At birth, ductus venosus collapses and changes to?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Anatomy and Physiology

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Explanation

The ductus venosus is a critical shunt in the fetal circulation that allows a significant portion of oxygenated blood from the umbilical vein to bypass the liver and enter the inferior vena cava directly.
After birth, the umbilical cord is clamped, stopping blood flow from the placenta.
This cessation of flow, along with hormonal changes (like decreased prostaglandins), causes the muscular wall of the ductus venosus to constrict.
Over the first few weeks of life, the closed ductus venosus undergoes fibrosis and becomes the ligamentum venosum, a fibrous remnant on the surface of the liver.

Option A: The ligamentum teres (or round ligament of the liver) is the postnatal remnant of the umbilical vein, which carries oxygenated blood from the placenta to the fetus.
Option C: The foramen ovale is a flap-like opening between the right and left atria in the fetal heart. It is not a vessel and its remnant is the fossa ovalis, a depression in the interatrial septum.
Option D: The septum secundum is an embryonic structure that is crucial for the formation of the atrial septum and the foramen ovale. It is part of the heart's structure, not a vessel that becomes a ligament.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Postnatal remnants of fetal circulatory structures as background academic context rather than a clinical decision trigger.
Understanding the transition from fetal to neonatal circulation is fundamental for newborn assessment. Nurses must recognize signs of persistent fetal circulation, which can indicate underlying cardiac or pulmonary problems.
The remnant of the umbilical vein, the ligamentum teres, can be recanalized in adults with severe portal hypertension, providing a portosystemic shunt.
What if? - If the ductus venosus fails to close after birth (a condition called patent ductus venosus), it creates an abnormal connection between the portal vein and the systemic circulation. This allows toxins from the intestines to bypass the liver's detoxification process, potentially leading to hyperammonemia and neurological complications.

How to Approach the Question

First, identify the key term in the question: 'ductus venosus'.
The question asks for the postnatal remnant of this specific fetal structure. This is a factual recall question from anatomy and physiology.
Systematically recall or look up the five major fetal circulatory structures and their corresponding adult remnants.
Match 'ductus venosus' to its correct remnant, which is 'ligamentum venosum'.
Evaluate the other options to confirm they are incorrect. 'Ligamentum teres' is the remnant of the umbilical vein. 'Foramen ovale' becomes the fossa ovalis. 'Septum secundum' is part of the atrial septum's formation.

Concept Tested & Keywords

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E6 Anatomy Grays 43e Vol 1 Part 2 pp. 59-61, 54-56

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 523-525