1. Dr.Omneya Nagy Elmakhzangy
Special Fetal Care Unit
Ain Shams University
ULTRASOUND DIAGNOSIS OF
PLACENTAL INVASION

2. DEFINITION AND TYPES
• Placenta accreta refers to an abnormality of placental
implantation in which the anchoring placental villi attach
to myometrium rather than decidua, resulting in a
morbidly adherent placenta.
• Placenta increta (chorionic villi penetrate into the
myometrium) and placenta percreta (chorionic villi
penetrate through the myometrium to the uterine serosa or
adjacent organs..
• The pathogenesis is primarily attributed to defective
decidualization of the implantation site

6. LOCALIZE YOUR PLACENTA

7. IS IT IMPORTANT TO DIAGNOSE?
• In 1950, placenta accreta was rare, occurring in 1 in 30,000
deliveries in the United States . During the 1980s and 1990s,
the incidence markedly increased, ranging from 1 in 533 to 1 in
2510 deliveries . The marked increase has been attributed to the
increasing prevalence of cesarean delivery in recent yeas
(uptodate sep.2014).
• Placenta accreta is undoubtedly a challenge, but with proper
diagnosis and preparation, the goal is to decrease the morbidity
of this rapidly increasing obstetric complication.
• In other words Proper Diagnosis gives a chance for a well
prepared and well planned management

8. DIAGNOSTIC PERFORMANCE OF DIFFERENT
ULTRASOUND MODALITIES
Sensitivity (%) Specificity (%) Positive
predictive
value (%)
Risk
Grey scale 95 76 82 93
Colour Doppler 92 68 76 89
Three-
dimensional
power Doppler
100 85 88 100
RCOG Green–top Guideline No. 27 , January 2011

9. 1ST TRIMESTER PLACENTA ACCRETA
• Placenta accreta (and percreta) does occur in the first trimester.
It is usually discovered during dilatation and curettage when
massive bleeding occurs due to placental invasion of the
myometrium by placenta (H¨ opker M, 2002)
• Individuals who are at risk for placenta accreta at term are also
at risk for placenta accreta in the first trimester.
• This type of pregnancy, in which a sac is abnormally attached
in the lower uterus, needs to be differentiated from ‘Cesarean
scar pregnancy’ because in the latter, the pregnancy is entirely
contained within the myometrial confines of the scar, with no
part within the cavity itself.

10. Placenta Percreta in a patient with five previous Cesarean
sections. The sac is low in the uterus and appears to be attached
to the bladder wall.
Reproduced with permission of AIUM, J Ultrasound Med 2003

11. Placenta accreta at 8 weeks. This pregnancy progressed to term.
Note that there is little myometrium between the sac and the
bladder (arrow).
Reproduced with permission of AIUM, J Ultrasound Med 2003

12. Placenta increta at 6 weeks. Note almost no myometrium between the
sac and bladder wall (arrow).
Reproduced with permission of AIUM, J Ultrasound Med 2003

13. SIGNS SUGGESTIVE OF PLACENTAL INVASION
ON GRAYSCALE ULTRASOUND:
• Loss of the retroplacental sonolucent zone
• Irregular retroplacental sonolucent zone
• Thinning or disruption of the hyperechoic serosa–bladder interface
• Presence of focal exophytic masses invading the urinary bladder
• Abnormal intraplacental lacunae.

14. ABNORMAL PLACENTAL LACUNAE
• Visualization of lacunae had the highest sensitivity (79%) in the 15–
20-week range and a sensitivity of 93% in the 15–40-week gestational
age time frame (ISUOG 2005).
• They usually, but not always, have turbulent flow within them, and
they appear irregular, often more linear rather than rounded and
smooth bordered. They do not have the highly echogenic border that
standard venous sinuses have.(Tornado-shaped flow)
• To predict placenta accreta the lacunae have to be highly vascular
intraplacental rather than well defined extraplacental low flow blood
vessels

15. Vascular sinuses in patients without placenta accreta.
-Vascular areas lie between the placenta and myometrium rather
than within the placenta; they have low flow.
- Large well-defined vessels with low flow at the edge of the placenta

17. MYOMETRIAL THICKNESS
• Measurement of the thickness of the lower uterine segment in women
who had had a previous Cesarean section and had a low-lying anterior
placenta or placenta previa by measuring between the bladder wall
and the retroplacental vessels, as seen by color Doppler.
• All patients later proven to have placenta accreta had myometrium of
less than 1 mm, which was as predictive of accreta as lacunae.

18. Normal ‘clear’ or echolucent space
between the
placenta and myometrial wall .
Lack of the clear zone in a
normal anterior placenta
The area near the arrow appears to be abnormal,
possibly due in part to drop-out. The
transducer should be perpendicular to the bladder wall
during evaluation of its integrity
Translucency zone

19. DOPPLER IN DIAGNOSIS OF PLACENTAL
INVASION

20. • Christian Andreas Doppler ( 29 November
1803 – 17 March 1853) was an Austrian
mathematician and physicist. He is celebrated
for his principle — known as the Doppler effect
— that the observed frequency of a wave
depends on the relative speed of the source and
the observer.

