Highest oxygen content in Fetal blood

Fetal blood from the placenta is about 80% oxygenated. However, mixture with unoxygenated blood at various points reduces the oxygen content.Which of the following fetal vessels contains blood with the highest oxygen content?

• a.Abdominal aorta
• b.Common carotid arteries
• c.Ductus arteriosus
• d.Pulmonary artery
• e.Pulmonary vein

The answer is:  ( b ).
Blood from the placenta in the umbilical cord is about 80% oxygenated. Mixture with unoxygenated blood from the vitelline veins and the inferior vena cava reduces the oxygen content somewhat. However, this stream with relatively high oxygen content is directed by the valve of the inferior vena cava directly through the foramen ovale into the left atrium. This prevents admixture with oxygen-depleted blood entering the right atrium from the superior vena cava.

Thus, the oxygen-saturated blood entering the left ventricle and pumped into the aortic arch, subclavian arteries, and common carotid arteries has the highest oxygen content. The oxygen depleted blood from the superior vena cava is directed into the right ventricle and then to the pulmonary trunk. Although a small portion of this flow passes through the lungs (where any residual oxygen is extracted by the tissue of the non-respiring lung), most is shunted into the thoracic aorta via the ductus arteriosus and thereby lowers the oxygen content of that vessel. This occurs distal to the origins of the carotid arteries and ensures that the rapidly developing brain has the best oxygen supply. The pattern of blood supply in the fetus and the changes that occur at birth are shown in the following figures.

Amniotic band sequence

Amniotic band sequence is a disruption sequence with a broad spectrum of clinical manifestations (The frequency is comprised between 1/1200 to 1/15 000 births) it is ranging from partial amputations to major craniofacial and limb-body wall defects.

This amniotic bands are the result of adhesions between the amnion and embryonic or fetal parts. Their . Amniotic bands cause masive malformations with limb amputations, sever abdominal or cranial wall defects. Two different theories have been proposed: constrictive amniotic bands secondary to early amnion rupture, and vascular disruption events.

The anomalies are characteristically asymmetrical and usually prediposed by:
- familial predisposition
- amniocentesis

Associations:
- short umbilical cord
- early amnion rupture-oligohydramnios disruption (EAROD)
- amniotic deformity-adhesion mutilation (ADAM)

EX: limb anomalies

•  intrauterine amputations
•  limb constriction rings
•  pseudosyndactyly
•  club feet
•  abnormal dermatoglyphs

This term infant was born with foot and finger anomalies resulting from amniotic bands.

The Wonders of Fetal Circulation-Amazing video

Fetal Circulation & Changes After Birth
*The superior vena cava enters the right atrium (not right ventricle as mentioned/labeled)*

MNEMONIC for Features of Potter syndrome

All the features can be collected in the name of disease:
Potter syndrome: features POTTER:

• Pulmonary hypoplasia
• Oligohydrominios
• Twisted skin (wrinkly skin)
• Twisted face (Potter facies)
• Extremities defects
• Renal agenesis (bilateral)

Potter syndrome refers to the typical physical appearance and associated pulmonary hypoplasia of a neonate as a direct result of oligohydramnios (lack of amniotic fluid and kidney failure )and compression while in utero.

Potter phenotype refers to a typical facial appearance that occurs in a newborn when there is no amniotic fluid. The lack of amniotic fluid is called oligohydramnios. Without amniotic fluid, the infant is not cushioned from the walls of the uterus. The pressure of the uterine wall leads to an unusual facial appearance, including widely separated eyes .

Potter phenotype may also lead to abnormal limbs, or limbs that are held in abnormal positions or contracturescontractures.
Oligohydramnios also stops development of the lungs, so the lungs do not work properly at birth.

What`s Caroli Disease and Caroli syndrome??

Caroli disease is one of non-obstructive biliary diseases that cause biliary dilatation,Once you have excluded obstruction, you have to think about nonobstructive biliary diseases as:

1- Caroli disease
2- Choledochal cyst
3- Recurrent pyogenic cholangitis
4- Primary sclerosing cholangitis

Caroli disease is an autosomal recessive disease secondary to malformation of the ductal plate .
It is associated with polycystic kidney disease, medullary sponge kidney and medullary cystic disease.
So looking at the kidneys can sometimes help you make this diagnosis.

In images below Notice the intrahepatic duct dilatation and the normal caliber of the choledochal duct (extrahepatic bile duct).

Saccular intrahepatic duct dilatation with normal sized choledochal duct in Caroli disease

Saccular bile duct dilatation in Caroli disease

**The hallmark of Caroli disease is intrahepatic duct dilatation.
The dilatation can be very large and saccular as seen in the image or it can be very linear.

The duct dilatation in Caroli disease is due to a congenital malformation of the ductal plate, which is the precursor of the intrahepatic bile ducts.we can see in this diagram the normal development of the ductal plate .
Embryologically each bile duct starts as a single layer of cells that surrounds a portal vein.after that this layer duplicates.
Portions of this double layer fuse and resorb leaving unfused portions that become the bile ducts.

So in the normal condition each portal vein is surrounded by interconnecting bile ducts .However if the patient has ductal plate malformation, the bile ducts are too numerous and they are ectatic (as seen below).
Whether or not we see this on imaging depends on which portion of the bile ducts is affected.
If the large ducts are involved, we see this as Caroli disease.
However if only the very small ducts are involved, the result is congenital hepatic fibrosis.
If all ducts are involved, then there is a combination of fibrosis and Caroli disease, which is also known as the Caroli syndrome.

circulacion fetal animacion