Fetal Environment and Maternal Complications

what is the maternal contribution of the placenta

decidua basalis, the endometrium beneath the developing placenta

what is the fetal contribution to the placenta

The chorion frondosum, the portion derived from the blastocyst and containing the chorionic villi

The placenta produces human chorionic gonadotropin, which maintains the

corpus luteum of the ovary.

In later pregnancy, the placenta also produces

estrogen and progesterone, taking over that function from the corpus luteum.

. One major function of the placenta is to

act as an excretory organ for the fetus, performing imperative exchanges of waste products and gases with valuable nutrients and oxygen from the mother

A definitive placenta may not be identified sonographically until after

after 10 to 12 weeks.

The placenta consists of three parts:

the chorionic plate: element of the placenta closest to the fetus.

the placental substance: the functional parts of the placenta and is located btw chorionic plate and basal layer

the basal layer or basal plate: area adjacent to the uterus.

what are Venous lakes, also referred to as maternal lakes or placental lakes

pools of maternal blood within the placental substance. Anechoic or hypoechoic and may contain swirling blood. Little clinical significance

A bilobed placenta consists of

two separate discs of equal size connected by an isthmus of placental tissue

what is an accessory lobe or a succenturiate lobe of the placenta,

additional smaller lobes located separate from the main segment of the placenta

what is a circumvallate placenta

an abnormally shaped placenta caused by the membranes inserting inward from the edge of the placenta, producing a curled-up placental contour

A circumvallate placenta may lead to

vaginal bleeding and placental abruption, among other complications.

with advancing gestation,

Calcifications may be noted within the placenta, and indentations may be seen within the basal and chorionic plates

Classic placental grading with associated sonographic findings

Grade 0 - Uninterrupted chorionic plate and homogeneous placental substance

Grade I - Subtle indentations on the chorionic plate, with some small calcifications within the placental substance

Grade II - Moderate indentations in the chorionic plate with “comma-like” calcification in the placental substance

Grade III - Prominent indentation in the chorionic plate that extends to the basal layer with diffuse echogenic and anechoic areas noted within the placental substance

The thickness of the placenta should be evaluated with sonography. It should not exceed

4 cm

a thick (placentomegaly) and thin placenta are both associated with

maternal and/or fetal abnormalities

Possible causes of a thick placenta (6 causes)

Diabetes mellitus

Maternal anemia

Infection

Fetal hydrops

Rh isoimmunization

Multiple gestations

Possible causes of a thin placenta (6 causes)

Diabetes mellitus (long standing)

IUGR

Placental insufficiency

Polyhydramnios

Preeclampsia

Small-for-dates fetus

what is placenta previa

placenta covers the internal os of the cervix.

Placenta previa is a common cause of

painless vaginal bleeding in the second and third trimesters

placenta previa is more commonly found in mothers who have

Multiparous

AMA

Prior abortion

Prior c-section

Term Associated with Placenta Previa

Complete (total) previa - Placenta covers the internal os completely

Partial previa - Placenta partially covers the internal os

Marginal previa - Placenta lies at the edge of the internal os

Low-lying previa - placenta edge is 2cm away from internal os

The placenta should be evaluated for placenta previa after

20 weeks with an empty maternal bladder using a transabdominal approach

a cause of false-positive placenta previa is

painless myometrial contractions that occur in the lower uterine segment.

Clinical Findings of Placenta Previa

Previous C-section or uterine surgery

Painless vaginal bleeding

Possibly asymptomatic

what is vasa previa

fetal vessels resting over the internal os of the cervix. May lead to exsanguination of the fetus

Vasa previa is often associated with

velamentous cord insertion and, possibly, a succenturiate lobe

Sonographic Findings of Vasa Previa

Identification of vessels over the internal os of the cervix with the use of color Doppler

Velamentous cord insertion

Placental abruption, also referred to as abruptio placentae, is the

premature separation of the placenta from the uterine wall before the birth of the fetus, thus causing hemorrhage

Placental abruption can be further described as

complete abruption -- (most severe) retroplacental hematoma between uterus and myometrium

partial abruption - few cm of separation

marginal abruption - subchorionic hemorrhage (edge of placenta)

Maternal conditions that are linked to the development of placental abruption include (6 conditions)

hypertension

preeclampsia

cocaine use

cigarette smoking

poor nutrition

trauma.

