Week 23: Pediatric Endo/GI

The criterion standard for diagnosing urinary tract infections is the isolation of a pathogen from a urine culture obtained via suprapubic aspiration. Although not commonly performed, this is the gold standard technique. Most experts consider any bacterial growth from a suprapubic aspiration sample positive, whereas others require >1000 CFU of a single organism. The only exception is the growth of coagulase-negative staph. such as Staph. epidermidis, which are normal skin flora that may contaminate an aspiration performed with poor technique. In such cases, there would have to be >3000 CFU of S. epidermidis to be considered positive.

Bag collection (A) has a high false positive rate. Urine cultures are considered positive with the identification of >100,000 CFU of a single organism. Suprapubic aspiration (B) of 2,000 CFU of Staph. epidermidis is generally considered contamination because S. epidermidis is normal skin flora. Urethral catheterization (D) is considered positive with >50,000 CFU of a single organism.

A child that presents with a new onset seizure that is unresponsive to multiple doses of conventional medications should alert the physician to the possibility of hyponatremia or other electrolyte abnormality as the cause of the seizure. Hyponatremia can occur in infants who are fed formula that is improperly made resulting in excess free water consumption. Sodium levels < 120 mEq/L can cause seizures and will respond to sodium correction. Typically raising the sodium levels only 3-5 mEq will result in cessation of seizure activity. A seizing patient with hyponatremia should be treated with 3% hypertonic saline 2 mL/kg over 20-30 minutes. The goal is to raise the sodium level above 120 mEq/L acutely and then correct to normal levels slowly over the next 24 hours. 25% dextrose (A) can be given to correct hypoglycemia which may cause a seizure. However, this infant has a normal glucose level. Levetiracetam (C) and midazolam (D) can be given to control seizures but are likely to be ineffective in this child given the likelihood of hyponatremia as the cause of her seizures.

This patient’s history is consistent with tracheoesophageal fistula (TEF). The most common TEF discovered outside of the newborn period is the H-type fistula. A water soluble contrast swallow is the diagnostic test of choice as barium provokes an extensive inflammatory reaction in the lungs and hinders surgical exploration. In combination with decubitus views, the fistula tract will be identified. Tracheoesophageal fistula is the most common cause of esophageal obstruction in neonates. During embryonic development, the trachea and esophagus normally separate and develop in a linear fashion. With a TEF, there is abnormal communication between the trachea and esophagus.

An arterial blood gas (A) would help to determine if an arterial-alveolar gradient exists for shunting problems or issues with diffusion of oxygen, but it would not be helpful in determining this patient’s diagnosis. A chest radiograph (C) can help in diagnosing an associated pneumonia but will not assist in determining the etiology of this condition. Barium (B) provokes an extensive inflammatory reaction in the lungs and hinders surgical exploration.

This child is exhibiting signs and symptoms consistent with breast milk jaundice. Breast milk jaundice is an indirect hyperbilirubinemia in an exclusively breastfed newborn that develops after the first 4 to 7 days of life, persists longer than physiologic jaundice, and has no other identifiable cause. An unusual metabolite of progesterone, a substance in the breast milk that inhibits uridine diphosphoglucuronic acid (UDPGA) glucuronyl transferase frequently causes the indirect hyperbilirubinemia seen in breast milk jaundice. There is also evidence that exclusive breastfeeding delays establishment of the gut flora and results in increased enterohepatic circulation and reabsorption of bilirubin. Management of breast milk jaundice is by continued breastfeeding as this is most often a benign condition. In rare instances, a breastfeeding holiday may be required for bilirubin levels > 20 mg/dL.

ABO incompatibility (A) often presents in the first day of life with severe jaundice, lethargy, and poor feeding. These children require phototherapy for treatment to prevent kernicterus. Breastfeeding failure jaundice (B) is seen in exclusively breastfed infants who are not getting enough breast milk. This leads to decreased stool output and accumulation of bilirubin. Physiologic jaundice (D) is usually seen at 2 or 3 days of life due to decreased conjugation of bilirubin by the immature liver.

This patient is presenting with signs and symptoms consistent with necrotizing enterocolitis (NEC). NEC is defined as bowel necrosis of an unknown etiology. It classically affects premature infants at a much higher rate than those born at term. Signs and symptoms of NEC include abdominal distension, poor feeding, vomiting, and bloody stool. Abdominal wall erythema seen on physical exam is a rare, but pathognomonic finding of NEC. Diagnosis of NEC is with abdominal radiograph, which reveals pneumatosis intestinalis (intramural air within the bowel wall). This radiographic finding is pathognomonic for NEC. Management is first with prolonged bowel rest, nasogastric decompression, and antibiotics.

