Diagnostic testing used to determine well being of fetus

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Diagnostic testing used to determine well being of fetus
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2011-11-28 12:11:05
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Diagnostic testing used determine well being fetus
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Diagnostic testing used to determine well being of fetus
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  1. External abdominal ultrasound
    noninvasive, painless and safe procedure (requires a full bladder)

    abdominal ultrasound is more useful after the first trimester when the gravid uterus is larger

    the ultrasound transducer is moved over a client's abdomen to obtain an image
  2. Internal transvaginal ultrasound
    Invasive procedure: a probe is inserted into vagina and allows for more accurate evaluation (does not require a full bladder)

    useful in patients who are obese and those in the first trimester to detect an ectopic pregnancy, identify abnormalities, and help to establish gestational age


    • may also be used in the third trimester in conjunction with abdominal scanning to evaluate for preterm labor
  3. Indications for the use of an ultrasound during pregnancy
    • confirming pregnancy
    • confirming gestational age by biparietal diameter (side to side) measurement
    • identifying multifetal pregnancy
    • site of fetal implantation (uterine or ectopic)
    • assissing fetal growth and development
    • assessing maternal structure
    • confirming fetal viability or death
    • ruling out or verifying fetal abnormalities
    • locating the site of placental attachment
    • determining amniotic fluid volume
    • fetal movement observation (fetal heart beat, breathing, and activity)
    • placental grading (evaluating placental maturation)
    • adjunct for other procedures (e.g. amniocentesis, biophysical profile)
  4. The physician will order an ultrasound for patients with these conditions during pregnancy
    • vaginal bleeding evaluation
    • questionable fundal height measurement in relationship to gestational weeks
    • reports of decreased fetal movement
    • preterm labor
    • questionable rupture of membranes
  5. How to prepare the patient for an external abdominal ultrasound
    • explain the procedure to the patient that it presents no known risk to her or her fetus
    • advise the patient to drink 1-2 quarts of fluid prior to the ultrasound to fill the bladder to lift and stabilize the uterus, displace the bowels away and act as a transducer to better reflect sound waves and to get a better image of the fetus
    • assist the patient into a supine position with a wedge placed under her right hip to displace the uterus (prevent supine hypotension)
    • apply an ultrasonic/transducer gel to the patients abdomen before the transducer is moved over the skin to obtain a better fetal image, asssuring that the gel is at room temperature or warmer to prevent uterine cramping
    • allow the patient to empty her bladder at the termination of the procedure
  6. How to prepare the patient for a transvaginal ultrasound
    • assist the client into a lithotomy position
    • the vaginal probe is covered with a protective device, lubercated with a water-soluable gel
    • explain that probe or tilt of the table may be changed to facilitate a full view of the pelvis
    • inform the client that some pressure may be felt as the probe is moved
    • fetal and maternal sructures may be pointed out to the patient as the ultrasound procedure is performed
  7. Biophysical profile
    The BPP (Biophysical profile) assess a total of five parameters of fetal well-being.

    Uses real time ultrasound to visualize physical and physiological characteristics of the fetus and observes for fetal biophysical resonses to stimuli

    • the NST (nonstress test)
    • 1) fetal breathing movements
    • 2) gross fetal movements (large trunk movements)
    • 3) fetal tone (small or fine body movements such as limb or hand extension and flexion or sucking movements)
    • 4) anmiotic fluid volume

    The last four perameters require an ultrasound evaluation

    if all four are reassuring the nonstress test is not essential

    • usually performed
    • in third trimester or for post-term fetus
    • premature rupture of membranes
    • maternal infection
    • decreased fetal movement
    • intruterine growth restriction

    prepare the patient the same as you would for an ultrasound

    • interpretation of findings
    • total score of 8-10 is being normal
    • 6=equivocal
    • <4 is abnormal