21. SIGNS SUGGESTIVE OF PLACENTAL INVASION
ON COLOR DOPPLER
• Diffuse or focal lacunar flow
• Vascular lakes with turbulent flow (peak systolic velocity over 15
cm/s)
• Hypervascularity of serosa–bladder interface
• Markedly dilated vessels over peripheral subplacental zone.

22. Gray-scale image of a tornado-shaped sinus (moth Eaten) Color Doppler image
showing placenta accreta with many sinuses.

23. Color Doppler images showing diffuse dilated intraplacental vasculature and
marked periplacental vascularity between bladder and
uterine serosa , compared with a normal placenta at the same gestational age

25. Color Doppler image of a tornado-shaped sinus
Am J Obstet Gynecol 2004

26. Color Doppler of placenta percreta with invasion of bladder wall

27. 3D POWER DOPPLER

28. WHY DO WE USE 3D ACQUISITION
RATHER THAN 2D?
 The use of color and power Doppler in the
early 1990's has improved perinatal
diagnosis of complex C.V.S malformations
over the grey scale ultrasound.
 The draw back in using 2D color or power
Doppler is that they generally allow the
visualization of vessels running in a straight
course or lying on the same 2D plane.

29.  In most cases the examiner has to mentally
reconstruct a spatial image of the vessels examined.
 In recent years 3D Doppler has helped in the
reconstruction of the vessels of interest and thus
improves the understanding of the spatial
appearance of the Vascular tree.
 The images acquired were close to X-ray or MR
angiography.

30. TECHNICAL BACKGROUND
 Two main aspects have to be taken in
consideration when acquiring a volume
image :
1- Volume Data Acquisition.
2-Image rendering .

31. VOLUME DATA ACQUISITION
There are two ways to achieve :
1- Static 3D mode which is a series of still
images.
2- A 4D mode which can be either by a real time
3D scanning or an offline 4D which is one of
the recent advents in the software that allows
spatial and temporal image correlation known
as "STIC".

32. IMAGE RENDERING
 It is the process of creating a 3D visual
presentation of parameters of interest.
 The main principle behind this is "planar
geometric projection" i.e a 2D image to
represent the 3D data the third dimension
impression is acquired through online rotation of
the image along X , Y and Z axis

33.  The exam can show the vessel of interest alone
"Inversion mode" or along with the gray scale
image in what's called the "Glass body rendering
mode".

34. ARE WE LOOKING AT A VESSEL
OR AT A SPECIFIC ORGAN
VASCULARITY?
If a specific vessel is targeted we simply apply 3D
power or Color Doppler on the vessel of interest but
if an organ or a structure as a whole is targeted we
use a software technology known as VOCAL
(virtual organ computer aided analysis).

35. QUANTIFYING THE BLOOD FLOW BY
3D POWER DOPPLER

36. 1- VI (Vascularization index): Vascularization index is
the ratio of the number of color voxels (volumetric
pixel) to the total number of voxels in the sampled
tissue, thus it represents the percentage of
vascularized tissue

37. 2- FI (flow index) : Flow index is the average colour
value of all colour voxels and it describes the mean
velocity of flow in the sampled tissue.

38. 3- VFI (vascularization flow index) : is the average colour
value of all colour and grey voxels and describes both:
the vascularization and the blood flow.

39. SIGNS SUGGESTIVE OF PLACENTAL INVASION
BY 3D POWER DOPPLER
• Numerous coherent vessels involving the whole uterine serosa–
bladder junction (basal view)
• Hypervascularity (lateral view)
• Inseparable cotyledonal and intervillous circulations, chaotic
branching, detour vessels (lateral view).

42. RARE FORMS OF INVASIVE PLACENTA

43. FUNDAL INVASIVE PLACENTA

44. PLACENTA ACCRETA WITHOUT
PLACENTA PREVIA OR UTERINE SCAR
• These patients may present at birth, but often present earlier with an
acute abdomen and copious free blood within it (heamoperitonium)
• There are no ultrasound series published as yet that have evaluated
the ultrasound appearance of these atypical situations.
• The present ultrasound literature exclusively addresses the appearance
in patients at risk, either with placenta previa or previous uterine
surgery or both.

45. ROLE OF MRI
• Compared to US. US examination is fundamental in the diagnosis
due to its low cost and wide availability
• . US has a sensitivity of 83% and a specificity of 72%. When it is
associated with Color Doppler, a sensitivity close to 97% and a
specificity of 92% has been reported.
• The positive predictive value (PPV) of MR is of 100% (65% US),
while the negative predictive value (NPV) is greater for ultrasound
(98% versus 82%).
• MRI should be reserved for cases with equivocal ultrasound findings
or to evaluate uterine zones difficult to assess with US, like the
posterior aspect of the placenta.

46. SPECIFIC FINDINGS OF PLACENTAL INVASION
ON MRI
•
- Bulging of the uterus.
- Placenta of heterogeneous signal intensity on T2WI.
- Dark and thick intraplacentarian bands on T2-weighted images

47. FOR FURTHER INFORMATION ON DIAGNOSIS
AND MANAGEMENT OF PLACENTAL INVASION
• http://www.uptodate.com.search.sti.sci.eg:2048/contents/clinical-
features-and-diagnosis-of-placenta-accreta-increta-and-
percreta?source=search_result&search=placenta+accreta&selectedTitl
e=1~38
• RCOG Green-top Guideline No. 27