Imaging of Abnormal Placental Implantation: A Patient with Placenta

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Imaging of Abnormal Placental Implantation: A Patient with Placenta Percreta

Sonya Trinh, Harvard Medical School Year IIIGillian Lieberman, MD

June 2009

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Agenda

• Patient L.S.• Menu of Tests• Anatomy of Female Pelvis and Placenta• Abnormal Placental Implantation• Film interpretation• Differential Diagnosis • Conclusions

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Agenda: Patient L.S.

• Patient L.S.• Menu of Tests• Anatomy of Female Pelvis and Placenta• Abnormal Placental Implantation• Film interpretation• Differential Diagnosis• Conclusions

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Patient L.S.: History of Present Illness

CC: Placenta previa with vaginal bleeding

HPI:• 32 year old female G3P2 at 18 weeks GA • Presents with episode of bright red vaginal blood

• Bleeding has subsided• Denies contractions, cramping, pain

• Bleeding episode at 5 weeks GA• Diagnosed with placenta previa by US• No bleeding since first episode

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Patient L.S.: Past Obstetrical History

Past Obstetrical History:• Cesarean section

– Arrest of descent• Cesarean section

– Repeat, twin intrauterine pregnancy

Reason for Imaging: Narrow differential diagnosis• Placenta accreta• Placenta increta• Placenta percreta

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Agenda: Menu of Tests

• Patient L.S. • Menu of Tests• Anatomy of Female Pelvis and Placenta• Abnormal Placental Implantation• Film interpretation• Differential Diagnosis• Conclusions

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Menu of Tests: Obstetrical Imaging in 2nd and 3rd Trimester

Preferred imaging modalities:• Ultrasound (US)• Magnetic Resonance Imaging (MRI)

– Abdominal MRI, -contrast

Lesser used studies:• Radiograph• Computed Tomography (CT)

– Abdominal CT, -contrast

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Effects of Ionizing Radiation

Increased risk:• Miscarriage• Congenital anomalies• Genetic disease• Growth restriction• Developmental disorders

When imaging modality necessary:• Radiograph

– Wear lead apron to minimize fetal exposure– Fast film/screen combination or digital radiography

• Computed Tomography– Narrow collimation and wide pitch– Patient moves through scanner at faster rate

Brent, 2009

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Menu of Tests: Ultrasound

Description:• Transducer emits and receives sound waves• Spatial distribution determined by time for sound waves to return

Advantages:• No biologic effects documented• No contraindications

Limitations:• Difficult to image fetus in obese patients• Operator dependent

– Image quality depends on sonographer skill

Lieberman, Gillian. http://eradiology.bidmc.harvard.edu/primarycare/radiologicmenu.html

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Menu of Tests: Magnetic Resonance Imaging

Description:• Magnets and radiowaves causes alignment of hydrogen protons• Different electronic environments lead to different signals

Advantages:• No ionizing radiation• No reported harmful effects • Excellent images of soft tissue

Limitations:• Avoid in first trimester

– No experience with safety during organogenesis• Potential safety concerns

– Induce local electric fields and currents– Radiofrequency radiation heats tissue– Projection of metal objects

• Gadolinium contrast not recommended

Lieberman, Gillian. http://eradiology.bidmc.harvard.edu/primarycare/radiologicmenu.htmlShellock et al., 2004

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Agenda: Anatomy of Female Pelvis and Placenta


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Anatomy of Female Pelvis: Sagittal View

http://www.rush.edu/rumc/page-1098987343902.html

Anterior Posterior

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Anatomy of Female Pelvis: Placenta


Anterior Posterior

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Anatomy of the Placenta: Close-Up

http://utdol.com/online/content/image.do;jsessionid=F77F02EF28252E1638A20B402D73CB4E.1103?imageKey=obst_pix/placen4.htm&title=Placental%20vasculaturehttp://www.rush.edu/rumc/page-1098987343902.html

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Anatomy of the Placenta: Maternal Surface


Myometrium

Endometrium

Decidua•Acts as barrier to invasion by fetal chorionic villi

Myometrium EndometriumDecidua

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Anatomy of the Placenta: Fetal Surface


