Download diagniosis and management of pregnancy with severe fetal growth

Archives of Perinatal Medicine 15(3), 170-175, 2009
CASE REPORT
Diagnosis and management of pregnancy
with severe fetal growth restriction – a case report
PIOTR SZYMAŃSKI1, GRZEGORZ H.BRĘBOROWICZ2, MICHAŁ SZUBER2, JAKUB KORNACKI3
Abstract
Intrauterine growth restriction is a pregnancy complication of multifactorial etiology and its association with
increased risk of perinatal mortality and morbidity is generally known. The main issue in the management of
growth restricted fetuses is an appropriate fetal monitoring that enables to identify these at high risk of stillbirth.
This paper presents a case report of pregnancy complicated by severe intrauterine growth restriction. The diagnosis and fetal surveillance were discussed, taking into consideration the problem of timing of the delivery in the
aspect of iatrogenic prematurity. The role of Doppler blood flow velocimetry in the monitoring of preterm growth
restricted fetuses was presented.
Key words: intrauterine growth restriction, fetus, Doppler velocimetry
Introduction
Intrauterine growth restriction (IUGR) is a complication that affects 3 to 7% of pregnancies in developed
countries [1-3]. Its association with increased perinatal
morbidity and mortality is generally known; mortality
rate among growth restricted infants is 5 to 10 times
higher than in those with body weight appropriate for
gestational age [4]. However, long-term sequelae of impaired fetal growth also are of importance; they include
neurodevelopmental deficits [5], heart disorders, diabetes
and others [6]. The causes of IUGR are divided into three
main categories: fetal, maternal and uteroplacental [7].
Accurate pregnancy dating is essential for assessment of fetal growth; crown-rump length measured in
first trimester is the most reliable parameter that enables
for the correction of gestational age when last menstrual
period is uncertain [8]. Additional parameters helpful in
evaluation of gestational age are transcerebellar diameter,
foot length and epiphysial centers, which are gestational
age-dependent, but are not influenced by factors related
to IUGR [8]. Estimated fetal weight below 10 percentile
defines the fetus as a small for gestational age (SGA) [7].
However, to diagnose a IUGR one should demonstrate
reduced growth of the fetus in consecutive ultrasound
measurements performed at least two weeks apart. Gestational age-independent femur length (FL)/abdominal circumference (AC) ratio reflects the nutritional condition
of the fetus and is another parameter used in dealing
with fetuses suspected to be growth restricted [8].
1
The real challenge in management of pregnancies
complicated by IUGR is the assessment of fetal wellbeing. Analysis of data obtained by the use of biophysical
methods is essential in decision making process aimed
to establish the time of intervention. The difficulty particularly arises in severely growth restricted fetuses before 30-32 week, when the risk related to prematurity superimposes on the risk related to IUGR. As the majority
of IUGR cases are caused by vascular placental insufficiency, the techniques focused on evaluation of fetal and
utero-placental circulation are considered as a useful
modalities of biophysical surveillance.
This paper presents a case report of pregnancy complicated by severe restriction of fetal growth and the use
of arterial and venous Doppler blood flow velocimetry in
the assessment of the fetal condition and timing the delivery.
Case report
22-years old primiparous woman with a non-contributive history was admitted to the tertiary perinatal care
center at 30 weeks of singleton pregnancy because of
severe fetal growth restriction, non-reassuring CTG
tracings and abnormal results of Doppler examination.
Except for an episode of minor bleeding at 7 weeks and
irregular uterine contractions at 27 weeks, the course of
pregnancy prior to hospitalization was uneventful. On
admission, basic parameters of the patient such as blood
pressure, heart rate and temperature were normal; no
Department of Gynecology, University of Medical Sciences in Poznań, Poland
Department of Perinatology and Gynecology, University of Medical Sciences in Poznań, Poland
3
Department of Reproduction, University of Medical Sciences in Poznań, Poland
2
Diagnosis and management of pregnancy with severe fetal growth restriction
signs of oedema were noted. Clinical examination revealed effaced cervix, and uterine fundal height was corresponding with 26 weeks of pregnancy. Her menstrual
periods were regular; pregnancy dating based on the
first trimester scan performed at 6 weeks of pregnancy
confirmed actual gestational age. Blood test results as
well as urinalysis were normal.
