Diagnostic Procedures

• Ultrasound

  Purpose:

  • diagnose pregnancy
  • confirm sex
  • confirms growth and abnormalities
  • fetal maturity
• Ultrasound

  2 types:

  • Transvaginal - void (to avoid discomfort); used in early pregnancy
  • Abdominal - drink 2 to 3 glasses of water (to distend abdomen = uterus ); used in later pregnancy
• Alpha-fetoprotein

  • this procedure requires maternal blood sample
  • done during 15-18 weeks of gestation


  Increased AFP = neural tube defects

  Decreased AFP = down syndrome
• Chorionic Villus Sampling (CVS)

  • done on 8 to 12 weeks of gestation
  • done to detect congenital defects including chromosomal defects
  • blood is collected from chorionic villi
  • Rho-Gam is administered to Rh (-) women to prevent formation of antibodies against Rh (+) fetus
• Kick Counts

  • the mother will sit or assume side-lying for 1 hour after meals and count fetal kicks for 30 minutes 


  Cardiff method

  • count-to-ten
  • if <10 = walk around and check
  • if <10/hr = notify HCP = hypoactive/hypoxic
• Amniocentesis 


  This is done to determine chromosomal defects, neural tube defects, sex of fetus, fetal lung maturity.
• Amniocentesis

  • this involves aspiration of amniotic fluid
  • done from 14 weeks of gestation and above


  Implementation:

  • Informed consent
  • empty bladder before the procedure to prevent puncture
  • prepare ultrasound to locate placenta
• Amniotic Fluid

  • normal: 800 to 1200 mL
  • protection
  • cushion
  • regulation of temperature
  • prevents cord compression
• Amniotic Fluid

  • baby urinates = swallows (to maintain normal amount of amniotic fluid) 


  Oligohydramnios: <500 mL (x)urinating, (/) swallowing = kidney defect

  Polyhydramnios: >1200 mL (/) urinating, (x) swallowing = esophagus problem

  Strong yellow color: suggest blood incompatibility

  Green: meconium staining
• Fern Test

  • done by collecting specimen from external os of the cervix and vaginal pool

  Position: lithotomy
• Fern Test

  Detects presence of amniotic fluid leakage ( fern-like pattern is formed when vaginal fluids is placed on a glass slide and allowed to dry because of high sodium and high protein content of amniotic fluid.
• Nitrazine Test


  Detects presence of amniotic fluid in vaginal secretions
• Nitrazine Test

  Vaginal secretions: ph 4.5 to 5.5

  Amniotic fluid: ph 7.0 to 7.5 (alkaline) turns the yellow nitrazine to blue

  Position: Dorsal lithotomy

  Membranes have ruptured: blue-green, blue-gray, deep-blue
• Nonstress Test


  To assess fetal oxygenation and neurological function by measuring the fetal heart rate in response to its movements.
• Nonstress Test

  What are we looking for? Accelerations - normal.
• Nonstress Test


  Two belts are placed around the mother’s abdomen:

  • One measures fetal heart rate using an external ultrasound transducer.
  • The other measures uterine contractions using a tocodynamometer.
• Nonstress Test

  Tracings of uterine contractions for 20 minutes are recorded.

  Position: left lateral
• Nonstress Test

  Interpretations of results:

  Reactive NST: Normal

  • 2 or more FHR accelerations of at least 15 bpm, lasting at least 15 seconds from the beginning to the end of uterine contraction.

  Non-reactive NST: Abnormal

  • No acceleration during uterine contractions; or acceleration of less than 15 bpm.
• Nonstress Test

  Invasive or non? Non
• Contraction Stress Test 


  Performed if NST is abnormal
• Contraction Stress Test

  Contractions Induced:

  • nipple stimulation
  • oxytocin challenge test
• Contraction Stress Test

  Look for 3 contractions in 3 minutes.
• Contraction Stress Test

  What are we looking for? Decelerations - abnormal.
• Contraction Stress Test

  Results:

  Negative Contraction Stress Test

  • reassuring or normal
  • no late or variable decelerations of FHR
• Contraction Stress Test

  Results:

  Positive Contraction Stress Test

  • abnormal
  • shows late or variable decelerations of FHR
• Contraction Stress Test

  Results:

  Equivocal CST

  • contains decelerations but less than 50% of the contractions
  • unclear or inconclusive
• Contraction Stress Test

  Bradycardia, late deceleration, variable deceleration indicate: fetal distress
• Contraction Stress Test

  Early deceleration: head compression

  Variable deceleration: cord compression

  Late deceleration: uteroplacental insufficiency
• Early decelerations 


  occurs during contractions as the fetal head is pressed against the woman's pelvis or soft tissues such as cervix, and return to the baseline FHR by the end of the contraction.
• Early decelerations 


  Decreases in FHR below baseline, the rate at the lowest point of the deceleration usually remains greater than 100 beats/min.
• Late decelerations


  Are non-reassuring patterns that reflect impaired placental exchange or uteroplacental insufficiency.
• Variable decelerations 


  Are caused by conditions that reduce flow through the umbilical cord.