Q4: Maternal Disease/fetal hydrops, IUGR, & Fetal Doppler

What is the definition of hydrops

• End-stage process for a number of different diseases

• Abnormal accumulation of fluid in at least two body cavities or one body cavity in association with anasarca (generalized massive edema)

What is anasarca

• Generalized massive edema

What are the sonographic findings in hydrops?

• Varies; can occur as isolated/ pleural ascities or pericardial effusion

• Other findings: subcutaneous edema, polyhydramnios, and placentomegaly

What is the appearance of fetal ascites?  What is pseudoascites?

• Abnormal anechoic fluid collection within abdominal cavity

• Normal appearance of fluid in fetal abdomen; in presence of thin layer of subcutaneous fat; mimics ascities fluid

What is the appearance of fetal pleural effusion? Pericardial effusion? How do you tell the difference?

• Fetal pleural effusion = fluid in pleural space

• Pericardial effusion = fluid around the heart

• Location: pleural effusion = lateral to lungs & pericardial effusion = around heart

 What is the appearance of subcutaneous edema?

• Hypoechoic or anechoic area beneath skin; abnormal fluid accumulation

• Seen as thicker skin; 5mm = cutoff value + diffuse swelling around neck and abdomen

What appearance could the placenta have with hydrops?  When does this usually occur?

• Thickened, echogenic, spongy, ground glass, or heterogenous

• Fetal anemia, Rh disease, or other maternal conditions

How might amniotic fluid volume be altered with hydrops?

• Polyhydramnios; increases risk of prematurity; adds to morbidity

What are the two main types of hydrops?  Which is more common?

• Immune hydrops (> 80%)

• Non-immune hydrops (90%; more common)

List the most common & several other causes for each of the two main types of hydrops

• Immune hydrops = Rh disease, ABO incompatibility

• Non-immune hydrops = congenital anomalies, infections, maternal diabetes, and spontaneous abortion

What is the pathogenesis of immune hydrops?  In Rh sensitization, what is the Rh status of the mother & fetus? How can fetal red blood cells enter the maternal circulation?  Which pregnancy is least affected?

• The pathogenesis of immune hydrops = maternal sensitization to Rh-positive blood cells from an Rh-positive fetus; production of antibodies that cross the placenta

• Mother = Rh-negative; fetus = Rh-positive

• Enter = during fetal-maternal hemorrhage; trauma or delivery complications

• Initial pregnancy = least affected; subsequent pregnancies = most at risk

What is erythroblastosis fetalis?  What is extramedullary erythropoiesis?

• Fetus produces excessive number of red blood cells in response to hemolysis caused by maternal antibodies; cases of Rh incompatibility

• Production of red blood cells outside the bone marrow; often occurring in liver and spleen during severe fetal anemia

What is the management of an Rh- pregnant woman?

• Rh immunoglobulin to the mother at 28 weeks of gestation and within 72 hours after delivery if the infant is Rh-positive; prevent sensitization

List 7 subdivisions of cardiovascular causes of non-immune hydrops (NIH)

• Structural heart disease

• Myocarditis/cardiomyopathy

• Valvular disease

• Myocardial or pericardial tumors

• Premature closure of foramen ovale or ductus arteriosus

• Twin-twin transfusion syndrome

• Arrhythmia

• High-output cardiac failure

What are the chromosomal abnormalities associated with NIH?

• Turner’s syndrome

• Trisomy 13, 18, 21

What abnormality is classically associated with Turner’s syndrome.

• Cystic hygroma in 1st and early 2nd trimesters

• Ovarian dysgenesis and short stature

List at least 5 sonographic findings that may be seen with  trisomy 13

• Holoprosencephaly

• Microcephaly

• Neural tube defects

• Facial clefts

• Cystic hygroma

List at least 4 abnormalities associated with trisomy 18

• IUGR

• Polyhydramnios

• Cystic hygromas

• Omphaloceles

• CNS anomalies

List at least 8 ultrasound findings associated with trisomy 21

• Nuchal fold

• Absent/hypoplastic nasal bone

• Short femur/ humerus

• Echogenic bowel/ intracardiac focus

• Heart defect

• Pyelectasis

List at least 5 infectious agents that are known to cause NIH.  What is the most common congenital viral infection in humans?

