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fetal circulation & Rh incompatibility

fetal circulation & Rh incompatibility



fetal circulation & Rh incompatibility

fetal circulation & Rh incompatibility



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    fetal circulation & Rh incompatibility fetal circulation & Rh incompatibility Presentation Transcript

    • Fetal Circulation and Rh incompatibility Done by: AMAL AL-JEDANI AMAL BRNAWI Supervised By: Dr.Sahar
    • Outline:
      • - Introduction.
      • - Blood circulation during pregnancy.
      • - The development of the fetal circulatory system.
      • - How does the fetal circulatory system work.
      • - Blood circulation before birth.
      • - Blood circulation after birth.
      • - Definition of Rh incompatibility.
      • - Causes of Rh incompatibility.
      • - Signs & symptoms of Rh incompatibility.
      • - Detection of Rh incompatibility .
      • - Treatment of Rh incompatibility
      • - Prevention of Rh incompatibility.
      • - Summary.
      • - References.
    • Objective
      • At the end of this presentation the student will be knowledge about:
      • Blood circulation during pregnancy
      • The development of the fetal circulatory system
      • How does the fetal circulatory system work
      • Blood circulation before birth
      • Blood circulation after birth
      • Definition of Rh incompatibility.
      • Causes of Rh incompatibility.
      • Signs & symptoms of Rh incompatibility.
      • Detection of Rh incompatibility .
      • Treatment of Rh incompatibility
      • Prevention of Rh incompatibility .
    • Fetal circulation Introduction:
    • The development of the fetal circulatory system
    • - Begins to develop toward the end of the third week. - Heart starts to beat at the beginning of the fourth week. - The critical period of heart development is from 20 day to 50 day after fertilization. - Many critical events occur during cardiac development, and any deviation from this normal pattern can cause congenital heart defects, if development of heart doesn't occur properly.
    • -The fetus is connected by the umbilical cord to the placenta, the organ that develops and implants in the mother's uterus during pregnancy. -Through the blood vessels in the umbilical cord, the fetus receives all the necessary nutrition, oxygen, and life support from the mother through the placenta. -Waste products and carbon dioxide from the fetus are sent back through the umbilical cord and placenta to the mother's circulation to be eliminated. The fetal circulatory system works differently than after birth
    • Inside the fetal heart: -Blood enters the right atrium, the chamber on the upper right side of the heart. Most of the blood flows to the left side through a special fetal opening between the left and right atria, called the foramen ovale . -Blood then passes into the left ventricle (lower chamber of the heart) and then to the aorta, (the large artery coming from the heart). -From the aorta, blood is sent to the head and upper extremities. After circulating there, the blood returns to the right atrium of the heart through the superior vena cava. -About one-third of the blood entering the right atrium does not flow through the foramen ovale, but, instead, stays in the right side of the heart, eventually flowing into the pulmonary artery.
    • Inside the fetal lung: Because the placenta does the work of exchanging oxygen (O2) and carbon dioxide (CO2) through the mother's circulation, the fetal lungs are not used for breathing. Instead of blood flowing to the lungs to pick up oxygen and then flowing to the rest of the body, the fetal circulation shunts (bypasses) most of the blood away from the lungs.
    • Three shunts in the fetal circulation 1. Ductus arteriosus - In the fetus, blood is shunted from the pulmonary artery to the aorta through a connecting blood vessel “ ductus arteriosus”. - Protects lungs against circulatory overload. - Allows the right ventricle to strengthen. - High pulmonary vascular resistance, low pulmonary blood flow. - Carries mostly med oxygen saturated blood.
    • 2. Ductus venosus - Fetal blood vessel connecting the umbilical vein to the IVC - Blood flow regulated via sphincter.( The sphincter in the ductus venosus constricts, so that all blood entering the liver passes through the hepatic sinusoids) - Carries mostly hi oxygenated blood 3. Foramen ovale shunts highly oxygenated blood from right atrium to left atrium
    • Control of circulation is a reflex function regulated:-
      • Peripherally by the baroreceptors in the aortic arch and carotid sinus Centrally by baroreceptors in the cardiovascular center of the medulla (in close proximity of the chemoreceptor that regulate respiration) … Respiratory and circulatory reflexes are usually strong in the healthy full-term newborn, but their efficiency in controlling cardiovascular function is susceptible to environmental factors.
