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Digestive System: Congenital Anomalies


Digestive System: Congenital Anomalies
Time period: birth
Facial abnormalities
A relatively common congenital abnormality is cleft lip and/or cleft palate which affects around 1 in 600–700 live births and has a collection of defects.

Cleft lip (cheiloschisis) can be incomplete (affects upper lip only) or complete (continues into the nose) and unilateral (Figure 35.1) or bilateral. It is caused by the incomplete fusion of the medial nasal prominence with the maxillary process (Figure 35.2). When these fuse normally they form the intermaxillary segment, which goes on to become the primary (soft) palate.
The secondary (hard) palate forms from outgrowths of the maxillary process called the palatine shelves. Failure of these shelves to fuse or ascend to a horizontal position causes cleft palate (palatoschisis). In very severe cases the cleft can continue into the upper jaw. Cleft palate is often accompanied by cleft lip (complete), but not always (incomplete; Figure 35.3), and can also be unilateral or bilateral.
A cleft lip is generally diagnosed at the 20‐week anomaly scan, whereas cleft palates are diagnosed after birth. Cleft lips require surgical intervention before 3 months, whereas cleft palate surgery should happen before the child reaches 12 months old. Cleft lip and palate can affect feeding and speech, but also hearing. To aid prevention of cleft lip and palate maternal dietary folic acid is recommended (see also spina bifida, Chapter 17).
Digestive System: Congenital Anomalies

Foregut abnormalities
Abnormalities in development of the foregut can include stenosis and atresia at various points along its length, and hypertrophy of the pylorus of the stomach. Depending upon the point of restriction projectile vomiting can be a symptom, and the presence or absence of bile in the vomit can help diagnose the location.
The respiratory tract forms as a bud from the foregut, so a tracheoesophageal fistula can form (Figure 35.4). The most common variant sees the proximal oesophagus end blindly and the trachea connected to the distal oesophagus. There are many other variations and frothy oral secretions are often a symptom. Surgery is required.
A congenital hiatal hernia is caused by the oesophagus not
lengthening fully, preventing the diaphragm from forming normally and pulling the top of the stomach up into the thorax. This can affect the development of respiratory structures, and occurs in varying severity.

Midgut abnormalities
A remnant of the vitelline duct that connected the yolk sac to the midgut may persist as an ileal diverticulum (also known as Meckel’s diverticulum; Figure 35.5) or as a vitelline cyst (also known as an omphalomesenteric duct cyst) in the distal ileum. An ileal diverticulum is present in around 2% of the population, but the majority are asymptomatic. Ulceration may form here with bleeding. If the vitelline duct persists as fibrous cords between the abdominal wall and the ileum loops of intestine may become twisted around it. The duct may survive as a true duct between the ileum and the external umbilicus.
The midgut may fail to complete its rotation or to fail to rotate in the normal direction during development, giving abnormal rotation or reverse rotation of intestine. Abnormal rotation is caused by only a 90° rotation and gives a left‐sided colon, whereas reverse rotation causes the transverse colon to lie posterior to the superior mesenteric artery after a 90° clockwise rotation of the midgut instead of the normal 270° counterclockwise rotation.

Omphalocoele (or exomphalos) is the herniation of abdominal contents into the umbilicus, and the contents remain covered by peritoneum and amnion (Figure 35.6). This can normally be diagnosed by antenatal ultrasound scanning. Omphalocoele is thought to occur as a failure of the midgut to reenter the abdominal cavity after the normal herniation of weeks 6–10. Omphalocoele is often associated with cardiac and neural tube defects, trisomy 13 and 18 and Beckwith–Wiedemann syndrome.

Hindgut abnormalities
The urorectal septum normally separates the cloaca into urogenital and hindgut spaces. If this fails to occur normally links between the two spaces can occur, such as a rectourethral (urorectal) fistula (Figure 35.7) or a rectovaginal fistula (Figure 35.8).
Anal atresia can occur, possibly as a result of interrupted blood supply during development. Imperforate anus may also occur if the cloacal membrane does not break down. There are different degrees of severity, and some require a colostomy whereas others are repairable with surgical intervention, often within 24 hours of birth.

Associated organs
Liver
Jaundice affects 60% of healthy newborn infants and has multi- ple causes, often categorised by age of onset. It is normally identified through the infant’s skin colour and bilirubin levels. Most cases of jaundice do not need treatment, but phototherapy helps reduce bilirubin levels. In extreme cases an exchange transfusion is necessary.
Pancreas
Due to abnormalities in the rotation of the ventral bud pancreatic tissue can end up surrounding the duodenum. This is called an annular pancreas. It is possible that this tissue can constrict the duodenum and cause a complete blockage. Early signs can include polyhydramnios. It is normally treated with surgery.
Spleen
Splenic lobulation and an accessory spleen are relatively common. Rarer conditions include a wandering spleen and polysplenia (multiple accessory spleens).
Splenogonadal fusion, a very rare developmental anomaly, results from the abnormal fusion of the splenic and gonadal primordia during prenatal development.
Hyposplenism (reduced splenic function) may occur because of a congenital failure of the spleen to ted individuals are at increased risk of bacterial sepsis.

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