• Parvovirus

• CMV (Cytomegalovirus (most common))

• Toxoplasmosis

• Myocardium, rubella, syphilis, varicella

What are the sonographic findings that may be seen with intrauterine infections

•  Calcifications in the pericardium or brain and ventriculomegaly

 List at least 4 neck/thoracic anomalies that may cause hydrop

• Teratomas

• Lymphangiomas

• Cystic hygroma

• Nuchal translucency > 3 mm

List 3 reasons why fetal anemia may occur

• Decreased RBC production

• Increased hemolysis

• Hemorrhage

What information should be obtained in a detailed history from a woman whose baby has NIH?

• Systemic lupus erythematosus, diabetes, blood type, previous pregnancy losses, chromosome rearrangements, and family history

What are the two types of maternal diabetes that can affect the fetus?

• Gestational and insulin-dependent (long term)

Which type is associated with fetal anomalies?  What systems are affected & what are the anomalies?

• Gestational diabetes; cardiovascular, neural tube, and musculoskeletal systems

• Anomalies may include = congenital heart defects, spinal cord defects, and limb malformations

What is the role of ultrasound in the management of diabetic mothers?

• Monitor fetal growth + development, detect abnormalities, assess amniotic fluid levels, and overall health of the fetus

What is chronic hypertension, pregnancy induced hypertension (PIH), preeclampsia, HELLP syndrome & eclampsia?

• Chronic hypertension = reoccurring HTN

• Pregnancy induced hypertension (PIH) = HTN that occurs during pregnancy and resolves after delivery

• Preeclampsia = HTN after 24 weeks gestation with proteinuria and edema

• HELLP syndrome = severe variant of preeclampsia, hemolysis, elevated liver enzymes, and low platelets

• Eclampsia: preeclampsia with seizures

What is the cure for PIH?

• Bedrest, hospitalization, Magnesium sulfate, or immediate delivery of fetus

What sonographic findings may be observed in PIH?

• Small placenta

• Abruption

• Oligohydramnios

• IUGR

• Increased placental resistance

• Accelerated placental maturation

• Fetal distress

 List 5 sonographic findings that may be seen with  fetal alcohol syndrome?

• IUGR

• Microcephaly

• Micrognathia

• Microphthalmia

• Cleft lip/palate

• VSD/ ASD

What increased risks are associated with tobacco / smoking?

• IUGR

• Decreased birth weight

• Abruption/ previa

• Preterm labor/ PROM

• Spontaneous abortion

• Perinatal mortality

What is the increased risk of perinatal mortality for an IUGR fetus?

• Mortality rate = 4-8 times higher than non-IUGR fetuses

• Half of surviving infants have serious short/ long-term morbidity, meconium aspiration, pneumonia, and metabolic disorders

What are the two definitions of IUGR have been fairly widely used?

• Gestational age-specific growth restriction

• Fetal weight less than the 10th percentile

What is the prevalence of IUGR?

• Occurs in 5-10% of pregnancies; higher rates in certain populations + conditions; maternal smoking, hypertension, and diabetes

What are the significant maternal factors for IUGR?

• HTN

• Collagen vascular disease

• Poor nutrition

• Substance abuse

• HX of fetus w/ IUGR

• Presence of uterine anomaly

• Significant placental hemorrhage

• Placental insufficiency

What are the two categories of IUGR listed in Rumack?  What are these categories based on? What is the problem with this categorization?

• Symmetrical and asymmetrical

• Symmetrical = proportionately reduced in size

• Asymmetrical = fetal abdomen disproportionately small compared to head & limbs

 

What are the two alternative main types of  fetal growth restriction listed by De Lange & Rouse?

• Adequate fetal nutrition = occurs earlier in 2nd trimester; growth reduction typically symmetric

• Inadequate fetal nutrition = occurs in the late 2nd & 3rd trimester; fetal growth can be asymmetric

List reasons why a fetus may be growth restricted despite getting adequate nutrition. How is fetal growth typically affected?

• Chromosomal abnormalities, congenital malformations, multiple gestations, and placental factors

• Fetuses with symmetrical IUGR are proportionately reduced in size

When does IUGR from inadequate fetal nutrition usually occur & how can it affect fetal growth?

• Occurs in the late 2nd or 3rd trimester

• Fetal growth = asymmetrical; fetal abdomen is disproportionally small in relation to the head and limbs

List as many causes of inadequate fetal nutrition as you can

• Genetic/constitutional

• Nutrition/starvation

• Hypoxic

• Vascular

• Renal

• Antiphospholipid antibody environment

• Drugs

• Poor obstetric history

List causes of IUGR when the mother is healthy & has adequate nutrition

• Aneuploidy

• Trisomy 13, 18, 21

• Triploid

• Turner’s syndrome

What are the 3 steps to determining weight percentile?