Ultrasound examination performed on admission
revealed single viable fetus in a breech position. Estimated fetal weight was 620 g, which corresponded with
gestational age of 24 weeks. Fetal heart rate was within
normal range (145 bpm); cardiac rhythm was regular.
Amniotic fluid index was slightly reduced according to
gestational age (82 mm). Spectral Doppler blood flow
velocimetry revealed absent end-diastolic flow in umbilical artery waveform, with the episodes of reversed
flow, while the middle cerebral artery presented markedly reduced vascular resistance, expressed by pulsati-
171
lity index below normal value for gestational age. Taking
into consideration abnormal findings from both MCA and
UA, the presence of brain sparing effect was noted. On
admission, fetal venous system was assessed only qualitatively; constant umbilical vein blood flow pattern without signs of pulsation as well as antegrade flow in ductus
venosus during atrial contractions (a-wave) were recorded. Uterine artery Doppler velocimetry revealed unilateral early – diastolic notching in right uterine artery; left
uterine artery blood flow spectrum was normal. Because
of prematurity and severe growth restriction an expectant management including administration of steroids for
fetal lung maturation and intensive monitoring was
undertaken. Doppler examinations performed on the
fourth and fifth day of hospitalization did not revealed
any further deteriorations in fetal arterial as well as
venous blood flow parameters. The results of the consecutive Doppler examinations are presented in Table 1.
Table 1. The results of consecutive Doppler examinations
Days of
hosp.
EFW
[g]
AFI
[mm]
UA
MCA
UV
DV
1.
620
82
AEDF/REDF
1.4
N
antegrade
a-wave
4.
–
–
AEDF
1.64
N
–
5.
–
30
AEDF
1.9
N
7.
–
70
REDF
1.17
pulsation
8.
Before
delivery
630
55
REDF/AEDF
1.3
pulsation
Fig. 1. Reversed end – diastolic flow
in the umbilical artery waveform
antegrade
a-wave
8PIV
8PLI, S/a
8PIV
8PLI, S/a
other
GV
pulsation
GV
pulsation
Fig. 2. Umbilical venous pulsation in the free part
of umbilical cord
172
P. Szymański, G.H. Bręborowicz, M. Szuber, J. Kornacki
Fig. 3. Pulsatile pattern in intrahepatic portion
of umbilical vein
in free-floating loop of the cord (Fig. 2 and 3). Although
a-wave of ductus venos blood flow waveform remained
antegrade, detailed analysis of this vessel revealed abnormal venous indexes: Pulsatility Index for Veins (PIV,
1.39), Preload Index (PLI, 0.89) and S/a ratio (8.84)
(Fig. 4). Additionally, impairment of the fetal venous
blood flow was reflected by the pulsation in the Galen
vein (GV, Fig. 5). Continuous fetal monitoring using cardiotocography revealed repetitive decelerations and decreased heart rate variability; Doppler velocimetry performed 24 hours later revealed no improvement. Because of an overt signs of fetal distress the decision about
delivery was undertaken. A live male infant of birth
weight 690 g was delivered of by cesarean section with
an Apgar score of 8 at 1 min. Umbilical artery and vein
pH were 7.33 and 7.29, respectively. The infant was
transferred to the Neonatal Intensive Care Unit and required non-invasive ventilation using Infant Flow method
only for the first four days after delivery.
