eligible studies were reviewed by two authors independently using the following inclusion criteria: singleton pregnancies, velamentous cord insertion, marginal cord insertion, and pregnancy outcomes. Case reports and series were excluded. The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Outcomes for meta-analysis were dichotomous and results are presented as summary risk ratios with 95% confidence intervals.ResultsSeventeen studies were included in the systematic review, all of which were assessed as good quality. Normal PCI and MCI were grouped together as non-VCI and compared with VCI in seven studies. Four studies compared MCI, VCI, and normal PCI separately. Two other studies compared MCI with normal PCI, and VCI was excluded from their analysis. Studies in this systematic review reported an association between abnormal PCI, defined differently across studies, with preterm birth, small for gestational age (SGA), low birthweight (< 2500 g), emergency cesarean delivery, and intrauterine fetal death. Four cohort studies comparing MCI, VCI, and normal PCI separately were included in a meta-analysis resulting in a statistically significant increased risk of emergency cesarean delivery for VCI (pooled RR 2.86, 95% CI 1.56–5.22, P = 0.0006) and abnormal PCI (pooled RR 1.77, 95% CI 1.33–2.36, P < 0.0001) compared to normal PCI.ConclusionsThe available evidence suggests an association between abnormal PCI and emergency cesarean delivery. However, the number of studies with comparable definitions of abnormal PCI was small, limiting the analysis of other adverse pregnancy outcomes, and further research is required.
Highlights
Abnormal placental cord insertion (PCI) includes marginal cord insertion (MCI) and velamentous cord insertion (VCI)
The available evidence suggests an association between abnormal PCI and emergency cesarean delivery
PCI was categorized based on gross examination in three studies [14,15,16], from ultrasound examination in two studies [17, 18], or from secondary analysis of existing databases in the other 12 studies (Table 1)
Summary
Abnormal placental cord insertion (PCI) includes marginal cord insertion (MCI) and velamentous cord insertion (VCI). VCI has been shown to be associated with adverse pregnancy outcomes. This systematic review and meta-analysis aims to determine the association of abnormal PCI and adverse pregnancy outcomes. The umbilical cord insertion site to the placenta can be described as central, eccentric, marginal (battledore), and velamentous (membranous) insertions. Central and eccentric insertions account for more than 90% of term placentas [1]. Marginal cord insertion (MCI) and velamentous cord insertions (VCI) are categorized as abnormal PCI [1]. In MCI, the cord inserts at the edge of the placenta, but still arises directly from the placental mass. In VCI, the umbilical vessels insert into the membranes, the vessels traverse between the amnion and the chorion before reaching the placenta. VCI occurs in approximately 1% of singleton pregnancies and MCI in approximately 7% [1]
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