Chorionic villi

Umbilical cord

Chorionic villi•Can invade past decidua into maternal surface

Umbilical cord

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Anatomy of the Placenta: Maternal and Fetal Surface


Myometrium

Endometrium

Decidua

Chorionic villi

Umbilical cord

Myometrium EndometriumDecidua

Chorionic villi

Umbilical cord

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Agenda: Abnormal Placental Implantation

• Patient L.S.• Menu of Tests • Anatomy of Female Pelvis and Placenta• Abnormal Placental Implantation• Film interpretation• Differential Diagnosis• Conclusions

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Placenta Previa: Definition and Types

Definition:• Placenta overlies or lies

proximal to internal cervical os

Types:A. MarginalB. PartialC. Complete

http://myhealth.ucsd.edu/library/healthguide/en-us/support/topic.asp?hwid=aa154120http://www.aafp.org/afp/AFPprinter/20070415/1199.htmlMagann et al., 2007

A.

B.

C.

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Placenta Previa: Clinical Facts

http://myhealth.ucsd.edu/library/healthguide/en-us/support/topic.asp?hwid=aa154120http://www.aafp.org/afp/AFPprinter/20070415/1199.htmlFaiz et al., 2003Cotton et al., 1980

A.

B.

C.

Risk factors:•Endometrial scarring•Cesarean delivery•Increasing parity•Increasing maternal age•Prior curettage for abortion

Clinical presentation:•Painless vaginal bleeding after 20 weeks•Can present with uterine contractions

Diagnosis:•Straightforward by US

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Placenta Accreta: Definition and Types

Definition:• Chorionic villi attach to myometrium• Villi invade past maternal decidua layer

Types• Accreta

– Attach to myometrium• Increta

– Invade into myometrium• Percreta

– Invade past uterine serosa into organs

http://embryology.med.unsw.edu.au/Notes/images/placenta/anchoring-villi2.jpghttp://embryology.med.unsw.edu.au/Notes/placenta2.htmMiller et al., 1997

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Placenta Accreta: Clinical Facts

Risk Factors:• Previous uterine surgery• Prior cesarean delivery

Clinical Manifestations:• Profuse hemorrhage after delivery• Inability to separate placenta from uterus• Life-threatening

Diagnosis:• US and MRI• No imaging modality determines diagnosis with

absolute accuracy– US=Sensitivity 0.8, Specificity 0.95– MRI=Sensitivity 0.88, Specificity 1.00

http://embryology.med.unsw.edu.au/Notes/images/placenta/anchoring-villi2.jpghttp://embryology.med.unsw.edu.au/Notes/placenta2.htmMiller et al., 1997Warshak et al., 2006

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Agenda: Approach to OB US

• Patient L.S.• Menu of Tests• Anatomy of Female Pelvis and Placenta• Abnormal Placental Implantation• Film interpretation

– Approach to Obstetrical Ultrasound• Differential Diagnosis• Conclusions

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Approach to Obstetrical Ultrasound EvaluationCompanion Patient 1, Normal

Transabdominal US, Mid Uterus, Sagittal View

Transabdominal US, Cervix, Sagittal ViewPACS, BIDMC

Check relevant structures:•Anterior abdominal wall•Uterus

•Myometrium•Placenta•Amniotic Fluid•Fetus•Cervix•Ovaries•Bladder

Placenta Location:•Anterior vs. Posterior uterine wall•Cervical status

Placenta previa?

Placenta texture:•Homogeneous vs. heterogeneous•Distinct myometrial surface?

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Approach to OB US Evaluation: Practice on Companion Patient 1, Normal Pelvic Anatomy

Companion Patient 1, Normal



Analyzing ultrasound images can be difficult, especially when the orientation of the images are not apparent.

Now that we have learned an approach to obstetrical ultrasound evaluation, let’s practice on Companion Patient 1 who has normal pelvic anatomy during pregnancy.

Refer back to these normal images and the color coding of the anatomical structures when examining the US images for our patient L.S.

