Fetal Chest, Abdomen, Pelvis

List 5 general parameters/structures/aspects that we evaluate on sonogram of the fetal chest

• Chest size/shape

• Heart position/axis

• Fetal ribs

• Lung echo texture

• Diaphragm

Describe normal sonographic appearance of the fetal ribs and thorax.

• Fetal ribs = ossification (echogenic) + length should wrap around half way around chest

• Thorax = symmetricaly bell shaped with ribs forming the lateral margins; clavicles forms upper margin, diaphragm forms lower margin

What is the TC:AC ratio?  Where is the TC measurement obtained? 

• TC = AC ; indirect assessment of fetal lung volume

• Measured @ level of 4 heart chamber

Describe the normal fetal cardiac position and normal axis within the fetal chest

• Midline + left of chest

• Apex point towards spleen (left side)

• Fetal cardiac axis is measured by the angle formed between intraventricular septum and the line perpendicular to the spine; 22-75 degrees

What is the normal fetal lung echogenicity, in comparison to the fetal liver, in early and late gestation?

• Early gestation = similar/ slightly less echogenic compared to liver

• Late gestation = echogenic compared to liver

The fetal heart occupies approximately what portion of the fetal chest?

• 1/3 thoracic volume on transverse

List 4 (listed 5) “general” types of abnormalities in the thorax, that we can see on ultrasound

• Chest mass

• Pleural effusion

• Lung abnormalities; pulmonary hypoplasia

• Congential diaphragmatic hernia

• Heart defects

Define pulmonary hypoplasia. List 6 potential causes of pulmonary hypoplasia

• Small & inadequately developed lungs; reduction in lung volume due to prolonged oligohydramnios or small thoracic cavity

• Large mass on neck or sacrum, severe prolonged oligohydramnios, poor prognosis, congenital diaphragmatic hernia (compressed lungs), abdominal mass, chest mass, renal abnormalities

List sonographic signs of pulmonary hypoplasia (list 3)

• Small chest to abdomen (bell-shaped)

• Prominent heart (>1/3 of chest)

• Absence of fetal breathing movement in setting of oligohydramnios due to PROM

What is the sonographic sign given to the “small chest” seen in pulmonary hypoplasia?

• Concave or bell-shaped thorax

Describe pulmonary artery Doppler to determine pulmonary hypoplasia

• Detect changes in pulmonary artery waveforms; predict pulmonary hypoplasia

• PSV in proximal artery flow velocity reduced in hypoplasia

What is “isolated” hydrothorax/ pleural effusion?

• Accumulation of fluid within pleural cavity that appears as isolated lesion or multiple fetal anomalies

What is “secondary” hydrothorax/pleural effusion? List 5 abnormalities associated with it

• Bulid-up fluid in pleural space associated with another underlying condition rather than primary problem of pleura itself

• Associated with = Turner’s syndrome, Trisomy 21, congestive heart failure, hamartoma, infection, genetic syndromes, high output failure in fetus

What is the usual progression of hydrothorax?

• Effusions conforms to thoracic cavity + compress lung tissue

• Lung appears to float in fluid; compression of lung parenchyma may cause pulmonary hypoplasia

List 5 abnormalities associated with pleural effusions in the fetus

• Infection

• Trisomy 21

• Cystic CPAM

• Congential diaphragmatic hernia

• Hydrop fetails

• Congenital heart disease

Pleural effusions in the fetus have the highest mortality rate when what 3 conditions are present?

• Lung hypoplasia

• Hydrops

• Diagnosed at early gestational age

Describe ultrasound’s role in the evaluation of fetal chest fluid

• Evaluate fetal chest to see fluid collection, location, and if its bilateral/unilateral

List 6 causes of fetal ascites

• Twin-twin transfusion syndrome

• Urinary perforation

• Hydrops, infections

• Tumors

• Bowel perforation

• Heart failure

List 3 most common chest masses diagnosed on ultrasound prenatally

• Congenital diaphragmatic hernia

• Congenital pulmonary airway malformation

• Congenital cystic adenomatoid malformation

• Bronchopulmonary sequestration

CDH is most often located on what side and what position, involving what foramen?

• Side = left side

• Position = posterolateral

• Foramen = foramen of Bochdalek

What is a less common site for CDH and the name of that specific location?