Intussusception (A) presents with vomiting and colicky severe abdominal pain. A late finding of intussusception is currant jelly stool. Midgut volvulus (B) presents with bilious emesis. Pyloric stenosis (D) presents with projectile nonbilious vomiting after feeding followed by immediate hunger.

This patient had a brief resolved unexplained event (BRUE). Clinicians should use the term BRUE to describe an event occurring in an infant younger than 1 year when the observer reports a sudden, brief, and now resolved episode of ≥ 1 of the following: (1) cyanosis or pallor; (2) absent, decreased, or irregular breathing; (3) marked change in tone (hyper- or hypotonia); and (4) altered level of responsiveness. Moreover, clinicians should diagnose a BRUE only when there is no explanation for a qualifying event after conducting an appropriate history and physical examination. Approximately50% of all cases of BRUE have no apparent cause. Among the other 50% of cases, the 3 most common conditions are gastroesophageal reflux (GER), seizure, and lower respiratory tract infection. These 3 accounts for 50% of all diagnoses eventually made. GER is a normal physiologic process defined by the passage of gastric contents into the esophagus with or without vomiting or regurgitation that occurs in healthy infants, unlike gastroesophageal reflux disease (GERD) in adults, which is a pathological process. The infant in this vignette has a clinical history that suggests a diagnosis of GER that was exacerbated by overfeeding. The best approach is to reduce feeding volumes and increase feeding frequency.

A diagnosis of GER in infants is based upon a history of spitting up. A formal intraesophageal pH monitoring (C) is of no value in routine evaluation. Although seizure is 1 of the most common causes of BRUE, the patient in this vignette has no historical features in the parental report that suggest seizures; therefore, an EEG (B) is not indicated. In addition, an EEG is difficult to obtain in the ED and has low sensitivity for diagnosing chronic epilepsy. Most patients who have epilepsy return with a 2nd episode. Therefore, it has been suggested that EEG be reserved for patients with recurrent BRUE. Older studies had suggested that a mechanism for reflux-induced apnea involves acid stimulation of pharyngeal and esophageal chemoreceptors that lead to laryngospasm. However, recent large studies and additional studies have failed to show correlation between acid reductions with a H₂ blocker or a proton pump inhibitor (PPI) and apneic events. Therefore, lansoprazole (A), a PPI, would not help this patient.

In the neonatal period, the most likely cause of lower gastrointestinal bleeding is swallowed maternal blood, from either delivery or cracked nipples during breast-feeding. The Apt test differentiates fetal from maternal blood. The blood in question is mixed with alkali to detect conversion of oxyhemoglobin to hematin. Fetal hemoglobin is more resistant to denaturation than adult hemoglobin is. If the supernatant stays pink after addition of alkali, the blood is fetal in origin (a positive test). This should not be confused with the Kleihauer-Betke test, used to detect fetal-maternal hemorrhage in the pregnant female.

Necrotizing enterocolitis (C) is a complication of premature infants and presents with abdominal distension, bloody stools, and feeding intolerance. Milk protein allergy (B) should be suspected after introduction of a new formula. Infants who are breastfed are not immune to this condition if Mom consumes cow’s milk in her diet. Since the mother in this vignette is a vegan and is breastfeeding, it is unlikely that a milk protein allergy is responsible for the patient’s guaiac-positive stool. In older infants with painless hematochezia, congenital malformations such as small intestine duplication and Meckel’s diverticulum (A) should be considered. Meckel’s diverticulum is most common at two years of age.

This patient is exhibiting signs and symptoms consistent with severe neonatal jaundice. Jaundice is defined as discoloration of the skin and sclera caused by the accumulation of unconjugated or conjugated bilirubin. Jaundice on the first day of life is frequently caused by blood group system or ABO incompatibility. Severe jaundice with a total bilirubin > 25 mg/dL places this patient at risk for kernicterus, which is defined as neurotoxic hyperbilirubinemia. Kernicterus presents in phases. The first phase, seen on the first few days of life, is characterized by lethargy, hypotonia, and poor feeding. Phase 2 is characterized specifically by hypotonia of the extensor muscles. Phase 3, which is seen with infants over 1 week of age with persistent severe jaundice, is characterized by diffuse severe hypotonia. Chronic bilirubin encephalopathy can lead to persistent hypotonia, hyperreflexia, delayed motor milestones, and variable cognitive deficits. MRI will classically reveal bilateral symmetric high-intensity signals in the globus pallidus in patients with kernicterus.

Gastric reflux disease (A) is not related to jaundice or elevated bilirubin levels. Necrotizing enterocolitis (D) will present with feeding intolerance and abdominal distension instead of jaundice. Abdominal radiographs reveal pneumatosis intestinalis. Muscular dystrophy (C) is a genetic disorder characterized by progressive muscle weakness, most often seen in the proximal lower extremities first. It is not associated with jaundice.