• Measure infant's weight

• Compare weight to standardized growth charts

• Determine percentile based on weight relative to peers of same age and sex

Discuss problems determining IUGR from just weight percentile

• Weight does not account for gestational age, variations in fetal growth patterns, or underlying maternal conditions

What other criteria has been considered to make the diagnosis of IUGR?

• Fetal anthropometric measurements

• Amniotic fluid index

• Doppler ultrasound assessments

What Doppler finding in the middle cerebral artery raises the concern of IUGR? Why does this occur?

• Elevated systolic-to-diastolic ratio (SDR) indicates increased vascular resistance, often due to compromised placental blood flow

• Best tool to identify small fetuses at risk for an adverse outcome

• Fetal cardiovascular system allow assessment of the blood flow redistribution observed in IUGR

How does Doppler compare to other criteria in predicting IUGR?

• Asses blood flow in fetoplacental or uteroplacental circulations; essential for fetal nourishment and oxygenation

What is the value of Doppler in IUGR?  Describe the significance of absent or reversed diastolic flow in the umbilical artery

• Assess placental blood flow and predict adverse outcomes

• Reversed diastolic flow in umbilical artery + absent diastolic flow or elevated systolic/diastolic ratio = very poor prognosis

• Elevated risk of fetal demise

What 3 findings are ominous for the development of severe IUGR?

• Chorionic hypertension

• Advanced-stage diabetes mellitus

• Placental insufficiency

Abnormal uterine artery Doppler carries an increased risk of what abnormalities? What are the Doppler characteristic of an abnormal uterine artery waveform

• Placental insufficiency, fetal growth restriction, and adverse pregnancy outcomes.

• Higher resistance pattern, increased end-diastolic velocity, and a notched waveform appearance

What method appears to be the best way of predicting IUGR (Rumack)?  What are the 3 key parameters of this method?

• Doppler ultrasound; important role in timing the delivery of some growth restricted fetuses

• 3 key parameters = estimated fetal weight, amniotic fluid volume, and maternal blood pressure status (normal vs. hypertensive)

Once IUGR has been diagnosed, what else should be done?

• Evaluation of both mother and fetus

• Maternal assessment = physical examination and blood tests; directed toward diagnosis of hypertension, renal disease and other maternal conditions that can cause IUGR

• Fetal assessment = sonographic examination (looking for suggestive chromosomal or viral etiology; holoprosencephaly, clenched hands, rocker-bottom feet, intracranial calcifications)

What is the definition of large for gestational age (LGA) & macrosomia?

• Large for gestational age (LGA) = weight above 90th percentile for gestational age

• Macrosomia = weight above 4000g (8lbs, 13 oz); other weight cutoffs (4100 g, 4500 g) are sometimes used)

What are the risk factors for LGA & macrosomia?

• Maternal obesity

• Diabetes

• History of previous LGA infant

• Prolonged pregnancy (>40 weeks)

• Excess pregnancy weight gain

• Multiparity

• Advanced maternal age

What complications are associated with these fetuses?

• Perinatal morbidity/ mortality

• Shoulder dystocia

• Fractures

• Facial and brachial plexus palsies; traumatic delivery

• Perinatal asphyxia

• Meconium aspiration

• Neonatal hypoglycemia

• Metabolic complications

What are the differences in LGA & macrosomic fetuses from diabetic & non-diabetic mothers?

• LGA & macrosomic fetuses from diabetic mothers = more severe metabolic complications + higher congenital anomalies

• Non-diabetic mothers = fewer associated risks

• Fetuses of insulin-dependent and gestational diabetic mothers = high levels of glucose throughout pregnancy; produce excess insulin —> greater degrees of fat deposition and organomegaly while the head and brain grow at a normal rate

Discuss how Doppler is used in pregnancy

• Assess blood flow in fetus and placenta

• Measures the velocity of blood flow in various fetal vessels

• Evaluate fetal well-being

• Detect potential complications; intrauterine growth restriction (IUGR) or placental insufficiency

What are three common quantitative methods of describing peak blood flow velocity waveforms?   How can the Doppler waveform be described qualitatively?

