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Case Report
Postpartum Management of
Placenta Previa Accreta Left In Situ
Role of 3-Dimensional Angiography
Orli Langer Most, MD, Tomer Singer, MD, Irving Buterman, MD,
Ana Monteagudo, MD, Ilan E. Timor-Tritsch, MD
P
lacenta previa accreta may require hysterectomy because of the potential of
massive obstetric hemorrhage. Overall, up to 92% of women require blood
transfusion when traditional surgical management is used.1 Hysterectomy
may not be sought as a viable option for women requesting to preserve future
fertility. Conservative management by leaving the placenta in utero and administration of methotrexate has been described in the literature. With the use of conservative management, the overall transfusion rate may be lowered substantially but still
may be as high as 80%.1 The problem faced at the conclusion of such management is
when to proceed with removal of the placenta.
This case report illustrates a new and objective way to determine when it is safest
to surgically remove the placental tissue without the risk of excess bleeding in hopes
of preserving reproductive function. The means to achieve this goal was the use of
3-dimensional (3D) power Doppler angiography to follow the receding blood vessels
to the placenta by quantifying its amount of vascularization.
Abbreviations
3D, 3-dimensional
Received July 30, 2007, from the Division of
Obstetric and Gynecologic Ultrasound, Department
of Obstetrics and Gynecology, New York University
School of Medicine, New York, New York USA.
Revision requested August 22, 2007. Revised
manuscript accepted for publication May 22, 2008.
Address correspondence to Ilan E. TimorTritsch, MD, Division of Obstetric and Gynecologic Ultrasound, Department of Obstetrics and
Gynecology, New York University School of
Medicine, 550 First Ave, NBV-9E2, New York, NY
10016 USA.
E-mail: [email protected]
Case Report
The patient was a 32-year-old woman with a history of
a previous cesarean delivery who in the subsequent pregnancy had a sonographic diagnosis of a fetal limb–body
wall anomaly and placenta previa accreta at her 19-week
anatomic survey. Transabdominal and transvaginal
sonography showed an enlarged and dysplastic placenta
with a “Swiss cheese” appearance. The placental vessels
appeared to invade through the thin myometrium anteriorly to the wall of the urinary bladder but not through it.
Multiple placental lakes were noted throughout the
entire placental tissue and the upper part of the cervix.
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After informed consent, including risks, benefits, and alternatives, termination of pregnancy
by high vertical hysterotomy was performed at
20 weeks’ gestation. The decision was made to
shorten the cord to its insertion and leave the
placenta in situ and to attempt conservative
management.
To visualize vascularization, 3D angiographic
imaging (Voluson 730 Expert; GE Healthcare,
Milwaukee, MI) was added as part of the
monthly monitoring of the placental volume.
Vascularization was determined in the following fashion: 3D volumes were acquired with
color Doppler imaging at 5 to 9 MHz with gain
set at 4, the notion filter set at 1, and a pulse
repetition frequency of 0.6 KHz. The volumes
were analyzed offline with the 4D View version
5.3 laptop computer–based software package
(GE Healthcare). Vascularity assessment was
done on the basis of the following 3D vascularity indices: the vascularization index, which
measures the ratio of color voxels over the total
gray and color voxels in an outlined volume
(virtual organ computer-aided analysis software; GE Healthcare) and practically represents the percentage of vessels in a region of
interest; the flow index, which is proportional
to the mean intensity of the color voxels compared to the total number of color voxels, indicating the average intensity of blood flow; and
the vascularization-flow index, which indicates the mean color value in all gray and color
voxels within the volume, representing a combination of both the flow index and vascularization-flow index and measuring tissue perfusion.
The last two are relative numbers on a scale of
0 to 100. Figure 1 shows the process of obtaining the quantitative evaluation of vascularity in
the placenta, and Figure 2 shows a 3D angiographic rendering of placental vessels during 3
months of observation. When subjectively
almost no power Doppler flow signals were seen
at the lowest pulse repetition frequency settings, that observation was used to determine
cessation of blood flow to the placenta.
To facilitate reduction of the placental mass,
the patient received methotrexate intramuscularly. Clinical, laboratory, and sonographic data
are summarized in Table 1.
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Figure 1. Three-dimensional images obtained 1 month after
hysterotomy. A, The placental volume is 399 cm3. The bottom right box is the “cut out” and rendered shape of the placenta in situ. B, Rendering of the placental vascularization by
3D angiography is shown in the bottom right box. This is a
qualitative expression of blood flow within the placenta in
situ. C, Histogram generated by the virtual organ computeraided analysis software expressing the flow indices.
A
B
C
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After a little more than 4 months of conservative management, the vascularization gradually
diminished to a minimum (Figure 3) considered
low enough to enable a minimal-risk surgical
procedure. At this time, dilation and curettage
was performed for an uncomplicated and relatively easy removal of the placental mass.
Figure 2. Gradual decrease in the vascularization of the placenta after hysterotomy, as followed by 3D power Doppler angiography. A, After 2 months. B, After 3 months. C, After 4 months.
A
B
C
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The patient was counseled that precautions
and close monitoring would be necessary for
future pregnancies. She conceived again 4
months after the surgical procedure and obviously was evaluated for a possible recurrence of
the placenta previa accreta. However, the posterior placenta appeared normal. The patient subsequently gave birth to a healthy and viable
full-term neonate by cesarean delivery without
any placental abnormalities.