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Companion Patient 1: Orientation of Sagittal View on US Companion Patient 1, Normal



In these ultrasound images:

•The transducer was placed on anterior abdominal wall

•For sagittal views, patient’s legs are always to the right

Anterior

Posterior

Caudal


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Companion Patient 1: Location of Cross-Sectional ViewsCompanion Patient 1, Normal



MU

Anterior

Posterior

Caudal

CX

For these sagittal views, the transducer was placed in the following locations:

•Mid-uterus (MU)

•Cervix (CX)


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Companion Patient 1: Normal Anterior Abdominal WallCompanion Patient 1, Normal



Anterior

Posterior

Caudal


Anterior abdominal wall

Hyperechoic structure with striations

Most anterior

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Companion Patient 1: Normal UterusCompanion Patient 1, Normal



Anterior

Posterior

Caudal


Uterus, Myometrium

Hypoechoic structure under anterior abdominal wall

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Companion Patient 1: Normal PlacentaCompanion Patient 1, Normal



Anterior

Posterior

Caudal

PlacentaHomogeneous hypoechoic structure lining uterine wall

Usually located on anterior uterine wall


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*

* *

* *

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Companion Patient 1: Normal Amniotic FluidCompanion Patient 1, Normal



Anterior

Posterior

Caudal

Amniotic FluidAnechoic area in uterine cavity, surrounding fetus


**

* * *

*

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Companion Patient 1: Normal FetusCompanion Patient 1, Normal



Anterior

Posterior

Caudal

FetusIn uterine cavity, surrounded by anechoic amniotic fluid


* **

**

*

*

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Companion Patient 1: Normal CervixCompanion Patient 1, Normal



Anterior

Posterior

Caudal

CervixAnechoic

Linear

Posterior to bladder


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Companion Patient 1: Normal BladderCompanion Patient 1, Normal



Anterior

Posterior

Caudal

BladderAnechoic

Inferior to uterus


*

**

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Companion Patient 1: Normal Pelvic Anatomy SummaryCompanion Patient 1, Normal



Anterior

Posterior

Caudal

Anterior abdominal wall

Uterus, Myometrium

Placenta

Amniotic fluid

Fetus

Cervix

Bladderhttp://www.rush.edu/rumc/page-1098987343902.html

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**

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* * *

** * *

*

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Companion Patient 1: Obstetrical US Evaluation Companion Patient 1, Normal



* * *

* * *

Now that we have reviewed the normal female pelvic anatomy on US, let’s make some impressions:

Placenta Location:•On anterior uterine wall•Placenta does not extend to internal cervical os

•No evidence of previa

Placental texture:•Homogeneous•Distinct interface between uterus and placenta

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Approach to Ultrasound Evaluation: Fetus

Number of gestations• Single or multiple

Position• Cephalic or breech

Fetal Heart Rate• Normal is >100 bpm

Dating by fetal measurements• Head size

– Biparietal diameter (BPD)– Head circumference (HC)

• Abdominal circumference (AC)• Femur length (FL)

Amniotic fluid volume

Umbilical cord structure

Morphologic AbnormalitiesTransabdominal US, Sagittal View, BreechPACS, BIDMC

Our Patient L.S.

Transabdominal US, Axial View, Heart

Transabdominal US, Sagittal View, Fetal HR Transabdominal US, Sagittal View, BPD, HC

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Agenda: Film Interpretation

• Patient L.S. • Menu of Tests• Anatomy of Female Pelvis and Placenta• Abnormal Placental Implantation• Film interpretation

– Patient MV• Differential Diagnosis• Conclusions

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Our Patient L.S.: Placenta Previa on US

Transabdominal US, Sagittal View, Cervix

Transabdominal US, Sagittal View, PlacentaPACS, BIDMC

* **

Film Findings:1. Placenta located on

anterior uterine wall

2. Placenta extends overinternal cervical os

Impression 1:Placenta previa

Our Patient L.S.

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Our Patient L.S.: Placenta Previa on US, Labeled



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Our Patient L.S.

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*

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Our Patient L.S.: Placenta Previa on US, Labeled



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Our Patient L.S.

* *

*

* **

* *

http://myhealth.ucsd.edu/library/healthguide/en-us/support/topic.asp?hwid=aa154120

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Our Patient L.S.: Increased Vascularity in Myometrium with Linear-Array US

Linear-array transducer• Fine image resolution• Sound waves cannot penetrate as deep

Transabdominal US, Low Uterus, Sagittal View Transabdominal US Doppler, Low Uterus, Sagittal ViewPACS, BIDMC

Our Patient L.S.

