Adverse perinatal outcomes following the prenatal diagnosis of isolated single umbilical artery in singleton pregnancies: a systematic review and meta-analysis

Objectives A systematic review and meta-analysis was conducted to quantitatively synthesize the current evidence on the association of prenatally diagnosed isolated single umbilical artery (iSUA) in singleton pregnancies with small for gestational age (SGA) neonates and other perinatal outcomes. Methods A search of PubMed/Medline, Scopus and The Cochrane Library was conducted, from inception to February 2021, in order to identify studies comparing the risk of SGA and other perinatal adverse outcomes in prenatally diagnosed iSUA singleton pregnancies vs. those with a 3-vessel cord (3VC). The quality of eligible studies was assessed according to the improved Newcastle-Ottawa Scale (NOS). The heterogeneity of results across the studies was tested using the I-2 test. Funnel plots and Egger's test were used to assess the possibility of publication bias. Prospero RN: CRD42020182586. Results The electronic search identified 7,605 studies, of which 11 were selected, including three retrospective cohort and eight retrospective case control studies, overall reporting on 1,533 iSUA cases. The risk of delivering SGA neonates was increased in cases with iSUA (OR: 2.90; 95% CI: 2.02-4.18; p<0.00001; I-2=71%). Similarly, iSUA was associated with an increased risk of pregnancy-induced hypertension (PIH) (OR: 2.23; 95% CI: 1.41-3.54; p<0.000; I-2=1%), intrauterine death (IUD) (OR: 2.62; 95% CI: 1.43-4.79; p=0.002; I-2=0%), preterm birth (PTB) (OR: 2.48; 95% CI: 1.73-3.56; p<0.00001; I-2=56%), cesarean section (CS) (OR: 1.64; 95% CI: 1.11-2.41; p=0.01; I-2=78%) and admission to neonatal intensive care unit (NICU) (OR: 2.28; 95% CI: 1.52-3.44; p<0.000001; I-2=73%). Conclusions In prenatally diagnosed iSUA there is a higher risk of SGA, PIH, IUD, PTB, CS and NICU admission. These findings support the value of prenatal diagnosis of iSUA, which may subsequently intensify surveillance for the detection of specific pregnancy complications.