9.2b Biophysical Assessment, Daily Fetal Movement Count, Ultrasonography, MRI Flashcards
Daily Fetal Movement Count (DFMC)
- Kick count
- Noninvasive way to monitor fetal oxygenation
- Fetal movement is a good sign
- If fetal movements cease for 12 hours, this is a cause for alarm
- Fewer than 3 fetal movements in an hour needs evaluation via Non-Stress Test (NST) or Contraction Stress Test (CST) and a biophysical Profile (BPP)
Polyhydramnios Risk Factors
- Poorly controlled DM
- Fetomaternal hemorrhage
- Fetal Congenital anomalies (GI obstruction, CNS abnormalities)
- Genetic Disorders
- Twin-to-Twin Transfusion syndrome
Intrauterine Growth Restriction
MATERNAL CAUSES
- Hypertensive Disorders
- Pregestational Diabetes
- Cyanotic Heart Disease
- Autoimmune Disease
- Restrictive Pulmonary Disease
- Multifetal Gestation
- Malabsorptive Disease
- Living in High Altitude
- Tobacco/substance abuse
FETAL CAUSES
- Genetic Disorders
- Teratogenic Exposures
- Fetal Injection
Oligohydramnios
- Renal agenesis (Potter Syndrome)
- PROM
- Prolonged Pregnancy
- Uteroplacental Insufficiency
- IUGR
- Hypertensive Disorders
- Dehydration/hypovolemia
Chromosomal Abnormailities
- Advanced maternal age
- Parental chromosomal rearrangements
- ## Previous pregnancy with autosomal trisomy
Common Maternal/Fetal indications for Antepartum Testing
- Chronic Hypertension
- Preeclampsia
- IUGR
- Multiple Gestation
- Oligohydramnios
- PROM
- Late or Post term gestation
- Previous still birth
- Decreased fetal movement
- Systemic Lupus Erythematosus
- Renal Disease
- Cholestasis of pregnancy
Ultrasound
- Transvaginal or abdominal during pregnancy
- Transvaginal allows evaluation of pelvic anatomies and intrauterine pregnancies to be diagnosed earlier
- Very useful in obese women where abdominal ultrasound may be harder
- Does not require full bladder
- Abdominal ultrasound is more useful in 1st trimester
- Requires full bladder to displace uterus up for a better picture
2D Ultrasound
- Image is black/white/shades of grey
- Standard medical scan used in pregnancy
- Soundwaves sent straight down
3D Ultrasound
- Soundwaves sent at different angles
- Computer creates a 3D image
- Used to find certain anomalies in fetuses,
4D Ultrasound
- Standard (Basic) - Used to evaluate fetal presentation, amniotic fluid volume (AFV), cardiac activity, placental position, fetal growth parameters, and number of fetuses
- Limited - Used to determine specific information about pregnancy (identifying fetal position during labor). Done by OB doctor
- Specialized - Preformed when women are suspected of a anatomically/physiologically abnormal fetus.
ULTRASOUND PURPOSE IN 1st TRIMESTER
- Confirm pregnancy/viability
- Determine gestational age
- Rule out ectopic pregnancies
- Detect multiple gestation
- Determine cause of vaginal bleeding
- Visualize chorionic villlus
- Detect maternal abnormalities (Bicornuate Uterus, Ovarian Cysts, Fibroids)
Primary Purpose of Ultrasound
- Confirm Viability
- Establish/confirm dates
- Detect Poly/Oligohydramnios
- Detect congenital anomalies
- Detect IUGR
- Assess placental location
- Visualize amniocentesis
- Evaluate pre-term labor
Ultra Sound Third Trimester
- Confirm gestational age
- Confirm viability
- Detect macrosomia
- Detect Congenital Anomalies
- Detect IUGR
- Determine fetal position
- Detect placental previa/abruption
- Amniotic fluid assessment
- Evaluation of preterm labor
Fetal Heart Rate Activity
- Seen at 6 weeks of gestation via transvaginal ultrasound
- Cardiac anatomy can be seen at 13 weeks of gestation
- Fetal death is confirmed via lack of heart motion, presence of fetal scalp edema, and maceration/overlap of cranial bones
Gestational Age Ultrasound
USED IF
- Date is unknown of last menstrual period
- Recently discontinued oral contraceptives
- Bleeding during 1st trimester
- Other high risk conditions
Most Useful Gestational Age Measurements
- Crown rump length in first trimester
- Biparietal Diameter
- Head circumference
- Abdominal Circumference
- Femur length after first trimester
Ultrasound for Fetal Growth
Used If..
