The anatomy and morphology of the ductus venosus in the human fetus: relevance to clinical practice

Abstract

Background: Doppler of the fetal ductus venosus (DV) is becoming increasingly commonplace in clinical practice. However, the true anatomical relationships of the DV are yet to be clearly defined. Furthermore, there is conflicting evidence regarding the structure of the DV, especially with regard to the presence of a DV inlet sphincter. The aim of the present study is to examine the anatomy and morphology of the DV.Design: A prospective study on 24 fetuses obtained from medical terminations between 13 and 17 weeks' gestation. Following microdissection of the liver, specimens were prepared for study of the anatomical relations, scanning electron microscopy or histology.Results: A venous confluence at the terminal end of the umbilical vein, termed the portal sinus, was identified connected to the right and left intrahepatic portal veins. The DV, a branchless hourglass shaped vessel, originated from the portal sinus ascended steeply in the direction of the diaphragm. The endothelial surface of the DV showed longitudinal corrugations and at the level of the inlet, there was ‘shelf’ separating the DV from the portal sinus. Histological studies revealed elastin fibers, six to seven cell layers thick at the DV inlet and a single layer of smooth muscle extending from the shelf to the DV outlet. A large number of nerve fibers were present in the adventia of the DV inlet.Conclusions: This study clearly delineates the anatomical relations of the fetal ductus venosus. The morphological findings refute the presence of a DV sphincter, but provide an insight into the physiology of the human fetal DV. In clinical practice, the consistent use of the suggested appropriate terminology would allow collection of comparable data between units and enable operators to be confident of which vessels they are sampling by Doppler ultrasound.