Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
7/29/2019
1
Nathan S. Fox, MD
Ultrasound of the Placenta:
What OBGYN Residents Want to Know
Gottesfeld Hohler Memorial FoundationResident Ultrasound Program
August 4, 2019
Financial Disclosures
� None
Objectives
� To learn how to assess placental location using transabdominal and transvaginalultrasound
� A few other things
Why Image the Placenta?
� Location, location, location !!
� Other
� (cord insertion)
� (function)
� (size)
� (morbidly adherent placenta)
� (hematomas)
� (tumors)
TransabdominalAbdominal Ultrasound Pearls
� Start sagittal, midline
� Make sure right of screen points towards her feet
� Check left and right
� Then turn 90 degrees to check transverse
� Make sure right of screen is to her left (as if you are looking at her from her feet)
� Then check superior and inferior
� REMEMBER THE UTERUS IS 3-D !!
7/29/2019
2
HEAD
ANTERIOR
POSTERIOR
FEET
SAGGITAL
RIGHT
ANTERIOR
POSTERIOR
LEFT
TRANSVERSE
SAGGITAL TRANSVERSE SAGGITAL TRANSVERSE
SAGGITAL TRANSVERSE SAGGITAL TRANSVERSE
7/29/2019
3
Transvaginal Vaginal Ultrasound Pearls
� Probe neutral position is sagittal
� Start midline
� Then check left and right
� Can assess placental edge in relation to cervix anteriorly / posteriorly
� Not as easy to do laterally (need 3D)
7/29/2019
4
TV SAGGITAL TA TRANSVERSE
TV SAGGITAL TA TRANSVERSE TV SAGGITAL TA TRANSVERSE
7/29/2019
5
Previas
� Previa – covers internal cervical os
� Low lying - within 2cm of the internal os
� Formerly known as “Marginal” Previa
� The more important detail is the actual distance from the internal os (or overlapping the os
Previa - Diagnosis
� Must be with transvaginal imaging
� Transabdominal has a 25% false positive rate
� Overdistended bladder
� LUS contraction
� Can gently lift head out of pelvis if needed.
Previas - Resolution
� The placenta only moves in one direction: UP!
� The earlier the diagnosis, the more likely it is to resolve
� The less it overlaps the cervix, the more likely it is to resolve
Morbidly Adherent Placenta Placenta Accreta
Placenta Accreta Spectrum
� Placental lacunae (swiss cheese)
� Disruption of bladder line
� Loss of clear zone (behind placenta)
� Myometrial thinning
� Abnormal vascularity
� Placental bulge
� Exophytic mass
Lacunae
Myometrial thinning
Focal mass
Increased vascularity
Normal
Accreta
� Ultrasound is not diagnostic
� (Neither is MRI)
� Ultimately, it is about the SUSPICION of accreta and preparing for it
7/29/2019
6
CS #1 CS #2 CS #3 CS #4 CS #5 CS #6+
Overall 0.2% 0.3% 0.6% 2.1% 2.3% 6.7%
No Previa 0.03% 0.2% 0.1% 0.8% 0.8% 4.7%
Yes Previa 3.3% 11% 40% 61% 67% 67%
Likelihood of Accreta
Silver et al, OBG 2008
Velamentous Cord Insertion
Normal Velamentous Velamentous Cord Insertion
� Risk of IUGR
� Due to velamentous cord itself?
� Due to abnormal placenta in general?
� Due to overlapping risk factors?
� Risk of vessel compression in labor
� Risk of vasa previa
Vasa Previa
Vasa Previa
� Risk Factors:
� Resolved previa
� Velamentous cord
� Succenturiate lobe
� (IVF, Twins)
� Diagnosis
� Color!!!
7/29/2019
7