Radiological evaluation of the Placenta

Evaluation of placenta - complete /attempt to be complete

1. EVALUATION OF PLACENTA Dr Lenon J. D’Souza

2. EVALUATION OF THE PLACENTA The early gestational sac is first visible at transvaginal sonography at about 4 weeks' menstrual age Its hyperechoic rim contains developing villi composed of fetal vessels surrounded by the lacunar space, which is the precursor of the intervillous space.

3. At about 5 weeks' menstrual age, those villi situated opposite the implantation site begin to atrophy, forming a smooth surface (chorion laeve ). The remaining villi, the chorion frondosum, become the placenta, which may be identified at sonography at about 8 weeks

4. EVAUATION OF THE PLACENTA

5. PLACENTAL LAKES Placental lakes represent inter villous space devoid of placental villous trees H ypoechoic structures with evidence of blood flow

6. PLACENTA Well formed by around 12 weeks Most commonly assessed at 18-20 weeks THINGS TO ASSESS: SIZE- >1 cm not >4 cm thick within 24 weeks TEXTURE PLACENTAL SITE N : anterior/posterior /fundal RETROPLACENTAL AREA= N : hypoechoic CORD : SITE OF INSERTION ( centre or within 2 cm) NO. OF VESSELS ( N = 3)

7. Small Placentas Toxemia Hypertension Chromosomal abnormality Severe diabetes mel1itus Chronic infection Large Placentas Blood group incompatibilities Diabetes mellitus Maternal anemia Fetal neoplasm Triploidy Homozygous alpha-thalassemia More than 4 : Ischemic thrombotic change Hemorrhage Chorioangioma hydrops

8. NORMAL PLACENTA ON USG

9. Placental calcium deposition is a physiologic process F ound along the basal plate, in the intraplacental septa, and in collections of fibrin in the intervillous and subchorionic spaces E xponential increase in placental calcification with increasing gestational age ;   more than 50% of placentas contain some degree of calcification after 33 weeks . Placental calcification is more common in women of lower parity .

10. TEXTURE :GRANNUM CLASSIFICATION OF PLACENTAL MATURITY GRADE 0 GRADE 1

11. GRANNUM CLASSIFICATION OF PLACENTAL MATURITY GRADE 2 GRADE 3

12. EVALUATION - MRI During the second trimester, most patients can tolerate supine imaging. However , in the third trimester, lateral decubitus imaging may be required A void the risk of impaired systemic venous return caused by uterine compression of the maternal inferior vena cava. Imaging late in the third trimester can be challenging, Positioning the patient Placenta is heterogeneous M yometrium thinner and more stretched

13. PREPARATION When evaluating the patient for placenta percreta , the bladder should be mildly distended. Completely collapsed bladder - Anatomic landmarks difficult to identify Full Bladder - exclusion of Bladder-wall invasion difficult when closely apposed to the uterus . No other patient preparation is typically required.

14. EVALUATION - MRI Between 19 and 23 weeks: homogeneous on T2 Between 24 and 31 weeks: the placenta becomes slightly lobulated conspicuous septae appear between placental lobules, leading to increased heterogeneity with increasing gestational age.

15. The normal myometrium - trilayered appearance on T2-weighted images The middle layer is a heterogeneously hyperintense vascular layer, with thinner low signal-intensity layers on either side .

16. D iffusion-weighted imaging: demonstrate the myometrial -placental interface . B lood oxygen level– dependent (BOLD) imaging: evaluate placental perfusion.

17. SHAPE Failure of villous regression results in abnormalities of placental shape. A more common result of failure of villous regression is the succenturiate (accessory) lobe, which is present in up to 8% of patients Recognition of succenturiate lobes is important because they may result in complications such as placenta previa , vasa praevia, and retained placenta after delivery.

18. SHAPE

19. The membranes of chorionic leave, instead of attaching to margin of placental disc, insert more towards centre of disc Disproportionate folding of placenta and fetal membranes, results in chorionic plate being smaller than basal plate CIRCUMVALATE PLACETA

20. CIRCUMVALATE PLACENTA

21. SHAPE Placenta membranacea is a rare anomaly in which almost all the chorion is diffusely covered by villi. A variant of this condition occurs when aberrant villous atrophy results in a ring-shaped (annular) placenta. Both entities are associated with recurrent antepartum bleeding.

22. CONTRACTIONS Transient changes in the appearance of the retroplacental myometrium and decidua are seen with contractions, which occur throughout pregnancy and are imperceptible to the mother. These are most commonly seen in the latter part of the first trimester and the early part of the second trimester Contractions are a source of considerable confusion because they often mimic retroplacental myomas and hematomas

23. RETROPLACENTAL MASS Contractions Myomas Retroplacental hematomas Abruptio placentae

24. MYOMAS W ell circumscribed and hypoechoic. D iagnosis easily confirmed if multiple myomas are present. Large myomas may have a complex echotexture as a result of degeneration and/or hemorrhage . M ay increase or decrease in size during the course of the pregnancy.

25. COMMON MACROSCOPIC LESIONS

26. SUBCHORIONIC FIBRIN DEPOSITION

27. PERIVILLOUS FIBRIN Anechoic-hypoechoic intraplacental "lakes" are not uncommon and may contain flow At delivery, these correlate with blood-filled spaces that presumably represent a stage in the evolution of either perivillous fibrin deposition or intervillous thromboses.