Clinical Findings of Placental Abruption

Abdominal pain (often sudden onset)

Possible vaginal bleeding

Uterine contraction

Uterine tenderness

Sonographic Findings of Placental Abruption

Hematoma located either at the edge of the placenta or between the placenta and the myometrium

Placenta accreta is frequently used as a universal term to describe the condition that is defined as the

abnormal adherence of the placenta to the myometrium in an area where the decidua is either absent or minimal. The placenta will not detach after birth

The placenta may attach to a uterine scar following a previous C-section and/or after uterine surgery. This explains the association between

anterior placenta previa and placenta accreta.

There are three different terms associated with this abnormality:

placenta accreta - adhesion and loss of clear zone

placenta increta - invasion of the placenta into the myometrium

placenta percreta - progression to urinary bladder or other organs, thus causing urinary complications

Depending upon the amount of invasion or penetration of the placenta into the myometrium, the patient could suffer from heavy bleeding at delivery and, possibly, uterine rupture. Therefore, an

emergency hysterectomy may be warranted

Clinical Findings of Placenta Accreta, Placenta Increta, and Placenta Percreta

Previous C-section or uterine surgery

Painless vaginal bleeding if placenta previa is present

Possibly asymptomatic

Sonographic Findings of Placenta Accreta, Placenta Increta, and Placenta Percreta

Placenta previa (frequent associated finding)

Loss of the normal hypoechoic interface between the placenta and the myometrium

what is the retroplacental clear zone?

normal hypoechoic interface between the placenta and the myometrium

what is the most common placental tumor

Chorioangioma

The most common location of Chorioangioma

is adjacent to the umbilical cord insertion site at the placenta

They typically do not carry any risks to the fetus or mother, although larger chorioangiomas have been associated with

polyhydramnios

intrauterine growth restriction (IUGR)

fetal hydrops

Clinical Findings of a Chorioangioma

Possible elevation in maternal serum alpha-fetoprotein

Sonographic Findings of a Chorioangioma

Solid hypoechoic or hyperechoic mass within the placenta (common area is adjacent to chord insertion)

Uterine synechiae, also referred to as amniotic sheets, are

linear bands of scar tissue within the uterus.

Although uterine synechiae are typically isolated, uterine synechiae have been associated with

premature rupture of membranes (PROM), premature delivery, and placental abruption.

Sonographic Findings of Uterine Synechia(E)

Linear, echogenic band of tissue traversing the uterine cavity

The band does not involve fetal parts, and the normal fetus appears to move freely

The umbilical cord, which normally inserts into the middle of the placenta, has

two arteries and one vein, surrounded by a gelatinous material called Wharton jelly

The cord develops from the fusion of the

yolk stalk and the vitelline duct (omphalomesenteric duct) early in gestation.

The 3 Vessel View

what is the most common abnormality of the umbilical cord

A single umbilical artery, or two-vessel cord (2VC); assoc. with abnormalities of all major organ systems and IUGR

Fetuses with a 2VC have an approximate

20% chance of having additional abnormalities, a thorough examination of the fetus for other findings is warranted.

The umbilical cord normally inserts into the central portion of the placenta. Abnormal cord insertion sites are described as either

Marginal cord insertion (battledore placenta) - insertion at edge of the placenta

Velamentous cord insertion - insertion in membranes beyond the placental edge

abnormal insertion is often seen in association with

vasa previa

Occasionally, the umbilical cord may be seen encircling the fetal neck. This is termed

nuchal cord

what is An allantoic cyst

a mass that may be noted in the umbilical cord adjacent to the umbilical vessels (NOT VASCULAR)

Sonographic Findings of Allantoic Cysts

Cystic mass within the umbilical cord

Most often noted close to the fetal abdomen

Umbilical cord cysts are most often found near the fetal abdomen and have been seen in connection with

omphalocele and aneuploidy, especially if noted in the second or third trimester

what is an umbilical vein varix

the focal dilatation of the abdominal portion of the umbilical vein

umbilical vein varix has been associated with

fetal aneuploidy,

IUGR,

hydrops,

demise.

