QuestionSBA
QuestionChoice
This is incorrect. This describes the role of the umbilical vein. This structure is closed after birth and becomes the round ligament of the liver. It can reopen later in life, for example in severe liver cirrhosis. However, it is not associated with a continuous 'machine' murmur and is therefore not the single best answer in this case.
10025803
d
Delivery of oxygenated blood from placenta to foetus
QuestionChoice
This is correct. The baby in the vignette has a patent ductus arteriosus, as indicated by the continuous 'machine whirring' murmur heard on examination. A machine whirring murmur heard across the cardiac cycle is characteristic of patent ductus arteriosus. In foetal circulation the ductus arteriosus connects the pulmonary artery and the aorta, allowing blood from the right ventricle to bypass the pulmonary artery (and so bypass the inactive lungs) and instead pass around the rest of the body via the aorta.
10025800
a
Allow blood to bypass the lungs
QuestionChoice
This is incorrect. This describes the role of the umbilical artery which after birth becomes two parts; one becomes the median umbilical ligament and another remains open as part of the internal iliac artery. It is not associated with a continuous 'machine' murmur and is therefore not the single best answer.
10025804
e
Delivery of deoxygenated blood from fetus to placenta
QuestionChoice
This is incorrect. This describes the role of the foramen ovale. This allows oxygenated blood from the placenta to pass from the right to the left atrium. It is a relatively common cause of a murmur on auscultation of the newborn heart. However, a patent foramen ovale causes a soft ejection systolic murmur heard best at the upper left sternal border, rather than a continuous 'machine' murmur. This is therefore not the single best answer.
10025802
c
Allow oxygenated blood can move from the right to left atrium
QuestionChoice
This is incorrect. This describes the function of the ductus venosus, which allows blood from the placenta to bypass the liver, which in foetal physiology is not as active. A patent ductus venosus is uncommon and would not cause a continuous 'machine' murmur, so this is not the single best answer.
10025801
b
Allow blood to bypass the liver
Concept
Chapter
2693
4579
Patent Ductus arteriosus
Topic
153
Paediatrics
17558
A newborn boy is examined on the labour ward following an instrumental vaginal delivery.  The baby was born at 35 weeks gestation, weighing 5 pounds 9 ounces. On examination of the heart sounds a continuous 'machine whirring' murmur is identified across all areas of the chest.

Which of the following best describes the function of the foetal circulatory structure that has remained potent in this patient?
a