    • Adult Derivatives of Fetal Vascular Structures
      • Because of certain changes in the cardiovascular system at birth, certain vessels and structures are no longer required. Over a period of months these fetal vessels form nonfunctional ligaments, and fetal structures such as the foramen ovale persist as anatomic vestiges of the prenatal circulatory system.
    • Blood circulation after birth:
    • 1- With the first breaths of air the baby takes at birth, the lungs are filled with air instead of fluid. 2- Alveoli filled with air instead of fluid allows for vascular resistance to decrease. 3- Increase in pulmonary blood flow. 4- Higher concentration of oxygen in the blood. 5- Placenta is removed from circulation. 6- Decreased prostaglandin levels. 7- When the umbilical cord is clamped, the umbilical vein closes, Systemic vascular resistance is increased . 8- Decreased pulmonary vascular resistance closes the ductus arteriosus . (The normal connection between the aorta and the pulmonary valve).
      • ( In premature infants and in those with persistent hypoxia the DA may remain open for much longer.
      • In full-term infants oxygen is the most important factor in controlling closure of the DA.
      • Closure of the DA appears to be mediated by bradykinin, a substance released by the lungs upon initial inflation it has potent contractile effects on smooth muscle).
      • 9- The circulation in the lungs increases and more blood flows into the left atrium of the heart. This increased pressure causes the foramen ovale to close and blood circulates normally.
      • 10- The right ventricular wall is thicker than the left ventricular wall in fetuses and newborn infants because the right ventricle has been working harder. By the end of the first month the left ventricular wall is thicker than the right because it is now working harder than the right one. The right ventricular wall becomes thinner because of atrophy associated with its lighter workload.
    • Rh incompatibility
    • Introduction:
      • There are four blood types ( A, B, AB, and O)
      • -Each of the four blood types is additionally classified according to the presence of another protein on the surface of red blood cells that indicates the Rh factor.”If the person carry this protein, he is Rh positive. If he doesn't carry the protein, he is Rh negative”
      • - Everyone is born with a certain blood type that is either Rh positive or Rh negative
      • - If the pregnant woman and her husband are Rh negative, there is no reason to worry about Rh incompatibility
      • - If her Rh negative and her husband Rh positive,
      • the baby will inherit the father's blood type ,creating incompatibility between mother and her fetus.
      • - If some of the fetal blood gets into mother's blood stream,
      • her body will produce antibodies.
      • - These antibodies could pass back through the placenta and harm the developing baby's red blood cells, causing very mild to very serious anemia in the fetus.
      • - Rh disease is much more common in second and subsequent Rh-incompatible pregnancies because fetal and maternal blood usually do not mix until delivery.
    • Definition:
      • Rh incompatibility is a condition which develops when there is a difference in Rh blood type between that of the pregnant mother (Rh negative) and that of the fetus (Rh positive)
    • Rhesus positive fetus
    • Causes of Rh incompatibility:-
      • During pregnancy, red blood cells from the fetus can get into the mother's bloodstream as she nourishes her child through the placenta. If the mother is
      • Rh negative, her system cannot tolerate the presence of Rh positive red blood cells
      • In such cases, the mother's immune system treats the Rh positive fetal cells as if they were a foreign substance and makes antibodies against the fetal blood cells. These anti-Rh antibodies may cross the placenta into the fetus, where they destroy the fetus' circulating red blood cells.
      • First-born infants are often not affected (unless the mother has had previous miscarriages/abortions, which could have sensitized her system) as it takes time for the mother to develop antibodies against the fetal blood. However, second children who are also Rh-positive may be harmed.
    • Sign &symptom of Rh incompatibility: -
      • Rh incompatibility can cause symptoms ranging from very mild to fatal.
      • Mildest form Rh incompatibility: ~
      • 1- Hemolysis (Destruction of the red blood cells) with the release of free hemoglobin into the infant's circulation.
      • 2- Jaundice (Hemoglobin is converted into bilirubin , which causes an infant to become yellow.
    • Sever form Rh incompatibility: ~
      • 1- Hydrops fetalis (Massive fetal red blood cell destruction).
      • It causes Severe anemia  Fetal heart failure  Death of the infant shortly after delivery.
