! Genetics study of heredity

!1!Chapter 3 Genetics, Conception, Fetal Development, and Reproductive Technology ! Genetics " study of heredity ! Genomics " addresses all genes and their interrelationships in order to identify their combined influence on growth and development of the organism

• Providing better methods for preventing disease and abnormalities, diagnosing diseases, predicting health risks,

personalizing treatment plans ! 30,000 genes in the human genome (organism’s complete set of DNA) ! 46 chromosomes; 22 homologous pairs of chromosomes and one pair of sex chromosomes ! genotype " person’s genetic makeup ! phenotype " how genes are outwardly expressed (eye color, hair color, height) ! recessive genetic disorders " sickle cell anemia, cystic fibrosis, thalassemia, Tay-Sachs disease ! carrier testing " identify individuals who carry one copy of a gene mutation that, when present in two copies causes a genetic disorder; used when there is a family history of genetic disorder ! preimplantation testing/preimplantation genetic diagnosis " used to detect genetic changes in embryos that are created using assisted reproductive techniques ! prenatal testing " early detection of genetic disorders ! risks for conceiving child with genetic disorder " maternal age older than 35, man/woman who has genetic disorder; family history of genetic disorder, history of previous pregnancy resulting in a genetic disorder or newborn abnormalities ! refer to support group whether they wish to terminate/continue with pregnancy ! sickle cell anemia

• most common of African ancestry
• sickle-cell hemoglobin forms rigid crystals that distort and disrupt RBCs; oxygen-carrying capacity of blood is

diminished ! cystic fibrosis

• most common genetic disease of European ancestry
• production of thick mucus clogs in bronchial tree and pancreatic ducts
• most severe effects are chronic respiratory infections and pulmonary failure

! Tay-Sach disease

• Most common among Jewish ancestry
• Degeneration of neurons and nervous system results in death by the 2 years old

! PKU

• Lack of enzyme to metabolize the amino acid phenylalanine " leads to severe mental and physical retardation
• Effects may be prevented by use of a diet at beginning of birth that limits phenylalanine

! Huntington’s Disease

• Uncontrollable muscle contractions between 30-50 years followed by memory loss and personality
• No treatment that can delay mental deterioration

! Hemophilia (X-linked)

• Lack of factor 8
• Can be controlled with factor 8 from donated blood

! Duchenne’s Musclular Dystrophy

• Replacement of muscle by adipose or scare tissue with progressive loss of muscle function; often fatal before age

20 due to involvement of cardiac muscle

! teratogens " any drugs, viruses, infections, or other exposures that can cause embryonic/fetal developmental abnormality ! degree or types of malformation vary on length of exposure, amount of exposure, and when it occurs during human development ! developing human is most vulnerable to effects of teratogens within first 8 weeks of gestation (organogenesis)" can cause gross structural defects ! exposure after 13 weeks may cause fetal growth restriction or reduction of organ size ! toxoplasma is a protozoan parasite found in cat feces and uncooked/rare beef and lamb

• can cause fetal demise, mental retardation, blindness when fetus is exposed
• avoid contact with cat feces and eating rare beef or lamb if pregnant or attempting pregnancy

! rubella " increased risk for heart defects, deafness and/or blindness, mental retardation, fetal demise ! cytomegalovirus " increased risk for hydrocephaly, microcephaly, cerebral calcification, mental retardation, hearing loss ! herpes varicella/chicken pox " increased risk for hypoplasia of hands and feet, blindness/cataracts, mental retardation ! syphilis " increased risk for skin, bone and/or teeth defects, fetal demise ! cocaine " increased risk for heart, limbs, face, GI/GU tract defects, cerebral infarctions, placental abnormalities

Chapter 4 Physiological Aspects of Antepartum Care

!2!! G/P System

o Gravida: # times a woman has been pregnancy including current pregnancy

o Para: # of births after 20 weeks’ gestation whether live or stillbirths

• Abortions are not accounted for in this system

! GTPAL

o G: # times pregnancy

o T: # of term infants born after 37 weeks

o P: # of preterm infants between 20 and 37 weeks

o A: # of abortions either spontaneous or induced before 20 weeks

o L: # of living children

! Nulligravida: woman who has never been pregnant or given birth

! Primigravida: woman who is pregnant for the first time

! Multigravida: someone who is pregnant for at least the second time

! Prenatal period " entire time period during which a woman is pregnant through birth of baby ! Nurse places emphasis on health education and health promotion ! Family-centered maternity care is a model of obstetrical care based on a view of pregnancy and childbirth as a normal life event, a life transition that is not primarily medical but rather developmental ! Low-risk population should have approximately 14-16 prenatal visits per pregnancy ! First trimester

• Woman learns frequency of follow-up visits and what to expect from pregnancy visits as pregnancy progresses

during initial visit

• Comprehensive health and risk assessment; currently pregnancy history; complete physical and pelvic examination;

nutrition assessment; psychosocial assessment; assessment for intimate partner violence

