Placenta

INTRODUCTION

At USG, the placenta may be visible as early as 10 weeks as a thickening of the hyperechoic rim of tissue around the gestational sac.

Fetal placenta—Chorion frondosum—develops from the blastocyst

Maternal placenta—Decidua basalis—develops from maternal uterine tissue

At 12–13 weeks, blood flow is easily demonstrable

By 14–15 weeks—Placenta is well established

Prominent hypoechoic retroplacental area composed of decidua, myometrium, and uterine vessels

Normal-term placenta measures 15–20 centimeters in length and 400–500 grams in weight at term Maximum—4–5 centimeters in thickness

Thin placenta—Small for date fetus

Sign of intrauterine growth retardation (IUGR)

Thick placenta (Placentomegaly)

Homogenous thickening

1.    Diabetes mellitus (Gestational)

2.    Anemia

3.    Hydrops

4.    Infections

5.    Aneuploidy

Heterogenous (With multiple cystic spaces)

1.    Triploidy

2.    Placental hemorrhage

3.    Villitis

4.    Mesenchymal dysplasia

5.    Beckwith–Wiedmann syndrome

Placental Grading—Grannum classification (Figures 21.1 and 21.2)

Grade 0—Homogenous placenta, uniform echogenicity—first and early second trimester

Grade 1—Occasional hypo-/hyperechoic areas—late second trimester

Grade 2—Larger calcifications along the basal plate—early third trimester

Grade 3—Larger and denser calcifications along with compartmentalization of placenta—late third trimester

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Acute Abdomen and Abdominal Tuberculosis Ectopic Pregnancy Basic Terminology Scrotum Recent Advances in Sonography Fetal Malformations

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