Chapter 8 Genetics, conception, fetal devlopment Flashcards Preview

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Flashcards in Chapter 8 Genetics, conception, fetal devlopment Deck (34):

A father and mother are carriers of phenylketonuria (PKU). Their 2 year old daughter has PKU. The couple tells the nurse that they are planning to have a second baby. Because their daughter has PKU, they are sure that their next baby won't be affected. What response by the nurse is most accurate?
A. Good planning, you need to take advantage of the odds in your favor.
B. I think you'd better check with your doctors first.
C. You are both carriers, so each baby has a 25% chance of being affected.
D. The ultrasound indicates a boy, and boys are not affected by PKU.

C. The chance is one in four that each child produced by this couple will be affected by PKU disorder. This couple still has an increased likelihood of having a child with PKU. Having one child already with PKU does not guarantee that they will not have another. These parents need to discuss their options with their physician. However, an opportune time has presented itself for the couple to receive correct teaching about inherited genetic risks. No correlation exists between gender and inheritance of the disorder, because PKU is an autosomal recessive disorder.


The nurse is providing genetic counseling for an expectant couple who already have a child with trisomy 18. The nurse should:
A. Tell the couple they need to have an abortion within 2 to 3 weeks.
B. Explain that the fetus has a 50% chance of having the disorder.
C. Discuss options with the couple, including amniocentesis to determine whether the fetus is affected.
D. Refer the couple to a psychologist for emotional support.

C. Genetic testing, including amniocentesis, would need to be performed to determine whether the fetus is affected. The couple should be given information about the likelihood of having another baby with this disorder so that they can make an informed decision. A genetic counselor is the best source for determining genetic probability ratios. The couple eventually may need emotional support, but the status of the pregnancy must be determined first.


The nurse is assessing the knowledge of new parents with a child born with maple syrup urine disease (MSUD). This is an autosomal recessive inherited disorder, which means that:
A. Both genes of a pair must be abnormal for the disorder to be expressed.
B. Only one copy of the abnormal gene is required for the disorder to be expressed.
C. The disorder occurs in males and heterozygous females.
D. The disorder is carried on the X chromosome.

A. MSUD is a type of autosomal recessive inheritance disorder in which both genes of a pair must be abnormal for the disorder to be expressed. MSUD is not an X-linked dominant or recessive disorder or an autosomal dominant inheritance disorder.


In presenting to obstetric nurses interested in genetics, the genetic nurse identifies the primary risk(s) associated with genetic testing as:
a. Anxiety and altered family relationships.
b. Denial of insurance benefits.
c. High false positives associated with genetic testing.
d. Ethnic and socioeconomic disparity associated with genetic testing.

B. Decisions about genetic testing are shaped by socioeconomic status and the ability to pay for the testing. Some types of genetic testing are expensive and are not covered by insurance benefits. Anxiety and altered family relationships, high false positives, and ethnic and socioeconomic disparity are factors that may be difficulties associated with genetic testing, but they are not risks associated with testing.


A man’s wife is pregnant for the third time. One child was born with cystic fibrosis, and the other child is healthy. The man wonders what the chance is that this child will have cystic fibrosis. This type of testing is known as:
A. Occurence risk
B. Recurrence risk
C. Predictive testing
D. Predisposition testing

B. The couple already has a child with a genetic disease; therefore they will be given a recurrence risk test. If a couple has not yet had children but are known to be at risk for having children with a genetic disease, they are given an occurrence risk test. This couple already has a child with a genetic disorder. Predictive testing is used to clarify the genetic status of an asymptomatic family member. Predisposition testing differs from presymptomatic testing in that a positive result does not indicate 100% risk of a condition developing.


A key finding from the Human Genome Project is:
a. Approximately 20,000 to 25,000 genes make up the genome.
b. All human beings are 80.99% identical at the DNA level.
c. Human genes produce only one protein per gene; other mammals produce three proteins per gene.
d. Single gene testing will become a standardized test for all pregnant clients in the future.

A. Approximately 20,000 to 25,000 genes make up the human genome; this is only twice as many as make up the genomes of roundworms and flies. Human beings are 99.9% identical at the DNA level. Most human genes produce at least three proteins. Single gene testing (e.g., alpha-fetoprotein) is already standardized for prenatal care.


