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2012-12-04 13:17:29

Placenta GTN NT Artifacts
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  1. flat, circular, vascular organ
    1.5 - 4.0 cm
    grows 1mm/week
    Placental shape and size
  2. T or F: placental calcifications are present in over 50% of placentas after 33 weeks
  3. increased placental calcifications are present with?
    • IUGR
    • Hypertension
    • Smoking
  4. Grading Placenta
    • Grade 0: homogeneous, straight chorionic plate
    • Grade I: scattered echogenic areas, subtle undulations
    • Grade II: linear echogenic, indentations
    • Grade III: Cystic areas, shadowing calcifications (after 38 wks), indentations to basal layer

  5. Placenta >4cm thick
    Placentomegaly (Thick Placenta)
  6. Etiologies of Placentomegaly
    • maternal Diabetes
    • maternal Anemia
    • hydrops
    • placental hemorrhage
    • intrauterine infection
    • partial Mole
    • chromosomal Abnormalities
  7. --> secondary to areas of vascular deficiencies or infarction
    **thickness depends on gestational age
    -may cause IUGR
    - <1.5cm
    • Thin Placenta "Placental Insufficiency"
    • Etiologies:
    • *Vascular infarction
    • *Pre-eclampsia (--> toxemia of late pregnancy (HTN, proteinuria, edema))
  8. - subchorionic fibrin deposition (maternal lakes)
    - perivillious fibrin deposition (placental lakes)
    - intervillous thrombosis
    - septal cysts
    - infarcts
    - tumors
    - hydidiform changes
    • Intraplacental Lesions/Lakes
    • *no Clinical significance
  9. --> results from pooling/stasis of blood; anechoic areas adjacent to chorionic place (rouleaux flow)
    Subchorionic Fibrin Deposits (Maternal Lakes)
  10. --> caused by turbulence and stasis of maternal blood in intervillous space with secondary fibrin deposition; intraplacental hypoechoic lesions; echogenic foci)
    • Perivillous Fibrin Deposits (Placental Lakes)
    • * occurs to some degree in every placenta
  11. --> caused by fetal bleeding into intervillous space (contain fibrin); hypoechoic lesions
    • Intervillous Thrombosis
    • ** significant if associated with Rh+ isoimmunization cases
  12. --> thought to result from obstructed venous drainage; hypoechoic intraplacental lesions; located at top of septa
    Septal Cysts
  13. --> caused by obstruction of maternal blood supply leading to necrosis; microscopic triangular shaped lesions on maternal side of placenta
    • Placental Infarcts
    • ** if involves >10% "extensive" and associated with IUGR, fetal hypoxia, fetal demise
    • **difficult to visualize
  14. DDx: for placental previa
    • - most placenta look low in the 1st and early 2nd trimester
    • - overdistended bladder (>3.5-4.0 cm cx)
    • - focal uterine contraction (wall > 1.5cm)
  15. Placenta Previa --> condition present whenever placenta can be shown to lie adjacent to internal cervical os

    • Low-Lying: <2cm from os, but not overlying it
    • Marginal/Partial: touching internal os
    • Complete/Total: completely overlies internal os
  16. R/O placental previa
    • overdistended bladder (>4.0cm cx)
    • focal uterine contraction (>1.5cm myometrial wall)
    • <2.0cm distance between fetal head and sacral promontory
    • move patient position
  17. --> separate masses of chorionic villi connected to main body of placenta by vessels within membrane

    complications: retained placenta post delivery, previa, bleeding
    Succenturiate (accessory lobe)

  18. --> membranes of chorion laeve do not insert at edge of placenta, but rather at some inward distance from the margin (towards umbilical cord) (chorionic membrane extends over placenta)
    **Partial or Complete

    may cause antipartum hemorrhage
    Extrachorial Placenta (circummarginate/circumvallate)

