OB- abnormal fetal growth Flashcards
Normal embryo-fetal growth can be defined as?
- growth that results from uneventful cell division and growth, yielding a full-term/healthy infant
Gestational age is determined by? (4)
- last menstrual period
- mean gestational sac
- CRL
- BPD, HC, AC, FL
What is small for gestational age (SGA)?
term used to describe a baby who is smaller than the usual amount for the number of weeks in a pregancy
what percentile are SGA babies?
Birth weight below 10th percentile
What causes SGA?
- fetal growth problems that occur during pregnancy
- IUGR or FGR
what does IUGR occur?
- when the fetus does not receive the necessary nutrients and oxygen needed for proper growth and developemnt of organs and tissues
- can begin at any time in pregnancy
Early-onset IUGR is often due to?
- chromosomal abnormalities
- maternal diseases
- severe problems with placenta
late-onset growth restriction IUGR?
- after 32 weeks
- usually related to other problems
Maternal factors the may contribute to SGA/IUGR? (8)
High blood pressure Chronic kidney disease Advanced diabetes Heart or respiratory disease Malnutrition, anemia Infection Substance use (alcohol, drugs) Cigarette smoking
Uterus and placenta factors that may contribute to SGA and/or IUGR (4)?
Decreased blood flow in the uterus and placenta
Placental abruption (placenta detaches from the uterus)
Placenta previa (placenta attaches low in the uterus)
Infection in the tissues around the fetus
Factors relating to fetus that may contribute to SGA/IUGR? (4)
Multiple gestation (for example, twins or triplets)
Infection
Birth defects
Chromosomal abnormality
why is SGA/IUGR a concern?
the fetus does not receive enough oxygen or nutrients during pregnancy, overall body and organ growth is limited, and tissue and organ cells may not grow as large or as numerous
SGA prognosis?
Perinatal mortality rate 8 times higher than infants born with appropriate weight for gestational age; the risk of asphyxia at childbirth is 7 times higher
Babies with SGA and/or IUGR may have problems at birth including? (6)
- decreased oxygen levels
- low apgar scores
- meconium aspiration
- hypoglycaemia
- difficulty maintaining normal body temperature
- polycuthemia
What does APGAR score stand for?
- newborn health assessment
A- apperance (skin colour) P- pulse (heart rate) G- grimance (reflex/response) A- activity (muscle tone) R- respiration (breathing
How does APGAR score?
0-3 critically low
4-6 below normal
7 concidered normal
Most cases of IUGR are caused by?
placental insufficiency, either primary or secondary to maternal etiology
2 IUGR classifications?
- symmetric SGA
2. asymmetric SGA
What is summetric SGA?
- all mesurements (HC, length, weight) are reduced
- usually due to causes that occur at early stages of pregnancy
asymmetric SGA?
- Only have a weight reduction
- due to insults that appear in the 3rd trimester
symmetric IUGR?
- characterized by early onest (begining of 2nd trimester)
- proportional reduction in all fetal parameters
- associated with chromosomal anomalies or infection
sono diagnosis or summetric IUGR?
- should be considered in the 1st trimester if there is a CRL
- suspicious cases should be re-evaluated at an appropriate interval (4-6 weeks) to confirm abnomral growth and to assess the fetus for anomalies
- most common cause of ealy onset IUGR is a chromosome abnormality (aneuploidy) and the 2nd most common cause is fetal infection
Asymmetric IUGR accounts for how many cases? how is it characterized?
- accounts for 1/3rd of cases and is characterized by late onset (end of 2nd or beginning of 3rd tri)
- it results from any cause of placental insufficiency
asymmetric IUGR on U/S?
- doppler studies or fetal umbilical, renal, and cerebral arteries
- results from preferential blood flow to the fetal brain at the expense of other organ systems
IUGR head characteristics?
- fetal head is typically normal until very late in pregnancy
what is the single best parameter for the diagnosis of IUGR?
- abnormal AC which reflects poor growth
- if dates are unknown, serial evalutations at 2 weeks intervals can be done to evaluate interval growth
- AC growth or <1cm in 14 days is indicative of IUGR
- FL is usually not affected until very late
- FL/AC ratio is also generally abnormally elevated in fetuses with asymmetric IUGR
- The HC/AC ratio is abnormally elevated in cases of asymmetric IUGR
Non-specific findings of IUGR?
- Oligohydramnios
- Placental senescence (grade 3 placenta before 36 weeks)
- Grade 3: calcification extending between the basal and fetal surface of placenta
- Delayed sonographic appearance of the distal femoral ossification center (DFE ossifies and becomes echogenic in normal growing fetuses about 32 to 33 weeks gestation)
Doppler and IUGR?
- doppler can play a useful role in determining the prognosis of fetus with IUGR
umbilical artery:
- Normal umbilical artery Doppler waveform has a rapid upstroke to peak systole and a gradual decline during diastole, while maintaining continuous forward flow during diastole until the onset of the next fetal cardiac heart beat
IUGR- macrosomia or larger for GA fetus?
- It refers to fetal weight above the 90th percentile for GA.
- Most often it is defined as fetal weight > 4000 grams. The most complications occur with fetuses weighing > 4500 grams.
Macrosomia or large for GA Fetus risk factors?
Most common: maternal diabetes (2%)
Previous delivery of a large infant Maternal obesity Mother is tall Excess pregnancy weight gain Multiparity Advanced maternal age (> 35) Post term delivery
Macrosomia FL/AC and HC/AC ratios?
FL/AC and HC/AC ratios are frequently low and show early evidence of macrosomia.
