Placenta and umbilical cord

Placenta and umbilical cord

abruptio placentae

premature detachment of the placenta from the maternal wall.

elongated duct that contributes to the development of the umbilical cord.

maternal surface of the placenta.

battledore placenta

cord insertion into the margin of the placenta.

Braxton-Hicks contraction

spontaneous uterine contraction occurring throughout pregnancy.

chorion frondosum

the portion of the chorion that develops into the fetal portion of the placenta.

chorionic leave

chorion around the gestational sac on the opposite side of implantation.

chorionic plate

fetal surface of the placenta.

chorionic villi

vascular projections from the chorion at the implantation and placental site.

circumvallate placenta

a placental condition in which the chorionic plate of the placenta is smaller than the basal plate.

occurs when the cord is completely wrapped around the fetal neck at a minimum of two times.

molar pregnancy

abnormal proliferation of the trophoblastic cells in the first trimester.

placental abruption

premature separation of the normally implanted placenta from the uterus.

placenta accreta

growth of the chorionic villi superficially into the myometrium.

placenta increta

growth of the chorionic villi deep into the myometrium.

placenta percreta

growth of the chorionic villi through the myometrium.

placenta previa

placenta completely covers the internal cervical os.

placental migration

as the uterus enlarges and stretches, the attached placenta appears to “move” further from the lower uterine segment.

retroplacental complex

area behind the placenta composed of the decidua, myometrium, and uteroplacental vessels.

succenturiate placenta

additional placenta tissue (lobes) connected to the body of the placenta by blood vessels.

umbilical herniation

failure of the anterior abdominal wall to close completely at the level of the umbilicus.

occurs when the intramembranous vessels course across the cervical os.

mucoid connective tissue that surrounds the vessels within the umbilical cord.

Placenta

Anatomy (fig. 28-1)

• Formed by the decidua basalis and decidua frondosum.

• Separated from the uterine myometrium by the retroplacental complex.

Physiology

• Vital support organ for the developing fetus.

• Chorionic villus is the major functioning unit of the placenta and contains the intervillous spaces.

• Maternal blood enters the intervillous spaces.

Functions

Respiration

• Oxygen in maternal blood passes through the placenta into the fetal blood.

• Carbon dioxide returns through the placenta to the maternal blood.

Nutrition

• Nutrients pass from the maternal blood through the placenta to the fetal blood.

Excretion

• Waste products cross from the fetal blood through the placenta to the maternal blood.

Protection

• Provides a barrier between the mother and fetus, protecting the fetus from maternal immune rejection.

Storage

• Carbohydrates, proteins, calcium, and iron are stored in the placenta and released into the fetal circulation.

Hormone production

• Produces human chorionic gonadotropin, estrogens, and progesterone.

Size

• Varies with gestational age.

• Generally measures 2 to 3 cm in greatest thickness.

• Maximum thickness should not exceed 4.0 cm.

Normal sonographic appearance

First trimester

• Thickened area of the hyperechoic gestational sac.

Second and third trimesters

• Solid, homogeneous medium-gray structure.

• Smooth edges and borders.

• Hyperechoic chorionic plate.

• Cystic areas directly behind chorionic plate (fetal vessels).

• Anechoic or hypoechoic sonolucent areas within placenta (placental lakes) are insignificant and commonly displayed after 25 weeks.

• Hypoechoic retroplacental complex.

• Myometrium appears as a thin hypoechoic layer posterior to the retroplacental complex.

Placental position

• The blastocyst may implant into any portion of the decidua (endometrium).

• The placenta may be located anterior, posterior, fundal, right lateral, or left lateral.

• The placenta may be implanted over or near the cervical os (previa).

Placental maturity and grading

• Grading scale of 0 to 3.

• Grading dependent on echogenicity attributed to calcium and fibrous deposition with advancing age.

• Maternal hypertension, cigarette smoking, intrauterine growth restriction, and multifetal gestation may cause premature maturation.

• Delayed maturation is most commonly associated with maternal diabetes mellitus.

Grade 0

• No calcifications.

• Smooth basal and chorionic plates.

• First and early second trimester.

Grade 1

• Scattered calcifications throughout the placenta.

• Most common up until 34 gestational weeks.

Grade 2

• Demonstrates calcifications along the basal plate.

• Chorionic plate becomes slightly lobular.

Grade 3

• Marked calcifications.

• Distinct hyperechoic lobulations extending from the chorionic to basal plate.

• Abnormal before 34 gestational weeks.

Placenta previa

• Placental placement in front of the fetus relative to the birth canal.

• Primary cause of painless vaginal bleeding in the third trimester.

• Risk factors include advanced maternal age, multiparity, and previous cesarean section, therapeutic abortion, or closely spaced pregnancies.