  19.  --> flat ring at attachment to chorionic place
    • Circummarginate
    • - no clinical significance
  20. --> fold "plication" in the membrane at site of attachment
    • Circumvallate
    • **Complete forms have been associated with increased incident of antepartum bleeding, marginal hemorrhage, threatened abortion, premature labor
    • ** look like synechiae (but on placental surface)
  21. --> area of scarring in endometrium, does NOT stretch like rest of uterus
    --> appearance of membrane that just ends
    --> fetal parts on both sides of membrane (but fetus not attached to it)
    Synechiae (Amniotic Sheet)
  22. --> entire surface of sac is covered with villa
    --> due to failur of regression in early stages
    • Placenta Membranacea (rare)
    • -- associated with antepartum and postpartum hemorrhage
  23. Variations in Insertion
  24. --> placenta in which the umbilical cord is attached at the border (<2cm to edge of center of placenta)
    --> insignificant

    Battledore "Marginal Insertion"

  25. --> cord inserts into chorionic membrane and than vessels track to placenta
    • Velamentous Insertion
  26. --> fetal vessels cross internal os (may rupture during delivery)
    ** colour doppler

    Vasa Previa
  27. --> premature separation of normally implanted placenta (marginal or retroplacental)
    • Placental Abruption
    • ** can occur as early as first trimester
  28. 3 formations of placental abruption
    • External bleeding w/o intrauterine hematoma
    • Retroplacental hematoma w/o bleeding
    • Subchorionic hematoma with/without external bleeding
  29. Sonographic appearance of Placental Abruption
    sonolucent or complex mass behind pplacenta/beneath chorionic membrane (hematoma)

    DDx: placental lakes
  30. Causes of Placental Abruption
    • abdominal trauma
    • short umbilical cord
    • sudden decompression of uterus
    • pregnancy induced HTN (PIH)
    • vascular disease
    • fibroids
    • smoking
    • drugs (cocaine)
  31. Symptoms of Placental Abruption
    • pre-term labor
    • vaginal bleeding
    • abdomen pain
    • fetal distress
    • uterine irritability
    • rock hard uterus (continuous contractions)
  32. --> contain elements of more than one of the three germ cell layers
    • Teratoma (Primary Tumor)
    • *rare
  33. --> vascular tumor surrounded by capsule, well defined complex mass within placental substance
    --> may cause polyhydramnios, hydops,heart failure,  and cardiomegaly
    --> usually single
    Chorioangioma (Primary Tumor)
  34. tumors originate from:
    --> Maternal: maternal melanoma, breast Ca, lung Ca
    --> Fetus: neuroblastoma and leukemia
    Metastatic Tumors
  35. --> complete or partial absence of decidua basalis underlying the placenta (placental villi adhering to myometrium but NOT invading it)