You are a maternal-newborn nurse caring for a mother who just delivered a baby born with Down syndrome. What nursing diagnosis would be the most essential in caring for the mother of this infant?
A. Disturbed body image
B. interrupted family processes
C. anxiety
D. risk for injury

B. This mother likely will experience a disruption in the family process related to the birth of a baby with an inherited disorder. Women commonly experience body image disturbances in the postpartum period, but this is unrelated to giving birth to a child with Down syndrome. The mother likely will have a mix of emotions that may include anxiety, guilt, and denial, but this is not the most essential nursing diagnosis for this family. Risk for injury is not an applicable nursing diagnosis.


A couple has been counseled for genetic anomalies. They ask you, “What is karyotyping?” Your best response is:
a. “Karyotyping will reveal if the baby’s lungs are mature.”
b. “Karyotyping will reveal if your baby will develop normally.”
c. “Karyotyping will provide information about the gender of the baby and the number and structure of the chromosomes.”
d. “Karyotyping will detect any physical deformities the baby has.”

C. Karyotyping provides genetic information such as gender and chromosome structure. The L/S, not karyotyping, reveals lung maturity. Although karyotyping can detect genetic anomalies, the range of normal is nondescriptive. Although karyotyping can detect genetic anomalies, not all such anomalies display obvious physical deformities. The term deformities is a nondescriptive word. Furthermore, physical anomalies may be present that are not detected by genetic studies (e.g., cardiac malformations).


In practical terms regarding genetic health care, nurses should be aware that:
a. Genetic disorders affect equally people of all socioeconomic backgrounds, races, and ethnic groups.
b. Genetic health care is more concerned with populations than individuals.
c. The most important of all nursing functions is providing emotional support to the family during counseling.
d. Taking genetic histories is the province of large universities and medical centers.

C. Nurses should be prepared to help with a variety of stress reactions from a couple facing the possibility of a genetic disorder. Although anyone may have a genetic disorder, certain disorders appear more often in certain ethnic and racial groups. Genetic health care is highly individualized because treatments are based on the phenotypic responses of the individual. Individual nurses at any facility can take a genetic history, although larger facilities may have better support services.


With regard to prenatal genetic testing, nurses should be aware that:
a. Maternal serum screening can determine whether a pregnant woman is at risk of carrying a fetus with Down syndrome.
b. Carrier screening tests look for gene mutations of people already showing symptoms of a disease.
c. Predisposition testing predicts with near certainty that symptoms will appear.
d. Presymptomatic testing is used to predict the likelihood of breast cancer.

A. Maternal serum screening identifies the risk for the neural tube defect and the specific chromosome abnormality involved in Down syndrome. Carriers of some diseases such as sickle cell disease do not display symptoms. Predisposition testing determines susceptibility such as for breast cancer; presymptomatic testing indicates that, if the gene is present, symptoms are certain to appear


With regard to the estimation and interpretation of the recurrence of risks for genetic disorders, nurses should be aware that:
a. With a dominant disorder the likelihood of the second child also having the condition is 100%.
b. An autosomal recessive disease carries a one in eight risk of the second child also having the disorder.
c. Disorders involving maternal ingestion of drugs carry a one in four chance of being repeated in the second child.
d. The risk factor remains the same no matter how many affected children are already in the family.

D. Each pregnancy is an independent event. The risk factor (e.g., one in two, one in four) remains the same for each child, no matter how many children are born to the family.
In a dominant disorder the likelihood of recurrence in subsequent children is 50% (one in two). An autosomal recessive disease carries a one in four chance of recurrence. Subsequent children would be at risk only if the mother continued to take drugs; the rate of risk would be difficult to calculate.


The nurse must be cognizant that an individual’s genetic makeup is known as his or her:
a. Genotype.
b. Karyotype.
c. Phenotype.
d. Chromotype.

A. The genotype comprises all the genes the individual can pass on to a future generation. The phenotype is the observable expression of an individual’s genotype. The karyotype is a pictorial analysis of the number, form, and size of an individual’s chromosomes. Genotype refers to an individual’s genetic makeup.


