Recognition of a Fetal Subdiaphragmatic Venous Vestibulum Essential for Fetal Venous Doppler Assessment

Abstract

ABSTRACT. Ultrasonic visualization of the human fetal subdiaphragmatic area demonstrated anatomical relationships, different from descriptions in the literature. Four human fetal postmortem specimens at 18, 26, 28, and 34 wk of gestation were examined to ascertain morphologic details of intra-and perihepatic vasculature. Drawings of these dissected preparations were compared with ultrasonic images from the same region. With both methods the presence of a venous vestibulum immediately proximate to the diaphragm could be demonstrated. The abdominal inferior vena cava ends in a funnel-like structure, which also contains the orifices of the hepatic veins, the ductus venosus, and a phrenic vein. A considerable variability in Doppler flow recordings could result from blood propelling out of these various vessels into the vestibulum. It is, therefore, suggested that information on blood-flow velocities in venous hepatic vessels should be obtained more distally in the separate vessels and not at the entrance into the right atrium. ( Recently, a sonographic method to obtain Doppler velocity wave forms from the human fetal IVC by ultrasonic guidance was described (1). The proposed site to direct the Doppler beam is situated just proximate to the RA. However, visualization of this area by two-dimensional real-time ultrasound demonstrated anatomical relationships that did not correlate with morphologic descriptions in the literature (2-7). The IVC is considered to course straight through the diaphragm into the RA, although other veins, such as the DV and the hepatic veins, discharge separately into this straight vessel at different locations along its subdiaphragmatic course through and above the fetal liver (4- During Doppler studies of the IVC immediately proximate to the RA, other flow velocity wave forms often were encountered, in particular from the left hepatic vein and DV. Also an unexplained large SD was found while analyzing IVC wave form parameters from this site (8). Two studies suggest a clinical importance of these parameters in cases of arrhythmias and growth retardation (1,9).The aim of the present study was to ascertain the exact anatomical relationship between IVC, DV, and the hepatic veins in the human fetus in the diaphragmatic and subdiaphragmatic area. MATERIALS AND METHODSPostmortem specimens of four human fetuses at 18, 26, 28 and 34 wk of gestation, taken at random, were examined.The abdominal cavity had been opened in all fetuses during autopsy, and in three fetuses heart and lungs had been removed immediately superior to the diaphragm to exclude cardiac anomalies. No macroscopically detectable congenital abnormalities were found.The umbilical vein served as a guide for the exposure of the hepatic vasculature. After the removal of surrounding liver parenchyma, the blood vessels in the hepatic region around and above the intra-abdominal part of the umbilical vein were carefully dissected, so they could be traced to their origin. Drawings were made of two of four specimens (Figs. 1-3). Interest was pa...

Intraobserver and interobserver variability of transabdominal Doppler velocimetry measurements of the fetal ductus venosus between 10 and 14 weeks of gestation

“…As the DV is much smaller in earlier gestation and is located in close proximity to various larger vessels, blood flow measurements may be subject to errors in acquisition. Indeed, contamination with blood flow signals originating from adjacent vessels is not uncommon 17 .…”

Correlação entre os índices dopplervelocimétricos da veia cava inferior e ducto venoso e a concentração de hemoglobina do cordão em fetos de gestantes isoimunizadas

“…A resultante desse processo será o surgimento de pulsatilidade na veia umbilical, indicando a existência de quadro de ICC 10,14,15 . A opção pela utilização desses índices dopplerfluxométricos deveu-se a três motivos: são independentes do ângulo de insonação, não sendo, portanto, necessária a sua correção; todos os três índices são de fácil obtenção; estão entre os mais utilizados pelos relatos da literatura 9,[13][14][15] . O estudo dopplervelocimétrico do compartimento venoso pode ser útil no acompanhamento de fetos anêmicos, transfundidos ou não, detectando casos onde já exista algum grau de comprometimento da função cardíaca.…”

“…O fluxograma da VCI foi obtido preferencialmente em corte parassagital direito, com o transdutor ligeiramente oblíquo, localizando o vaso de trajeto paralelo à aorta abdominal, dirigindo-se anteriormente em direção ao átrio direito fetal 13 . O DV foi insonado em seu ponto de origem na veia umbilical.…”

The assessment of fetal well-being by venous Doppler velocimetry

“…From its origin, the ductus venous courses posteriorly and cephalad to reach the inferior vena cava, just below the diaphragm. The hepatic veins reach the inferior vena cava at the subdiaphragmatic venous vestibulum 21 .…”