*2.3.5. Mesenteric and omentum cysts*

They are usually an accumulation of lymphatic fluid produced by lymphatic hamartomas or blockage of the lymphatic drainage. Ultrasound diagnosis can be suspected in the presence of a hypoechoic lesion located usually on the midline. The cysts can vary in size, their content can be unilocular or multilocular, or filled with echoic masses with solid content caused by secondary hemorrhage. The cysts can be filled with serous, hemorrhagic, or chylous fluid.

The prognosis of the cyst depends on the possible complications: intestinal obstruction, torsion, and hemorrhage. Malignant transformation of the cysts is rare. Prenatally, the cysts require drainage by puncture, only when they are of important size and can cause compression and secondary hydrops. After birth, the management is surgical but a complete resection of the cysts is difficult because of the close vicinity with large vessels and because of the 20% rate of recurrence.

The clear majority of the ovarian cysts is benign and resolves spontaneously after birth. The differential diagnosis has to be made with hydrocolpos, a condition that manifests itself as a hypoechoic or hyperechoic pelvic mass in a female fetus [20]. The prognosis is usually good but complications may appear like: torsion of the cysts, ascites, intracystic hemorrhage, rupture of the cysts, or cyst infarction. In such cases, the inner aspect of the cyst can change and speckles or hyperechoic structures inside the cyst can appear. When the cysts are large, intestinal compression could induce polyhydramnios. In such cases, cyst puncture and amniodrainage should be considered. There is no need for cesarean section, but when the risk of premature birth is high due to polyhydramnios, birth should take place in a tertiary unit.

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It is defined by a dilatation of the renal pelvis and calyceal system that exceeds the normal size according to the age of gestation (anteroposterior diameter of the renal pelvis over 4 mm at 20 weeks and over 7 mm at 32 weeks)—**Figures 9** and **10**. The most frequent cause is the ureteropelvic junction obstruction. When dilatation of the ureter occurs, the obstruction is lower usually at the vesicoureteral junction [21]. It is more common in males than in females, with a sex ratio of 5:1. Ureteropelvic junction obstruction is usually sporadic, but can also

Anatomic causes that produce ureteropelvic junction obstruction are: fibrous adhesions, bands, kinks, ureteral valves, aberrant lower pole vessels, abnormal ureteral insertion, and unusual shapes of the pyeloureteral outlet. They can be associated with urinary anomalies and extraurinary anomalies: vesicoureteral reflux, bilateral ureteral duplication, bilateral obstructed megaureter, contralateral nonfunctioning kidney, contralateral renal agenesis, Hirschsprung's disease, cardiovascular abnormalities, neural tube defects, sagittal synostosis, mandibular hypoplasia, esophageal atresia and distal fistula, imperforate anus, syndactyly, congenital hip

*2.3.9. Congenital hydronephrosis*

**Figure 8.** Duodenal stenosis—same case after birth.

dislocation, and adrenogenital syndrome.

be inherited.

#### *2.3.6. Hepatic cysts*

Hepatic cysts are a rare finding in the prenatal life. Usually, they are located in the right hepatic lobe and can produce obstruction of the intrahepatic biliary system. Their ultrasound aspect is of a unilocular anechoic round structure. Even after birth, they are asymptomatic and complications like infections and hemorrhage rarely occur. In approximately 30% of cases, hepatic cysts are associated with polycystic renal disease [19].

#### *2.3.7. Duplication intestinal cysts*

Duplication intestinal cysts are rare but located throughout the entire gastrointestinal tract. They appear in the form of tubular-like structures of variable sizes, and can occur singularly or associated with renal malformations, adenomatous cystic lung malformations, and lung sequestration. The thickening of the cystic wall and the peristaltic movements make the diagnostic process easier. The surgical excision of the cysts is the only therapeutic choice.

#### *2.3.8. Ovarian cysts*

Ovarian cysts are the most frequent fetal tumors and they are a relatively frequent finding during fetal autopsy (approximately 1/3 of fetuses). The cysts are usually asymptomatic and small. Ovarian fetal cysts are hormone-dependent (influenced by the human chorionic gonadotropin hormone, estrogens, and placenta hormones) and appear after 25 weeks of gestation [20].