    Placenta Accreta
  36. --> villi invades myometrium
    Placenta Increta
  37. --> villi penetrate completely through myometrium to the serosal surface
    Placenta Percreta
  38. --> when placenta does not attach properly to basalis and invades beyond its boundaries (3 forms)
    --> 1/500
    --> increased risk with prev C-sections
    --> increased risk for post partum bleeding (difficult to remove) **hysterectomy
    Placenta Accreta, Increta, or Percreta
  39. Sonographic Presentation of Placental Accreta, Increta and Percreta
    • difficult to diagnose (only anterior placentas easier)
    • absent/severe thinning of hypoechoic myometrium
    • extension of placental echogenicity beyond uterine serosa (bladder)
    • colour doppler
  40. this function is to gain access to maternal circulation?
    • Trophoblast Function
    • Can also:
    • infiltrate maternal tissues
    • invade vessels
    • can be transported to lungs
  41. --> refers to the cystic degeneration of chorionic villi in molar pregnancy; encompasses complete and partial molar pregnancies
    Hydatidform Mole
  42. --> abnormal proliferation of pregnancy related trophoblast with progressive malignant potential; includes complete/partial molar pregnancies, invasive molar and choriocarcinoma
    • Molar Pregnancy
    • 1/1000
  43. Risk factors of GTN pregnancies
    • increased maternal age
    • prior molar pregnany
    • asian ancestry
  44. Complete Molar Pregnancy
    46xx/46yy, or 46xy
    • **most common form of GTN
    • 80% benign
    • no fetus; no normal placenta (hydropic chorionic villi with excessive trophoblastic proliferation
  45. 80% of complete molar pregnancies have this Karyotype?
    • 46xx/46xy
    • paternal in origin
    • absent ovum fertilized by normal haploid sperm (which duplicate to diploid)
  46. 20% of complete molar pregnancies have this Karyotype?
    • 46xy
    • paternal origin
    • absent ovum fertilized by 2 haploid sperm
  47. Signs and Symptoms of Complete Molar Pregnancy
    • LGA
    • vaginal bleeding (90%)
    • passage of hydropis villi (80%)
    • ++hCG serum (>100000 miu/ml)
    • hyperemesis gravidarum
    • toxemia/preeclampsia
    • respiratory failure
  48. Sonographic Presentation of Complete Molar Pregnancy
    • 1st Trimester: incomplete abortion
    • 2nd Trimester: echogenic tissue that expands the endometrial canal with multiple cystic spaces (up to 2cm) "grape like appearance"
    • Theca lutein cysts bilaterally (25%)
  49. Partial Molar Pregnancy "Diandric Triploidy"
    • fertilization of normal ovum by 2 haploid sperm
    • 95% will be benign
    • abnormal fetus; normal/hydropic placenta
    • (triploidy from maternal origin is NOT associated with GTN)
  50. Sonographic Presentation of Partial Molar
    • increased size of placenta
    • numerous cystic spaces nonuniform
    • 1st Trimester: missed/incomplete abortion
    • 2nd/3rd Trimester: severe asymmetric IUGR fetus; may see triploidy signs (hydrocephalus, syndactyly)
  51. Treatments for Complete/Partial Molar Pregnancies
    • evacuaton (induced labor/D&C)
    • hCG titer sampling (weekly/monthly)
    • no pregnancy for 1 year
  52. T or F: it is possible to have a complete mole with coexistent twin pregnancy?
    True: would see separate and normal pregnancy
  53. Persistent Trophoblastic Neoplasia (PTN)
    • invasive mole and choriocarcinoma
    • **most curable gynecological malignancy
    • life threatening
    • malignant potential
    • 20% of complete molar pregnancies develop persistent disease
    • rarely occurs after normal term delivery, SA, or ectopic
  54. Risk factors of PTN
    • molar pregnancy with coexistent twin
    • **low risk wiht partial mole (5%)
  55. Signs and Symptoms of Invasive mole/choriocarcinoma (PTN)
    • vaginal bleeding
    • respiratory compromise
  56. --> presence of chorionic villi and proliferating trophoblast deep in myometrium
    • Invasive Mole "Chorioadenoma Destruens"
    • 80-95% of PTN
    • stages: confined to UT; spread to adjacent organs; embollize (lungs/brain)
  57. --> abnormal proliferating trophoblast with NO formed villi (purel cellular lesion)
    • Choriocarcinoma
    • 1/30,000
    • often begins as Molar pregnancy (50- 80%) 
    • can present after miscarriage, abortions, or normal pregnancies
  58. Diagnosis of Persisent Trophoblastic Neoplasia
    • follow serum hCG after evacuation