Discussion
Fig. 4. Blood flow waveform in ductus venosus
Fig. 5. Pulsation in the Galen vein
Progression of fetal blood flow abnormalities was
observed on the seventh day of hospitalization. Doppler
ultrasound revealed permanent reversed end – diastolic
flow in the umbilical artery (Fig. 1) and pulsatile pattern
in the umbilical vein, both in intrahepatic part as well as
Placental function is one of the most important
factors which determine the ability to fulfill genetically
determined growth potential of the fetus. Obliteration of
placental vessels and thus increased vascular resistance
is reflected in alterations of umbilical artery blood flow
waveform before the onset of growth rate impairment
and the reduction of amniotic fluid volume. Early changes in umbilical artery blood flow dynamics occur when
30% of villous vessels are abnormal and include a decrease of end – diastolic velocity and elevation of flow indices
[9]. Absent or even reversed end-diastolic flow in umbilical artery waveform are the utmost signs of increased
placental resistance and occur when 60-70% of villous
vessel are damaged [10]. As the placental blood flow
constitutes about 40% of combined fetal cardiac output,
elevated flow resistance in this vascular bed increases
after – load, especially of the right ventricle [11], since
this chamber is responsible for perfusion of lower part
of the body. Due to the parallel arrangement of fetal
circulation, it results in a shift of cardiac output towards
left ventricle, with preferable perfusion of the upper part
of the body [12]. This compensatory mechanism is augmented by local autoregluation in vital organs, which
maintains oxygen delivery by reduction of vascular resistance; brain sparing effect observed in the middle cerebral artery reflects cerebral vasodilatation in a response
of perceived hypoxemia [13].
As the deterioration of metabolic status progresses,
a failure of compensatory mechanisms is reflected in
Diagnosis and management of pregnancy with severe fetal growth restriction
fetal venous system. Decrease of forward cardiac function, primary due to elevated after-load, and secondary
due to myocardial dysfunction caused by hypoxemia results in elevation of central venous pressure. This is
reflected by alterations of blood flow waveforms in ductus venosus (DV), inferior vena cava and umbilical vein
(UV) [14]. Abnormal venous flow is described by the use
of several Doppler indices for both DV and IVC [15]; in
clinical practice, a qualitative description of antegrade,
absent or retrograde flow in DV during atrial contraction
and presence or absence of umbilical venous pulsations
are widely used.
The present case-report shows a wide spectrum of
problems which are met by clinician dealing with preterm growth restricted-pregnancies. As it was written
previously, diagnosis of IUGR is based on the failure of
fetal growing expressed by the results of consecutive
measurements performed at least two weeks apart. However, if gestational age is concordant with pregnancy
dating from first trimester scan, and if estimated fetal
weight is below 10 percentile, the diagnosis of IUGR
seems to be unequivocal. Moreover, there was no possibility to repeat biometry because of progression of circulatory compromise in discussed case. At this stage of
management, umbilical artery velocimetry appears to be
a useful tool in differentiation between SGA or constitutionally small fetuses and IUGR fetuses, since abnormal umbilical artery waveform identifies fetuses with
growth delay due to placental insufficiency [16-18]. In
such circumstances one should expect increased vascular resistance in uterine arteries; however, in the
present case only unilateral notching was observed. This
finding may suggest, that impaired placental perfusion
was not caused by impaired trophoblast invasion of spiral
arteries, but rather by the reduction of villous vessels
number; the former phenomenon is commonly accepted
mechanism of preeclampsia and preeclampsia-related
IUGR [19]; the latter is reflected by alterations with umbilical artery waveform [9], as it was mentioned earlier.
Decreased amniotic fluid volume supports the diagnosis of fetal growth restriction related to placental insufficiency [20]. In the temporal sequence of fetal response to impaired placental function, reduction of amniotic fluid volume follows the changes in umbilical blood
flow, redistribution of cardiac output and the onset of
growth restriction [13]. In the present case amniotic
fluid index was below 5 percentile [21] at each measurement; however, ultrasound assessment of this parameter appeared to be poorly sensitive as a screening test
for detection of growth restriction [22]. Pregnancies
173
with growth delay of the fetus due to chromosomal/
structural abnormality or fetal infection, may present
normal or increased amniotic fluid volume [23].