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Our Patient L.S.: Increased Vascularity in Myometrium on Linear-Array US, Findings

Film Findings:1. Loss of the myometrial and placental interface anteriorly2. Increased vascularity extending into myometrium


Our Patient L.S.

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Our Patient L.S.: Increased Vascularity in Myometrium on Linear-Array US, Labeled

Film Findings:1. Loss of the myometrial and placental interface anteriorly2. Increased vascularity extending into myometrium


Our Patient L.S.

* * *

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Our Patient L.S.: Increased Vascularity in Bladder Wall on US, Labeled

Film Findings:1. Hypoechoic tubular structure representing placental vein extending

into myometrium

2. Increased vascularity in bladder wall

Our Patient L.S.

Transvaginal US, Bladder, Sagittal View Transvaginal US Doppler, Bladder, Sagittal ViewPACS, BIDMC

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Our Patient L.S.: Increased Vascularity in in Bladder Wall on US, Labeled

Film Findings:1. Hypoechoic tubular structure representing placental vein extending

into myometrium

2. Increased vascularity in bladder wall

Our Patient L.S.


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*

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Our Patient L.S.: Increased Vascularity in Bladder Wall on US, Labeled

Impression 2: Differential DiagnosisPlacenta accretaPlacenta incretaPlacenta percreta

Our Patient L.S.


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*

http://embryology.med.unsw.edu.au/Notes/placenta2.htm

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Our Patient L.S.: Fetal Examination on US

Number of gestations•Single

Position•Breech

Fetal Heart Rate•Normal 154 bpm

Dating by fetal measurements•BPD=3.45 cm•HC=13.63 cm•Age by US=17 weeks

Amniotic fluid volume•Normal

Umbilical cord structure•Normal

Morphologic Abnormalities•None

Our Patient L.S.

Transabdominal US, Mid Uterus, Sagittal View, Breech

Transabdominal US, Fetal Heart Rate

Transabdominal US, Upper Uterus, Transverse ViewPACS, BIDMC

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Our Patient L.S.: Follow-Up

Impression:1. Placenta previa2. Placenta accreta, possible placenta percreta3. Normal survey of fetus

Recommendations:• Follow-up with US and MRI closer to delivery

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Our Patient L.S.: Loss of Placental Myometrial Interface on F/U US

Film Findings:1. Loss of normal placental myometrial interface anteriorly2. Increased vascularity extending to bladder wallImpression:• Suggestive of Placenta Percreta

Transabdominal US, Low uterus, Transverse View Transabdominal US Color Doppler, Low uterus, Transverse View

PACS, BIDMC

Our Patient L.S.

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Our Patient L.S.: Loss of Placental Myometrial Interface on F/U US, Labeled

Film Findings:1. Loss of normal placental myometrial interface anteriorly2. Increased vascularity extending to bladder wallImpression:• Suggestive of Placenta Percreta

Transabdominal US, Low uterus, Transverse View Transabdominal US Color Doppler, Low uterus, Transverse View

PACS, BIDMC

Our Patient L.S.

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* ** *

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Our Patient L.S.: Increased Vascularity in Bladder Wall on F/U US

Film Findings:1. Irregular superior bladder wall2. Increased vascularity in bladder wallImpression:• Suggestive of Placenta Percreta

Transvaginal US, Low Uterus, Transverse View Transvaginal US Color Doppler, Low Uterus, Transverse View

Our Patient L.S.

PACS, BIDMC

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Our Patient L.S.: Increased Vascularity in Bladder Wall on F/U US, Labeled

Film Findings:1. Irregular superior bladder wall2. Increased vascularity in bladder wallImpression:• Suggestive of Placenta Percreta

Transvaginal US, Low Uterus, Transverse View Transvaginal US Color Doppler, Low Uterus, Transverse View

Our Patient L.S.