What is the most common tumor of the umbilical cord

hemangioma

Sonographic Findings of Hemangiomas of the Umbilical Cord

Solid hyperechoic mass within the umbilical cord

Most often noted close to the cord insertion into the placenta

Fetal well-being can be evaluated using pulsed Doppler of the umbilical cord by measuring the systolic-to-diastolic ratio (S/D ratio). The S/D ratio assesses the vascular resistance in the placenta by taking a sample of the umbilical artery. It can be performed anywhere along the length of the cord, although a free loop of cord will tend to offer the most accurate measurement. Normally, the S/D ratio will

decrease with advancing gestation

Therefore, an elevated S/D ratio with absence or reversal of diastolic flow in the umbilical artery is associated with

increased placental resistance and an increase in the risk of perinatal mortality and morbidity i.e : IUGR and oligohydramnios

. Echogenic debris in the amniotic fluid may be

vernix or meconium, with meconium being the least likely to be observed

The fluid that is seen in early gestation is thought to arise from water and various other materials passing freely through the membranes surrounding the embryo. In the second half of the pregnancy, the

fetal kidneys and lungs produce the majority of amniotic fluid, with urine being the greatest contributor

The maximum vertical pocket, also referred to as the deepest vertical pocket, can be used to asses volume of amniotic fluid. This pocket should contain no fetal parts or umbilical cord and measure at least

2 cm, with a normal range between 2 and 8 cm

The most widely accepted means of evaluating the volume of amniotic fluid is the amniotic fluid index (AFI). The AFI is measured using the

anteroposterior dimensions obtained from the four quadrants of the amniotic sac and adding them together. measurements should not include fetal parts or umbilical cord.

Fetal malformation and complications associated with oligohydramnios (GENITOURINARY)

Bilateral multicystic dysplastic kidney disease

Bilateral renal agenesis

Infantile polycystic kidney disease (ARPKD)

IUGR

Posterior urethral valves

PROM

Fetal malformations and complications associated with polyhydramnios

Cardiac and/or chest abnormalities

Chromosomal abnormalities

Duodenal atresia

Esophageal atresia

Gastroschisis

Omphalocele

Neural tube defects

Rh incompatibility

TTS

TORCH, an acronym that stands for

toxoplasmosis, other infections, rubella, cytomegalovirus, and herpes simplex virus, is a group of infections that can cross the placenta and influence the development of the fetus.

what is the most common congenital infection

cytomegalovirus

Sonographic Findings of Torch

Intracranial calcifications

Microcephaly

Microphthalmia

Ventriculomegaly

Hepatosplenomegaly

what is the most common cause of intellectual disability in the United States

Fetal alcohol syndrome (FAS)

Sonographic Findings of Fetal Alcohol Syndrome

Microcephaly

Dysgenesis of the corpus callosum

Microphthalmia

Malformed ears

Long round philtrum

Cleft palate

Heart defects such as ventricular septal defects

what is Intrauterine Growth Restriction

an estimated fetal weight (EFW) that is below the 10th percentile at a given gestational age.

IUGR typically results from the

inadequate transfer of nutrients from the mother to the fetus and thus is the dysfunction of the placenta

The fetus is at risk of IUGR if the mother suffers from

chronic disease,

drinks alcohol,

smokes cigarettes,

has poor nutrition,

is younger than 17 or older than 35 years,

or has a history of previous pregnancies that were considered growth restricted

The measurement that should be scrutinized closely in fetuses that are at risk for growth abnormalities is the

abdominal circumference (AC), because it carries a sensitivity of greater than 95% for the diagnosis of IUGR.

