Diagnostic Testing/ Third Trimester 27-40 weeks Flashcards
Non stress test (NST)
Purpose: (4)
NST is based on?
When is it performed?
Purpose:
1) To assess placental function and oxygenation
2) Fetal well-being
3) Evaluate fetal heart rate response to fetal movement
(L 283) (Saunders 321)
Performed during third trimester
Contraction stress test (CST)
Purpose: (3)
When is this test performed?
Purpose:
1) To evaluate the respiratory function (exchange) of the placenta.
2) Determines fetal ability to tolerate labor and fetal well-being
3) Fetus is exposed to the stress of contractions to assess the adequacy of placental perfusion under simulated labor conditions
Test is performed if non stress test is abnormal
(Saunders 321)
Biophysical Profile (BPP)
Generalized description
Ultrasound used for fetal breathing, movement of body or limbs, fetal tone, amniotic fluid volume.
Reactive Fetal Heart Rate (FHR) with NST
Use of real-time ultrasound to visualize physical and physiological characteristics of the fetus and observe for fetal biophysical responses to stimuli
Test for fetal lung maturity (L/S ratio, PG)
1) What does L/S stand for?
2) When is is performed?
3) How is it performed?
1) Lecithin and sphingomyelin
This test measures the amount of two substances, lecithin and sphingomyelin, that are found in the amniotic fluid during pregnancy. The two substances are surfactants, chemicals made by the lungs that allow them to work properly. Without surfactants, the small air sacs in your lungs, called alveoli, would collapse, preventing oxygen from entering the bloodstream.
2) In the last three months of pregnancy, your fetus’ lung surfactants can freely pass into the amniotic fluid. Once the surfactant becomes part of the amniotic fluid, your doctor can measure it.
3) via amoniocentesis
(URMC Web)
Percutaneous umbilical blood sampling (PUBS)
1) What is it?
2) What type of blood studies can be done via this test? (6)
1) Technique used for obtaining blood that allows for
2
a) rapid chromosome dx karyotyping (visualize chromosomes)
b) Kleihauer-Betke test- ensures its fetal blood obtained
c) Indirect Coomb’s test: transfusion for Rh isoimmunization
d) Hydrops fetalis
e) CBC with differential
f) Blood gases
(London 154)
Fetal Kick Count
Determine:
Purpose:
Determine:
Purpose:
Nonstress Test
Nursing Interventions: (6)
1) External ultrasound transducer and tocodynamometer applied to client
2) 20 tracing obtained to observe FHR and uterine activity
3) Baseline BP obtained and monitored frequently
4) Client in side lying position to avoid vena cava compression
5) Client presses button every time she feels fetal movement
6) The monitor records a mark at each point of fetal movement which is used as reference point to assess the FHR response
(Saunders 321)
Nonstress Test Results
Reactive Nonstress Test (Normal, Negative) (4)
Reactive-indicates healthy fetus
1) The result requires 2 or more FHR accelerations of at least 15 beats/minute
2) Lasting at lease 15 seconds from the beginning of the acceleration to the end
3) In association with fetal movement
4) During a 20 minute period
(Saunders 321)
Nonstress Test Results
Nonreactive Nonstress Test (Abnormal) (2)
1) No accelerations or accelerations of less than 15 beats/min
2) 0r lasting less than 15 seconds duration occurs during a 40 minute observation
(Saunders 321)
Nonstress Test Results
Unsatisfactory
The result cannot be interpreted because of the poor quality of the FHR tracing
Contraction Stress Test
Interventions
1) External fetal monitor is applied to pt
2) 20 to 30 minute baseline strip is recorded
3) Uterus is stimulated to contract via oxytocin (Pitocin) or by nipple stimulation until 3 palpable contractions with duration of 40 seconds or more in 10 minute period have been achieved
4) Monitor maternal BP frequently
Contraction Stress Test Results
Negative Contraction Stress Test (Normal)
A negative result is represented by no late decelerations of the fetal heart rate
Contraction Stress Test Results
Positive Contraction Stress Test (Abnormal)
A positive result is represented by late decelerations of FHR, with 50% or more of the contractions in the absence of hyper stimulation of the uterus.
Contraction Stress Test Results
Equivocal
An equivocal result contains decelerations, but with less than 50% of the constructions or uterine activity shows a hyperstimulated uterus
Contraction Stress Test Results
Unsatisfactory
An unsatisfactory result means that adequate uterine contractions cannot be achieved or the FHR tracing is of insufficient quality for adequate interpretation
Biophysical Profile 5 variables that are measured
ATI 52
1) Reactive FHR (reactive nonstress test)=2, nonreactive=0
2) Fetal breathing movements (1 episode greater than 30 seconds duration in 30 min)= 2, absent or less than 30 seconds duration =0
3) Gross body movement: (at least 3 body or limb extensions with return to flexion in 30 min) =2
4) Fetal tone (at least 1 episode of extension with return to flexion) =2; slow extension and flexion, lack of flexion or absent movement =0
Qualitative amniotic fluid volume (at lease 1 pocket of fluid that measures at least 2 cm in 2 perpendicular planes) =2; pockets absent or less that 2 cm =0
Test for fetal lung maturity (L/S ratio, PG):
What do the results mean?