PACS, BIDMC

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Our Patient L.S.: F/U Fetal US Examination

Film Findings:• Fetal Heart Rate

– Normal 158 bpm• Normal growth

– BPD=7.01 cm– HC=9.08 cm– Age by US=28 weeks, 1 day

PACS, BIDMC

Transabdominal US, Axial View, Fetal Heart Rate Transabdominal US, Axial View, BPD, HC

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Approach to Obstetrical MRI Evaluation

• Check relevant structures:– Anterior abdominal wall– Uterus

• Myometrium– Placenta– Amniotic Fluid– Fetus– Cervix– Ovaries– Bladder

• Placenta Location:– Anterior vs. Posterior uterine wall– Cervical status

• Placenta previa?

• Placenta texture:– Homogeneous vs. heterogeneous– Distinct myometrial surface?


Abdominal T2 Weighted MRI, Sagittal ViewPACS, BIDMC

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Approach to MRI Evaluation: Fetus

Number of gestations• Single or multiple

Position• Cephalic or breech

Morphologic Abnormalities• Better soft tissue contrast

• Head, face, heart, outflow tracts, stomach, kidneys, cord insertion site, bladder, spine, extremities

• Congenital abnormalities


Abdominal T2 Weighted MRI, Coronal ViewPACS, BIDMC

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Our Patient L.S.: Marginal Placenta on MRI

Film Findings:1. Placenta location

• Low anterior position• Extends more posterior on left

2. Placenta extension• Margin of the internal cervical os• But does NOT cover os

Impression 1:Marginal Placenta

Our Patient L.S.

Abdominal T2 Weighted MRI, Coronal View

PACS, BIDMC

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Our Patient L.S.: Marginal Placenta on MRI, Labeled

Film Findings:1. Placenta location

• Low anterior position• Extends more posterior on left

2. Placenta extension• Margin of the internal cervical os• But does NOT cover os

Impression 1:Marginal Placenta

Our Patient L.S.


PACS, BIDMC

***

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Companion Patient 2: Normal Interface between Myometrium and Placenta on MRI


Abdominal T2 Weighted MRI, Sagittal View

PACS, BIDMC

Before examining the placenta on MRI in our patient L.S., let’s first examine the placenta in a normal pregnancy.

When examining a normal pregnancy on MRI,there is a distinct interface between the placenta and uterus.

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Our Patient L.S.: Loss of Interface between Myometrium and Placenta on MRI

Film Findings:1. Anterior loss of normal myometrium overlying the placenta2. Prominent intramural vessels in anterior wall of uterus

Companion Patient 2, NormalOur Patient L.S.

Abdominal T2 Weighted MRI, Sagittal View Abdominal T2 Weighted MRI, Sagittal View

PACS, BIDMC

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Our Patient L.S.: Loss of Interface between Myometrium and Placenta on MRI, Labeled

Film Findings:1. Anterior loss of normal myometrium overlying the placenta2. Prominent intramural vessels in anterior wall of uterus



PACS, BIDMC

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Our Patient L.S.: Placenta Extending to Roof of Bladder on MRI

Film Findings:1. Loss of normal myometrial signal at lower uterine segment2. Placental tissue extends to roof of the bladder3. Vessels contiguous with placenta extend into bladder roof


Our Patient L.S. Our Patient L.S.

PACS, BIDMC

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Our Patient L.S.: Placenta Extending to Roof of Bladder on MRI, Labeled

Film Findings:1. Loss of normal myometrial signal at lower uterine segment2. Placental tissue extends to roof of the bladder3. Vessels contiguous with placenta extend into bladder roof



PACS, BIDMC

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Our Patient L.S.: Placenta Extending to Roof of Bladder on MRI, Labeled

Impression 2:Placenta percreta involving inferior aspect of lower uterine

segment, tissue extends into roof of bladder



PACS, BIDMC

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Companion Patient 2: Normal Fetal Examination on MRI



PACS, BIDMC

Before examining the fetusin our Patient L.S. on MRI, let’s first examinethe fetus in a normal pregnancy.

In a normal pregnancy, the fetus is usually in a cephalic position, with the head pointing towards the cervix.

