Normal Diagnostic Laboratory Findings

• Normal Diagnostic Laboratory Findings during Pregnancy

  • A medical diagnosis of pregnancy serves to date when the birth will occur and also helps predict the existence of high-risk status
  • Pregnancy tests - are commercially available and can be performed by the trained personnel that are highly accurate and precise, if done with the correct technique
• Pregnancy testing​ – relies on the detection of an antibody to the hormone human chorionic gonadotropin (hCG) or a subunit in the urine or serum
• Human Chorionic Gonadotropin- the first placental hormone produced and can be found shortly after implantation
• Urine – test to yield accurate results and it should be done 10 – 14 days after the missed menstrual period.
• Gravindex and Pregnosticon - are immunologic pregnancy test and approximately 95% accurate in diagnosing pregnancy and accurate in determining the absence of pregnancy
• Radioimmunoassay​ – tests for the beta subunit of hCG and considered to be so accurate as to be diagnostic for pregnancy.
• Blood –​ with sensitive assays hCG can be detected in maternal blood at 7 days after conception and are accurate close to 100% of the time​
• Progesterone Withdrawal test – a contraceptive pill is taken OD or TID (3xdays)
• If menstruation occurs within 10-15 days, the woman is not pregnant
• If corpus luteum produces enough hormones to neutralize the effect of withdrawn synthetic progesterone and no bleeding occurs, the woman is pregnant
• Ultrasound imaging​ – (Ultrasound scanning or Scanning) - involves exposing a part of the body to high frequency sound waves to produce pictures of the inside of the body
• The sound waves reflect best if the uterus can be held stable and it is helpful if the woman has a full bladder at the time of procedure
• Ultrasound imaging​

  • It provides the physician, the ability to approach the developing fetus a separate patient with an identifiable set of reflexes reactions
  • 7-11 wks. if the date of LMP is unknown, between 16-20 wks. Gestation to verify fetal structures and gender
• Types of Pelvic Ultrasound

  • Abdominal or Transabdominal
  • Vaginal or Transvaginal
• Abdominal or Transabdominal ​– the woman in supine position, the sonographer/radiologist applies the transducer on the lower abdomen
• Vaginal or transvaginal ​– the woman in lithotomy position, the sonographer/radiologist inserts into the vagina 2-3 inches of the vaginal transducer’s end with the protective cover and lubricating ge
• Biparietal diameter – used to predict fetal maturity:
• Measurement of fetal head - (8.5 cm. or greater)
• Doppler Umbilical Velocimetry ​– measures the velocity at which RBC in the uterine and fetal vessels travel to assess blood flow through the uterine blood vessels
• Decreased Velocity – predictor of Uterine Growth Restriction
• Placental grading for maturity – can be graded based on the amount of calcium deposits present in the based of the placenta (Ring-like structures)
• Grades:

  • 0 - between 12 and 24 wks.
  • 1 - 30 to 32 wks.
  • 2 – 36 wks.
  • 3 – 38 wks. – suggest fetus is mature
• A calcified placenta occurs when small, round calcium deposits build up on the placenta, causing it to deteriorate gradually. The process occurs naturally as closer to the end of pregnancy.
• Placental grading for maturity

  • Fetal growth restriction
  • Fetal distress in cases of preterm placental calcification.
  • Decreased blood flow in the placenta and compromise fetal circulation and growth
  • Preterm birth
  • Low birth weigh
  • Low Apgar score
  • Postpartum hemorrhage
  • Placental abruption
  • Fetal distress
  • Stillbirth
• Grade 0

  • between 12 and 24 wks. gestation
  • No calcification, no indentations
• Grade 1

  • 30 – 32 wks. gestation
  • small diffuse calcifications
  • randomly distributed in placenta
• Grade 2

  • 36 wks. gestation
  • dot dash calcifications along the basal plate
  • larger indentations
• Grade 3

  • 38 wks. – suggest fetus is mature
  • complete indentations of the chorionic plate
  • hyper mature placenta associated with placental insufficiency
• The amount of amniotic fluid can estimate fetal health because a portion of the fluid is formed by fetal kidney output
• If a fetus is becoming so stressed in utero that circulatory and kidney function is failing urine output and the volume of amniotic fluid will decrease
• AMNIOTIC FLUID VOLUME – THE AMOUNT OF AMNIOTIC FLUID PRESENT ESTIMATE FETAL HEALTH
• > 20 - 24 cm. – amount greater than indicates Hydramnios
• 12 -15 cm. average between 28 and 40 wks.
• < 5 - 6 cm – Oligohydramnios
• Decrease in amniotic fluid volume puts the fetus at risk for compression of the umbilical cord
• NUCHAL TRANSLUCENCY SCREENING

  • a number of genetic disorders can be detected on sonogram during the 11 wks.-13 wks. of pregnancy
  • children with a number of chromosomes anomalies have unusual pockets of fat or fluid deposits at the back of the fetal neck
• NON INVASIVE FETAL TESTING

  • noninvasive method of assessing the general wellbeing of the fetus and fetal assessment
  • 26-28 weeks
  • electronic fetal monitor and the observation time takes about 30 mins
• FETAL BIOPHYSICAL PROFILE: Five Parameters

  • Fetal reactivity
  • Fetal breathing movements
  • Fetal body movements
  • Fetal tone
  • Amniotic fluid volume
• Fetal Breathing - at least one episode of 30 sec of sustained fetal breathing movements within 30 min of observation
• Fetal Movement - At least 3 separate episodes of fetal limb or trunk movement within 30 mins. observatio