• Fetal heart tones are auscultated with US Doppler, initially by 10 and 12 weeks
• At end of first trimester, fetus is 3 inches in length and weights 1-2 ounces, all organ systems are present
• Assessment of uterine growth after 10-12 weeks is measured by height of fundus with centimeter measuring tape;

zero point of tape is placed on the symphysis pubis and tape is extended to top of fundus; MEASUREMENT

SHOULD EQUAL # OF WEEKS PREGNANT

• Certain types of fish (king mackerel, shark, swordfish, tilefish) should be avoided due to high levels of

methylmercury ! Second trimester

• Chart review; interval history; focused physical assessment; pelvic exam/sterile vaginal exam if indicated; confirm

EDD

• Triple/quad screen (neural tube defect); US; screening for gestational diabetes; hemoglobin and hematocrit;

antibody screen if Rh-negative (Administration of RhoGAM if Rh-negative and anti-body screen negative) # Administered prophylactically at 28 weeks to prevent isoimmunization from potential exposure to Rh- positive fetal blood during normal course of pregnancy # Adverse reaction " pain at IM site; fever

• Slight decrease in blood pressure toward end of second trimester
• Assess for quickening " when the woman feels baby move for first time
• Leopold’s maneuvers to identify position of fetus
• Slight lower body edema is normal due to decreased venous return
• At 20 weeks, fetus is 8 inches long and weights 1 pound
• Increase in calorie intake by 340 kcal/day

! Third trimester

• Chart review; interval history; nutrition follow-up; focused physical assessment; pelvic exam/sterile vaginal exam if

indicated

• Group B Strept at 35-37 weeks; H&H if not done in second trimester; repeat GC, chlamydia, RPR, HIV HbSAg; 1-

hour glucose challenge test at 24-28 weeks

• Record fetal movement count " 10 distinct fetal movements within 2 hours is considered reassuring OR 4

movements in 1 hour

• At term, fetus is 17-20 inches long, 6-8 pounds
• Increase in calorie intake by 452 kcal/day

Chapter 6 Antepartal Tests ! Chorionic villus sampling " aspiration of a small amount of placental tissue for chromosomal, metabolic, or DNA testing

• Between 10 and 12 weeks to detect fetal abnormalities caused by genetic disorders
• Tests for cystic fibrosis but not neural tube defects
• Supine position for transabdominal aspiration with US to guide placement
• Lithotomy for transvaginal aspiration with US to guide placement
• Small biopsy of chorionic (placental) tissue is removed
• Assess fetal and maternal well-being post-procedure; FHR is auscultated twice in 30 minutes

!3!

• Instruct woman to report abdominal pain/cramps, leaking of fluid, bleeding, fever, chills
• Results within 1 week

! Amniocentesis

• Needle is inserted through maternal abdominal wall into uterine cavity to obtain amniotic fluid
• Genetic testing, fetal lung maturity, assessment of hemolytic disease in fetus or for intrauterine disease

# Fetal lung maturity, monitor for L/S RATIO, PG, LBC

• Usually performed 14-20 weeks gestation
• Results within 2 weeks
• FULL BLADDER MAY BE REQUIRED FOR ULTRASOUND VISULIZATION IF WOMAN IS LESS THAN 20

WEEKS ! Delta OD 450

• Evaluation of amniotic fluid obtained via amniocentesis to predict life-threatening anemia in fetus during second and

third trimester

• Used in a lab to determine if there is a deviation of optical density at 45 nm

! Fetal blood sampling/percutaneous umbilical blood sampling (CORDOCENTESIS)

• Removal of fetal blood from umbilical cord " used to test for metabolic and hematological disorders, fetal infection,

fetal karyotyping

• may be done as early as 11 weeks but usually done in second trimester
• results within 48 hours
• POSITION WOMAN IN LATERAL/WEDGED POSITION TO AVOID SUPINE HYPOTENSION DURING FETAL

MONITORING TESTS

• Have terbutaline ready as ordered in case uterine contractions occur during procedure
• Assess fetal well-being post-procedure 1-2 hours via external fetal monitoring

! Alpha-fetoprotein (AFP)

• Done at 15-20 weeks gestation
• Assessed in maternal blood to screen for certain developmental defects in the fetus (NTD, ventral abdominal wall

defects)

• Increased levels associated with NTDs, anencephaly, omphalocele, gastroschisis
• Decreased levels associated with Down syndrome
• Abnormal findings require additional testing " amniocentesis, VNS, US

! Multiple marker screen

• Combination of AFP, human chorionic gonadotropin (hCG), estriol levels
• Detects for some trisomies and NTDs
• done at 15-16 weeks gestation
• maternal blood is drawn and sent to lab
• low levels of maternal serum alpha-fetoprotein and unconjugated estriol levels suggest an abnormality
• hCG and inhibin-A levels are twice as high in pregnancies with trisomy 21 (Down’s Syndrome)
• decreased estriol levels are an indicator of NTDs

! Daily fetal movement

• Proposed as primary method of fetal surveillance after 28 weeks gestation
• Instruct woman to palpate abdomen and track fetal movements daily for 1-2 hours
• 10 distinct fetal movements within 2 hours is normal