• Side = right side

• Position = anterior

• Foramen = foramen of Morgagni

List 4 sonographic findings associated with CDH.  Which is the key sonographic feature

• Fetal stomach displaced

• Abdominal circumference appears smaller

• Heart shifts to right side

• Bowel peristalsis in thoracic cavity

• Polyhydramnios

Describe lung:head ratio and its significance to diagnosis of pulmonary hypoplasia

• Measure lung behind heart

• Normal measurement = <2 mm (1.4 - 2 = good prognosis, <1.0 = poor prognosis)

List 2 factors affecting prognosis of CDH.

• Size of contralateral lung

• Size of herniated mass

Define CAM.  Is it usually bilateral or unilateral?

• Rare lung abnormality; part of fetal lung develops cystic or solid masses instead of normal lung tissue

• Unilateral (bilateral = rare but more severe)

What are the 3 types of CAM, describe their sonographic appearances

• Type I = replace normal lung tissue, can compress heart, alter hemodynamics, cause hydrops, cystic adenomatoid malformation, larger cyst; > 2 cm

• Type II = multiple small cysts; often < 1 cm, echogenic

• Type III = large, bulky, non-cystic lesion, solid mass, echogenic-dense, and resembles normal lung

List 5 differentials for CAM

• Pleural effusion

• Mediastinal teratoma

• Bronchopulmonary sequestration

• Congenital diaphragmatic hernia

• Bronchial cysts

Define bronchopulmonary sequestration and “intralobar vs. extralobar”.  What is the key sonographic feature to differentiate this entity from CAM?

• Rare lung condition of non-functioning lung tissue develops without connection to normal airway + receives own blood supply from systemic circulation

• Intralobar = located within normal lung tissue with no separate pleural covering; diagnosed later in childhood/adulthood with recurrent lung infections

• Extralobar = located outside of normal lung with own pleural covering; diagnosed in infancy

• Key sonographic feature: own systemic blood supply, unlike CAM.

List 4 differentials for BPS

• Congenital pulmonary airway malformation (CPAM)

• Bronchial atresia

• Lobar emphysema

• CDH

• CAAM

• Persistent pneumonia

 Describe CHAOS, and what are the associated findings?

• Congenital High Airway Obstruction Syndrome (CHAOS) = respiratory distress due to obstruction of the fetal airway; lungs becomes hyperexpanded & diaphragms is inverted or flattened

• Associated findings: laryngeal atresia, laryngeal or tracheal webs, laryngeal cysts, tracheal atresia, subglottic stenosis, and laryngeal or tracheal agenesis

When can the fetal esophagus be visualized on sonography (EV)? Where is the transducer placed to visualize the esophagus?

• 12 - 16 weeks (EV)

• Coronal view of fetus’s neck and chest; sagittal is secondary view

Esophageal atresia is most commonly associated with what syndrome?  List 3 sonographic findings associated with esophageal atresia

• Associated = tracheoesophageal fistula & trisomy 18

• Sono findings = absent/small stomach, polyhydramnios, and esophageal pouching

The fetal stomach can be “reliably” visualized when?

• 13 weeks

List 5 possible causes for non-visualization of the fetal stomach on sonogram.  List 3 abnormalities that can result in abnormal location of the stomach

• Possible causes = Physiological emptying, disorders affecting swallowing, esophageal obstruction, severe oligohydramnios or hydramnios, tumors in the esophagus/pharynx/ mediastinum, and congenital diaphragmatic hernia

• Abnormal location causes = diaphragmatic hernia, situs abnormalities, and abdominal wall defects (gastroschisis or omphalocele)

Define duodenal atresia.  List the primary sonographic features that are associated.  What syndrome is it associated?

• Blockage of duodenal lumen by membrane that prohibits passage of swallowed amniotic fluid

• Sono features = echogenic-free stomach and duodenum found in upper fetal abdomen w/ communication (double bubble sign)

• Double bubble sign associated w/ Down syndrome

• Associated w/ = Trisomy 21, cardiovascular anomalies, genitourinary anomalies, & gastrointestinal abnormalitites

What is the normal size for fetal small bowel?  List 5 causes of dilatation of the fetal small bowel

• Normal size: >/= 6mm; >7mm = abnormal

• Causes = Atresia, volvulus, malrotation, peritoneal bands, & cystic fibrosis

List 5 abnormalities associated with echogenic small bowel.

• Fetal ingestion of blood

• Trisomy 21

• Hypoperistalsis

• Cytomegalovirus

• Primary bowel abnormalities

• Severe growth restriction

• Decreased water content

List 5 differentials for cystic structures in the fetal abdomen.