1) 2:1 , presence of PG
2) L/S ratio less than 2:1 and/or absence of PG
3) L/S ratio greater than 2:1 and PG trace/present, Lamellar body count (LBC) over 50,000
The results of this test are given as a ratio of lecithin to sphingomyelin:
1) Correlates with 35 weeks gestation.
2) May indicate under inflation of lungs an increased risk for developing RDS
3) Predictive of fetal lung maturity
(London 289)
Test for fetal lung maturity (L/S ratio, PG):
Numerous factors can affect your test results. These include: (3)
Numerous factors can affect your test results. These include:
1) Presence of fetal or maternal blood in the amniotic fluid
2) Abnormally high volumes of amniotic fluid, which may give false-low test values
3) Presence of fetal meconium, which is fetal stool; this happens if the fetus has a bowel movement in the womb
Test for fetal lung maturity (L/S ratio, PG):
The risks of complications are rare but can include: (3)
If amniocentesis is performed, the risks of complications are rare but can include:
1) Leaking of amniotic fluid. Sometimes this can lead to infection, which can lead to miscarriage early in pregnancy, or preterm labor and preterm birth later in pregnancy.
2) Injury to the baby if the needle touches the fetus.
3) Leaking of blood from the placenta into your own bloodstream. This can cause problems for later pregnancies.
Test for fetal lung maturity (L/S ratio, PG):
1) What is the PG?
1) Phos/pha/tidyl/glycerol: A phospholipid in surfactant
Both the lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol (PG) concentration increase with gestational age and correlate with lung maturity. Testing both the L/S ratio and the presence or absence of PG provides a better assessment of neonatal risk than the use of either test alone.
(Mayo FLP: Fetal Lung Profile)
Test for fetal lung maturity (L/S ratio, PG):
1) What do PG results indicate?
Phos/pha/tidyl/glycerol
1) L/S ratio of 2:1 and presence of PG correlates with 35 wks gestation.
Hydrops Fetalis
1) What is it?
2) How is it dx?
1) Hydrops fetalis is a serious condition. It occurs when abnormal amounts of fluid buildup in two or more body areas of a fetus or newborn. It is a symptom of underlying problems.
2) Percutaneous Umbilical Blood Sampling?
(London 154)
Immune Hydrops Fetalis: There are two types of hydrops fetalis – immune and nonimmune. The type depends on the cause of the abnormal fluid.
Immune hydrops fetalis is a complication of a severe form of Rh incompatibility. This is a condition in which mother who has Rh negative blood type makes antibodies to her baby’s Rh positive blood cells, and the antibodies cross the placenta. Rh incompatibility causes a large number of red blood cells in the fetus to be destroyed. This leads to problems including total body swelling. Severe swelling can interfere with how the body organs work.
(MedlinePlus)
Nonimmune Hydrops Fetalis: There are two types of hydrops fetalis – immune and nonimmune. The type depends on the cause of the abnormal fluid.
Nonimmune hydrops fetalis occurs when a disease or medical condition upsets the body’s ability to manage fluid. There are three main causes for this type: heart or lung problems, severe anemia (e.g. from thalassemia or infections), and genetic or developmental problems, including Turner syndrome.
(MedlinePlus)
Biophysical Profile
Can be done when?
After 28 weeks
London 285
Contraction Stress Test (CST)
4 Indications to do the procedure
1) Advanced maternal age
2) Post maturity
3) Decreased fetal movement
4) IUGR
Is Amniotic fluid emboli and indication for CST ?
No, amniotic fluid emboli is a complication of amniocentesis
Indications do use PUBS: (4)
1) Fetal blood type, RBC, chromosomal disorders
2) Karyotyping and malformed fetuses
3) Fetal infection
4) Altered acid-base balance of fetuses with IUGR
PUBS:
Complications (5)
1) Cord lacerations
2) Preterm labor
3) Amnionitis
4) Hematoma
5) Fetomaternal hemmorrhage
Hematoma
Collection of blood outside of the blood vessel, that has clotted. Damage to the vessel wall followed by leakage of blood that has started to clot. Hematomas are often described depending on where they are located in the body.
Hemorrhage
Hemorrhage is the term used to describe active bleeding and is often graded on a severity score of one to four (15% to >40% of total blood
NST is based on what knowledge?
The knowledge that when the fetus has adequate oxygenation and and intact central nervous system, there are accelerations of FHR and FM.
