Embryonic Development, Pregnancy Dating, Maternal Adaptations to Pregnancy Flashcards
process of gametogenesis
development of gametes (when haploid male or female germ cell is able to unite with another of the opposite sex in sexual reproductive to form a zygote); oogenesis or spermatogenesis
meiosis vs mitosis
meiosis: a process of two successive cell divisions, producing cells, egg, or sperm that contain half the number of chromosomes found in somatic cells
mitosis: type of cell division of somatic cells in which each daughter cell contains the same number of chromosomes as the parent cell
oogenesis vs spermatogenesis
OOGENESIS: developmental process by which the mature human ovum is formed; haploid number of chromosomes
SPERMATOGENESIS: formation of mature functional spermatozoa; haploid number of chromosomes
haploid = how many chromosomes?
23 (i.e. half of 46)
what is the definition of fertilization?
union of ovum and spermatozoan; usually occurs in the fallopian tube within minutes or no more than a few hours of ovulation
most pregnancies occur when intercourse occurs within how many days of ovulation?
2 days
the stages of development
1. zygote
2. blastomeres
3. morula
4. blastocyst
5. embryo
6. fetus
7. conceptus
- zygote: diploid cell with 46 chromosomes; results from the fertilization of the ovum by the spermatozoan
- blastomeres: mitotic division of the zygote (cleavage) yields daughter cells called blastomeres
- morula: the solid ball of cells formed by 16 or so blastomeres; mulberry-like ball of cells that enters the uterine cavity 3 days after fertilization
- blastocyst: after the morula reaches the uterus, a fluid accumulates between blastomeres, converting the morula to a blastocyst; the inner cell mass at one pole becomes the embryo, the outer cell mass becomes a trophoblast
- embryo: stage in prenatal development between the fertilized ovum and the fetus (i.e., between second and eighth weeks inclusive)
- fetus: the developing conceptus after the embryonic stage
- conceptus: all tissue products of cepception: embryo (fetus), fetal membranes, and placenta
physiology of implantation of the blastocyst
-definition
-how many days after fertilization does implantation occur?
-definition: blastocyst adheres to the endometrial epithelium by gently eroding between the epithelial cells of the surface endometrium; invading trophoblasts burrow into the endometrium; the blastocyst becomes encased and covered by the endometrium
-implantation occurs 6-7 days after fertilization and is usually in the upper, posterior wall of the uterus
-provides physiologic exchange between maternal and embryonic environment prior to full placental function
differentiate between
1. the chorion
2. the chorion frondosum
3. chorion laeve
- chorion- an extra-embryonic membrane that, in early development, forms the outer wall of the blastocyst
- chorion frondosum- outer surface of the chorion whose villi contact the decidua basalis; the placental portion of the chorion
- chorion laeve- smooth, non villous portion of the chorion
what develops from the chorion?
- chorionic villi- which establishes an intimate connection with the endometrium
what does the chorionic villi give rise to?
the placenta
what is the synctriotrophoblasts of the chorionic villi of the placenta doing?
making contact with maternal blood or decidua
decidua capsularias vs decidua basalis vs decidua parientalis (vera)
-capsularias: part of the decidua that surround the chorionic sac
-basalis: part of the uterine decidua that unites with the chorion to form the placenta
-parientalis (vera): the endometrium during pregnancy, except at the site of the implanted blastocyst
amnion is defined as…
the innermost fetal membrane; a thin, transparent sac that holds the fetus suspended in the amniotic fluid; it grows rapidly at the expense of the extra-embryonic coelom; by the end of the third month, it fuses with the chorion, forming the amniochorionic sac, commonly called the “bag of waters”
placental function…
- serves as fetal lungs, liver, and kidneys until birth while growing and maintaining the conceptus in a balanced, healthy environment
anatomy of the placenta includes…
a. trophoblasts
b. chorionic villi
c. intervillous spaces
d. chorion
e. amnion
f. decidual plate
trophoblasts of the placenta produce what 5 steroid hormones? what is each steroids function in pregnancy?
