The fetus at risk

Normal Fetus at risk
Causes
Maternal
chronic illness
Maternal
infections
Antepartum
haemorrhage
Connective
tissue
disorders
Endocrine
disorders
Malignancy
with
pregnancy

Foetal causes
Structural foetal defects
Congenital anomaly
TORCH infections
Multiple pregnancy

Placental
Placental causes
Placental tumours
Placental defects structural- annular,
circumferential placenta, tumours of vessels.
Praevia
Abruption

Effects on
the foetus
Acute foetal distress
Chronic foetal distress
Foetal growth restriction
Prematurity
Intrauterine death of the foetus

Methods
of
evaluation
Clinical assessment of growth and wellbeing ( fundal
height, abd girth and foetal movements)
Electronic foetal monitoring or foetal heart rate
changes with rest, movement, contractions.
Ultrasound scanning- number, lie, presentation,
viability, size and estimated weight of foetus, and any
defects.
Assessment of liquor and placenta
Assessment of cervix and any changes related to
labour

Indications for obstetric scanning
1. Wrong dates
2. Twins
3. IUGR
4. Fetal gender
5. Dating scans- level 1
6. Fetal size and gestational age estimation-level 1
7. Fetal anomaly detection- level 11
8. Interventional procedures
Maternal Fetal Medicine Unit, Ipoh Hospital

Wrong dates
• Importance of taking a good history
- Menstrual cycle
- LMP and EDD
- UPT
- SFH
- Quickening
• Importance of early booking
• Importance of early ultrasound

Dating scan
The reliability is
higher at earlier
gestations.
Correlation of the
history and
examination and
previous scan
findings
Foetal Bi-parietal
Diameter – BPD
Head Circumference
– HC
Abdominal
Circumference – AC
Femur Length – FL

Biparietal Diameter
(BPD)
• Bi-parietal diameter is measured to assess
gestational age after the head is formed and the
intracranial structures are visible.

Head
Circumference
(HC)
Less dependant on head
shape (eg dolicocephaly)
Measurement more
difficult in late pregnancy
BPD/HC affected by
“brain sparing effect”

Head Circumference (HC)
•Measurement made at the same level as BPD
•Involves the outer circumference
•Changes in HC tend to tail off towards term
•SD’s less & therefore IUGR identification higher

Abdominal Circumference
Best parameter to
assess fetal size and
growth
Measurement taken
at level of fetal liver
Steady  size with
gestation
Carefully defined
[intra-hepatic portion
of umbilical vein –
anterior 1/3 of AC]
Linear relationship
Allows fetal weight
estimation
Formulae for EFW
10-15% errors
AC + HC, FL + BPD
but best FL + AC
error 7.6%
Area & diameter no
additional value

Abdominal
Circumference
• The abdominal circumference is a measure to
rule out a growth restricted fetus with great
accuracy

Femur Length (FL)
Accurate at 15-25 weeks for gestational age
estimation
Limited use in estimating fetal growth

Assessment of Gestational age
Parameter Gestational age Range (2SD)
(weeks) (days)
CRL 5-12 ±5
BPD 12-20 ±8
20-30 ±14
>30 ±21
FL 12-20 ±7
20-36 ±11
>36 ±16
Iams JD, Gabbe SG. Intrauterine growth retardation. In: Iams JD, Zuspan FP, Quilligan EJ
(eds) Manual of obstetrics and gynaecology, 2nd ed. St Louis: Mosby 1990:165-173.

Twins
Importance of chorionicity determination
Specific problems
TTTS
Selective IUGR
IUD of one twin

•Maternal Fetal Medicine
Unit, Ipoh Hospital

Types of twins
•Maternal Fetal Medicine
Unit, Ipoh Hospital

Types of twins
2/3 of twins are
dizygotic
Monozygotic
twins occur at a
constant rate of
3-5/1000 births

Fetal complications
Perinatal mortality and
morbidity rate in monozygotic
twins (MZ) increased 3 -10 fold
compared to dizygotic twins
(DZ).
• Pasquini et al., 2004
Increased in PMMR appears to
be related to the timing of the
embryonic division and
subsequent chorionicity and
not zygosity.
• Dubé J et al., 2002

Fetal
complications
• MC twin are associated with
increased risk of low birth weight,
preterm delivery and neurologic
morbidity.
• Lynch et al., 2003

