*2.2.2. Absence of the kidney in the renal fossa*

It can be caused by renal agenesis or ectopic kidney. True isolated renal agenesis is confirmed by the absence of renal artery and is associated with oligoamnios if it is bilateral. Unilateral renal agenesis can be isolated but association as VACTERL is common [14]. Failing to visualize the urinary bladder can be caused more frequently by bilateral renal agenesis or exstrophy.

### *2.2.3. Renal agenesis*

It is defined as bilateral absence of kidneys with an incidence variable from 1 to 3/10000 births and it is more frequent in male fetuses—**Figures 3** and **4**. Renal agenesis can be sporadic (due to teratogens or diabetes mellitus), isolated, or part of syndrome association, the most frequent found being:

**Figure 3.** Renal agenesis—transverse abdominal section—no renal structure on the right side.

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


Oligohydramnios is a constant finding in bilateral renal agenesis, and it can be seen from 14 weeks of gestation. "Potter syndrome" associates the following abnormalities:


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

• oligohydramnios.

**Figure 3.** Renal agenesis—transverse abdominal section—no renal structure on the right side.

• facial cleft;

• congenital diaphragmatic hernia;

252 Congenital Anomalies - From the Embryo to the Neonate

studies have shown a neonatal mortality of 75%.

*2.2.2. Absence of the kidney in the renal fossa*

*2.2.3. Renal agenesis*

frequent found being:

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

It can be caused by renal agenesis or ectopic kidney. True isolated renal agenesis is confirmed by the absence of renal artery and is associated with oligoamnios if it is bilateral. Unilateral renal agenesis can be isolated but association as VACTERL is common [14]. Failing to visualize the urinary bladder can be caused more frequently by bilateral renal agenesis or exstrophy.

It is defined as bilateral absence of kidneys with an incidence variable from 1 to 3/10000 births and it is more frequent in male fetuses—**Figures 3** and **4**. Renal agenesis can be sporadic (due to teratogens or diabetes mellitus), isolated, or part of syndrome association, the most

• neuromuscular conditions [9].


The differential diagnosis should include other anomalies of the kidney, associated with oligohydramnios as polycystic kidney disease, multicystic kidneys, etc.

When bilateral renal agenesis is suspected, a detailed examination of the fetal anatomy should be performed considering the high risk of other anomalies association [15]:


The prognosis depends on the grade of urinary incontinence and the associated genital anomalies [17] with a survival rate of 80% in the cases where surgery interventions are needed to reconstruct the bladder wall and the genitalia. Although, it has been suggested that in the case of genital ambiguity, the sex should be deemed female, later follow-up has shown that the patients, male or female, can lead a normal life with a normal IQ and in some cases, corrective

Congenital Abdominal Anomalies

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

The presence of cystic lesions in the fetal abdomen can have many underlying conditions. The diagnosis can be made upon their appearance: unique or multiple, the situs of the abnormal structure, and its relations with the abdominal viscera, the aspect of the wall and content. In most cases, the correct prenatal diagnosis of these structures is difficult to make and their origin

**2.3. Abnormal structures present in the abdomen: cystic or hypoechoic masses**

and fertility surgery can improve the quality of life.

**Figure 5.** Bladder exstrophy—no urinary bladder can be seen.

• intestinal cysts (mesenteric or duplication intestinal cysts),

can be determined only after birth.

Single cystic masses can be:

• megacystis,

• ovarian cysts,

• choledocal cysts,

• kidney solitary cyst.

• multiple intestinal cysts,

Multiple cystic lesions can be more frequent: • double bubble image in duodenal atresia, • bowel dilatations in obstruction conditions,

• hepatic cysts,


The prognosis is usually lethal due to the association of pulmonary hypoplasia and growth retardation, the fetuses die in utero or in the first days of life.

#### *2.2.4. Bladder exstrophy*

Bladder exstrophy as well as cloacal exstrophy arise from the abnormal growth of the caudal fold, resulting in a anterior abdominal wall defect. The absence of the anterior abdominal wall and the anterior bladder wall will expose the posterior bladder wall to the amniotic fluid. Small defects result in epispadias, but a larger one might expose the posterior bladder wall. The incidence of bladder exstrophy is 1:30,000 births, with male fetuses being more affected [16]. These anomalies are frequently sporadic, although familial transmissions have been reported [16].

Positive and differential ultrasonographic diagnosis of bladder exstrophy should be suspected whenever the bladder cannot be visualized, even though the amniotic fluid volume is normal (the cycle of the bladder filling is 15 min)—**Figure 5**. Others ultrasound signs useful are:


Bladder exstrophy must be differentiated from gastroschisis and omphalocele. In those conditions, despite the abdominal wall defects, the bladder is still present within the fetal pelvis [17]. The risk of association with chromosomal and nonchromosomal syndromes is low. Perinatal counseling depends on the association with other anomalies. If the prenatal diagnosis of bladder exstrophy is made, therapeutic abortion must be offered as an option.

**Figure 5.** Bladder exstrophy—no urinary bladder can be seen.

The prognosis depends on the grade of urinary incontinence and the associated genital anomalies [17] with a survival rate of 80% in the cases where surgery interventions are needed to reconstruct the bladder wall and the genitalia. Although, it has been suggested that in the case of genital ambiguity, the sex should be deemed female, later follow-up has shown that the patients, male or female, can lead a normal life with a normal IQ and in some cases, corrective and fertility surgery can improve the quality of life.
