Maternal/Child Health (OB): Fetal and Maternal Assessment Techniques

I. ULTRASOUND (US)

  • used during first trimester to assess: # of fetuses, gestational age, uterine abnormalities, fetal cardiac movement and rhythm
  • used during second and third trimester to assess: size-date discrepancies, amniotic fluid volume, uterine anomalies, amniocentesis results, gestational age, fetal viability, placenta location and maturity
  • nursing implications: patient may need to maintain a full bladder prior to US if in the first or second trimester for the uterus to be observable (not needed for transvaginal US)
  • no known complications

II. CHORIONIC VILLI SAMPLING (CVS)

  • at 8 to 12 weeks gestation, a small piece of villi is removed guided under an US
  • determines genetic diagnosis in the first trimester
  • nursing implications: lithotomy position, patient may feel sharp pain when catheter inserted
  • complications: spontaneous abortion

III. AMNIOCENTESIS

  • at 14-16 weeks, amniotic fluid sample removed from uterus
  • used to assess: genetic diagnosis, fetal lung maturity, fetal well-being
    genetic disorders: trisomies, metabolic disorders, neural tube defects
    fetal lung maturity: L:S ratio (2:1) and presence of prostaglandins (PG) after 35 weeks is most accurate determination
    fetal well-being: bilirubin delta optical density, meconium may indicate fetal distress
  • nursing implications: supine position, use of Betadine to sterilize site, label samples, monitor FHR 1 hour after procedure; ***if amniocentesis is done in early pregnancy, bladder must be FULL; it done in late pregnancy, bladder must be EMPTY to prevent puncture
  • complications: spontaneous abortion, fetal injury, infection

IV. ELECTRONIC FETAL MONITORING (EFM)

  • variables of EFM:
    – contractions – duration, frequency, intensity
    – baseline fetal heart rate (FHR) – 110-160, measured over 10 minutes
  • variability: absent, minimal (< 5 bpm) , moderate (6-25 bpm), marked (>25 bpm)
  • VEAL CHOP
  • warning signs: absent or minimal FHR, bradycardia (< 110), tachycardia (>160), variable decelrations
  • emergent signs: severe variable decelrations (FHR <70, lasting > 30-60s), late decelerations

V. NONSTRESS TEST (NST)

  • assesses fetal response to movement which can determine fetal well-being in high-risk pregnancies
  • healthy “reactive” sign: fetus responds to movement by a fetal heart rate (FHR) acceleration of 15 beats, lasting 15 seconds after movement, occuring twice in a 20 minute period
  • nursing implications: apply fetal monitor, give handheld event marker to mother and instruct her to push button whenever she heels movement, it may also be recorded on FHR strip, *if there is not fetal movement, assume that the fetus is sleeping and stimulate it through sound or palpation or have mother move it and begin test again

VI. CONTRACTION STRESS TEST (CST) or OXYTOCIN CHALLENGE TEST (OCT)

  • assesses fetal response to low oxygen supply during induction of contractions (through nipple stimulation or Oxytocin)
  • nonreassuring “bad” sign: late decelerations = placental insufficiency!
  • contraindications: rupture of membranes (ROM), prematurity, hydramnios, multiple gestation, placenta previa, previous uterine classical scar
  • nursing implications: place external monitors of abdomen (ultrasound and tocodynanometer); record a 20 second baseline strip to determine reactivity (fetal well being) and presence/absence of contractions; for nipple stimulation, have patient use warm wet washcloths to roll nipple of one breast for 10 minutes and rol both if contractions don’t start within 10 minutes; oxytocin infused if no contractions after nipple stimulation
  • complications: hyperstimulation or tetany (contractions over 90 seconds OR contractions with less than 30 seconds in between) R/T overstimulating nipples
  • REMEMBER: a NEGATIVE test = GOOD (fetal well being)

VII. BIOPHYSICAL PROFILE (BPP)

  • ultrasound used to evaluated fetal health by assessing:
    1.) fetal breathing movements (FBM)
    2.) gross body movements (GBM)
    3.) fetal tone (FT)
    4.) reactive fetal heart rate (nonstress test)
    5.) qualitative amniotic fluid volume (AFV)
  • each variable = 2 points for a normal response; 0 points for an abnormal (either 2 OR 0)
  • nursing implications: prepare, inform, provide support; teach patient that a LOW score = fetal compromise and needs to be assessed further
  • a score of 8-10 = fetal well-being

VIII. FETAL PH BLOOD SAMPLING

  • determiens true acidosis when nonreassuring fetal heart rate is noted (tachycardia not related to maternal variables, decreased variability not related to nonasphyxial causes, severe variable decels unresponsive to treatment, late decels)
  • only performed in intrapartum period
  • sample taken from the presenting part (breech or scalp) when membranes have ruptured and cervix dilated to 2-3cm
Image Source: #1, #2, #3, #4, #5, #6, #7,
Content derived from HESI Comprehensive Review for the NCLEX-RN Examination.
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