Ovarian cysts (**Figure 8**) appear as anechoic round images located laterally to the urinary bladder. They are unilateral and unilocular and appear most frequently in isoimmunizationaffected fetuses or those coming from pregnancies associated with diabetes, probably due to placental hyperplasia.

**Figure 8.** Duodenal stenosis—same case after birth.

the upper right abdominal quadrant. The differential diagnosis includes intestinal duplication cysts, hepatic cysts, situs inversus, and duodenal atresia. The absence of polyhydramnios and the presence of intestinal peristalsis are useful for excluding intestinal obstruction. Common complications that intervene after birth are: biliary cirrhosis, hypertension, lithiasis, and rarely—adenocarcinoma. The complications can be prevented by early postnatal diagnosis

They are usually an accumulation of lymphatic fluid produced by lymphatic hamartomas or blockage of the lymphatic drainage. Ultrasound diagnosis can be suspected in the presence of a hypoechoic lesion located usually on the midline. The cysts can vary in size, their content can be unilocular or multilocular, or filled with echoic masses with solid content caused by secondary hemorrhage. The cysts can be filled with serous, hemorrhagic, or chylous fluid. The prognosis of the cyst depends on the possible complications: intestinal obstruction, torsion, and hemorrhage. Malignant transformation of the cysts is rare. Prenatally, the cysts require drainage by puncture, only when they are of important size and can cause compression and secondary hydrops. After birth, the management is surgical but a complete resection of the cysts is difficult because of the close vicinity with large vessels and because of the 20% rate of recurrence.

Hepatic cysts are a rare finding in the prenatal life. Usually, they are located in the right hepatic lobe and can produce obstruction of the intrahepatic biliary system. Their ultrasound aspect is of a unilocular anechoic round structure. Even after birth, they are asymptomatic and complications like infections and hemorrhage rarely occur. In approximately 30% of cases,

Duplication intestinal cysts are rare but located throughout the entire gastrointestinal tract. They appear in the form of tubular-like structures of variable sizes, and can occur singularly or associated with renal malformations, adenomatous cystic lung malformations, and lung sequestration. The thickening of the cystic wall and the peristaltic movements make the diag-

Ovarian cysts are the most frequent fetal tumors and they are a relatively frequent finding during fetal autopsy (approximately 1/3 of fetuses). The cysts are usually asymptomatic and small. Ovarian fetal cysts are hormone-dependent (influenced by the human chorionic gonadotropin hormone, estrogens, and placenta hormones) and appear after 25 weeks of gestation [20].

Ovarian cysts (**Figure 8**) appear as anechoic round images located laterally to the urinary bladder. They are unilateral and unilocular and appear most frequently in isoimmunizationaffected fetuses or those coming from pregnancies associated with diabetes, probably due to

nostic process easier. The surgical excision of the cysts is the only therapeutic choice.

and surgical resection. Surgical mortality rate is about 10% [19].

hepatic cysts are associated with polycystic renal disease [19].

*2.3.5. Mesenteric and omentum cysts*

260 Congenital Anomalies - From the Embryo to the Neonate

*2.3.6. Hepatic cysts*

*2.3.8. Ovarian cysts*

placental hyperplasia.

*2.3.7. Duplication intestinal cysts*

The clear majority of the ovarian cysts is benign and resolves spontaneously after birth. The differential diagnosis has to be made with hydrocolpos, a condition that manifests itself as a hypoechoic or hyperechoic pelvic mass in a female fetus [20]. The prognosis is usually good but complications may appear like: torsion of the cysts, ascites, intracystic hemorrhage, rupture of the cysts, or cyst infarction. In such cases, the inner aspect of the cyst can change and speckles or hyperechoic structures inside the cyst can appear. When the cysts are large, intestinal compression could induce polyhydramnios. In such cases, cyst puncture and amniodrainage should be considered. There is no need for cesarean section, but when the risk of premature birth is high due to polyhydramnios, birth should take place in a tertiary unit.

#### *2.3.9. Congenital hydronephrosis*

It is defined by a dilatation of the renal pelvis and calyceal system that exceeds the normal size according to the age of gestation (anteroposterior diameter of the renal pelvis over 4 mm at 20 weeks and over 7 mm at 32 weeks)—**Figures 9** and **10**. The most frequent cause is the ureteropelvic junction obstruction. When dilatation of the ureter occurs, the obstruction is lower usually at the vesicoureteral junction [21]. It is more common in males than in females, with a sex ratio of 5:1. Ureteropelvic junction obstruction is usually sporadic, but can also be inherited.