Fetal complications
Differentiation of chorionicity by:
Inter twin membrane
Number of yolk sacs
Number of extra-embryonic coelomic spaces
Lambda or twin peak sign (before 14 weeks)
Two separate placentas
Discordant fetal sexes

Fetal complications

Fetal complications
• Miscarriage and fetal loss
- More common (5% compared to 2% at 11-14 weeks)
- Death of one twin associated with 5-10% risk of death or
handicap to co twin
- In MC death of one fetus carries a risk of 25% death and
cerebral damage

Fetal complications
Fetal Growth Restriction
Twins are at 10-fold risk
Common to have birth weight difference of about 15%
34% at least 1 IUGR in MC and 23% in DC (Sebire NJ et al., 1998)
4-fold chance of both twins having IUGR in MC (Sebire NJ et al., 1998)

Fetal complications
• Discordant growth = >30% difference
- Most predictive of C section, non reassuring fetal status,
umbilical artery pH < 7.1, a 5 minute Apgar score of <7 and
NICU admission (Redman ME, 2002)
- Outcome correlated with gestational age and not percentage
of discordancy (Cohen SB, 2001)

Fetal complications
Preterm delivery
Average length of gestation is 35 weeks
Accounts for 12% of all preterm births
Higher in MC (9.2% vs. 5.5% in DZ) (Hill LM et al., 1996)
Risk of cerebral palsy is 8 times greater compared to singleton (Luke B & Keith LG, 1992)

Twin to Twin transfusion syndrome
• TTTS occurs in around 10% of all monochorionic twins
• Net transfer of blood from one fetus (donor) to the other
(recipient) through placental vascular communications

Twin to Twin
transfusion
syndrome
Maternal Fetal Medicine Unit,
Ipoh Hospital

Diagnosis - Previously
Inter-twin haemoglobin difference of >5g/dl
Birth weight difference of >20%
Before widespread use of antenatal ultrasound
Not prospective
Hb. difference not always present (75% of
TTTS don’t have it) – (Denbow M. et al., Prenatal
Diagnosis 1998)
Discordant growth common in dichorionic twins

Fetal complications
Diagnosis – now sonographic
Monochorionic
Oligo-polyhydramnios
Bladder/stomach
Abnormal Doppler

Clinical consequences to recipient twin:
Polyhydramnios
Enlarged bladder
Congestive heart failure
Death

Clinical consequences to donor twin:
Oligohydramnios
Small absent bladder
+/- growth lag
Death

Twin to
Twin
transfusion
syndrome
• Treatment
• Serial amnioreduction (57% overall
survival and risk of neurological sequelae
15%) (Saunders NJ et al., 1992)

• Treatment
- Fetoscopic laser
photocoagulation (66%
overall survival and risk of
neurological sequelae 5%
(Thilaganathan et al., 2000)

IUGR
• Definition of IUGR
- birth weight < 10th centile
for gestational age
• Growth affected by
- race
- gender
- socioeconomics
- altitude
• Growth rates
- 5g/d at 14-15w
- 10g/d at 20w
- 35g/d at 32-34w

PATHOPHYSIOLOGY
• IUGR – manifestation of many possible fetal & maternal
disorders
Maternal Fetal
Medicine Unit, Ipoh
Hospital

DIAGNOSIS
ULTRASOUND
Considered the standard for the diagnosis of IUGR
Reasonably precise EFW
Ability to to follow growth pattern
Usually used after screening
Standard measurements taken
- HC, BPD, AC and FL
3 to 4 weekly scans
* Plotting of growth chart extremely important

Growth charts

DIAGNOSIS
Reliability of diagnosis
- depends on accuracy of dating
- advantage of early U/S
- importance of documentation & tracing

DIAGNOSIS
Symmetrical IUGR
Small HC and FAC
Early insult
Insult happens during cell division
Fetal anomaly
Infection
Teratogens

DIAGNOSIS
B) Asymmetrical IUGR
Normal HC but small FAC(head sparing)
Consequence of extrinsic factors
Insult during cell growth
Decreased liver size and subcutaneous fat
Nutritional, severe PE
Late in pregnancy

DIAGNOSIS
Implications of asymmetrical and symmetrical IUGR
• Symmetrical IUGR
- poorer prognosis
- need appropriate evaluation
• Asymmetrical IUGR
- optimistic prognosis
- proper surveillance
* Symmetrical IUGR can also be due to normal fetus and early onset nutritional disease

