Placental US

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Placental US

• Andrea Jelks, MD
• 12/8/06

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Case of the Day

• 18 yo G2 P0101 at 18 weeks by 1st trimester sono
  presented for an anatomy ultrasound
• Size dates
• Fetus anatomically normal male
• Posterior placenta

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Outline

• Various placental ultrasound findings
• Changes with gestational age
• Echolucencies
• Others..

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This image shows

1. A posterior uterine contraction which gives a
   false impression of placenta previa
2. An anterior marginal placenta previa
3. A central placenta previa
4. A succenturiate lobe on the posterior uterine
   wall

(A.) The internal os is poorly seen, but
transvaginal US would almost certainly show that
this placenta does not cover the cervix The thick
area on the posterior uterine wall is a localized
uterine contraction. The impression that there
may be a previa is caused by the posterior
uterine contraction.
Source www.obgyn.ufl.edu
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• Another picture of uterine contraction
• Placenta would be of normal thickness if seen
  after the UC abated
• Importance of reimaging after a few minutes have
  elapsed

Source Google images
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These images show

• This is a 21-week-fetus pregnancy c/b Rh
  sensitization.
• Hydrops with extensive edema, ascites,
  hydrothorax and abnormal thickness of placenta
• Placental thickness judged subjectively
• At midposition or cord insertion 2-4 cm normal
• Source www.thefetus.net

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Normal Placental appearance

• 8-20 weeks uniform echotexture, 2-3 cm thickness
• gt20 weeks
• Measures 4-5 cm thick

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• Decidua basalis
• Measures 9-10 mm thickness
• Contains maternal blood vessels
• Easy to confuse with retroplacental hemorrhage,
  especially if posterior placenta
• Fluid side chorionic plate (chorioamniotic
  membrane) bright specular reflector

Source www.mysono.com
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• Grade 0
• Late 1st trimester-early 2nd trimester
• Uniform moderate echogenicity
• Smooth chorionic plate without indentations

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• Grade 1
• Mid 2nd trimester early 3rd trimester (18-29
  wks)
• Subtle indentations of chorionic plate
• Small, diffuse calcifications (hyperechoic)
  randomly dispersed in placenta

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• Grade 2
• Late 3rd trimester (30 wks to delivery)
• Larger indentations along chorionic plate
• Larger calcifications in a dot-dash
  configuration along the basilar plate

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• Grade 3
• 39 wks post dates
• Complete indentations of chorionic plate through
  to the basilar plate creating cotyledons
  (portions of placenta separated by the
  indentations)
• More irregular calcifications with significant
  shadowing
• May signify placental dysmaturity which can cause
  IUGR
• Associated with smoking, chronic hypertension,
  SLE, diabetes
• Found in 20 of pregnancies at 40 weeks

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Significance of Placental Grade

• N 1802 low-risk patients at 36 weeks
• Grade III placenta found in 3.8 (68/1802).
• Associated with young maternal age and cigarette
  smoking, p lt 0.01.
• PIH Study group 7.4 (5/68) and 1.56 of
  controls (27/1734), p lt 0.01.
• SGA 17.6 (12/68) vs. 5.6 (97/1734), p lt 0.01.
• Conclusion Ultrasound detection of a grade III
  placenta at 36 weeks' gestation in a low-risk
  population helps to identify the "at-risk"
  pregnancy

McKenna D, Ultrasonic evidence of placental
calcification at 36 weeks' gestation maternal
and fetal outcomes. Acta Obstet Gynecol Scand.
2005 Jan84(1)7-10.
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This placenta would most likely be associated
with

• A) Fetal hydrops
• B) Trisomy 18
• C) Lupus anticoagulant
• D) Maternal smoking

(A.) This is a very thick, echogenic placenta in
a fetus with hydrops. - Fetuses with Trisomy 18
have small placentas. - Pregnancies with lupus
anticoagulant would have a small or normal
placenta. - Maternal smoking results in an
echogenic grade III placenta, but not diffuse
thickening and echogenicity as seen here
Source www.obgyn.ufl.edu
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All of the following statements are true except

1. In the early second trimester approximately 5 of
   placentas appear to cover the internal os.
2. 80 of cases where previa is diagnosed in the
   early second trimester do not have placenta
   previa at term.
3. Since trophoblasts have the capacity to detach
   and reattach, many placentas migrate away from
   the internal os.
4. A full bladder can give a false positive
   diagnosis of placenta previa.

• (C.) Trophoblasts do not have the capacity to
  detach and reattach. So called "migration"
  results from other factors.

Source www.obgyn.ufl.edu
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This image demonstrates

• Placenta previa
• A venous lake
• An submembranous blood clot from an abruption
• Amniotic band syndrome

(C.) The appearance of this hypoechoic area
between the membranes and uterine wall is very
suggestive of a blood clot. The membranes are
separated from the uterine wall. Amniotic band
syndrome should not be diagnosed, however, unless
there is evidence of attachments of the membrane
to the fetus associated with fetal anomalies
Source www.obgyn.ufl.edu
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Amniotic Bands

• Multiple case reports of limb reduction/
  deformities, facial clefts, and/or IUFD due to
  umbilical cord entanglement
• Case controlled study (n 25 cases vs. 50
  controls) showed
• Unrestricted fetal movement on all US
• No fetal abnormalities at birth
• Increased incidence of PTD

Wehbeh H et al. The relationship between the
ultrasonographic diagnosis of innocent amniotic
band development and pregnancy outcomes. Obstet
Gynecol. 1993 Apr81(4)565-8.
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Which of the following is shown in this image?