• Ovarian cyst

• Bowel obstructions

• Hirshsprung

• Meckel’s diverticulum

• Meconium cyst

Describe Meckel Syndrome

• Rare, severe, and lethal autosomal recessive disorder charaterized by combination of multiple cysts on kidneys, occipital encephalocele, and polydactyly

List 3 sonographic findings associated with anal atresia. Anal atresia can be associated with what anomalies?

• Sono findings = dilated distal bowel segments, absent hypoechoic anal sphincter, and echogenic anal mucosa (“target sign”)

• Associated w/ = VACTERAL (vertebral, anal, cardiac, tracheoesophageal fistula, renal, and limb)

 Describe gastroschisis and typical sonographic findings.  What is the most common side involved?  What structures are usually protruding?

• Gastroschisis = periumbilical defect; located near right side of the umbilicus

  • Opening in layers of abdominal wall with herniation of bowel (mostly stomach and genitourinary organs but rarely the liver)

• Sono findings = free-floating loops of bowel in amniotic fluid, defect in the abdominal wall (usually right side of umbilicus), normal umbilical cord insertion, dilated/thickened bowel loops, and polyhydramnios

• Protrudes = small intestines, (occasionally) stomach or colon, and liver (rarely); herniation of the abdominal wall

Describe similarities and differences between gastroschisis and omphalocele. Describe omphalocele and classic sonographic findings

• Omphalocele = protruding mass; smooth + rounded contour & contained in a peritoneal membrane

• Gastroschisis = protruding mass; irregular contour + extruded abdominal content where bowel loops not contained by a membrane

• Sono findings = midline abdominal wall defect, herniated bowel/abdominal organs surrounded by a membrane

  • Higher risk chromosome abnormalities: omphaloceles > gastrochisis

List 4 anomalies associated with omphalocele

• Beckwith-Wiedemann syndrome

• Penology of Cantrell

• Cardiac anomalies

• Trisomy 13 and 18

Beckwith-Wiedeman syndrome includes what specific abnormalities?

• Macroglossia

• Hemi-hypertrophy

• Wilm’s tumor

• Omphalocele

• Organomegaly

  • Visceromegaly

  • Embryonal tumors

  • Neonatal hypoglycemia

  • Renal abnormalities

Umbilical cord cyst could be confused with?

• Warton’s jelly abnormalities

• Amniotic inclusion cysts

• Neoplasms

• Omphalomesenteric duct cysts

• Vascular anomalies

• Allantoic cysts

 List 3 examples of the midline disruption sequence anomaly

• Limb-body wall complex

• Pentalogy of Cantrell

• Cloacal exstrophy

 List 4 sonographic findings associated with Pentology of Cantrell

• Omphalocele

• Ectopia cordis

• Diaphragmatic hernia

• Ectopia cordis

Describe limb-body wall complex

• Aka. body stalk anomaly

• Rare + fatal birth defect resulting combination of congenital malformations such as body wall defects, limb deformities, and craniofacial abnormalities resulting form defective embryonic folding

 List 5 sonographic findings associated with bladder exstrophy.  What is OEIS?

• Infraumbilical anterior wall

• Echogenic soft tissue mass

• NTD

• Absent bladder

• Malformation of genitalia

• Omphalocele, bladder exstrophy, imperforate anus, spinal anomalies

The bladder is reliably seen at what number of weeks

12-13 weeks

Fetal urine production plays a major role after how many weeks? What is normal AFI and AFV?  When is fetal bladder filling seen on ultrasound.

• Production of urine = as soon as 9th week; reliable at 12-13 weeks

• After 16th week = amniotic fluid

• Normal AFI & AFV = 5-25cm; AFV/MVP = 2-8cm

• Seen = 2nd & 3rd trimester; empty/refill every 25-30 mins

What 2 structures can be seen with Doppler on either side of the fetal bladder?

• 2 umbilical arteries

When are kidneys visualized on ultrasound, as early as, reliably by?

• Seen early as 11 weeks (EV) or 12 weeks (TA)

• Reliable = 14-16 weeks

What sonographic information do we want to provide when evaluating the urinary tract (what questions do we answer) list 7

• Bladder appearance and size

• Bladder presence

• How the kidney is positioned

• Appearance

• Presented on both either one or both kidneys

• Valuate the collecting system for any dilation (one or both sides)

• Check for gender since some are more common in females or males

The fetal kidneys are normally what fraction (portion) of the AC?

