*2.3.3. Hirschsprung's disease*

It is caused by the congenital absence of intramural parasympathetic ganglia of the colon. The deficiency is caused by the lack in neuroblast migration from the neural crest, which occurs between the 6th and the 12th week of development. Also, the degeneration of the already migrated neuroblasts, which can occur before or after birth, may be involved. The incidence is approximately 1:3000 births. This disease is usually sporadic, but in 5% of cases there is a familial transmission. In a small number of cases, Hirschsprung's disease is associated with Down syndrome.

Ultrasound diagnosis can be suspected in the presence of the dilatation of the intestinal lumen produced by abnormal peristaltic movements. At the ultrasound scan, images are similar to those found in anorectal atresia, in which the colon is also affected. Similarly, when the small intestine loops are affected, the images are of an obstruction with dilated intestinal loops and polyhydramnios. The prognosis depends on the postnatal postoperative evolution, which aims to resect the affected intestinal segment, and can include a temporary colostoma with a neonatal mortality rate of 20%. Considering the prematurity risk due to associated polyhydramnios and the need for postnatal surgery, the birth must take place in a tertiary unit, but cesarean birth is not mandatory.

#### *2.3.4. Choledochal cysts*

**Figure 7.** Duodenal stenosis—in utero image.

unit to assure proper care for the neonate.

258 Congenital Anomalies - From the Embryo to the Neonate

• intestinal malrotations with volvulus,

extrinsic obstruction are most frequently represented by:

*2.3.2. Intestinal obstruction*

• peritoneal adherences,

• Hirschsprung's disease.

• meconium ileus.

anorectal atresia.

The prognosis of isolated duodenal atresia is favorable, the rate of survival after corrective surgery is over 95%. The incidence of early postoperative mortality is between 3 and 5%, and the long term postoperative mortality rate is 6%. Considering the high risk of chromosomal anomalies association, the karyotype analysis is mandatory whenever duodenal atresia diagnosis is made prenatally, and also a careful examination of the fetus anatomy. Polyhydramnios can cause preterm birth and although vaginal delivery is allowed, it must take place in a tertiary

Intestinal obstruction is defined by the total or partial intestinal obstruction, which can occur in an intrinsic or extrinsic manner. The intrinsic lesions are caused by intestine stenosis or atresia. In the case of atresia, the two intestinal segments can be completely separated or tied by a fibrous band. In the case of intestinal stenosis, the two segments can be separated by a septum or a central diaphragm or the intestinal lumen is very narrow. "Apple-peel" atresia is characterized by the absence of an important intestinal segment that can include the distal duodenum, the entire jejunum, or the proximal ileum—**Figure 7**. Conditions that can produce

The intestinal areas affected in the order of frequency are: the distal ileum (35%), the proximal jejunum (30%), distal jejunum (20%), proximal ileum (15%), or it can be multicentric in approximately 5% of cases. Anorectal atresia results from an abnormal cloacal division in the 9 weeks of gestation [5]. The incidence of intestinal obstruction is 1:2000 births. In half of the cases, obstruction of the small intestine is present, and the other half is made up by

> They are defined as cystic dilatations of the common bile duct; they are rare and are usually of unknown etiology. The diagnosis is made in the presence of a transonic image located in

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