MANAGEMENT
Once IUGR is detected, management depends on :
Gestation
Severity of IUGR
Type of IUGR
- KIV karyotyping or TORCHES in symmetrical IUGR
Quality of monitoring of pregnancy
SCN facilities
*If gestation is remote from term - surveillance

SURVEILLANCE
Biophysical profile(BPP)
Uses 5 parameters
- AFI
- Fetal tone
- fetal breathing
- fetal movements
- non stress CTG
Advantage of multiple parameters
Fetal death within 1 week of normal BPP is rare
Disadvantage - time

SURVEILLANCE
2. Amniotic fluid assessment
• Why low amniotic fluid
• Maximal vertical pool(MVP) of less than
2
• AFI of less than 6
• IUGR can also have normal amniotic
fluid amount
• Low AFI can also be no IUGR

Liquor -oligohydramnios
• Oligohydramn
ios
• Polyhydramni
os.

SURVEILLANCE
3. Doppler velocimetry
• Evaluation of flow impedance through
selected fetal vessels
• Use can reduce perinatal death in IUGR and
unnecessary IOL in the preterm IUGRs
• Absent or reversal of end diastolic flow in
umbilical artery
• Normal Doppler rarely associated with
significant morbidity
• Abnormal Doppler in venous system
suggests greater risk of imminent death
• Redistribution of flow in the fetus

Fetal gender
Rarely medically
indicated
Based on positive
identification of
genitalia
Assessment of
sex not 100%
accurate
Not accurate
before 16weeks

First trimester
gestational sac
• The crown rump length
helps to determine the
expected date of delivery
and the gestational age
with an accuracy of within
4-5 days.

Fetal pole in sac
with yolk sac

Gut
• Jejunal atresia with
multiple fluid levels

Combined
first
trimester
screening
• recommended screening test done during 1st
trimester for trisomy 21 and trisomy 18
• incorporates nuchal translucency, crown-
lump length and maternal age
• indication: done when the fetus has a CRL of
45 to 84mm = 11W to 13W6D
• 2 parts:
(1) Biochemical analysis
(2) Ultrasound measurement of fetal nuchal translucency

(1) Biochemical
analysis
• Blood collected ideally at 9 – 12W gestation for
biochemical analysis of
(1) Pregnancy associated Placental Protein-A (PAPP-A)
- highly expressed in 1st trimester trophoblasts
- participating in regulation of fetal growth
- levels in maternal serum increase throughout
pregnancy
(2) Free ßhCG
- synthesized by placental cells starting and serves
to maintain progesterone production
- the concentration begins to fall as the placenta
begins to produce steroid hormones
and the role of the corpus luteum in maintaining
pregnancy diminishes.

(2) Nuchal
translucency
• ultrasonographic sonolucency in the
posterior fetal neck
• gestational age dependent – increase
15 – 20 % /week averagely
• Increased nuchal translucency of
greater than 3.5 mm is associated with
major congenital heart defects, defects
of the great vessels, fetal
malformations, dysplasias,
deformations, disruptions, and genetic
syndromes

Maternal serum screening
• screening test done during 2nd trimester for trisomy 21, 18 and neural tube
defects
• Blood collected ideally 15 – 17W gestation for biochemical analysis of
(1)Alpha fetoprotein
(2)Free ßhCG (or total hCG)
(3)Unconjugated estriol
(4)Inhibin A
Triple screen
Quad screen

SCREENING
IN FIRST
AND
SECOND
TRIMESTER
Trimester Screening test Chromosomal
/structural
abnormalities
Substances
tested/ scanned
First Combined 1st
trimester
screening
Trisomy 21 and
trisomy 18
PAPP-A + ßhCG
+ NT
Second Maternal serum
screening
Trisomy 21,
trisomy 18 and
neural tube defect
AFP + Free
ßhCG (or total
hCG) +
Unconjugated
estriol + Inhibin
A
Second Fetal
morphology
ultrasound scan
Structural
abnormalities

conclusions
1.Electronic
monitoring is here to
stay
2. Training in the
interpretation of the
traces is essential
3.Routine continuous
monitoring during
labor is probably not
cost effective in
developing countries
4. More studies are
required for the intra-
partum techniques
before they are useful
clinically
5. Ultrasound is now
routinely
recommended for
each pregnancy at least
once around 20 weeks.

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