    • potential diagonsis:
    • nonreactive stress test
    • suspected oligohydramnios or polyhydramnios
    • suspected fetal hypoxemia and/of hypoxia
  8. Biophysical profile score's
    • Reactive: FHR:=2; nonreactive=0
    • fetal breathing movements (atleast 1 episode of 30 sec in 30 min)=2 absent or less thean 30 sec duration=0
    • gross body movements (atleast 3 body or limb extensions with return to flexion in 30 min)=2 less than 3 episodes=0
    • fetal tone (atleast 1 episode of extesion with return to felxion)=2; slow extension and flexion, lack of flexion, or absent of mouement= 0
    • amniotic fluid volume (at least 1 pocket of fluid that measures at least 1 cm in 2 perpendicular planes_=2 ; pockets absent or less than 1 cm =0
  9. Nonstress test
    • performed during the third trimester
    • noninvasive procedure that monitors response of the FHR and fetal movement
    • a doppler transducer is used to minitor the FHR, and a recotransducer is used to monitor uterine contractions (attached to the patients abdomen to obtain paper tracing strips
    • patient pushes a button attached to the monitor whenever she feels a fetal movement which is then noted on the paper tracing
    • allows assessment of the FHR in relationship to the fetal movement
  10. Indications for the use of a Nonstress test during pregnancy
    • assessing for an intact fetal CNS during the third trimester
    • ruling out the risk of fetal death in clients who have diabetes mellitus. used twice a week or, until after 28 weeks of gestation reasons for a Nonstress test:
    • decreased fetal movemet
    • intrauterine growth restriction
    • post-maturity
    • gestational diabetes mellitus
    • pregnancy-induced hypertention
    • history of previous fetal demise
    • advanced maternal age
    • sickle cell disease
    • interpertations of findings:
    • the NST is interpreted as reactive if the FHR is normal baseline rate with moderate variablility, accelerates to 15 beats/min for at least 15 seconds and occurs two or more time during a 20-min period
  11. A Nonreactive stress test indicates
    • that the fetal heart rate does not accelerate adequately with fetal movement
    • it does not meet the criteria after 40 minutes, if this is so a further assessment such a a contraction stress test (CST) or biophysical profile (BPP) is indicated
  12. Preparation of the patient for a Nonstress test (NST)
    • seat the patient in a reclining chair or place in a semi-fowler's or left-lateral position
    • apply conduction gel to the patients abdomen
    • apply two belts to the patients abdomen and attach the FHR and uterine contraction monitors
    • instruct patient to press the button on the handheld event marker wach time she feels the fetus move
    • if there are no fetal movements (fetus is sleeping), vibroacoustic stimulation (sound sourse, usually laryngeal stimulator) may be activated for 3 seconds on the maternal abdomen over the fetal heeat ot awaken a sleeping fetus
    • if NST is still non reactive, anticipate a CST and/or BPP
    • disadvantages of a NST include a high rate of false nonreactive restuls with the fetal movement response blunted by sleep cycles of the fetus, fetal immaturity, maternal medications, and chronic smoking
  13. Contraction stress test
    Nipple stimulated CST consists of a woman lightly brushing her palm across her nipple for 2-3 min, which causes the pituitary gland to release endogenous oxytocin, and then stopping the nipple stimulation when a contraction begins, the same process is repeated after a 5 min rest period

    Oxytocin (Pitocin) administered CST is used if nipple stimulation fails and consists of the IV administration of oxytocin to induce uterine contractions. Contractions started with oxytocin may be difficult to stop and can lead to preterm labor

    • Indications for CST:
    • high-risk pregnancies (gestational diabetes mellitys, postterm pregnancy)
    • Nonreactive stress test
    • decreased fetal movement
    • intrauterine growth restriction
    • postmaturity
    • gestational diabetes mellitus
    • pregnancy-induced hypertention
    • maternal chronic hypertension
    • history of fetal demise
    • advanced maternal age
    • sickle-cell disease