- estradiol-17B: responsible for the growth of the uterus, fallopian tubes, vagina, and breast development
- estriol- estrogen metabolite excreted by the placenta during pregnancy; found in urine of pregnant women
- progesterone- secreted by corpus luteum; essential in preparing the uterus for implantation of the fertilized ovum and maintaining the pregnancy
- aldosterone- responsible for regulation of the body’s salt and water balance
- cortisol- plays a role in the metabolism of fats, glucose, and proteins
there are 9 protein and peptide hormones produced by the placenta including…
- Human placental lactogen (hPL): placental hormone that inhibits maternal insulin activity during pregnancy; decreases to undetectable levels after delivery of placenta
- Human chorionic gonadotropin (hCG): hormone secreted by the placenta to help maintain corpus luteum function and production of progesterone; found in serum and urine as early as a week after conception
- placental adrenocorticotropin hormone (ACTH): plays a role in regulation of the secretion of glucocorticoids
- Pro-opiomelanocortin: precursor polypeptide
- chorionic thyrotropin: a type of hormone similar to TSH that has the ability increase metabolism
- growth hormone variant: plays vital role in growth control
- parathyroid hormone: related protein (PTH-rP)- essential for bone differentiation and formation/development of mammary glands
- Calcitonin: hormone responsible for calcium balance
- Relaxin: produced in placenta and corpus luteum; believed to help with relaxing the uterine myometrium during pregnancy
placental hypothalamic-like releasing and inhibiting hormones
1. TRH
2. GnRH
3. CRH
4. Somatostatin
- TRH/Thyrotropin-releasing hormone: responsible for TSH regulation
- GnRH: controls secretion of LH and FSH
- CRH/Coricotropin-releasing hormone: works with vasopressin hormone to regulate release of ACTH
- Somatostatin: inhibits release of growth hormone, prolactin, and thyrotropin
how are oxygen and glucose transported across the placenta
via facilitated diffusion (protein channels help sugars pass through!) oxygen is small and nonpolar so can easily cross membrane
umbilical cord anatomy
-size in cm
2 arteries, 1 vein
arteries: carry fetal deoxygenated blood to the placenta
one vein: carries oxygenated blood from the placenta to the fetus
.8 - 2 cm in diameter, 55 cm on avg in length; with range of 30-100 cm
what is Wharton’s jelly
extracellular matrix consisting of specialized connective tissue that serves as protection for the umbilical cord
extremely short umbilical cord is associated with…
abruptio placentae or uterine inversion
abnormally long umbilical cord is associated with
vascular occlusion by thrombi and true knots
polyhydramnios
-AFI>
-s/sx
-excess amniotic fluid
-50-60% are idiopathic
-an AFI > 24 cm or max vertical pocket > 8 cm
-SX: uterine size > EGA, difficulty auscultating fetal HR
how is amniotic fluid produced? how is it maintained?
-production: by amniotic epithelium; water transfers across amnion and through fetal skin; in second trimester fetus starts to swallow, urinate, and inspire amniotic fluid
-maintenance: fetal swallowing is critical; polyhydramnios is consistently present when fetal swallowing is INHIBITED;
diagnosis of polyhydramnios
-physical findings
-u/s findings
-fundal height measurements that are 3-4 cm greater than normal (warrants u/s)
-u/s: AFI > 24 cmw
what has hydramnios been linked to… (many things)
-fetal macrosomia
-PTL
-risk for PP hemorrhage (higher given the uterus is enlarged)
-increased risk for cord prolapse w/ ROM
management of polyhydramnios is only indicated if…
monitoring includes…
symptomatic and benefits outweigh the risks
-monitor with serial NSTs and BPPS starting at 34 weeks
- amniocentesis
- indomethacin: impairs production of lung liquid
oligohydramnios defined as…
decreased AFV, defined as AFI < 5 cm or a maximum deepest vertical pocket of fluid < 2 cm
conditions associated with oligohydramnios
1. fetal
2. placental
3. maternal
4. drugs
- fetal: chromosomal abnormalities, congenital anomalies, growth restriction, demise, post-term pregnancy, ROM, PROM
- placental: abruption, twin to twin transfusion syndrome
- maternal: uteroplacental insufficiency, hypertensive disorders (chronic, gestational), diabetes
- drugs: prostaglandin synthesis inhibitors, ACE-inhibitors
fetal surveillance with oligohydramnios…
once or twice weekly surveillance upon diagnosis
embryonic development
-organogenesis begins…. and lasts about…
-what week is the heart fully formed?