With regard to chromosome abnormalities, nurses should be aware that:
a. They occur in approximately 10% of newborns.
b. Abnormalities of number are the leading cause of pregnancy loss.
c. Down syndrome is a result of an abnormal chromosome structure.
d. Unbalanced translocation results in a mild abnormality that the child will outgrow.

B. Aneuploidy is an abnormality of number that also is the leading genetic cause of mental retardation. Chromosome abnormalities occur in fewer than 1% of newborns. Down syndrome is the most common form of trisomal abnormality, an abnormality of chromosome number (47 chromosomes). Unbalanced translocation is an abnormality of chromosome structure that often has serious clinical effects.


A woman’s cousin gave birth to an infant with a congenital heart anomaly. The woman asks the nurse when such anomalies occur during development. Which response by the nurse is most accurate?
a. “We don’t really know when such defects occur.”
b. “It depends on what caused the defect.”
c. “They occur between the third and fifth weeks of development.”
d. “They usually occur in the first 2 weeks of development.”

C. The cardiovascular system is the first organ system to function in the developing human. Blood vessel and blood formation begins in the third week, and the heart is developmentally complete in the fifth week. “We don’t really know when such defects occur” is an inaccurate statement. Regardless of the cause, the heart is vulnerable during its period of development, the third to fifth weeks. “They usually occur in the first 2 weeks of development” is an inaccurate statement.


A pregnant woman at 25 weeks’ gestation tells the nurse that she dropped a pan last week and her baby jumped at the noise. Which response by the nurse is most accurate?
a. “That must have been a coincidence; babies can’t respond like that.”
b. “The fetus is demonstrating the aural reflex.”
c. “Babies respond to sound starting at about 24 weeks of gestation.”
d. “Let me know if it happens again; we need to report that to your midwife.”

C. “Babies respond to sound starting at about 24 weeks of gestation” is an accurate statement. “That must have been a coincidence; babies can’t respond like that”
is inaccurate. Fetuses respond to sound by 24 weeks. Acoustic stimulations can evoke a fetal heart rate response. There is no such thing as an aural reflex. The statement, “Let me know if it happens again; we need to report that to your midwife” is not appropriate; it gives the impression that something is wrong.


At approximately _____ weeks of gestation, lecithin is forming on the alveolar surfaces, the eyelids open, and the fetus measures approximately 27 cm crown to rump and weighs approximately 1110 g.
a. 20 c. 28
b. 24 d. 30

C. These are all milestones in human development that occur at approximately 28 weeks.


The nurse caring for the laboring woman should know that meconium is produced by:
a. Fetal intestines.
b. Amniotic fluid.
c. Fetal kidneys.
d. The placenta.

A. As the fetus nears term, fetal waste products accumulate in the intestines as dark green to black, tarry, meconium.


A woman asks the nurse, “What protects my baby’s umbilical cord from being squashed while the baby’s inside of me?” The nurse’s best response is:
a. “Your baby’s umbilical cord is surrounded by connective tissue called Wharton jelly, which prevents compression of the blood vessels and ensures continued nourishment of your baby.”
b. “Your baby’s umbilical floats around in blood anyway.”
c. “You don’t need to worry about things like that.”
d. “The umbilical cord is a group of blood vessels that are very well protected by the placenta.”

A. “Your baby’s umbilical cord is surrounded by connective tissue called Wharton jelly, which prevents compression of the blood vessels and ensures continued nourishment of your baby” is the most appropriate response. “Your baby’s umbilical floats around in blood anyway” is inaccurate. “You don’t need to worry about things like that” is not appropriate response. It negates the client’s need for teaching and discounts her feelings. The placenta does not protect the umbilical cord. The cord is protected by the surrounding Wharton jelly.


The _____ is/are responsible for oxygen and carbon dioxide transport to and from the maternal bloodstream.
a. Decidua basalis
b. Germ layer
c. Blastocyst
d. Chorionic villi

D. Chorionic villi are fingerlike projections that develop out of the trophoblast and extend into the blood-filled spaces of the endometrium. The villi obtain oxygen and nutrients from the maternal bloodstream and dispose of carbon dioxide and waste products into the maternal blood. The decidua basalis is the portion of the decidua (endometrium) under the blastocyst where the villi attach. The blastocyst is the embryonic development stage after the morula. Implantation occurs at this stage. The germ layer is a layer of the blastocyst.