28. SITE : PLACENTA PREVIA 6% in the 1 st trimester 0.5% at term Predisposing factors for placenta previa Advanced maternal age 
 Multiparity 
 Prior cesarean section 
 Uterine curettage 
 Maternal cigarette smoking

29. PLACENTA PREVIA

30. MARGINAL PLACENTA PREVIA

31. PARTIAL PLACENTA PREVIA

32. COMPLETE PLACENTA PREVIA COMPLETE SYMMETRICAL COMPLETE ASSYMETRICAL

33. COMPLETE PLACENTA PREVIA

34. LOW LYING PLACENTA LESS THAN 2 CM FROM INTERNAL OS THICK: EDGE >1 CM

35. PLACENTA PREVIA Misdiagnosed : overdistended maternal bladder : uterine contractions (pseudo placenta previa If suspected : confirm with re scanning after voiding or after 20 to 30 minutes

36. PSEUDO PLACENTA PREVIA 15 min later

37. RETROPLACENTAL AREA : ABNORMAL INVASION OF PLACENTA 1 IN 2500 Abnormal adherence of placenta to the uterus Failure of separation on dellivery Deficiency of decidua basalis

38. PLACENTA ACCRETA Absence of the intervening myometrium between the placenta and uterine serosa Color Doppler image abnormal bladder-uterine wall vascularization numerous vascular lacunae within the placenta

39. PLACENTA PERCRETA

40. Distinguish placenta accreta from increta and increta from percreta - challenge , unless there is direct invasion of adjacent organs . Abnormal placental attachment to the myometrium may be complicated by postpartum hemorrhage and/or retained products of conception when the placenta fails to cleanly separate from the uterus at the time of delivery MRI – highly accurate

41. PLACENTA PERCRETA

42. PLACENTA PERCRETA

43. PLACENTA PERCRETA

44. PLACENTA ACCRETA AND PERCRETA

45. PLACENTAL HEMMORHAGES Indirect sign of a hematoma : apparent thickening of the placenta

46. MARGINAL HEMMORRHAGE

47. INTRAPLACENTAL HEMATOMA

48. SUBCHORIONIC HEMATOMA

49. SUBCHORIONIC HEMMORHAGE

50. BREUS MOLE

51. SUBAMNIOTIC HEMORRHAGE A subamniotic haematomas are classical placental pathological lesions resulting from the rupture of chorionic vessels ( allantochorionic vessels) close to the cord insertion. 

52. RETROPLACENTAL HEMATOMA

53. PLACENTAL ABRUPTION Premature separation of placenta from the myometrium Secondary to hemmorrhage into decidua basalis 20 wks to birth If >60 ml blood loss chances of fetal demise more

54. SONOGRAPHIC SIGNS OF ABRUPTION Diffuse placental thickness Retroplacental mass Rounded placental edge Separation of placental edge Intra -amniotic hemorrhage Preplacental or subamniotic mass Blood in the fetal stomach 


55. PLACENTAL ABRUPTION

56. PLACENTAL ABRUPTION

57. INTRAPLACENTAL LESIONS Chorioangioma Teratoma Metastases from maternal neoplasms Hydatidiform  mole Partial mole

58. CHORIOANGIOMA

59. Hydatidiform mole An enlarged uterus containing material with multiple anechoic vesicles of varying sizes, in the absence of a fetus , is seen with complete hydatidiform mole The vesicles represent dilated, hydropic villi that enlarge with advancing gestational age; no normal placental tissue is found .

60. Moles are believed to result from the abnormal fertilization of an empty ovum by a single sperm with a duplicated haploid genome (46,XX karyotype) or, less commonly, dispermy (46,XY).   A coexistent fetus may occur along with a mole in the case of a twin pregnancy with one empty ovum TROPHOBLASTIC DISEASE

61. PARTIAL MOLE An enlarged placenta with multiple anechoic lesions - P artial mole N ormal villi interspersed with hydropic villi; the fetus - abnormal. Most partial moles are triploid (69 chromosomes ). If they do not abort in the first trimester frequently cause symptoms of preeclampsia at about 18 weeks.

62. MOLAR PREGANNCY

63. PLACENTAL SITE TROPHOBLASTIC DISEASE Can follow commonly after normal pregnancy Arises from intermediate trophoblasts Rarest and most fatal B – HCG not significant

64. PLACENTAL SITE TROPHOBLASTIC DISEASE Pt usually presents as focal myometrial nodule Persisent trophoblastic neoplasia Abn uterine hypervascularity and low impedance and av shunting Floris color mosaic pattern with aliasing

65. INVASIVE MOLE HIGH SYSTOLIC – LOW RESISTANCE FLOW PSV > 50/cm AND RI <0.5 NORMALLY PSV <50 cm/s and RI 0.7

66. T he umbilical cord inserts into the fetal  ( chorio -amniotic) membranes outside the placental margin and then travels within the membranes to the placenta (between the amnion and the chorion). Remodelling of the placenta as a response to factors that affect distribution of uterine blood flow (a process known as trophotropism ). A marginal cord insertion may evolve into a velamentous cord insertion as the pregnancy progresses VELAMENTOUS CORD INSERTION

67. VELAMENTOUS CORD INSERTION

68. VASA PREVIA

69. CONCLUSION The placenta should be evaluated, not only as a necessary organ for fetal growth the development, but also as a potential source of fetal disease and/or compromise . USG is the modality of choice Patients with suspected accreta spectrum should undergo MR evaluation Patients with undiagnosed bleeding may undergo MR to rule out abruption

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