begins in the third week after fertilization and spans 8 weeks
fourth week- partitioning of heart begins; arm and leg buds form; amnion begins to unsheathe the body stalk that becomes the umbilical cord
sixth week: head is much larger than body; heart is completely formed; fingers and toes present
***all major organ systems are formed except for lungs
fetal development
-begins how many weeks after fertilization?
8 weeks after fertilization! 10 weeks after onset of LMP
@ 12 weeks: uterus palpable at the symphysis; fetus begins to make spontaneous movements
@ 16 weeks: experienced observes can determine sex on u/s
@ 20 weeks: uterus @ belly button; weight begins to increase
@ 24 weeks: fat deposition, terminal sacs in the lungs still not completely formed
@ 28 weeks: fetus weight 1100 g; papillary membrane has just disappearance from eyes; 90% chance of survival if otherwise normal
@ 32-36 weeks: fetus continues to increase in weight as more subcutaneous fat accumulates
diagnosis of pregnancy
-signs of pregnancy
a. presumptive
b. probable
c. positive
a. presumptive
(subjective)
-amenorrhea
-N/V
-urinary frequency
-fatigue
-breast tenderness
(objective)
-Chadwick’s sign (bluish discoloration of vagina/cervix)
-expression of colostrum
-appearance of Montgomery’s tubercles
b. probable
-enlargement of abdomen, uterus
-change in shape of uterus
-positive pregnancy test
c. positive
-FHTs (heard with doppler starting at 10 weeks)
-sonographic evidence
-palpation of fetal movement
methods for determining EDD
-Naegle’s rule
subtract 3 months, add 7 days to the first day of the LMP, then add 1 year
first trimester u/s are the most…
accurate! That is why we always use the earliest dating ultrasounds (w/ first day of LMP) to determine EDD
discrepancies only go up as baby grows
Maternal physiologic adaptations to pregnancy!
so many!
uterus
-first trimester
-early second trimester
-after 20 weeks
-by term
-first: 6 weeks uterus is soft, globular, and asymmetric (Piskacek’s sign); at 12 weeks, it is 8-10 cm and its moving out of the pelvis
-early second: 16 wks uterus is half way to belly button and at 20 weeks, the fundus is @ umbilicus
-after 20 weeks: number of cm with tape measure equals number of weeks of gestation within 2 cm
by term: uterus weighs about 1100 grams with a 5-L volume
cervix in pregnancy
-Hegar’s sign
-Chadwick’s sign
-Goodell’s sign
-increased vascularity, thick mucus plug forms secondary to glandular proliferation
-Hegar’s sign: softening of the isthmus
-Chadwick’s sign: bluish color of the cervix
-Goodell’s sign: softening of the cervix
how long is the corpus luteum under the influence of hCG?
until about 12 weeks
-corpus luteum secretes progesterone which maintains the endometrium and pregnancy until the placenta takes over
vagina in pregnancy
a. chadwick’s sign: bluish color
b. thickening of vaginal mucosa
c. increase in vaginal secretions
breasts in pregnancy
-increase in size secondary to mammary hyperplasia
-areola becomes more deeply pigmented and increases in size
-colostrum may be expressed after the first several months of pregnancy
-vascularity increases
four types of pelvis
a. anthropoid
b. android
c. gynecoid
d. patylpelloid
a. anthropoid
-shape favors posterior position of fetus
-adequate for vaginal birth due to large size
b. android
-commonly known as male pelvis
-heavy, heart shaped pelvis leads to increased posterior positions, dystocia, operative births
c. gynecoid
-commonly known as female pelvis
-41-42% of women
-good prognosis for vaginal birth
d. patylpelloid
-rare, vaginal delivery is poor secondary to short anterior-posterior diameter
pregnancy and the GI system
-mouth and pharynx
-esophagus
-stomach
-large and small intestines
-gallbladder
-liver
-mouth and pharynx: gingivitis, bleeding gums, increased salivation
-esophagus: decreased LES pressure and tone; heartburn is common
-stomach: decreased gastric emptying time, decreased gastric acidity and histamine output
-large and small intestines: decreased tone and motility; displaced by growing uterus
-gallbladder: decreased tone and motility
-liver: altered production of liver enzymes, plasma proteins, and serum lipids
pregnancy and its impact on the genitourinary/renal system
-decreased bladder tone
-renal blood flow increases by 35-60%
-GFR increases
-RAAS system increases: more sodium and water retention
increased risk of UTI in pregnancy is a result of…
dilation of renal calyces, pelvis, and ureters
musculoskeletal system in pregnancy
-what two hormones have biggest impact on this system?