# once movement is achieved, counts can be d/c for the day

• 4 movements in 1 hour is reassuring

# if decreased, have woman eat, rest and focus on fetal movement for 1 hour

• FEWER THAN 4 FETAL MOVEMENTS IN 2 HOURS SHOULD BE REPORTED
• LIE ON SIDE WHILE COUNTING MOVEMENTS

! Non-stress test

• Uses electronic fetal monitoring to assess fetal condition/well-being
• Looking for accelerations; baby is nice and active
• Used in women with complications such as HTN, diabetes, multiple gestation, trauma and/or bleeding, woman’s

report of lack of fetal movement, placental abnormalities

• Heart rate of normal fetus with adequate oxygenation and intact autonomic nervous system accelerates in

response to movement

• Monitored with external FHR until reactive (up to 40 minutes) while running FHR contraction strip for interpretation
• Considered reactive when FHR increases 15 beats above baseline for 15 seconds twice or more in 20

minutes

• In fetuses less than 32 weeks, two accelerations peaking at least 10 bpm above baseline and lasting 10

seconds in a 20-minute period is reactive

• Nonreactive NST is one without sufficient FHR accelerations in 40 minutes " followed up for further testing

!4!

• Presence of repetitive variable decelerations that are >30 seconds requires further assessment of

amniotic fluid

• VOID AND LIE IN A SEMI-FOWLER’S/LATERAL POSITION

! Vibroacoustic stimulation

• Uses auditory stimulation to assess fetal well-being with EFM when NST is nonreactive

# Used to elicit a change in fetal behavior, fetal startle movements, increased FHR variability

• Used only when baseline rate is determined to be within normal limits
• Conducted by activating an artificial larynx on the maternal abdomen near the fetal head for 1 second in conjunction

with NST; can be repeated at 1-minute intervals up to 3 times

• Reactive if FHR increases 15 beats above baseline for 15 seconds twice in 20 minutes

! Contraction stress test

• Assess fetal well-being and uteroplacental function with EFM in women with nonreactive NST at term gestation
• Identify a fetus that is at risk for compromise through observation of the fetal response to intermittent

reduction in utero placental blood flow associated with stimulated uterine contractions

• Monitor FHR and fetal activity for 20 minutes
• If no spontaneous UCs, initiate contractions by having woman brush nipples for 10 minutes

# Unsuccessful " oxytocin via IV until 3 UCs in 10-20 minutes lasting 40 seconds

• Negative or normal when there are no significant variable decelerations or no late decelerations in a 10

minute strip with 3 UCs > 40 seconds assessed with moderate variability

• Positive if late decelerations of FHR with 50% of UCs usually assessed with minimal or absent variability
• Equivocal or suspicious when there are intermittent late or variable decelerations
• POSITION IN SEMI-FOWLER’S POSITION

! Amniotic fluid index

• Measures volume or amniotic fluid with ultrasound to assess fetal well-being and how well the placenta is working
• Amniotic fluid based on fetal urine production
• Average measurement " 8-24 cm
• AFI less than or equal to 5 cm is indicative of oligohydramnios

# Associated with prenatal mortality

• AFI above 24 cm is indicative of polyhydramnios

# May indicate fetal malformation " NTDs, obstruction of fetal GI tract, fetal hydrops ! Biophysical profile

• NST with additional 30 minutes of ultrasound observation of fetal breathing movement, gross body movement, fetal

tone, amniotic fluid volume, heart rate reactivity

• One or more episodes of rhythmic breathing movements of 30 seconds or movement within 30 minutes is expected
• Three or more discrete body/limb movements within 30 minutes are expected
• One or more fetal extremity extension with return to fetal flexion or opening and closing of hand is expected
• Pocket of amniotic fluid that measures at least 2 cm in 2 planes perpendicular to each other is expected
• Score of 2 is assigned to each component

# 8/10 is reassuring # 6/10 is equivocal and may indicate need for delivery depending on gestational age # 4/10 delivery is recommended because of a strong correlation with chronic asphyxia # 2/10 or less prompts immediate delivery ! modified biophysical profile

• combines NST as an indicator of short term fetal well-being and AFI as indicator of long-term placental function
• considered normal when NST is reactive and AFI is greater than 5cm

Chapter 8 Intrapartum Assessment and Interventions ! true labor

• occur at regular intervals and increase in frequency, duration and intensity
• bring about changes in cervical effacement and dilation

! false labor

• irregular contractions with little or no cervical changes

! spontaneous rupture of the membranes can occur before onset of labor but typically occurs during labor

• woman should deliver within 24 hours to reduce risk of infection

! confirmation of rupture of membranes (ROM)

• speculum exam to asses for fluid in the vaginal vault
• Nitrazine paper " paper turns blue when in contact with amniotic fluid
• Ferning " ferning pattern confirms ROM
• AmniSure testing kit

! INCREASED RISK OF UMBILICAL CORD PROLAPSE WITH ROM

! Normal amniotic fluid is clear/cloudy with normal odor (similar to ocean water or loam of a forest floor)