The subjective assessment of echogenic fetal bowel

Objectives To assess the subjective interpretation of the echogenicity of fetal bowel compared to bone from antenatal ultrasound images taken during examinations conducted between 17 and 22 weeks of gestation. Methods Eighty-seven women attending for their antenatal scan were selected in a random prospective manner over a 9-month period. Images of the fetal bowel were taken and evaluated by 10 sonographers, one consultant obstetrician and one consultant radiologist. Images from a further 13 fetuses, in which the subjective assessment of echogenic bowel was made, were also included. All ultrasound images were acquired on a dedicated ultrasound scanner, with a standard transducer, thermal paper printer and single operator using standardized equipment settings and reproducible image sections. Questionnaires with 100 sets of images of fetal bowel were distributed to the participants. Performance was assessed by means of percentage agreement and levels of chance corrected agreement (Kappa). Results The subjective assessment of fetal bowel echogenicity is very variable. Intra- and inter-observer variation discrepancies in the assessment of bowel echogenicity compared to bone were demonstrated between the sonographers. Good agreement was identified between the consultants with good to almost perfect intra-observer agreement. Overall, only moderate agreement was observed between the sonographers and the consultants. Conclusions The lack of agreement demonstrated between sonographers when evaluating the echogenicity of fetal bowel should be addressed if this ultrasound marker is to be incorporated into routine fetal screening programs.