- There is poor maternal weight gain
- History of IUGR
- Chronic infections or substance abuse
- Maternal diabetes
- HTN
- Multifetal pregnancy
Macrosomia
- Larger than 4000g
- Increased risk for traumatic injury and asphyxia
Symmetric IUGR
- Fetus is small in all parameters CAUSES - Low genetic growth potential - Intrauterine Infection - Chromosomal Anomalies - Maternal undernutrition - Heavy smoking
Asymmetric IUGR
- Head and body do not match
- Caused by placental insufficiency due to hypertension, renal disease, cardiovascular disease
- Reduced fetal growth is one of the most frequent reasons of stillbirth
Nuchal Translucency (NT) Screening
- Helps identify fetal anomalies in the 10-14th week via ultrasound of fluid in fetal neck
- Elevated levels indicate increased risk of congenital heart defects
- Elevated levels with abnormal serum marker levels shows risk of chromosomal abnormalities
- Diagnostic genetic testing recommended for abnormal NT levels
Trisomy 21 (Down Syndrome) Ultrasound Findings
- Absent nasal bone
- Short femur/humerus
- Echogenic intracardiac focus
- Enlarged pelvis where kidneys collect urine
- Fast/Slow HR
Globular Placenta
- Globular placenta with narrow base is associated with increased risk of IUGR, fetal death, and other complications
Amniocentesis
- Safer when position of fetus, placenta, umbilical cord, and pockets of amniotic fluid are known.
- Ultrasound is used to detect these locations
- Percutaneous umbilical cord sampling (PUBS)
- Chorionic Villus Sampling (CVS)
- Both guided by ultrasound
What can ultrasound Measure
- Amniotic Fluid Volume
- Heart motion
- Fetal breathing
- Fetal urine production
- Fetal limb/head movements
Doppler Blood Flow Analysis
- Estimates blood flow in arteries by measuring systolic/diastolic flow ratios
- Reverse flow during diastole could be caused by restricted umbilical artery blood flow
- Associated with IUGR
- Increased systolic peak velocity is associated with fetal anemia
- Abnormal maternal uterine artery wave forms are associated with fetal growth restriction
Oligohydramnios
- Decreased amniotic fluid
- Subjectively determined via small fundal height and easily palpable fetus
- Objectively determined if maximum vertical pocket of amniotic fluid is less than 1-2 cm
Polyhydramnios
- Increased amniotic fluid
- Subjective includes large fundal height and fetus that is difficult to palpate and also ballotable (ballottement)
- Objectively defined as amniotic fluid pockets measuring 8+ cm
AFV Calcuation
- Measure vertical depths of the largest pocket of amniotic fluid in all 4 quadrants and adding them together. This provides amniotic fluid index (AFI)
- AFI less than 5 cm is oligohydramnios
- AFI more than 25 cm is polyhydramnios
Oligohydramnios/Polyhydramnios Risks
- Oligo (Potter Syndrome or renal failure, PROM)
- Poly (GI and CNS abnormalities, multiple fetuses, fetal hydrops (fluid buildup in fetus))
Biophysical Profile
- Assessment of fetus based on markers of fetal disease INCLUDES - AFV (Amniotic fluid volume) - FBM (Fetal breathing movements) - Fetal movements - Fetal tone (via ultrasound) - FHR based off NST (Non-stress test)
- Used in second and third trimester to predict fetal well being
- A level of 8-10 is normal
- Test may require longer time if fetus is asleep
Modified BPP
- Used for shorter test times
- Combines NST (assesses fetal condition) with AFV (indicates placental function)
- Recommended to measure AFV via single deepest pocket instead of AFI
- Desired results are reactive NST and Deepest vertical pocket of amniotic fluid greater than 2 cm
BPP
Fetal Breathing
2 - At least 1 episode of FBM of at least 30 seconds within 30 minutes
0 - Absent or less than 30 seconds of sustained FBM in 30 minutes
Fetal Movements
2 - At least 3 movements within 30 minutes
0 - Fewer than 3 movements within 30 minutes
Fetal Tone
2 - At least 1 extension and flexion of limb. Opening and closing of hand
0 - No movement or slow extension/flexion
Amniotic Fluid (AFI)
2 - Deepest pocket >2cm
0 - Deepest pocket <2cm
Nonstress Test
2 - Reactive
0 - Nonreactive
BPP Scores
10 - Low risk for asphyxia (repeat test 1-2 times a week)
8 - Low risk (repeat test 1-2 times a week)
6 - Suspected asphyxia
(If greater than 36 weeks or less than 36 weeks with positive fetal maturity, consider delivery)
(If less than 36 weeks and negative fetal maturity repeat test every 4-6 hours. Deliver is oligohydramnios is also present)
4 - Suspected asphyxia
(If greater than 36 weeks deliver)
(If less than 32 weeks, repeat score)
0-2 - High risk for asphyxia
(Extend the test to 120 min and if the score is still under 4, deliver baby immediately)
Non-medical Ultrasound
- Ultrasounds are generally safe but repeated high frequency sound waves to the baby for non-medical purposes should be avoided
MRI
- Similar to CT scans
- Can detect soft tissue, and vascular structures without using radiation or contrast which eliminates biological risk
- There are no interferences in picture from bones, fat, or gas and bladder does not need to be filled to view pelvic structures
- Able to see CNS, thorax, abdomen, GU, musculoskeletal, placenta, amniotic fluid, uterus, cervix, pelvis, pH of tissues and organs, soft tissue, metabolic/functional anomalies
