The ductus venosus connects the umbilical vein and inferior vena cava, bypassing the hepatic circulation.
Oxygen and nutrient-rich blood from the mother follows the following path in the fetal circulation:
2. Umbilical vein (Site of highest oxygen content. Adult remnant is ligamentum teres.)
3. Ductus venosus (Bypasses hepatic circulation. Adult remnant is ligamentum venosum.)
6a. Travel directly from the right atrium to the left atrium through the foramen ovale and out to the aorta.
6b. Travel into the pulmonary circulation. From the pulmonary circulation, blood may travel to the lungs, or through the ductus arteriosus directly to the descending aorta. (Adult remnant of ductus arteriosus is ligamentum arteriosum.)
8. Fetal tissues
9. Umbilical arteries (Return deoxygenated blood to the placenta.)
As reviewed by Edelstone, "The ductus venosus, which is situated within the liver parenchyma, is a vascular shunt unique to the fetal and neonatal circulations. In fetal life, the ductus venosus allows variable portions of the umbilical and portal venous blood flows to bypass the liver microcirculation. After birth, when the umbilical circulation ceases, blood flow through the ductus venosus decreases substantially."
Fuloria et al. discuss the newborn examination. Most murmurs heard in the newborn period reflect the transition from fetal to neonatal circulation and are innocent. A thorough understanding of fetal circulation is important to care for newborns and infants.
Illustration A depicts the flow of blood in fetal circulation as described above.
Answer 1: The ligamentum venosum is the adult remnant of the ductus venosus.
Answer 3: The ligamentum arteriosum is the adult remnant of the ductus arteriosis.
Answer 4: The umbilical artery returns deoxygenated blood to the placenta.
Answer 5: The ligamentum teres is the adult remnant of the umbilical vein.
Edelstone DI. Regulation of blood flow through the ductus venosus. J Dev Physiol. 1980 Aug;2(4):219-38. Review.
PMID:7012226 (Link to Abstract)
Fuloria M, Kreiter S. The newborn examination: part I. Emergencies and common abnormalities involving the skin, head, neck, chest, and respiratory and cardiovascular systems. Am Fam Physician. 2002 Jan 1;65(1):61-8.
PMID:11804443 (Link to Abstract)
USMLE World Step 1 QBank Question #1833. Copyright © USMLEWorld, LLC 2012