Biomaterial Database

Umbilical vein and middle cerebral artery blood flow response to partial occlusion by external compression of the umbilical vein (pressure test). 2002

C L Ramón y Cajal

Unit of Prenatal Diagnosis, Xeral Hospital, Vigo, Pontevedra, Spain.

OBJECTIVE We studied the responses of flow in the umbilical vein and of the circulation in the proximal segment of the middle cerebral artery (MCA) during partial external compression of the umbilical vein. METHODS Partial occlusion of the umbilical vein was achieved by the pressure test, consisting of applying external pressure on the maternal abdominal wall for 1-2 s. RESULTS During 60 pressure tests in 45 fetuses with nuchal cords, we observed complete cessation of the umbilical vein flow, while blood flow in the umbilical arteries was preserved, and proximal MCA flow was moderately or markedly decreased. Blood flow in other segments of the MCA was unchanged. This effect, which was more pronounced before the 32nd week of gestation, was also observed in association with spontaneous fetal movements. CONCLUSIONS The pressure test decreases flow in the proximal MCA, and interrupts umbilical vein blood flow. Further analysis of this response suggested the presence of associated vasoconstriction of the proximal MCA.

UI	MeSH Term	Description	Entries
D009333	Neck	The part of a human or animal body connecting the HEAD to the rest of the body.	Necks
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011263	Pregnancy Trimester, Third	The last third of a human PREGNANCY, from the beginning of the 29th through the 42nd completed week (197 to 294 days) of gestation.	Pregnancy, Third Trimester,Trimester, Third,Last Trimester,Last Trimesters,Pregnancies, Third Trimester,Pregnancy Trimesters, Third,Third Pregnancy Trimester,Third Pregnancy Trimesters,Third Trimester,Third Trimester Pregnancies,Third Trimester Pregnancy,Third Trimesters,Trimester, Last,Trimesters, Last,Trimesters, Third
D001783	Blood Flow Velocity	A value equal to the total volume flow divided by the cross-sectional area of the vascular bed.	Blood Flow Velocities,Flow Velocities, Blood,Flow Velocity, Blood,Velocities, Blood Flow,Velocity, Blood Flow
D005260	Female		Females
D005333	Fetus	The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.	Fetal Structures,Fetal Tissue,Fetuses,Mummified Fetus,Retained Fetus,Fetal Structure,Fetal Tissues,Fetus, Mummified,Fetus, Retained,Structure, Fetal,Structures, Fetal,Tissue, Fetal,Tissues, Fetal
D005865	Gestational Age	The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated from the onset of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization. It is also estimated to begin from fertilization, estrus, coitus, or artificial insemination.	Embryologic Age,Fetal Maturity, Chronologic,Chronologic Fetal Maturity,Fetal Age,Maturity, Chronologic Fetal,Age, Embryologic,Age, Fetal,Age, Gestational,Ages, Embryologic,Ages, Fetal,Ages, Gestational,Embryologic Ages,Fetal Ages,Gestational Ages
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D014471	Umbilical Veins	Venous vessels in the umbilical cord. They carry oxygenated, nutrient-rich blood from the mother to the FETUS via the PLACENTA. In humans, there is normally one umbilical vein.	Umbilical Vein,Vein, Umbilical,Veins, Umbilical