    • Interpretation of findings:
    • a negative CST (normal findings) is indicated if within a 10-min period, with three uterine contractions, there are no late decelerations of the FHR
    • a postitve CST (abnormal findings) is indicated with persistent and consistent late decelerations on more than half of the contaction. This is suggestive of unteroplacental insufficiency
    • Variable deceleration may indicate cord compression, and early decelerations may indicate fetal head compression based on these findings, physician may determine to induce labor or perform a cesarean birth
  14. Nursing actions/ongoing care/ interventions when preforming a Contraction Stress test (CST)
    • obtain a base line of the FHR, fetal movement, and contractions for 10-20 min. and document
    • explain the procedure to the patient and obtain an informed consent form from her
    • complete an assessment without artificial stimulation if contreactions are occurring spontaneously
    • ongoing care:
    • initiate nippple stumulation if there are no contractions instruct the patient to roll a nipple between her thumb and fingers or brush her palm across her nipple and to stop when a uterine contraction begins
    • monitor and provide adequate rest periods for the patient to avoid hyperstimulation of the uterus
    • Interventions:
    • initiate IV Oxytocin administration if nipple stimulation fails
    • If hyperstimulation of the uterus and/or preterm labor occurs:
    • monitor for contracions lasting longer than 90 sec and/or occurring more frequently than every 2 min
    • provide administration of tocolytics as prescribed
    • maintain bed rest during the procedure
    • observe the patient for 30 min afterward to see that contractions have cased and preterm labor does not begin
    • Possable complications:
    • potential for preterm labor
  15. Amniocentesis
    • May be performed after 14 weeks if gestation
    • the aspiration of amniotic fluid for analysis by insertion of a needle transabdominally into the patients urerus and amniotic sac under direct ultra sound guidance locating the placenta and determining the position of the fetus

    • Indications for the use of an amniocentesis
    • maternal age greater than 35 years
    • previous birth with a chromosomal anomaly
    • a parent who is a carrier of a chromosomal anomaly
    • a family history of neural tube defects
    • prenatal diagnosis of a ganetic disorder or congenital anomaly of the fetus
    • alpha fetoprotein level for fetal abnormalitites
    • lung maturity assessment
    • fetal hemolytic disease diagnosis
    • meconium in the amniotic fluid

  16. Alpha-fetoprotein (AFP)
    measured in the amniotic fluid by amniocentesis between 16-18 weeks of gestation

    used to assess for neural tube deects in the fetus or chromosomal disorders

    High levels of AFP are associated with neural tube defects such as anencephaly (incomplete development of fetal skull and brain), spina bifida (open spine), or omphalocele (abdominal wall defect). High AFP levels may also be present with normnal multifetal pregnancies

    • Low levels of AFP are associated with chromosomal disorders (Down syndrome) or gestational trophoblastic disease (hydatidiform mole)
  17. Amniocentesis for lung maturity
    • performed if gestation is less than 37 weeks
    • in the event of rupture of membranes
    • preterm labor
    • for a complication indicating a cesarean birth
    • amniotic fluid is tested to determine if the fetal lungs are mature enough to adapt to extauterine life or if the fetus will likely have respiratory distress
    • determination is made whether the fetus should be removed immediately or if the fetus requires more time in utero with the administration of glucocorticoids to promote fetal lung maturity
  18. Nursing actions/Patient teaching
    associated with amniocentesis
    • explain the procedure and obtain an informed consent form from patient
    • instruct the patient to empty bladder prior to the procedure to reduce its size and reduce the risk of inadvertent puncture
    • assist the patient into a supine position and place a wedge of rolled towel under her right hip to diaplace the uterus off the vena cava and place a drape over the patients exposing only her abdomen
    • prepart the client for an ultrasound to locate the placenta
    • obtain the patients baseline vital signs and FHR and document prior to the procedure
    • cleanse the patients abdomen with an antiseptic solution prior to the administration of a local anesthetic given by the physician
    • take maternal blood pressure and obtain the FHR baseline levels
    • advise the client that she will feel slight pressure as the needle is inserted for aspiration, however she should continue breathing because holding her breath will lower the diaphragm agianst the uterus and shift the intrauterine contents
    • Postprocedure:
    • monitor the patient's vital signs, FHR, and uterine contractions throughout and 30 mins following the procedure
    • have patient rest for 30 min
    • administer Rho(D) immune golbulin (RhoGAM) to the patient id she is Rh-negitive (standard proceedure for all women who are Rh-negitive to protect against Rh isoimmunization)
    • Client education:
    • advist the patient ro report to her physician if she experiences fever, chills, leakage of fluid, or bleeding from the isertion site, decreased fetal movement, vaginal bleeding, or uterine contractions after the procedure
    • encourage the patient to drink plenty of liquids and rest for the next 24 hours post procedure
  19. Complications that can arise due to amniocentesis
    • amniotic fluid emboli
    • maternal or fetal hemorrhage
    • fetomaternal hemorrhage with Rh isoimmunization
    • maternal or fetal infection
    • inadvertent fetal damage or anomalies involving limbs
    • fetal death
    • inadvertent maternal intestinal or bladder damage
    • miscarriage or preterm labor
    • premature rupture of membranes
    • leakage of amniotic fluid
  20. Percutaneous umbilical blood sampling (PUBS)
    • most common method used for sampling a fetal blood transfusion
    • obtains fetal blood sampling from the umbilical cors by passing a fine-guage fiber optic scope (fetoscope) into the amniotic sac using the amniocentesis technique. The needle is advanced into the umbilical cord under ultrasound guidance and blood is aspiratied from the umbilical vein
    • Blood studies consist of:
    • Kleihauer-Betke test that ensures blood is obtained from the fetus
    • CBC count with differential
    • indirect Coombs' test for Rh antibodies
    • Karyotyping (visualization of chromosomes)
    • Blood Gases
    • Indications for the use of PUBS:
    • diagnosing prenatal blood and chromosomal disorders
    • Karyotyping of malformed fetuses
    • detecting of fetal infection
    • determinng the acid-base balance status of fetuses with IUGR

