*2.2.1. Esophageal atresia*

normal renal cortex is as echogenic as the liver or spleen and that the normal renal medulla

• the small bowel is visible as a uniform, echogenic mass that can be differentiated from the colon by its central layout, aspect, and peristaltic changes, until the third trimester when its aspect is of round anechoic image with peristalsis (large intestinal loops filled with me-

• the colon appears as a tubular structure located at the periphery of the abdomen, meanwhile the small intestine is centrally placed. The haustration of the wall serves to differentiate from other anechoic or hypoechoic structures. Meconium production begins at 16 weeks of pregnancy, giving the ultrasound-like appearance of the intestinal wall.

The echogenicity of the colon is established in comparison to other structures such as the liver

• grade 1: the colon is hypoechogenic, isoechoic with the stomach and the bladder, haustrations

• grade 2: the colon's echogenicity is higher than the bladder, but lower than the liver and occurs

Coronal or sagittal section of the fetal abdomen allows the visualization of the urinary bladder. It can be identified starting at 11–12 weeks of gestation as an anechoic mass with a thin

The most common condition is the nonvisualization of the stomach, kidneys, or urinary

Nonvisualization of the gall bladder occurs in rare chromosomal diseases, mucoviscidosis,

Absent stomach or small stomach can be associated with mechanical or functional absence of

• absent or reduced fetal swallowing: facial clefts, neuromuscular conditions, infections, SNC

• mechanical obstruction or compression: esophageal atresia, diaphragmatic hernia, and thoracic

• reduced amniotic fluid production: oligohydramnios of any cause.

• grade 0: the abdomen is uniformly homogeneous and the colon cannot be visualized.

• grade 3: echogenicity is similar to the liver's and occurs after 34 weeks.

is relatively hypoechogenic, which leads to a well-defined CMD [4].

conium) [5].

250 Congenital Anomalies - From the Embryo to the Neonate

or bladder:

bladder.

stomach filling:

tumors.

being present.

after 29 weeks.

wall, delineated by two umbilical arteries.

**2.2. Absence of normal abdominal structures**

and in 20% of the fetuses with biliary atresia [6].

conditions, and fetal hydrops.

There are five types of esophageal atresia, but the most common one after de Jong is the type with esophageal stump and trachea-esophageal connection below the interruption. In such cases, it is important to look after other indirect signs, like polyhydramnios and small for gestational age. Many of the anomalies are nonisolated [7]. Still, 44% of the anomalies are not diagnosed during the prenatal period [7].

Esophageal atresia is a condition defined by the lack of continuity between the proximal and the distal esophagus. The missing portion is the middle one and the main cause is poor blood flow. The anomaly appears during the 8th week of pregnancy when the primitive intestine fails to divide forming the trachea anteriorly and esophagus posteriorly. According to de Jong, in 90% of cases, esotracheal fistulae are associated. There are five types of esophageal atresia considering the anatomical location of the defect and the existence of the tracheoesophageal fistula [7]:


The incidence of this anomaly is 1:3500 live born and usually is nonisolated, being associated with CNS anomalies, VACTERL association, T21, T18, diaphragmatic hernia, and abdominal wall anomalies. [7]. Twenty percent of cases of the associations are with chromosomal anomalies (trisomy 13, 18, 21) [8] and cardiac defects may be present in 50% of cases. VACTERL syndrome is comprised of vertebral defects, ventricular septal defect, anal atresia, esotracheal fistula, renal anomalies, radial aplasia, and single umbilical artery [9].

Ultrasound diagnosis of esophageal atresia can be missed in pregnancy according to Brandberg and 44% of the cases cannot be diagnosed.

The prenatal diagnosis of esophageal atresia is difficult due to the absence of specific signs. The rate of detection varies between 8 and 24% [10, 11], and the lack of detection is due in 85% of cases to the tracheoesophageal fistulae association.

Prenatal esophageal atresia must be suspected if polyhydramnios is present after the 25th week of gestation and if the gastric pouch is absent. Sometimes, gastric secretions are sufficient to distend the gastric pouch, and make the diagnosis more difficult; if an esotracheal fistula is present, the gastric pouch may appear normal. Sometimes, the distal dilated portion of the esophagus may be observed as a hypoechoic area in the mediastinum, behind the heart (blind pouch aspect). Although the sign has a great diagnostic value, it is rarely present before 25 weeks of gestation [8, 12, 13]. The detection rate is improved if an antenatal MRI is performed.

The differential ultrasound diagnosis can be made with other conditions with absent stomach, the most frequent are:


The risk of association with other anomalies, chromosomal and nonchromosomal, is high rising to 30–40% of cases: trisomy 21 and 18, VACTERL association. Perinatal approach implies karyotype analysis when the diagnosis is made. The birth should take place in a tertiary center with a neonatal intensive department considering the high risk of fetal hypotrophy (40% of cases) and prematurity (due to polyhydramnios). Surgical reconstruction of the esophagus is possible. The prognosis depends on the association with other congenital anomalies and on the gestational age at birth. After 32 weeks of gestation, if the prenatal diagnosis is achieved, reflux and aspiration pneumonia can be prevented and the survival rates are over 95%. Long time prognosis is affected by the high rate of postoperative complications [9]. The postoperative mortality is approximately 9%, with a intrauterine fetal mortality of 22%. Retrospective studies have shown a neonatal mortality of 75%.

• Cat's eye syndrome, characterized by iris coloboma, anal atresia, preauricular tags, and renal

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http://dx.doi.org/10.5772/intechopen.72170

• 4p-Syndrome is characterized by multiple heterotopies of cells (in adrenals, brain, pancreas,

• Fraser syndrome with: cryptophthalmos, syndactyly, auditory canal atresia, cleft palate,

• a very severe syndrome: cerebro-oculo-facio-skeletal syndrome, characterized by: microcephaly, microphthalmia, narrow palpebral fissures, high nasal bridge, large ears, micrognathia, kyphosis, scoliosis, flexion contraction of the extremities, and rocker-bottom foot.

Oligohydramnios is a constant finding in bilateral renal agenesis, and it can be seen from

• abnormal position of the hand and foot and bowed legs, clubbed feet, hip dislocation.

• bilateral absence of the fetal kidney (sometimes the adrenal glands can be confused with the kidneys therefore the visualization of the normal cortical and medular structures is

• absence of the urinary bladder. If the urinary bladder is present the bilateral adrenal agenesis

14 weeks of gestation. "Potter syndrome" associates the following abnormalities:

• typical face—low set ears, epicanthus, parrot-beak nose, and receding chin.

Ultrasound diagnosis of bilateral renal agenesis is based on three main elements:

and skin), renal agenesis, cardiac, facial, and genital anomalies.

**Figure 4.** Unilateral renal agenesis—coronal section depicting only one renal artery.

• in some cases, Müllerian duct anomalies can be associated.

renal agenesis, and genital anomalies.

anomalies.

• pulmonary hypoplasia.

• oligohydramnios.

is excluded.

useful for exclusion).

• intrauterine growth retardation.

• absence of urinary bladder visualization.