-relaxin and progesterone affect cartilage and connective tissue: loosening of sacroiliac joint and symphysis pubis
-lordosis
respiratory changes in pregnancy include
-level of diaphragm rises about 4 cm
-thoracic circumference increases by 5-6 cm
-respiratory rate changes very little, but tidal volume increases appreciably
-some women experience a physiologic dyspnea due to increased tidal volume and lower PCO2 (respiratory alkalosis)
hematologic changes in pregnancy
-blood volume increases by 30 to 50%
-plasma volume expands, resulting in physiologic anemia
-some require iron supplements
-hypercoagulable state because fibrinogen and factors VII-X increase during pregnancy
cardiovascular system changes in pregnancy
-resting pulse increases by 10-15 beats per minute, peaks at 28 weeks
-90% develop a physiologic systolic heart murmur
-exaggerated splitting of Sz
-cardiac output is increased
-diastolic BP is lower in first two trimesters because of the development of new vascular beds and relaxation of peripheral tone by progesterone which results in decreased flow resistance
skin changes in pregnancy
a. vascular changes
b. hair growth
a. vascular: palmar erythema, spider angiomas, varicose veins and hemorrhoids, hyperpigmentation (r/t estrogen and progesterone which have a melanocyte-stimulating effect), scars may darken, linea nigra, increased sweat/sebaceous activity
b. hair growth: estrogen increases length of the growth phase of hair follicles, mild hirsutism may develop in early pregnancy
endocrine changes in pregnancy
a. pituitary
b. thyroid
c. adrenal
d. pancreas
a. pituitary: prolactin levels are 10 times higher at term, enlarges by more than 100%
b. thyroid: increases in size, normal pregnant women is euthyroid because of estrogen-induced increase in thyroxin-binding globulin (TBG); TSH does not cross placenta
c. adrenal: two fold increase in serum cortisol
d. pancreas: hypertrophy and hyperplasia of B cells, insulin resistance as results of placental hormones, especially hPL
metabolism in pregnancy
-recommended weight gain
WEIGHT GAIN
1. BMI <18.5: 28-40 lbs total
2. BMI 18.5-24.9: gain 25-35 total
3. BMI 25-29.9: gain 15-25 lbs
4. BMI 30 or >: 11-20 lbs total
avg weight gain is 28 lbs
others: protein metabolism is increased, fat deposit and storage are increased to prepare for breastfeeding, carbohydrate metabolism altered: blood glucose levels are 10-20% lower than pre-pregnant states
IMPORTANT DEFINITIONS
1. fertility rate vs birth rate
2. perinatal period
3. neonatal mortality rate
4. perinatal mortality rate
5. infant mortality rate
6. maternal mortality ratio
- fertility rate is number of live births/1000 females 15-44 years old; birth rate is number of births divided by total population in given year
- perinatal period: from end of 22 weeks GA up to 7 days after birth;
- neonatal mortality rate: the number of neonates dying before reaching 28 days of age per 1000 live births in given year
- perinatal mortality rate: the number of stillbirths and perinatal death (in the first week of life) per 1000 total births
- infant mortality rate: number of infant deaths (in the first 12 months of life) per 1000 live births
- maternal mortality ratio: number of maternal deaths that result from reproductive process/100,000 live births
neonatal period is defined as
28 completed days after birth
neonatal death is death during the first ____ days after birth, late neonatal death is between ____
7 days; 7 days and 28 days
fetal death/stillbirth is spontaneous death of a fetus at…
any time in the pregnancy
stillbirth is after 20 weeks gestation
infant death is considered death of an infant in the first ___ months of life
12
late preterm infant vs early term infant
late preterm: 34 and 0/7 - 36 and 6/7
early term: 37 0/7 - 38 6/7
a term infant is an infant born after how many weeks?