The fetus with IUGR can be monitored with sonography by evaluating the flow within the umbilical artery with the S/D ratio . The S/D ratio evaluates the sufficiency of the placenta by pulsed Doppler interrogation of the umbilical artery. An abnormally high S/D ratio, resulting from a reversal or absence of diastolic flow within the umbilical artery, is associated with a

poor outcome

Suspected causes of symmetric intrauterine growth restriction

Genetic disorders

Fetal infections

Congenital malformations

Syndromes

Suspected causes of asymmetric intrauterine growth restriction

Placental dysfunction

Nutritional deficiency

Oxygen deficiency

When a fetus presents with measurements that lead to suspected small for gestational age, sonography can further assess the pregnancy for signs of IUGR by performing the biophysical profile

Doppler assessment of the middle cerebral artery has also been shown effective at evaluating for

hypoxia in a fetus that is measuring small for dates

the pulsatility index of the middle cerebral artery varies with gestational age but normally decreases as the pregnancy progresses toward term. When comparing the two Doppler signals, the middle cerebral artery should generate a

higher resistance flow pattern than the umbilical artery

Maternal uterine artery Doppler may be useful at anticipating the progression of IUGR in high-risk pregnancies. In the first trimester, the uterine artery is analyzed with spectral Doppler before it enters the uterus at the level cervix. the portion of the main uterine artery as it crosses over the external iliac artery may be utilized for this sample in the second/third trimester. The normal flow pattern is said to be

low resistance (high resistance is abnormal)

Abnormal flow may also be a forewarning of

preeclampsia and preterm delivery.

In the neonatal period, macrosomia is technically defined as the

neonate that measures more than 4,500 g in nondiabetic mothers and 4,000 g in diabetic mothers (90th precentile)

Mothers who are prone to have a macrosomic fetus are those who suffer from

diabetes, whether pregestational or gestational.

A macrosomic fetus is predisposed to

shoulder dystocia secondary to fetal size and has an increased risk of hypoglycemia and lifelong struggles with obesity. Therefore, they will most often be delivered by means of C-section.

occasionally, during the second half of pregnancy, the cervix can be difficult to image with a transabdominal approach. Translabial scanning, also referred to as transperineal scanning, can offer a useful, noninvasive glimpse at the cervix

ccasionally, during the second half of pregnancy, the cervix can be difficult to image with a transabdominal approach. Translabial scanning, also referred to as transperineal scanning, can offer a useful, noninvasive glimpse at the cervix

Cervical incompetence, or an incompetent cervix, is the

painless dilation of the cervix in the second or early third trimester.

what is an early sign of an incompetent cervix

Funneling of the cervix is a result of the premature opening of the internal os and the subsequent bulging of the membranes into the dilated cervix.

Funneling width can be measured

May take a “U” or “V” shape

Patients who are at risk for cervical incompetence include those with

uterine malformations

previous pregnancy loss in the second trimester

Intrauterine exposure to diethylstilbestrol

A sonographic assessment of the cervix can be performed with transvaginal or translabial imaging as mentioned earlier. There are two measurements of the cervix that can be obtained utilizing these techniques. The most often employed sonographic measurement for the assessment of cervical incompetence is the length measurement taken from the

internal os to the external os,

The cervical length should measure at least 3 cm.

Therefore, the shorter the cervical length, the more likely the patient will suffer from preterm delivery

The treatment of an incompetent cervix is a

cerclage (Shirodkar and the McDonald.)

Clinical Findings of Cervical Incompetence

Painless dilation of the cervix

PROM

Vaginal bleeding

Sonographic Findings of Cervical Incompetence

Cervical length of less than 3 cm

Funneling of the cervix (can produce a “U” or “V” shape)

Fetal hydrops can be categorized as either immune or nonimmune

Immune hydrops is caused by the absence of a detectable circulating fetal antibody against the red blood cells in the mother. This results in incompatibility between the fetal and maternal red blood cells, a condition known as erythroblastosis fetalis