• A placental abruption
• A grade III placenta
• Venous lakes
• Placental infarcts

(D.) These hypoechoic areas surrounded by
echogenic placenta are characteristic of
infarcts. Infarcts frequently show an echogenic
rim and absence of swirling blood on Doppler
flow.
Source www.obgyn.ufl.edu
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This area in the placenta represents

• A) A large venous lakeB) An abruptionC) An
  infarctD) A chorioangioma

This hypoechoic area on the surface of the
placenta is characteristic of a venous lake.
Blood flow can usually be seen with real time
imaging with the gain set low. Represent pooling
of maternal blood. An infarct would be a
hypoechoic area within the placenta. An abruption
would show a hypoechoic area below rather than on
the surface of the placenta.
Source www.obgyn.ufl.edu
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Placental Chorioangioma

• A rare placental tumor composed of vascular
  spaces.
• Usually seen as circumscribed solid mass or
  complex mass that protrudes from the fetal
  surface of the placenta.
• It has been postulated that these tumors begin
  around the 16th-17th day of development when a
  newly formed angioblastic mass becomes isolated
  from the rest of the proliferating trophoblast
• May cause
• Cord compression
• AV fistula ? high output cardiac failure in the
  fetus ? hydrops
• Turbulence ? microangiopathic anemia ? hydrops
• Polyhydramnios is present in one third of the
  cases. Assoc with PTD, IUFD and IUGR

Source www.thefetus.net
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These images show
Source Sharma et al, 2003
Source www.emedicine.com
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Clinical Significance of Subchorionic
Collections

• 122 cases of SCC in 10 years at 1 institution
  detected between 5-22 weeks, (no controls)
• 63 c/b bleeding
• 88 of those with PTD had bleeding
• 59 of those del at term had bleeding
• Outcomes
• 5 SAB at 17-24 weeks
• 18 PTD (median 35 wks)
• 77 term delivery
• Outcome not assoc. with maximal size, GA at
  detection

Sharma, et al. Prognostic factors associated with
antenatal subchorionic echolucencies. Am J Obstet
Gynecol 2003189 994-6
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Sharma, et al. Prognostic factors associated with
antenatal subchorionic echolucencies. Am J Obstet
Gynecol 2003189 994-6
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Significance of 1st trim SCC

• Matched case control study 238 cases and 648
  controls w/o VB
• Cases comprised 1.3 of total scanned population

• SAB OR 2.8
• Stillbirth OR 4.5
• Abruption OR 11.2
• PTD No difference

Ball, RH, et al. The clinical significance of
ultrasonographically detected subchorionic
hemorrhages (Am J Obstet Gynecol
1996174996-1002.
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Clinical Significance of 1st trim SCC

• Prospective study of those with 1st trimester
  hematoma (n230) vs. controls (n6488)
• Outcomes similar subchorionic vs. retroplacental
  location
• 18.7 had loss at less than 24 weeks

• Relative Risk (all signif.)
• Preeclampsia 4.0
• Abruption 5.6
• Retained Plac 3.2
• IUGR 2.4
• Fetal distress 2.6
• Meconium 2.2
• NICU admit 5.6
• PTD NS

Nagy et al. Clinical significance of subchorionic
and retroplacental hematomas detected in the
first trimester of pregnancy. Obstet Gynecol.
2003 Jul102(1)94-100
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This image shows..

• A marginal abruption
• A large venous lake
• A placental hemangioma.
• A retroplacental abruption

(D.) The hypoechoic area represents a blood clot
behind the placenta. A placental hemangioma
would be within the placenta, not behind the
placenta as this mass is. This hypoechoic area
underlies the placenta.
Source www.obgyn.ufl.edu
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• Placental abruption. This retroplacental
  hemorrhage is visualized in a patient during the
  third trimester of her pregnancy.
• Source www.sunyabem.org/ultrasound.shtml

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US diagnosis of Placental Abruption

• Nyberg et al.. Variety of ultrasonographic
  appearances
• Acute phase hyperechoic to isoechoic
• 1 week hypoechoic
• 2 weeks sonolucent
• Glantz, et al retrospective cohort study
• Sensitivity 24, specificity 96, and positive
  88, and negative predictive values 53 of
  ultrasonography for placental abruption.

Oyelese Y, Ananth CV. Placental abruption. Obstet
Gynecol. 2006 Oct108(4)1005-16.
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This image shows

1. Placental abruption
2. Venous lakes
3. Partial mole
4. A degenerating fibroid

(C.) The "Swiss-cheese" appearance of this
placenta, with the presence of a fetus (seen to
the right of the image) are characteristic of
partial mole. A fibroid would have a more
rounded appearance. The cystic spaces are within
the placenta. These cystic spaces are scattered
throughout the placenta. The irregular cystic
areas are within the placenta itself, and don't
have the appearance of a retroplacental blood
clot
Source www.obgyn.ufl.edu
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These images show

• Color Doppler scan in a 21-year-old woman in 33rd
  week of pregnancy (same patient as in Image 12)
  demonstrates prominent retroplacental vessels
  mimicking a retroplacental hematoma.

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These images show

• Sagittal endovaginal scan of the uterus in a
  29-year-old woman in 9th week of gestation
  demonstrates nonfusion and separation of chorion
  and amnion.
• Source www.emedicine.com/radio/topic662.htm

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This image shows

• 6w3d, bleeding, dichorionic twins with one dead
  twin, subchorionic hemorrhage of both chorions,
  the living sac with a larger hemorrhage than the
  dead sac.
• Sourcewww.obgyn.net/.../us/cotm/9904/cotm_9904

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Back to the case.
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A few more details

• Per patient.Previous delivery at 28 weeks (baby
  weighed 1.5 lbs) after pt presented with sudden
  vaginal bleeding and contractions
• No bleeding yet in this pregnancy