37 completed weeks of gestation up until 42 completed weeks of gestation
post term infant is any infant born any time after the completion of what week?
42
gravida vs para
gravida: the number of time a women has been pregnant regardless of the outcome
para: number of pregnancies carried to the 20th week of gestation or the delivery of an infant weighing more than 500 g
nulligravida is a woman..
nullipara is a woman…
who has never been pregnant
who has not carried a baby to 500 g or past 20 weeks
primigravida vs multigravida vs primirpara
primigravida : a woman who is pregnant for the first time
multigravida: pregnant two or more times
primipara: a women who has carried a pregnancy past the 20th week of gestation who is currently pregnant for the first time and is carrying past the 20th
TPAL =
term= 37 weeks and beyond/2500 g
premature = 20-36 weeks and 6 days; 500-2499 g
abortions = any fetus born < 20 weeks and 500 g
living = current living children
fundal height is a measurement
in cm, from top of symphysis to the fundus of the uterus
leopold’s maneuvers help as determine…
fetal:
-lie
-presentation
-position
-attitude
-variety
-estimated fetal weight
pelvis
-the three planes of significance and the critical diameters for evaluation of pelvic adequacy
planes: inlet, midplane, and outlet
diameters:
-inlet, midplane, and outlet
initial visit labs to be drawn include…
-blood type
-Rh factor
-antibody screen
-CBC
-RPR or VDRL
-rubella titer
-hep B surface antigen
-urine culture/drug screen
-HIV testing
-Gonorrhea, chlamydia, trich
-TSH
-HgBA1c
-pap test up to date
carrier screening vs prenatal genetic screening
a. carrier screening: serologic testing on mother or father to determine if they carry specific genetic illnesses
b. prenatal genetic screen: serologic testing combined with USG performed during pregnancy to screen for aneuplooidy and spine and brain defects
first trimester screening
-between what weeks
-what tests are offered?
-between 10-13 weeks
-u/s to measure nuchal translucency
-pregnancy associated plasma protein and hCG
second trimester screening includes…
the quad screen
-serologic test between 15-22 weeks to detect NTDs and trisomies 18 and 21; serologic testing measuring MSAFP, estriol, inhibin A, and hCG
-u/s exam between 18-20 weeks to identify anatomic fetal defects
cell-free DNA testing
-serologic test on mother analyzes small amount of DNA that is release from the placenta into the bloodstream and screens for aneuploidy (trisomies 13, 18, 21) and problems with sex chromosomes;
-early as 10 weeks
what does a + cell-free DNA test warrant?
follow up w/ diagnostic test (CVS or amniocentesis)
a prenatal screen positive test result
NOT DIAGNOSTIC
-remember, this is only a SCREENING
-indicates increased risk
GDM screening between
24-28 weeks (early glucose screening as indicated)
what tests are repeated at 26-28 weeks?
antibody screen for Rh- mothers. repeat CBC, VDRL/RPR, chlamydia/gonorrhea, HIV, HBsAG as indicated
GBS screening between…
35-37 weeks
prenatal risk factors
a. genetic factors
-maternal age > 35
-previous child with chromosomal abnormality
-fam hx of birth defects
-African: sickle cell, Mediterranean or East Asian: B thalassemia, Jewish: Tay-Sachs
common discomforts of pregnancy
lots!
