ch. 18 fetal assessment Flashcards
fetal assessment 1st trimester (6)
1) viability: 20 weeks
2) beta HCG:
- doubles Q2 days in 1st 10 days of pregnancy
- peaks 60-90 days POST CONCEPTION
- accurate marker
- needs 48 hours between tests
3) progesterone: level testing
4) ultrasound:
- 10 to 13 6/7 weeks
- indication: crown rump length (after 8 weeks, can opt for genetic testing)
5) gestational age (due date)
6) genetic screening options
- nuchal folds, serum testing (DNA assay, chorionic villi, maternal serum alpha fetoprotein, amniocentesis)
TIP:
- increased nuchal folds + 3 mm -> can indicate trisomy 13/18/21 (Down syndrome)
- amniocentesis: after 20 weeks
- HCG (supports corpus luteum to produce more estrogen/progesterone) peaks: 7-11 weeks then placenta takes over
- corpus luteum: produces progesterone
progesterone levels (normal levels, low level, ____ _____ secretes progesterone until…, if low give, extra)
- normal pregnancy levels: 10-25 ng/mL
- low levels: SAB and ectopic pregnancies
- corpus lutetium secretes progesterone until 6-8 weeks gestation, then placenta takes over
- PO/intravaginal progesterone given if NOT
- testing not needed after 12 weeks
TIP:
- if low, risk of miscarriage, cervical insufficiency
review: crown to rump measurement
measurement from top of fetal crown (head) to bottom of the rump (buttocks)
nuchal translucency testing (what, screen, look at, accurate)
combination of U/S and maternal serum testing
- screen fetus: 11wks 1d - 13wks 6d
- looks at nuchal folds
- >3mm (82-87%) accurate for detecting: trisomy 21 (Down syndrome), trisomy 13/18
fetal assessment 2nd trimester (3)
- MSAFP: quad screen
- amniocentesis (remove 20-30cc fluid) after 20wk
- ultrasound indication: dating/anatomy
TIP:
- ultrasound done 10-13 wks for 1st trimester
- ultrasound done 18-22 wks for 2nd trimester
amniocentesis (indication, when, 2 components (5)
- indication: done to assess fetal lung maturity, genetic study
- when: 34-36 weeks (adequate surfactant 36 wks)
- 2 components surfactant:
(a) phospholipids
(b) lowers alveoli surface tension
(c) stabilizes alveoli - L/S ratio 2:1
- PG: 36 weeks, indicates lung maturity
what does L/S stand for
lecithin sphingomyelin
nursing care during amniocentesis (8)
- obtain baseline VS before & after procedure
- assess needle insertion site for fluid leakage (amniotic fluid)
- monitor fetal heart rate for 20-30 minutes
- observe for MATERNAL HYPOTENSION
- administer rhogam if mom Rh negative
- instruct mother on signs of labor (fever)
- engage in light activities for 24 hours (lay low)
- encourage fluids
basis for fetal monitoring (what, decrease in ____ ____ due to (4))
oxygen supple must be maintained to prevent fetal compromise
decrease in oxygen supply d/t:
- reduction of blood flow through maternal vessels
- reduction in oxygen content in maternal blod
- alterations in fetal circulation
- reduction in blood flow to intervillous space in placenta
2 indications basis for monitoring
1) uterine activity: monitoring provides information on uterine contractions (how often, how intense, duration)
2) fetal compromise: goals of intrapartum FHR monitoring are to IDENTIFY and DIFFERENTIATE normal (reassuring) patterns from the abnormal (non reassuring) patterns, which can be indicative of fetal compromise
monitoring techniques (2)
1) intermittent auscultation
2) electronic fetal monitoring
intermittent auscultation (3, disadvantage)
- listen to fetal heart sounds at periodic intervals to assess FHR (doppler)
- easy to use, inexpensive, less invasive than EFM (listen for full minute)
- doppler probe provides closer uterine proximity, making it easier to auscultate the FHR when the woman is obese or early in gestation
disadvantage:
- does not provide permanent record (no continuous stretch, cerebral palsy -> #1 cause is premature baby
electronic fetal monitoring (3)
1) external monitoring
- U/S transducer
- toco transducer (tacodynamometer): one monitor contraction, the other monitors baby
- wireless external monitor: portable monitor
2) internal monitoring:
- spiral electrode: internal fetal scalp lead
- intrauterine pressure catheter (IUPC): measures contractions
- Montevideo units (MVUs)
3) display:
- FHR upper section
- UA lower section
- each small square represents 10 SECONDS
baseline fetal heart rate (4)
average rate: 110-160 bpm during 10 minute segment that excludes:
- periodic or episodic changes
- periods of MARKED variability
- segments of the baseline that differ by more than 25 bpm
types of fetal variability (4)
1) absent variability:
- amplitude range undetectable
- ex: 150 -> 150 -> 150 -> 150
- NOT GOOD
2) minimal variability:
- <5 bpm change
- ex: 150 -> 145 -> 152 -> 149
- CAUTION, monitor baby
- reflects sleep state or IV fent/morphine IVP (compromise)
3) moderate variability:
- 6 to 25 bpm (98%)
- GOOD, BEST
4) marked variability:
- >25 bpm change
- ex: 150 -> 176 -> 148 -> 155
- BABY STRUGGLING
TIP: fetal monitoring mostly R -> R
