o_1977r8vv9vk1ts2ms0kd8pksa.pdf

a Chapter 20 Doppler Velocimetry and Multiple Gestation 321
Table 20.3. Fetal Doppler evaluation of the umbilical artery in TTS. CW continuous-wave Doppler, S/D systolic/diastolic
ratio, US ultrasonography, PI pulsatility index, IUGR intrauterine growth retardation, UA umbilical artery, MCA middle cerebral
artery
Reference Technique No. of
pregnancies
Method of
assessment
Doppler findings
Conclusions
[24] CW 5 CW; S/D ratio
differences
[25] CW 2 CW; S/D ratio
differences >0.4
abnormal
[74] Pulsed
Doppler
[75] Pulsed
Doppler
duplex
[31] Pulsed
Doppler
[76] Pulsed
Doppler;
individual
Doppler
values
[78] Pulsed
Doppler
1 CW/real-time US;
serial PI values
in donor and
recipient
8 Pulsed Doppler;
individual
S/D ratios
6 Pulsed Doppler;
PI differences
11 Pulsed Doppler;
high-resolution
US
4 Pulsed Doppler;
PI in MCA, UA
No S/D ratio differences;
2 of 10 perinatal deaths
S/D ratio difference
Case 1: 1.9, SGA twin:
abnormal value
Case 2: one twin with
abnormal value
PI in small donor cyclical
but showed 0 to reversal
during diastole;
PI recipient normal
All S/D differences
between twins >0.4
Five fetuses had absent/
reversal of diastolic flow
One recipient and
6 donors with abnormal
Doppler
Of 31 sets of twins,
PI difference >0.5 in
7 cases; 6 of the 7 were
associated with TTS
Of 11 donor twins,
7 showed severe IUGR
and elevated S/D ratios;
2 of recipient fetuses also
showed abnormal values
Oligohydramnios in
donor sac; hydramnios
in recipient sac
UA increased resistance in
3, absent end-diastolic
flow in 1 (recipient)
MCA decreased resistance
in 3 that could be
measured (recipient)
UA and MCA PI in
donors were normal
No S/D ratio difference
in presence of size (US)
difference suggests TTS
TTS: high/low resistance
values
Artery-to-artery
anastomosis suspected;
morbidity not confined
to volume exchange
alone in TTS
Variable findings unable
to differentiate donor and
recipient; poor outcome
with abnormal Doppler
Of 12 infants with
abnormal ratios,
5 suffered perinatal death
Variable Doppler findings,
but donor SGA fetuses
more commonly had
high S/D ratios than did
recipient fetuses
Doppler velocimetry helps
explain changes in fetal
hemodynamics in TTS
and in all cases the A/B ratio differences were > 0.4.
Pretorius et al. [75] concluded that Doppler findings
are commonly abnormal in the presence of TTS, differing
with Giles et al. [24], and that the Doppler
findings were variable, suggesting ªan extremely complex
dynamic physiologic state.º
Later, in 31 twin pregnancies, Doppler ultrasound
findings were described for six pregnancies with TTS
[31]. The PI was determined using pulsed-wave Doppler
interrogation of the umbilical artery. Of the 31
twin pregnancies, 7 had intrapair differences for PI of
> 0.5; 6 of the 7 were associated with TTS.