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Our Patient L.S.: Fetal Examination on MRI

Film Findings:1. No gross fetal abnormality2. Footling breech

Abdominal T2 Weighted MRI, Coronal ViewAbdominal T2 Weighted MRI, Coronal View


PACS, BIDMC

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Our Patient L.S.: Fetal Examination on MRI, Labeled

Film Findings:1. No gross fetal abnormality2. Footling breech

Abdominal T2 Weighted MRI, Coronal ViewAbdominal T2 Weighted MRI, Coronal View


PACS, BIDMC

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Use of Imaging in Abnormal Placental Implantation

Impression:1. Marginal Placenta2. Placenta Percreta

Recommendations:• Prevention of life-threatening delivery• Prepare Urology, Gyn/Onc, Interventional Radiologist Consult• Prepare for Cesarean Hysterectomy, Partial Cystectomy• Prepare fluids, RBC, FFP availability at delivery

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Our Patient L.S.: Cystogram after Partial CystectomyOur Patient L.S.

KUB Cystogram with Contrast: Scout, Filling, Frontal View, Right Oblique View. PACS, BIDMC

At 29 weeks GA, presented with progressive bleeding and contractionsProceeded with deliveryCesarean delivery, supracervical hysterectomy, partial cystectomy

Estimated blood loss: 4500ccReceived 5 liters IV fluids, 6 units of packed RBC, 2 units of FFP

Cystogram after partial cystectomyIrregular contour consistent with partial cystectomyNo evidence of bladder leak

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Our Patient L.S.: Epilogue

• Baby girl was born at 31.1 weeks– Liveborn female weighing 1550 grams– APGARs of 2 and 8– Admitted to NICU

• Last progress report indicates: – The baby was still in NICU at 37 weeks– She would go home at 39 weeks– She has been successfully breastfeeding

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Agenda


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Conclusions

• US and MRI are preferred imaging modalities during pregnancy to avoid fetal exposure to ionizing radiation

• Abnormal placental invasion can lead to life-threatening hemorrhage

• No imaging modality diagnoses abnormal placental invasion with absolute accuracy

• US and MRI can help make pre-operative plans to prevent life-threatening emergencies

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Acknowledgments

• Gillian Lieberman, MD• Tejas Mehta, MD, MPH• Kei Yamada, MD• Shayna Roberts-Klein, MD• David Li, MD, PhD• Aaron Hochberg, MD• Maria Levantakis

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References

1. Brent, RL. Saving lives and changing family histories: appropriate counseling of pregnant women and men and women of reproductive age, concerning the risk of diagnostic radiation exposures during and before pregnancy. Am J Obstet Gynecol 2009; 200:4.

2. Lieberman, Gillian. Lieberman’s Primary Care Radiology. Menu of Radiologic Tests: Ultrasound. http://eradiology.bidmc.harvard.edu/primarycare/radiologicmenu.html. Accessed on June 16, 2009.

3. Lieberman, Gillian. Lieberman’s Primary Care Radiology. Menu of Radiologic Tests, Magnetic Resonance Imaging. http://eradiology.bidmc.harvard.edu/primarycare/radiologicmenu.html. Accessed on June 16, 2009.

4. Shellock, FG, Crues, JV. MR procedures: biologic effects, safety, and patient care. Radiology 2004; 232:635.

5. Magann, EF, Doherty, DA, Turner, K, et al. Second trimester placental location as a predictor of an adverse pregnancy outcome. J Perinatol 2007; 27:9.

6. Faiz, AS, Ananth, CV. Etiology and risk factors for placenta previa: an overview and meta- analysis of observational studies. J Matern Fetal Neonatal Med 2003; 13:175.

7. Cotton, DB, Read, JA, Paul, RH, Quilligan, EJ. The conservative aggressive management of placenta previa. Am J Obstet Gynecol 1980; 137:687.

8. Miller, DA, Chollet, JA, Goodwin, TM. Clinical risk factors for placenta previa-placenta accreta. Am J Obstet Gynecol 1997; 177:210.

9. Warshak, CR, Eskander, R, Hull, AD, et al. Accuracy of ultrasonography and magnetic resonance imaging in the diagnosis of placenta accreta. Obstet Gynecol 2006; 108:573.

Documents

Imaging of Abnormal Placental Implantation: A Patient with Placenta