A woman who is 8 months pregnant asks the nurse, “Does my baby have any antibodies to fight infection?” The most appropriate response by the nurse is:
a. “Your baby has all the immune globulins (Ig) necessary: IgG, IgM, and IgA.”
b. “Your baby won’t receive any antibodies until he is born and you breastfeed him.”
c. “Your baby does not have any antibodies to fight infection.”
d. “Your baby has IgG and IgM.”

D. During the third trimester the only Ig that crosses the placenta, IgG, provides passive acquired immunity to specific bacterial toxins. The fetus produces IgM by the end of the first trimester. IgAs are not produced by the baby. By the third trimester the fetus has IgG and IgM. Breastfeeding supplies the baby with IgA. “Your baby does not have any antibodies to fight infection” is not an accurate statement.


The measurement of lecithin in relation to sphingomyelin (L/S ratio) is used to determine fetal lung maturity. Which ratio reflects maturity of the lungs?
a. 1.4:1
b. 2:1
c. 1.8:1
d. 1:1

B. A ratio of 2:1 indicates a two to one ratio of L/S, an indicator of lung maturity. Ratios of 1:4:1, 1.8:1, and 1:1 indicate immaturity of the fetal lungs.


Sally comes in for her first prenatal examination. This is her first child. She asks you (the nurse), “How does my baby get air inside my uterus?” The correct response is:
a. “The baby’s lungs work in utero to exchange oxygen and carbon dioxide.”
b. “The baby absorbs oxygen from your blood system.”
c. “The placenta provides oxygen to the baby and excretes carbon dioxide into your bloodstream.”
d. “The placenta delivers oxygen-rich blood through the umbilical artery to the baby’s abdomen.”

C. The placenta functions by supply oxygen and excreting carbon dioxide to the maternal bloodstream. The fetal lungs do not function for respiratory gas exchange in utero. The baby does not simply absorb oxygen from a woman's blood system. Blood and gas transport occur through the placenta. The placenta delivers oxygen rich blood through the umbilical vein and not the artery.


The most basic information a maternity nurse should have concerning conception is that:
a. Ova are considered fertile 48 to 72 hours after ovulation.
b. Sperm remain viable in the woman’s reproductive system for an average of 12 to 24 hours.
c. Conception is achieved when a sperm successfully penetrates the membrane surrounding the ovum.
d. Implantation in the endometrium occurs 6 to 10 days after conception.

D. After implantation, the endometrium is called the decidua. Ova are considered fertile for about 24 hours after ovulation. Sperm remain viable in the woman’s reproductive system for an average of 2 to 3 days. Penetration of the ovum by the sperm is called fertilization. Conception occurs when the zygote, the first cell of the new individual, is formed.


A maternity nurse should be aware of which fact about the amniotic fluid?
a. It serves as a source of oral fluid and a repository for waste from the fetus.
b. The volume remains about the same throughout the term of a healthy pregnancy.
c. A volume of less than 300 ml is associated with gastrointestinal malformations.
d. A volume of more than 2 L is associated with fetal renal abnormalities.

A. Amniotic fluid serves as a source of oral fluid, a repository for waste from the fetus, and also cushions the fetus and helps maintain a constant body temperature. The volume of amniotic fluid changes constantly. Too little amniotic fluid (oligohydramnios) is associated with renal abnormalities. Too much amniotic fluid (hydramnios) is associated with gastrointestinal and other abnormalities.


With regard to the structure and function of the placenta, the maternity nurse should be aware that:
a. As the placenta widens, it gradually thins to allow easier passage of air and nutrients.
b. As one of its early functions, the placenta acts as an endocrine gland.
c. The placenta is able to keep out most potentially toxic substances such as cigarette smoke to which the mother is exposed.
d. Optimal blood circulation is achieved through the placenta when the woman is lying on her back or standing.

B. The placenta produces four hormones necessary to maintain the pregnancy. The placenta widens until week 20 and continues to grow thicker. Toxic substances such as nicotine and carbon monoxide readily cross the placenta into the fetus. Optimal circulation occurs when the woman is lying on her side.