      • 2- Total body swelling .
      • 3- Respiratory distress (if the infant has been delivered)
      • 4- Circulatory collapse .
      • 5- Kernicterus . (Neurological syndrome in extremely jaundiced infants, especially those with severe Rh incompatibility). It occurs by bilirubin deposition into the brain (CNS) tissues of the fetus. It occurs several days after delivery and is characterized initially by...
      • A) Loss of the Moro reflex.
      • B) Poor feeding .
      • C) Decreased activity.
    • Later 
      • A) High-pitched shrill cry may develop along with unusual posturing,
      • B) Bulging fontanel,
      • C) Seizures .
      • D) Decreased muscle tone
      • E) Movement disorders,
      • F) High-pitched hearing loss
      • J) Decreased mental ability.
      • H) Infants may die suddenly.
    • Detection of Rh incompatibility:~
      • 1-There are no any physical symptoms that would allowthe woman to detect on her own if she is Rh incompatible with her baby .
      • 2-If the woman just found out she is pregnant, one of the first and most important tests she should expect is a blood-type test. This basic test determines her blood type and Rh facto , her Rh factor may play a role in her baby's health, so it's important to know this information early in her pregnancy .
      • 3-Blood test that will determine whether she is Rh positive or Rh negative .
    • Treatment of Rh incompatibility:~
      • During prenatal care:
      • - If antibodies are present and anemia is detected in the fetus, a blood transfusion is performed to replace the fetus's blood supply with Rh-negative blood, which will not be damaged by the antibodies her body has created.
      • - The transfusion is administered through the umbilical cord while the fetus is still in the uterus, beginning at 18 weeks of pregnancy or beyond. This procedure can be somewhat risky, so some surgeons prefer to induce an early labor. The blood transfusion is then administered after the baby is born.
    • Prevention of Rh incompatibility:-
      • By using special immune globulins, called “ - RhoGAM" Hydrops fetalis and kernicterus have decreased markedly in frequency as a result of these preventive measures. at 28 weeks of pregnancy, regardless of the blood type of the fetus. This vaccine will destroy any fetal red blood cells that have entered mother's bloodstream before her body has a chance to create any antibodies.
      • If the baby is born Rh positive, another dose is administered within 72 hours after delivery. This will prevent her body from creating any future antibodies that could cause harm during a pregnancy .
      • .
      • -If a doctor determines that a woman has already developed Rh antibodies, then the pregnancy will be closely monitored to make sure that those levels are not too high. In rare cases, if the incompatibility is severe and the baby is in danger, a series of special blood transfusions (called exchange transfusions ) can be performed either while the baby is still in the uterus or after delivery.
      • -Exchange transfusions replace the baby's blood with red blood cells that have the Rh-negative factor. This procedure stabilizes the baby's level of red blood cells and minimizes further damage caused by circulating Rh antibodies already present in the baby's bloodstream. .
      • -Because of the success rate of the Rh immune globulin shots, exchange transfusions are needed in fewer than 1% of Rh-incompatible pregnancies today.
    • What Can Happen if Rh Disease Is Not Prevented
      • Rh incompatibility rarely causes complications in a first pregnancy and does not affect the health of the mother. But Rh antibodies that develop during subsequent pregnancies can be potentially dangerous to mother and child .
      • Rh disease can result in:
      • - Severe anemia.
      • -Jaundice.
      • -Brain damage.
      • -Heart failure in a newborn.
      • - In extreme cases… it can cause the death of the fetus because too many red blood cells have been depleted .
    • Summary: **There is 3 major shunts exist in the fetal circulation: “ Ductus arteriosus, ductus venosus & foramen ovale”. -Blood is shifting from the Rt atrium to the Lt atrium through the foramen ovale. -The ductus venosus allow blood to bypass the fetal liver partially. -The ductus arteriosus allow blood to bypass the lung & enter the descending aorta “these structures functionally close shortly after birth”. ** Rh incompatibility is a condition which develops when there is a difference in Rh blood type between that of the pregnant mother (Rh negative) and that of the fetus (Rh positive).
    • References:
      • Myles textbook for midwives
      • http:// www.childrenscentralcal.org
      • http://mcb.berkeley.edu/courses/mcb135e/fetal.html
      • http:// www.catalog.nucleusinc.com
      • http://www.medical-illustrator.co.uk
      • http:// www.brainconnection.com