• Complications of placenta previa include premature delivery, life-threatening maternal hemorrhage, and increased risk of placenta accreta, stillbirth, and intrauterine growth restriction.

• Only 5% of cases diagnosed with placenta previa in the second trimester remain at term, a result of placental migration.

Placenta Previa

TYPE	CLINICAL FINDINGS	SONOGRAPHIC FINDINGS	DIFFERENTIAL CONSIDERATIONS
Complete	Painless vaginal bleeding	Placenta covers the entire cervical os	Myometrial contraction Overdistention of the urinary bladder Uterine leiomyoma Improper technique
Partial (incomplete)	Painless vaginal bleeding	Placenta covers one side of the cervical os	Myometrial contraction Overdistention of the urinary bladder Uterine leiomyoma Improper technique
Marginal	Asymptomatic Painless vaginal bleeding	Edge of the placenta abuts the cervical os	Myometrial contraction Overdistention of the urinary bladder Uterine leiomyoma Low-lying placenta
Low-lying	Asymptomatic	Edge of the placenta lies close but does not abut the cervical osWithin 2 cm of the internal os	Myometrial contraction Overdistention of the urinary bladder Uterine leiomyoma Marginal previa
Vasa previa	Bleeding Cord compression Prolapsed cord Transverse fetal lie	Fetal vessels cross over the internal os	Normal free-floating cord Velamentous cord Succenturiate placenta Myometrial contraction

Placental Abnormalities

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Tags: Abdomen, Obstetrics and Gynecolo, Sonography Exam Review Physics

Jun 15, 2016 | Posted by admin in GYNECOLOGY | Comments Off

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ABNORMALITY	INFORMATION	SONOGRAPHIC FINDINGS	DIFFERENTIAL CONSIDERATIONS
Abruption	Premature placental detachment Clinical findings include severe pelvic pain and vaginal bleeding Risk factors include maternal hypertension, smoking, diabetes, trauma, placenta previa, and short umbilical cord	Hypoechoic retroplacental mass Placental thickening Well-defined margins Elevation of placental edges Subamniotic or preplacental locations are rare	Normal retroplacental complex Amniochorionic separation Myometrial contraction Uterine leiomyoma
Accreta	Accreta Chorionic villi of the placenta are in direct contact with the uterine myometrium Attributed to complete or partial absence of the decidua basalis Risk factors include multiparity, placenta previa, and previous cesarean section Increta—placenta invades the uterine myometrium Percreta—placental vessels invade the uterine serosa or urinary bladder	Accreta Obscured or absent retroplacental complex Numerous placental lakesIncreta Extension of villi into the myometrium Percreta Extension of villi outside of the uterus	Adenomyosis Myometrial contraction Uterine leiomyoma
Amniochorionic separation	Amnion can be separated from the fetal surface of the placenta but cannot be separated from the umbilical insertion site Chorion can be separated from the endometrial lining but cannot be separated from the placental edge	Localized fluid between the fetal side of the placenta and the amniotic membrane Membrane may move	Placental abruption Normal venous lakes
Battledore placenta	Cord inserts into the end margin of the placenta	Insertion of the cord into the end margin of the placenta	Normal cord lying adjacent to the placental margin Velamentous cord
Calcifications	Sign of maturing placenta Associated with maternal cigarette smoking or thrombotic disorders	Hyperechoic focus within the placental tissue Posterior acoustic shadowing	Molar pregnancy
Circumvallate placenta	Abnormal placental shape in which the membranes insert away from the placental edge toward the center Increases risk for abruption, intrauterine growth restriction, premature labor, and perinatal death	Rolled up placental edge Irregular fold or thickening of the placenta Upturned placental edge contains hypoechoic or cystic spaces Thick placental cord insertion	Abruption Amniotic shelf Synechiae
Fibrin deposits	More commonly located along the subchorionic region of the placenta Attributed to the regulation of intervillous circulation	Hypoechoic area beneath the chorionic plate of the placenta Triangular or rectangle in shape	Venous lake Subchorionic hematoma
Intervillous thrombosis	Presence of thrombus within the intervillous spaces Occurs in one third of pregnancies Little risk to fetus	Anechoic or hypoechoic intraplacental mass Nonvascular	Chorioangioma Placental lakes
Placental infarct	Result of ischemic necrosis Occurs in 25% of pregnancies No clinical risk when small	Hypoechoic focal placental mass Calcification may occur	Intervillous thrombosis Placental lake
Placental lakes	Also called venous lakes	Anechoic or hypoechoic area within the placenta Internal blood flow	Intervillous thrombosis Placental infarct
Placentomalacia	Small placenta Intrauterine growth restriction Intrauterine infection Chromosomal abnormality