Anatomic causes that produce ureteropelvic junction obstruction are: fibrous adhesions, bands, kinks, ureteral valves, aberrant lower pole vessels, abnormal ureteral insertion, and unusual shapes of the pyeloureteral outlet. They can be associated with urinary anomalies and extraurinary anomalies: vesicoureteral reflux, bilateral ureteral duplication, bilateral obstructed megaureter, contralateral nonfunctioning kidney, contralateral renal agenesis, Hirschsprung's disease, cardiovascular abnormalities, neural tube defects, sagittal synostosis, mandibular hypoplasia, esophageal atresia and distal fistula, imperforate anus, syndactyly, congenital hip dislocation, and adrenogenital syndrome.

*2.3.10. Multicystic kidney disease*

difficult to diagnose prenatally.

tertiary unit (**Figures 13** and **14**).

*2.3.11. Autosomal dominant polycystic kidney disease (ADPKD)*

It is a congenital disorder characterized by cystic lesions that correspond primarily to dilated collecting tubules. The disease can be bilateral, unilateral, or segmental and it is known also as

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It can be isolated or associated with urinary or extraurinary disorders such as: malrotations, ureteropelvic junction obstruction, horseshoe kidney, cardiovascular malformations, CNS abnormalities (anencephaly, hydrocephalus, iniencephaly, spina bifida, occipital meningocele), diaphragmatic hernia, cleft palate, microphthalmia, duodenal stenosis and imperforate anus, esotracheal fistula, and bilateral absence of radius and thumb. Association with liver

Ultrasound diagnosis of multicystic kidneys (**Figure 11**) is made in the presence of an enlarged unilateral or bilateral kidney with multiple round anechoic structures peripheral located and variable in size. In some cases, the kidneys can be small but the renal sinus cannot be identified. Oligohydramnios is a common association, but in some cases, when the lesion is unilat-

Differential diagnosis includes infantile polycystic kidney disease, single cyst, ureteropelvic junction obstruction, Wilms tumor and hamartoma that has undergone necrosis, but can be

The prognosis of bilateral disease is poor and termination of pregnancy can be offered. Unilateral isolated disease prognosis can be favorable, but delivery should take place in a

Adult polycystic kidney disease (APKD) is an autosomal dominant condition characterized by the presence of multiple cysts of variable size in the renal parenchyma. The cysts can replace the parenchyma and are produced by the dilatation of the collecting tubules and other tubular segments

**Figure 11.** Hydronephrosis—significant dilatation of the renal pelvis and reduced thickens of the renal functional tissue.

Potter's type II syndrome, cystic kidney disease, and multicystic dysplastic kidneys.

cysts or pancreatic cysts is not characteristic for Potter II syndrome [24].

eral or the obstruction is incomplete, amniotic fluid may have normal volume.

**Figure 9.** Intestinal obstruction—small bowel dilatations above the obstruction level.

Ultrasound diagnosis is based on the evidence of the dilated renal pelvis and on the measurement of the anteroposterior diameter of the dilatation on transverse abdominal section. Former criteria of hydronephrosis dilatation included also the ratio between the maximum transverse pelvic diameter and the renal diameter at the same level with ratios above 50% being the cut-off for hydronephrosis. Most UPJ obstructions are unilateral and bladder should fill normally. In case of severe oligohydramnios, association of unilateral hydronephrosis contralateral renal agenesis or dysplasia should be suspected. Differential diagnosis includes multicystic dysplastic kidneys, polycystic kidneys, and other condition associated with anechoic abdominal masses [22].

The prognosis of ureteropelvic obstruction is generally good, but requires serial ultrasound scans to evaluate the progress of the dilatation. In most cases, the surgery is not needed, but the postsurgery mortality is absent [23].

Concerning the prenatal management, there is no need for premature intervention and vaginal birth is preferred (**Figures 11** and **12**).

**Figure 10.** Ovarian cyst—two anechoic round structures in the fetal pelvis with no Doppler signal.
