Outcome of antenatally diagnosed bowel echogenicity and bowel dilatation: a systematic review of the literature and meta-analysis

Objective Bowel echogenicity (BE) and bowel dilatation (BD) have been described as markers for a variety of conditions (chromosomal and infectious disorders, cystic fibrosis, etc. ) and gastro-intestinal (GI) anomalies. However, in the absence of other conditions, the association of isolated BE and BE+BD with GI anomalies is unclear and poses a significant dilemma for antenatal counselling. This study aims to evaluate the incidence of GI anomalies in fetuses with antenatally diagnosed isolated BE and BE+BD. Methods A systematic review and meta-analysis (1990-2017) was conducted according to the PRISMA guidelines. The study was registered with PROSPERO (CRD42017074139). Selected studies included retrospective and prospective case series with data regarding post-natal outcome of isolated BE and BE+BD. Proportion meta-analysis for non-comparative studies (Freeman-Tukey transformation) was conducted using the random-effect model. Comparison of proportions between the two groups was performed using the "N−1" Chi-squared test [95% CI]. Heterogeneity was assessed using I2 values. Relative risk (RR) with [95% CI] was calculated. P value <0. 05 was considered significant. Results We identified 1630 studies: after duplicates were removed, 89 studies were analysed; 72 did not meet the inclusion criteria; 17 were included. Of 902 cases diagnosed with isolated BE, 16 presented with a GI condition at birth (1. 9% [0. 8- 3. 3]; I2 =43. 9% [0. 0-68. 8; p=0. 03]). Of 57 cases diagnosed with BE+BD, 17 presented with a GI condition at birth (42. 4% [10. 8-78. 0]; I2 =88. 1% [74. 9-94. 4; p<0. 01). Comparison of proportions showed a significant difference between the two groups (40. 5% [27. 4-54. 3]; p<0. 0001). Risk of having a GI anomaly was significantly higher in BE+BD group compared to BE group (RR 16. 8 [8. 9-31. 5]; p<0. 0001). Conclusion Despite some heterogeneity between studies, current evidence suggests that the finding of isolated BE is associated with <2% incidence of a GI anomalies at birth. On the other hand, the finding of BE+BD is associated with >40% incidence of GI anomalies at birth. This study provides the best available evidence for antenatal counselling of parents with fetuses with BE or BE+BD and no other associated conditions.