• Resistive index (RI), pulsatility index (PI), and S/D ratio (systolic/diastolic ratio)

• Doppler waveform can be described based on its shape, presence of diastolic flow, and the degree of resistance

List two fetal factors that can affect the Doppler waveform

• Placental dysfunction; blood flow may be absent or reserved

• Uterine artery waveforms should be obtained during periods of fetal apnea because fetal breathing affects waveforms

What artery supplies the majority of blood to the uterus?  Describe this artery’s origin & its branches to the endometrium

• Uterine artery

• Common iliac → internal iliac → uterine → arcuate artery → radial artery → spiral artery

Where should the Doppler waveform of the uterine artery be obtained? Describe the normal uterine artery Doppler waveform in nonpregnant  female.

• Soon after crossing of the iliac vessel

• Uterine arterial blood flow in a nonpregnant women = 50 ml per minute and increases to over 700 mL/min

How does the uterine artery Doppler waveform change with pregnancy? Why does this occur? When does this effect on the Doppler waveform occur? How does placental location affect the uterine artery Doppler?

• During pregnancy, uterine artery Doppler waveform decreased resistance and increased blood flow due to the vascular adaptations necessary for fetal growth

• Occurs as early as the first trimester

• Placental location influences the waveform by altering blood flow dynamics and resistance

What are the characteristics of an abnormal uterine artery Doppler waveform during pregnancy?

• Increased resistance and impaired diastolic flow; placental insufficiency or other complications

• High pulsatility index and a delayed/ absent diastolic notch

What problems are associated with abnormal uterine artery Doppler waveforms?

• IUGR

• Fetal death

• Fetal neurologic outcome

• Pre-eclampsia

Describe the characteristic of the Doppler waveform of the umbilical artery in the 1^st trimester? How & when does umbilical artery Doppler waveform change?

• 1st trimester, umbilical artery Doppler waveform shows low resistance and high blood flow; healthy placental perfusion

• As pregnancy progresses, waveform demonstrates increased resistance and a higher pulsatility index, indicating potential complications

What is a worrisome appearance of the umbilical artery Doppler waveform & what does this put the fetus at risk for?  What is the cause for the abnormal Doppler & what does it lead to?

• Reduced or absent diastolic flow; fetus at risk for IUGR and fetal demise

• Abnormal Doppler often caused by placental insufficiency, leading to compromised blood flow to the fetus

• Lead to poor fetal nutrition and oxygenation; increasing risk for adverse outcomes

How does the resistance in the middle cerebral artery change as pregnancy advances?  How does resistance in the middle cerebral artery compare to resistance in the umbilical cord?

• As pregnancy advances, resistance in middle cerebral artery typically decreases, demonstrating increased blood flow to the fetal brain

• In contrast, resistance in umbilical artery increases; reduced blood flow to fetus

What causes the resistance in the middle cerebral artery to decrease from normal?  What is this process called?

• Due to increased blood flow and vessel dilation

• "Brain-sparing"; effect observed in fetal circulation during compromised conditions

What characteristic of middle cerebral Doppler is used in the evaluation of the anemic fetus?

• Decreased resistance index; increased blood flow to the brain in response to anemia

Describe the findings in acute fetomaternal hemorrhage.

• Presence of fetal blood in the maternal circulation; leads to tachycardia in the fetus and possible anemia or hypovolemic shock in maternal

• Elevated MCA or hemorrhage

Review fetal circulation & blood flow through the ductus venosus.  Be able to describe the S, D, & A waves of the DV waveform

• Ductus venosus = transports oxygenated blood from the umbilical vein to the left atrium and ventricle, then to the myocardium and the brain

• “S”'; peak systolic velocity (PSV); highest velocity of the blood in systole

• Isovolumetric relaxation (IRV) = period of decreased velocity

• “D” = rapid filling of ventricles that is followed by a nadir

• “A” wave = atrial contraction

 What constitutes an abnormal DV waveform & what are the associated abnormalities?

• “A” wave of reversed flow

• “A” wave becomes more pronounced closer to the time of fetal demise

What hemodynamic changes occur with hypoxia?

• Hypoxia leads to increased systemic vascular resistance and decreased cardiac output

• In response, the body initiates compensatory mechanisms, such as increased heart rate and redistribution of blood flow to vital organs

What are the ominous Doppler signs in the umbilical artery, fetal aorta, umbilical vein, & ductus venosus?

• Reversed diastolic flow in the aorta or umbilical artery

• Pulsatile venous flow waveform

• Absent end diastolic flow in the umbilical artery in the midsecond trimester is abnormal