T/F 50% of pregnant women experience N/V
TRUE!
nonpharm therapies for NVP
a. prevention: women taking multivitamins @ time of conception are less likely to need tx for vomiting (rec taking prenatal vitamins 3 months prior to conceiving)
b. avoid triggers
c. small, frequent meals every 1 to 2 hours
d. avoid spicy and fatty foods; eat foods high in protein!
e. eat bland or dry foods such as crackers or toast before getting up and out of bed
f. d/c prenatal vitamins with iron until N/V has resolved, but continue folic acid
backache nonpharm suggestions in pregnancy
-massage, application of heat or ice, hydrotherapy, good body mechanics, pillow in lumbar area when sitting or between legs when lying on side, pregnancy support belt, supportive low heeled shoes
fatigue in pregnancy
-counseling patients
-reassure of normalcy in first trimester and will pass
-mild exercise and good nutrition
-decrease activities, plan rest
-decrease fluid intake in evening to decrease nocturia
heartburn in pregnancy
-counseling patietns
-small, frequent meals
-decrease amount of fluids take with meals; drink fluid between meals
-papaya
-elevated HOB 10-30 degrees
-antacids
-PPI/H2 blockers (Omeprazole)
constipation in pregnancy
-counseling
-increase fiber, fluids
-prune juice or warm beverage in the morning
-encourage exercise
-stool softeners
hemorrhoids in pregnancy
-counseling
-avoid constipation and straining
-elevate hips with pillow or knee-chest position
-sitz baths
-witch hazel or epsom salt compress
-topical anesthetics
***educate patient that if hemorrhoid becomes a deep purple or black they need to go to the ER
recommendations for leg cramps
-decrease phosphate; no more than two glasses of milk a day
-calcium and magnesium tablets
presyncopal episodes in pregnancy
-counseling
-change positions slowly
-push fluids
-avoid lying flat on back; avoid prolonged standing or sitting
headaches in pregnancy
-r/o…
-rule out migraines or other pathologic causes of headache
-hot or cold compress
-rest
-follow regular sleep schedule
-aromatherapy
-mild analgesic ok: acetaminophen 325 mg one to three tablets every 4 hours as needed
leukorrhea in pregnancy
-r/o
rule out vaginitis and STIs
skin rash in pregnancy
-recommendations
-oatmeal bath
-ice
-diphenhydramine: 25 mg PO every 4 hours PRN for itching
nutrition recommendations in pregnancy
-calories
-protein
2500 calories and 60 grams of protein a day
recommended patterns and quantity of weight gain
-normal pre-pregnant weight
-underweight
-overweight
-obese
-normal pre-pregnant weight: 0.8-1 lb/week during second and third trimesters, total of 25-35 lbs
-underweight: 1.0-1.3 lbs per week in second and third trimesters, total of 28-40 lbs
-overweight: .5-.7 lbs per week in second and third trimesters; 15-25 lbs
-obese: .4-.6 lbs per week in second and third trimesters, total of 11-20 lbs
T/F live vaccines are ok in pregnancy
FALSE
generally contraindicated because of concerns about the risk of transmitting the virus to a developing fetus; recommendation to give the vaccine 4 weeks prior to pregnancy or to wait until the postpartum period
(HPV, rubella, MMR)
Vaccines that are considered safe in pregnancy include…
- Tdap: give in every pregnancy at 32 weeks; protects against whopping cough
- Hep B: high risk women who are antigen and antibody negative can be vaccinated during pregnancy
- Tetanus
- Influenza: the trivalent inactive influenza vaccine ok (NOT the live attenuated)
when is doppler velocimetry blood flow assessment use?
in tertiary settings only if uteroplacental insufficiency resulting in IUGR is suspected or present
-detects velocity of blood flow through the fetal umbilical artery to the placenta
-normal waveforms produced when ratio of systolic to diastolic blood flow (s/d ratio) is approx 3; abnormal ratio is > 3
amniocentesis
-when its performed dictates what its assessing for…
-risks??