    • NORMAL hCG disappears ~7-14 weeks following molar pregnancy
    • dx can be confusing if many systems are affected (ex. lungs/brain)
  59. Sonographic Presentation of PTN
    • EV scan**
    • often focal echogenic myometrial nodule
    • may be hyperechoic, comples or multicystic "grape like" lesions
    • may see anechoic regions due to necrosis
    • may see bulky uterus (heterogeneous/lobulates) if tumor replaces entire myometrium
    • extension of tumor to other organs
  60. DDx of PTN pregnancies (2D)
    • adenomyosis
    • fibroid
    • aV malformation
  61. Doppler with PTN (can also see abnormal trophoblastic flow with early pregnancy, missed abortion, or retained products of conception)
    • color aliasing due to AV shunting
    • chaotic vascular arrangement
    • increased peak systolic velocity (>50 -100cm/s)
    • low resistive index RI <0.5
  62. Therapy of PTN
    • Non Metastatic PTN: excellent prognosis (Tx: methotrexate)
    • Metastatic PTN: 1) Low risk (tx: chemo) 2) High risk
  63. High Risk Metastatic PTN
    • --> having disease for more than 4 months and a pretreatment hCG level >40000miu/ml
    • presence of brain/liver mets
    • poor prognosis
    • tx: multi-agent chemotherapy, radiotherapy, surgery
  64. Non Gestational Trophoblastic Neoplasia
    choriocarcinoma can occur with dysgerminoma (produces hCG, highly malignant) of ovary
  65. DDx for PTN  (Doppler)
    --> other conditions that would have same high velocity; low impedance type flow
    • PID
    • pelvic abscess
    • benign/malignant ovarian neoplasia
  66. when is a nuchal translucency scanned?
  67. why start at 11 weeks for NT?
    • nuchal fluid in chromosomally abnormal fetuses begins to increase at 11 wks
    • can appreciate other abnormalities (acrania, omphalocele)
  68. why end at 13w6d for NT?
    • nuchal fluid in chromosomally abnormal fetuses decreases after 14 wks
    • can abort in 1st trimester
    • more difficult to obtain after 14 wks
  69. Accuracy of NT scan?
    • NT alone 80% accurate
    • NT + blood work 90% accurate
    • 60-70% of fetuses with T21 nasal bone not visible
  70. Causes for thick Nuchal Translucency?
    • cystic hygroma
    • cardiovascular defect
    • pulmonary defect
    • skeletal dysplasia
    • congenital infections
    • hematologic disorders (anemia)
    • metabolic disorders (hypoproteinemia)
  71. Minimal CRL
    45mm (11 wks)
  72. Maximal CRL
    84mm (13w6d)
  73. 5 criteria for perfect NT image
    • Magnification (head/thorax)
    • Position (sagital/neutral)
    • Amnion (should be off amnion)
    • Measurement Area (widest portion)
    • Caliper Placement (inner to inner)
  74. Magnification Criteria for NT?
    • zoom to fetal head and thorax
    • 3-4cm depth
  75. Position Criteria for NT?
    • neutral position
    • true sagittal
    • hyperextension 6.0mm increase
    • flexion 4.0mm decrease
    • head turn increase also
  76. Parameters that influence RISK ASSESSMENT for NT?
    1/300 or greater ratio is + risk (offered amniocenteses)
    • maternal age (>40 = +risk assessent)
    • CRL
    • NT measurement
    • Blood work
    • heart rate
  77. other structures assessed in NT scan?
    • heart rate
    • cranium
    • abd wall
    • bladder
    • stomach
    • limbs
    • chorionicity/amnionicity in multiple gestations
  78. 4 assumptions of beam travel
    • beam travels in straight line
    • returning pulse is received before next pulse is sent
    • round trip time is proportional to distance traveled
    • objects viewed are located in central portion of beam
  79. --> sound beam bounces off an interface without entering second medium
    • Reflection
    • ex) reflective shadowing (critical angle shadow)
  80. --> change in direction of acoustic beam as it travels from one medium to another
    • Refraction
    • ex) curved edge refraction shadows
    • ex) split image artifact (double) - beam travels through fat
  81. --> multiple reflection of sound between structure and tx face (high degree of acoustic mismatch)
    • Reverberation
    • ex) Multipath/mirror/pseudomass reverberation
    • ex) Comet tail
    • ex) Ring-Down
  82. what are two artifacts that clarify u/s?
    attenuation (shadow), and enhancement; also comet tail
  83. How to reduce artifacts?
    • appropriate gains
    • proper frequency
    • focus correct location
    • change scanning location