AssessmentsCongenital disorders: Clinical practice
USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A 5-year-old boy comes to the clinic because of a recent diagnosis of ectopia lentis. The mother is concerned about the health of her son and claims concern surrounding his development. He is very tall for his age with long limbs, thin, with clear mental deficiencies. He is very pale but has malar flush. Laboratory studies show elevated concentrations of homocysteine and methionine in the serum as well as an elevated concentration of homocysteine in the urine. He is diagnosed with an autosomal recessive disorder that affects amino acid metabolism. Which of the following is the most appropriate treatment of this disease?
Content Reviewers:Rishi Desai, MD, MPH
Congenital anomalies appear as the baby develops in utero and vary in severity and presentation, ultimately impacting the infant's health, development, and survival.
We can talk about some of the more common and severe defects, beginning with the head and then making our way down the body: cleft lip, esophageal atresia, congenital diaphragmatic hernia, gastroschisis, omphalocele, biliary atresia, bladder exstrophy, and open neural tube defects.
So first, a cleft lip is when the individual’s upper lip doesn’t form completely and has an opening in it. It is usually associated with a cleft palate, which is when the palate doesn’t form completely and has an opening in it.
Now, these defects can occur as isolated malformations or as part of a syndrome involving multiple other organs, including the heart.
Regarding prenatal diagnosis, cleft lip can be diagnosed with accuracy via ultrasound after 13 or 14 weeks of gestation. Ultrasound images in the coronal view and axial planes can help see the fetal lip and palate and assess if there are any associated abnormalities like lower limbs or the vertebral column defects.
After birth, diagnosis is clinical.
Early management is mostly supportive, and it aims to help the baby eat. It can be done with devices like specially designed bottle nipples, dental appliances, a feeder that can be squeezed to deliver formula, and an artificial palate molded to the individual’s own palate.
However, surgical closure is the definitive treatment. For a cleft palate, a 2-stage procedure is often done. First, the cleft lip, nose, and soft palate are repaired at age 3 to 6 months. Then, the residual hard palate cleft is repaired at age 15 to 18 months.
Esophageal atresia is a birth defect resulting in an interrupted esophagus. This way, the esophagus has two separate sections—the upper and lower esophagus—that do not connect. One or more fistulas between the esophagus and trachea may also occur.
Prenatal diagnosis is rare, but it can be suspected on an ultrasound that detects polyhydramnios and an absent or small stomach in the second or third trimester.
After birth, clinically, the newborn chokes or vomits most or all the food they consume.
Next, if esophageal atresia is suspected, a gastric tube inserted in the infant’s nose or mouth. If it cannot pass down into the stomach, diagnosis is confirmed and an x-ray is needed to assess the location of the obstruction.
Treatment consists of surgery to remove the obstruction and reconnect the two segments of the esophagus. If presents, any fistula will also need to be litigated.
Third, congenital diaphragmatic hernia is due to absent or abnormal fusion of the pleuroperitoneal folds during the formation of the diaphragm. This causes the organs in the abdomen to slip into the chest.
Around half of the cases have associated anomalies, most commonly cardiac, urogenital, and musculoskeletal.
Now, because usually herniation occurs on the left, the lung on the affected side doesn’t develop as it should and it becomes hypoplastic.
Diagnosis for congenital diaphragmatic hernias is prenatally done by ultrasound. Left-sided defects are characterized by the presence of the small bowel in the left chest, which is distinguished from other lesions by its peristalsis and fluid content. The fluid-filled stomach may be absent from the abdomen, and it might be displaced into the lower thorax next to the left heart. A portion of the liver may be herniated as well, appearing as a homogeneous dark mass in the chest.
Postnatal diagnosis evaluation begins with a clinical examination. Because the lung is underdeveloped, after birth, newborns will mostly present respiratory distress, usually within the first hours after birth. Other common findings include a barrel-shaped chest, a scaphoid or boat-appearing abdomen since the abdominal contents migrate into the chest, and absence of breath sounds on the affected side. More often than not, the heartbeat is displaced to the right because of a shift in the mediastinum.
Next, diagnosis is confirmed by chest radiography showing herniation of the bowels into the hemithorax with little or no visible lung on the affected side. Other radiographic findings include displacement of mediastinal organs like the heart on the opposite side, compression of the healthy lung, and a small abdomen with no visible bowel. In the rare instances when the defect is right sided, the liver may be the only herniated organ and will appear as a large thoracic mass.
Postnatal management can be divided into two parts. Preoperative medical management consists of correcting the individual’s oxygenation, blood pressure, and acid-base status if these are disturbed.
And the second part consists of surgical repair, which includes closure of the diaphragmatic defect and reduction of the viscera into the abdominal cavity.
Next, gastroschisis is an abdominal wall defect through which the bowel, and sometimes other abdominal organs, slips outside the abdomen.
Prenatal diagnosis can be made by maternal serum alpha-fetoprotein assessment and ultrasound by 12 weeks of gestation.
On ultrasound examination, gastroschisis appears located to the right of the umbilical cord insertion site and tends to be under 4 centimeters in diameter. Sometimes, when the bowels herniate, it can compromise the mesenteric blood supply, which combined with the exposure to the toxic environment of the amniotic fluid, it leads to bowel wall inflammation and decreased bowel motility. The stomach is usually in the wrong position, even when intra-abdominal. The eviscerated intestinal loops lack a covering membrane and float freely in the amniotic fluid.
After birth, the diagnosis is clinical and it is based on the exteriorization of the bowels through the midline defect and on the absence of the covering membrane.
Treatment begins with delivery room care. Neonatal fluid and heat losses are 2.5 times that of a healthy newborn and it only increases when the bowels are exposed. This is why covering the bowels with sterile saline dressings and wrapping them with a plastic wrap is mandatory.
Additional steps include inserting an orogastric tube to decompress the stomach and providing respiratory support if required.
The defect must then be closed via surgery, which can be difficult if the defect is large and other abdominal organs are also herniated; however, the prognosis is generally very good.
Ok, fourth, omphalocele is also a midline abdominal wall defect through which the abdominal contents eviscerate.
However, omphalocele is covered by a membrane of amnion and peritoneum, with an additional layer of Wharton’s jelly between those two.
The defect occurs at the base of the umbilical cord, with the cord and umbilical vessels inserting at the apex of the omphalocele sac.
Prenatal diagnosis is possible through ultrasound by the end of the first trimester. Ultrasonography can also categorize omphaloceles are in either non-liver-containing or liver-containing omphalocele.