With regard to the development of the respiratory system, maternity nurses should be aware that:
a. The respiratory system does not begin developing until after the embryonic stage.
b. The infant’s lungs are considered mature when the lecithin/sphingomyelin (L/S) ratio is 1:1, at about 32 weeks.
c. Maternal hypertension can reduce maternal-placental blood flow, accelerating lung maturity.
d. Fetal respiratory movements are not visible on ultrasound scans until at least 16 weeks.

C. A reduction in placental blood flow stresses the fetus, increases blood levels of corticosteroids, and thus accelerates lung maturity. Development of the respiratory system begins during the embryonic phase and continues into childhood. The infant’s lungs are mature when the L/S ratio is 2:1, at about 35 weeks. Lung movements have been seen on ultrasound scans at 11 weeks.


Many parents-to-be have questions about multiple births. Maternity nurses should be able to tell them that:
a. Twinning and other multiple births are increasing because of the use of fertility drugs and delayed childbearing.
b. Dizygotic twins (two fertilized ova) have the potential to be conjoined twins.
c. Identical twins are more common in Caucasian families.
d. Fraternal twins are same gender, usually male.

A. If the parents-to-be are older and have taken fertility drugs, they would be very interested to know about twinning and other multiple births. Conjoined twins are monozygotic; they are from a single fertilized ovum in which division occurred very late. Identical twins show no racial or ethnic preference; fraternal twins are more common among African-American women. Fraternal twins can be different genders or the same gender. Identical twins are the same gender.


The nurse caring for a pregnant client knows that her health teaching regarding fetal circulation has been effective when the client reports that she has been sleeping:
a. In a side-lying position.
b. On her back with a pillow under her knees.
c. With the head of the bed elevated.
d. On her abdomen.

A. Optimal circulation is achieved when the woman is lying at rest on her side. Decreased uterine circulation may lead to intrauterine growth restriction. Previously it was believed that the left lateral position promoted maternal cardiac output, thereby enhancing blood flow to the fetus. However, it is now known that either side-lying position enhances uteroplacental blood flow. If a woman lies on her back with the pressure of the uterus compressing the vena cava, blood return to the right atrium will be diminished. Although this position is recommended and ideal for later in pregnancy, the woman must still maintain a lateral tilt to the pelvis to avoid compression of the vena cava. Many women will find this position uncomfortable as pregnancy advances. Side-lying is the ideal position to promote blood flow to the fetus.


Congenital disorders refer to conditions that are present at birth. These disorders may be inherited and caused by environmental factors or maternal malnutrition. Toxic exposures have the greatest effect on development between 15 and 60 days of gestation. For the nurse to be able to conduct a complete assessment of the newly pregnant client, she should understand the significance of exposure to known human teratogens. These include (choose all that apply):
a. Infections.
b. Radiation.
c. Maternal conditions.
d. Drugs.
e. Chemicals.

A, B, C, D, E
Exposure to radiation and a number of infections may result in profound congenital deformities. These include but are not limited to varicella, rubella, syphilis, parvovirus, cytomegalovirus, and toxoplasmosis. Certain maternal conditions such as diabetes and phenylketonuria may also affect organs and other parts of the embryo during this developmental period. Drugs such as antiseizure medication and some antibiotics, as well as chemicals, including lead, mercury, tobacco, and alcohol, also may result in structural and functional abnormalities.


Which congenital malformations result from multifactorial inheritance? Choose all that apply.
a. Cleft lip
b. Congenital heart disease
c. Cri du chat syndrome
d. Anencephaly
e. Pyloric stenosis

A, B, D, E
All these congenital malformations are associated with multifactorial inheritance. Cri du chat syndrome is related to a chromosome deletion.


____________________ twins is another term for fraternal twins. These twins may be the same or different sexes and genetically are no more alike than siblings born at different times.



The ability of the fetus to survive outside the uterus is called ____________________.



Very fine hairs, called ____________________, appear first at 12 weeks of gestation on the fetus’s eyebrows and upper lip. By 20 weeks they cover the entire body. By 28 weeks the scalp hair is longer than these fine hairs, which thin and may disappear by term gestation.



The fetal concentration of glucose is lower than the glucose level in the maternal blood because of the rapid metabolism by the fetus.

True or False