In the presented case, a progression of circulatory
disturbances in both arterial and venous system was observed. On the seventh day from admission reversed
end-diastolic flow in umbilical artery waveform, umbilical
venous pulsations and abnormal DV Doppler indices
were found; in the presence of decelerative CTG tracings the decision about cesarean delivery for fetal distress was undertaken. Reversed and absent umbilical
end-diastolic flow observed after, respectively, 32 and 34
weeks of pregnancy were considered as a indications for
delivery [24]. However, since these abnormalities may
be present over several days without further deterioration of the fetal condition [25-28], this approach to the
problem of timing the delivery on the base umbilical
artery velocimetry is questionable. Several studies confirmed the role of evaluation of venous system in surveillance and planning the intervention in IUGR-complicated
pregnancies. Venous flow alterations are considered as
late Doppler changes [12, 13, 26], and their presence is
a strong predictor of acid-base status [14] and perinatal
mortality [24, 27, 29]. Summary of eight studies on venous flow in fetuses with IUGR and with umbilical artery
absent or reversed end – diastolic flow demonstrated,
that total perinatal mortality is constituted mainly by
neonatal deaths in those with normal DV flow, while
stillbirths and neonatal deaths equally contribute to the
perinatal mortality if abnormal DV flow is observed [29].
In the temporal sequence of late Doppler changes in
fetal venous system, abnormal venous waveform indexes
in precordial veins proceed pulsatile pattern in umbilical
vein; the utmost degree of venous flow alterations is
reversed blood flow in DV during atrial contractions [13].
In the present case DV antegrade a-wave was preserved,
but abnormal flow was reflected by elevated Doppler
parameters, namely the pulsatility index for veins (PIV),
preload index (PLI) and S/a ratio (S/a). The calculated
values were above 95 percentile for gestational age [30,
31], thus indicating for increased central venous pressure. According to the cited paper [29], increased DV parameters and reversed a-wave are associated with similar
stillbirth, neonatal and perinatal mortality rates. Although
umbilical vein pulsation was the most severe sign of fetal
compromise in the present case, assessment of venous
waveform indices allowed for the better insight into fetal
condition and supported the decision about the delivery
before terminal changes in venous flow, i.e. DV reversed
a-wave occur. This approach was consisted with the
174
P. Szymański, G.H. Bręborowicz, M. Szuber, J. Kornacki
results of Brodszki et al., who revealed high 2-year survival rate and low morbidity among growth restricted
fetuses with absent or reversed flow in umbilical artery
delivered before severe changes in DV waveform occurred [32].
Abnormal venous pulsation due to increased central
venous pressure was found in the Galen vein. In normal
pregnancies blood flow in this vessel of cerebral circulation is characterized by constant pattern, similarly to
the umbilical venous flow in second and third trimester
[33]. According to the data from literature, pulsatile
pattern of Galen vein flow was associated with poor perinatal outcome and correlated with low umbilical pH and
the number of operative deliveries for fetal distress [34].
The course of circulatory disturbances in described
case is consisted with observations of Turan et al., who
analyzed the sequence of arterial and venous Doppler
abnormalities in pregnancies complicated by IUGR [35].
They revealed that the characteristic of circulatory compromise is determined by gestational age at onset and
the severity of placental disease identified by UA velocimetry. According to results of this study, further deterioration of UA blood flow within first 7-10 days of monitoring predicts progression to venous abnormalities and
very early intervention, while if initial abnormalities have
not worsened in this period, they remain confined to the
umbilical and mild cerebral changes.
Conclusions
1. Accurate pregnancy dating and analysis of fetal
growth rate in serial ultrasound measurements is
essential for the diagnosis intrauterine growth restriction.
2. Abnormal umbilical artery blood flow allows to differentiate between constitutionally small fetuses and
IUGR fetuses due to placental insufficiency and
progression of blood flow changes in this vessel identifies a group of the highest risk of adverse pregnancy
outcome.
3. Evaluation of venous flow is a valuable method in
timing of delivery, when the risk stillbirth should be
weighing against the risk preterm delivery.
The work done under the grant MNiSW 162/E-392/CD/
DFS-4/2004
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J
Piotr Szymański
University of Medical Sciences in Poznań
Department of Perinatology and Gynecology
60-535 Poznań, Polna 33, Poland
e-mail: [email protected]