Discussion
Placenta accreta is defined as an abnormal
attachment of the placenta to the myometrium
and occurs at an incidence of 1 per 5332 to 1 per
70003 deliveries. Risk factors for placenta accreta
include a history of cesarean delivery, prior
curettage, uterine instrumentation, multiparity,
and placenta previa in the current pregnancy.
Miller et al4 studied 155,670 deliveries and found
placenta accreta incidence rates of 9.3% in women
with placenta previa and 0.004% in women without placenta previa. The risk of having placenta
accreta in the presence of placenta previa varies
from 2% in women with no previous cesarean
deliveries, to 24% in women with 1 previous
cesarean delivery, to 67% in women with 3 or
more previous cesarean deliveries.5 Because placenta accreta is associated with potentially lifethreatening hemorrhage and an average blood
loss at delivery of 3000 to 5000 mL,5 it is important to make an early and accurate diagnosis to
allow for management, treatment, and reduction
of associated morbidity.
This diagnosis can be made prenatally by
sonography or magnetic resonance imaging.
Since the introduction of transvaginal sonography for diagnosing placenta previa6,7 and the
pathologically adherent placenta8,9 with gray
scale and color or power Doppler imaging, it has
become relatively easy to diagnose pregnancies
with the above-mentioned conditions. More
challenging cases may require repeated sonographic examinations later in gestation or magnetic resonance imaging, mainly for posterior
placentas. Sonographic findings suggestive of
placenta accreta include irregularly shaped
placental lacunae, myometrial thinning in the
area over the placenta, bulging of the placenta
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into the bladder, increased vascularity at the
bladder border, and possible increased vascularity in the lacunae (shown on Doppler sonography). Comstock10 described the presence of
placental lacunae as the most predictive sonographic determinant of placenta accreta and
described an increasing risk of placenta accreta
with an increasing number of lacunae noted on
sonography.
The goal of treatment for placenta accreta is
to achieve the least possible blood loss for
the patient. Traditionally, it has involved total
abdominal hysterectomy without an attempt to
detach the placenta to avoid massive hemorrhage. Because hysterectomy eliminates future
fertility and may also be associated with multiple complications and surgical risks to the
patient, conservative management of placenta
accreta is sometimes desired. The placenta is
left in situ, and additional treatment such as
methotrexate11,12 or uterine embolization of the
pelvic vessels13,14 is given. Alternatively, Kayem et
al1 left the placenta in situ and followed with serial sonographic examinations, blood cell counts,
and clinical examinations without the use of
adjunctive treatment and found a reduction in
the hysterectomy rate, transfusions needed, and
disseminated intravascular coagulation.
Three-dimensional color and power Doppler
angiography enables a simultaneous display of
gray scale and color flow images while the
Doppler or power Doppler mode is on.15 This
enables a display of vessels within certain designated volumes such as the fetal kidneys and other
vital organs.16,17 Furthermore, it allows evaluation
of the vascular anatomy and possible detection of
organ perfusion. Previous studies18,19 have described the use of 3D color and power Doppler
imaging in assessment of the fetal cardiovascular
system. In a real-time approach using Doppler
video images, Downey and Fenster19 concluded
that power Doppler data were better than color
Doppler data for restoration of 3D images. They
further noted that power Doppler imaging is a
less expensive modality that allows good visualization of both larger and smaller vessels without
the need for a contrast medium.
Our conservative approach of adding 3D angiographic imaging to a traditional serial sonographic evaluation of the vascularization indices
increased the accuracy of placental mass and
blood supply evaluations. We found 3D angiography to be instrumental in assessing the connection of the feeding vessels to the placenta to
determine the proper timing for its removal.
Because conservative management of placenta
previa accreta to preserve future fertility is a relatively new concept, extensive patient counseling and discussion regarding risks, benefits, and
alternatives are required. We think that this
innovative management of placenta previa accreta left in situ could benefit women requesting
conservative management for potential future
fertility.
Table 1. Summary of Clinical Information Over Time
Time After
Hysterotomy
2
1
2
3
4
3
3
wk
mo
mo
mo
mo
wk after D&C
mo after D&C
Placental,
Volume, cm3
638
528
362
217
85
POC
Normal
Uterine
Size, cm
18
16
12
13
10
9
8
×
×
×
×
×
×
×
13 × 12
12 × 10
9.5 × 10
7×8
8×7
5×4
5×4
VI
Vascularity Indices
FI
24.6
49.7
17.3
42.3
20
42.3
12.4
39.5
0.19
18.9
No appreciable flow
No appreciable flow
VFI
8.2
7.3
4.3
1.3
0.5
β-hCG,
mIU/mL (IRP)
5470
3900
ND
ND
9.7
ND
ND
D&C indicates dilation and curettage; FI, flow index; hCG, human chorionic gonadotropin; IRP, international reference preparation; ND, not determined; POC, products of conception; VFI, vascularization-flow index; and VI, vascularization index.
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Figure 3. Three weeks after hysterotomy, the placenta is in place, as shown on 2-dimensional imaging. A, Gray scale longitudinal section
showing the empty cavity, which is the placenta (arrows). CX indicates cervix. B, Power Doppler image showing the intensive blood
supply to the placenta. C and D, Gray scale and color Doppler images of the placenta in situ 3 months after hysterotomy. E and
F, Gray scale and power Doppler images of the placenta in situ 4 months after hysterotomy. Note the absence of flow in F. Ut-W
indicates uterine width.
A
B
C
D
E
F
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