• 1/3 of AC

 Before 20 weeks the renal pelvis should not be greater that ___mm?

• 4mm

List 4 sonographic findings associated with bilateral renal agenesis

• Nonvisualization of the kidneys

• Severe oligohydramnios

• Flattened appearance of the adrenal gland on sagittal

• Bell-shaped thorax

Describe Potter’s Syndrome and associated sonographic findings. List 3 other anomalies associated with Potter’s.  List 3 technical limitations when renal agenesis is present.

• Aka. Potter sequence

• Changes neonate's physical appearance due to oligohydramnios; caused by kidney problems, leading to underdeveloped lungs and other organ issues

• Associated anomalies = renal agenesis, mermaid syndrome, musculoskeletal anomalies, GI and cardiovascular anomalies

• Technical limitations = severe oligohydramnios, urachal diverticulum, and fetal bowel/adrenals that can mimic kidneys

The fetal kidneys initially develop where?  List 2 other renal developmental anomalies

• Initially develops in pelvis but ascends by 11th week

• Other anomalies = unilateral renal agenesis, horseshoe kidneys, and cross-fused

What is the most common renal abnormality seen in the fetal kidney?  What is the most common site for this abnormality?

• Fetal hydronephrosis

• Ureteropelvic junction obstruction

 What is normal pyelectasis >20 weeks?

• 5-7mm

Describe normal measurements of pyelectasis in third trimester

• <7 mm

List 6 potential causes of congenital fetal urinary obstruction

• Posterior urethral valves

• Ureteropelvic junction obstruction

• Ureterovesical junction obstruction

• Prune belly syndrome

• Multicystic dysplastic kidney

• Bladder exstrophy

Discuss the most common postnatal cause of infants with obstruction

• UPJ

 What is the 2^nd most common cause of obstruction?

• UVJ

 Describe “duplication” of the kidney

• Congenital condition where kidney has 2 separate non-communicating renal pelvis; potentially 2 ureters instead of 1

What is “BOO”, what is the classic sonographic finding associated with it?

• Bladder outlet obstruction; blockage at base of bladder that reduces or prevents urine flow into urethra (urine backup + other complications)

• Sono findings = more common in males, “keyhole” sign, posterior urethral valve, urethral atresia, caudal regression

List 9 possible sonographic characteristics of urinary tract abnormalities that can be seen on ultrasound

• Pelvic dilation of greater than 7mm

• Enlarged bladder

• Small kidneys

• Thickening of pelvis or urethral wall

• Calyceal dilation

• Urethral dilation of greater than 3mm

• Lack of corticomedullary differentiation

Discuss 3 renal cystic disease classifications and what disease processes are associated with each

• Dysplastic cysts = isolated multicystic dysplastic kidney and dysplastic kidney resulting from early severe obstruction; associated with MCDK and dysplastic early obstruction

• Hereditary cysts = polycystic kidney disease and inherited syndromes; associated with ARPKD and ADPKD

• Nondysplastic/nonhereditary cysts = associated with simple cysts, multilocular cysts, and medullary sponge kidneys

Describe sonographic findings associated with IPKD

• Bilaterally enlarged kidneys

• Increased renal echogenicity

• Loss of corticomedullary differentiation

• Oligohydramnios

• Absent or small bladder

• Compressed thorax (can lead to pulmonary hypoplasia)

Meckel (Meckel Gruber) syndrome can include what three abnormalities?

• Polydactyly

• Encephalocele

• Large echogenic kidney

• MCDK

 MCDK can be associated with what abnormalities on the contralateral side?  Describe a potential pitfall when evaluating renal cystic disease

• Abnormalities = UPJ, MCDK, renal agenesis

• Pitfall = mistaking normal fetal kidney appearance for pathology or misidentifying other structures as cystic kidneys

  • Common pitfalls = hyperechoic kidneys in 2^nd trimester, transient fetal pyelectasis, and adrenal gland mimics dysplastic kidneys

Fetal gender can be determined by what number of weeks?

• 16-20 weeks

 List 3 differentials for cystic masses in the female fetus?

• Mesenteric cysts

• Ovarian cysts

• Enteric duplication cysts

• Urachal cysts

• Hydrometrocolpos

The fetal adrenal gland in 3^rd trimester is approximately what % of the kidney length?

• 48-66%

List 4 potential masses of the adrenal gland

• Adrenal adenomas

• Pheochromocytomas

• Adrenocortical carcinomas

• Myelolipomas