    • interpretation of findings:
    • evaluate for isoimmune fetal hemolytic anemia and assessing the need for a fetal blood transfusion

    • patient education:
    • provide medication administration as prescribed
    • deucate client and provide support

    • Complications that may arise:
    • cord laceration
    • repterm labor
    • amnionitis
  21. Chorionic villus sampling (CVS)
    assessment of a portion of the developing placenta (chorionic villi) is aspirated through a thin sterile catheter or syringe through the abdomen or intravaginally throught hte cervix under ultrasound guidance and analyzed

    first trimester alternative to amniocentesis with one of its advantages being an earlier diagnosis of any abnormalities. CVS can be performed at 10-12 weeks of gestation and rapid results with chromosome studies are available in 24-48 hours following aspiration

    • Indication for CVS during pregnancy:
    • women at risk for giving birth to a neonate who has a genetic chromosomal abnormality (can not determine spina bifida or anencephaly)

    • Patient teaching:
    • instruct the patient to drink plenty of fluid to fill the bladder prior to the procedure to assist in positioning the uterus for catheter insertion

    • Complications that can arise:
    • spontaneous abortion (higher risk with CVS than with amniocentesis
    • risk for fetal limb loss
    • miscarriage
    • chorioamnionitis and rupture of membranes

    • advantages of an earlier diagnosis should be weighed against the increased risk of fetal anomalies and death
  22. Alpha-Fetoprotein screening (MSAFP)
    • Description of proceedure:
    • Quad Marker screening- blood test done between 15-20 weeks of gestation that will ascertain information about the likelihood of fetal birth defects. It does not diagnose the actual defect. It may be performed instead of the maternal serum alpha-fetoprotein yielding more reliable findings

    • The test screens for presence of hCG, AFP, estriol and Inhibin-A
    • Human chorionic gonadotropin (hCG)- a hormone produced by the placenta
    • Alpha-fetoprotein (AFP)-a protien produced byt the fetus
    • Estriol-a protien produced by the fetus and placenta
    • Inhibin-A-a protein produces by the ovaries and placenta

    • Indication for:
    • 15-20 weeks of gestation
    • women at ridk for giving birth to a neonate who has a genetic chromosomal abnormality

    • Interperation of findings:
    • Low levels of AFP: indicates a risdk for Down syndrome
    • High levels of AFP: indicates a risk for neural tube defects
    • High levels than normal of hCG and Inhibin-A: indicates a risk for Down syndrome
    • Lower levels than normal of estriol: may indicate a risk for Down syndrome
    • AFP is a screening tool used to detect neural tube defects. Patients with abnormal findings should be referred for a quad marker screening, genetic counseling, ultrasound, and amniocentisis

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