-between 14-16 weeks: genetic evaluation or assessment of NTDs
-later in pregnancy: assessment of lung maturity; rule out amnionitis or fetal hemolytic disease (Rh or anti-D)
RISKS: infection, bleeding, PRL, PROM, fetal loss
what special precautions must you take when doing an amniocentesis with a mother who is Rh negative?
administer RhoGAM with amniocentesis
CVS/chorionic villus biopsy
-when is it performed
-sample of chorionic villi from placenta is aspirated; outer trophoblastic layer obtained since it has the same genetic makeup as the fetus
-between 10-13 weeks (which is about 3-4 weeks earlier than amniocentesis)
-risks: infection, bleeding, miscarriage, risk of limb deformities when performed before 9 weeks
T/F most women are aware of fetal movement between 16 and 22 weeks and multiparas are generally aware of movement sooner than nulliparas
true
fetal kick counting
- Sanvosky’s protocol
- Cardiff “count to 10” method
- Sanvosky’s protocol: count FM 30 minutes three times daily; four or more movements in 30 minute period is reassuring. If < 4 in 30, then continue for 1 hour. Contact care provider if fewer than 10 movements
- Cardiff “count to 10” method: start at same time daily, if fewer than 10 movements in 10 hours or amount of time to reach 10 movements increases, NST should be performed
Nonstress test (NST) assesses fetal well being by…
observing the FHR response to fetal movement
75% of fetuses at 28 weeks experience HR accelerations w/ movement
fetal hypoxia depresses the medullary center in the brain that controls FHR response, resulting in…
depression of frequency or amplitude of FHR
3 indications for assessment of fetal well-being with NST
- decreased fetal movement
- post term
- diabetes, HTN, IUGR
reactive NST vs nonreactive NST
a. REACTIVE: two or more accelerations in FHR of 15 or more bpm, lasting for 15 or more seconds, within 15-20 minutes period for > 32 weeks GA; if between 28-32 weeks, criteria is 10 x 10
b. non reactive: further evaluation needed
factors that potentially affect NST results
- fetal sleep
- smoking 30 minutes prior
- maternal intake of medications
- fetal CNS anomalies
- fetal hypoxia
contraction stress test (CST)/oxytocin challenge test (OCT)
-where is test conducted?
assessment of fetal well-being by observing FHR response to uterine contractions
in a hospital only!! EFM to monitor FHR response to uterine contractions which can be spontaneous, from oxytocin admin, or nipple stimulation
an acceptable CST test would be ____ palpable contractions lasting ______ seconds
three; 40-60 seconds
CST results
-negative
-equivocal
-positive
-negative: no late or variable decels
-equivocal or suspicious: presence of non-repetitive or non-persistent decelerations
-positive: persistent late decels with 50% or more of the contractions
absolute contraindications to CST
previous classical c/s or myomectomy, placenta previa, at risk for PTL
relative: GA less than 37 weeks, multiple gestation
AFV measurement
a. single deepest pocket of fluid
b. AFI
a. single deepest pocket of fluid: normally between 2 cm and 8 cm
b. AFI: divide uterus into four quadrants and measure the deepest vertical pocket of fluid in each quadrant; AFI is sum of the four and is normally between 5 and 24 cm
BPP utilizes u/s to evaluate five fetal variables to assess fetal risk…
- breathing movements: one or more episodes in 30 minutes; none = 0, present = 2
- body movement: three or more discrete movements in 30 minutes
- tone: one or more episodes of extension with return to flexion; none = 0, present = 2
d. qualitative AFV: at least one pocket of amniotic fluid that measures at least 2 cm in two perpendicular planes
e. reactivity: reactive NST; nonreactive = 0, reactive = 2
scoring interpretation of BPP
-8 to 10
-6
-4 or less
8-10: normal
6 is equivocal, repeat testing
4 or less is abnormal
Percutaneous umbilical blood sampling (PUBS) or cordocentesis
needle inserted through moms abdomen into umbilical cord and blood is aspirated or medications are introduced
-usually performed after 20 weeks
assessment of fetal lung maturity is accomplished by..
assessing the amniotic fluid
prior to 39 weeks gestation, evaluate lung maturity if scheduled to deliver early with a lecithin to sphingomyelin ratio….
what ratio is indicative of fetal lung maturity (except in diabetes?)
a ratio of 2:1 or greater
*may not be accurate in hydrops fetalis
