Neonatal Gastrointestinal Disorders

Overview (Failure to Pass Meconium)

Hallmark sx on neonatal bowel obstruction include: Failure to pass mconium in 24 hours, Abdominal distention, Reluctance to feed, AND Bilious vomiting. If there is failure to pass meconium:

1. R/o imperforate anus (or any other anal abnormality)
2. Order abominal XR
   1. Double-bubble sign = duodenal atresis or malrotation
   2. Multiple dilated loops of bowel = distal intestinal obstruction
3. Order upper GI series
   1. Duodenal C-loop does not coross midline = malrotation
   2. Bird’s beak sign = malrotation and volvulus
   3. Transition zone in small bowel = jejunal/ileal atresia
4. Order contrast enema
   1. Total microcolon = Meconium ileus
   2. Filling defects in the large bowl = Meconium plug syndrome
   3. Transition zone = Hirschprung’s disease
5. Strongly consider rectal manometry

Esophageal atresia/Tracheoesophageal fistula

Esophageal atresia involves incomplete formation of the esophagus, and can include a fistula between the esophagus and trachea. Part of the VACTERL sequence, hence get an echo and renal function tests to rule out cardiac and renal defects which may not be apparent on physical exam. Esophageal atresia w/distal TEF is the most concerning.

• VACTERL sequence
  • Vertebral anomalies
  • Anus (imperforate)
  • Cardiac defects
  • TracheoEsophageal fistula/atresia
  • Renal defects
  • Limb defects
• Signs and symptoms
  • Respiratory distress
    • Shortly after birth
    • Worsens with feeding
  • Regurgitation
  • Excessive salivation
  • Drooling
  • Sx of aspiration pneumonia
    • Fever
    • Tachypnea
    • Adventitious lung sounds
  • Failure to pass NG tube
  • Mother has a Hx of polyhydramnios
• Investigations
  • CXR/AXR: best initial test
    • Blind upper pouch (92%, NG tube is coiled before reaching the stomach)
  • Echocardiogram
  • U/E/Cs
• Treatment
  • Consult peds surg for surgical repair
  • NG decompression
  • IV fluids
  • IV nutrition or gastrostomy
  • IV antibiotics
  • Echo (for concurrent heart defects

Duodenal atresia

Duodenal atresia is a congenital absence or complete closure of part of the duodenal lumen. Defect occurs in early embryonic stages and may be detected antenatally on U/S (consider when baby is born to mother w/polyhydramnios). Associated with trisomies, cardiac lesions, and VACTERL. Presents earlier with less abdominal distension than more distal lesions. Annular pancreas may be found incidentally during surgery (Tx is the same – duodeno-duodenostomy, do not divide the annular pancreas)

• Signs and symptoms
  • Bilious vomiting within hours after birth (may be non-bilious)
  • Failure to pass meconium (unreliable d/t how proximal the atresia is)
  • Abdominal distension
• Investigations
  • Abdominal XR
    • Double-bubble sign (stomach and duodenum)
• Treatment
  • Consult peds surg for corrective surgery (duodeno-duodenostomy)
  • NG decompression
  • IV fluids and nutrition
  • May defer sx (perform a contrast enema to r/o malrotation)
• Post-op notes
  • Observation
  • Continue parenteral nutrition (until first stool is passed)
  • Prophylactic IV antibiotics

Intestinal atresia

Intestinal atresia is atresia elsewhere distal in the GI tract caused by vascular accidents in utero. Less association w/congenital anomalies. 10% have Cystic Fibrosis.

• Signs and symptoms
  • Bilious vomiting
  • Failure to pass meconium
  • Abdominal distention (proportion to how distal the obstruction is in the GI tract)
• Investigation
  • Abdominal XR: base suspicion to location. Can also do w/contrast enema
    • Multiple dilated loops of bowel
    • Microcolon (in colonic atresia)
• Treatment
  • Consult ped surg for Corrective surgery
  • NG decompression
  • IV fluids and nutrition
• Post-op notes
  • Parenteral nutrition (until baby passess first stool)
  • Prophylactic antibiotics

Hypertrophic pyloric stenosis

Hypertrophic pyloric stenosis is hypertrophy of the muscular layer of the pylorus resultin in gastric outlet syndrome. Typically presents between 2 weeks and 2 months of life.

4:1 M>F preponderance. Increased risk in 1st borns. Increased risk if the parent has a Hx.

• Signs and symptoms
  • Projectile nonbilious vomiting
    • f/b desire to feed (baby still hungry)
  • Sx consistent w/dehydration
  • “Constipation” (baby not making wet diapers)
  • Palpable “olive-like” nodular mass over epigastric/RUQ
• Investigations
  • U/E/Cs and BGA: hypokalemic, hypochloremic metabolic alkalosis
  • UGI contrast studies:
    • Transition zone between stomach and duodenum
    • String sign
  • Abdominal U/S
• Treatment
  • Correct dehydration and electrolyte/metabolic abormalities
    • NS bolus
    • Potassium
  • Monitor urine output (nl = 1 mg/kg/d) to ensure adequat hydration
  • Consult peds surg for surgical correction (Pyloromyotomy)
    • Serosa is incised over the pylorus → muscles of the antrum are divided (do not disrupt the duodenum nor enter the stomach)
• Post-op notes
  • Begin liquids 4-6 hrs post-op
  • Begin full feeds 24 hrs post-op
• Post-op complications
  • Post-op vomiting (50-80% of pts, self-limiting)
  • Apnea (put patient on apnea monitor)
  • Duodenal perforation during surgery
    • Repair
    • IV Abx
    • NG decompression

Malrotation and volvulus

Malrotation is abnormal/incomplete rotation of the bowel during fetal development. The bowel are not in anatomical position and there are fibrous bands (Ladd’s bands) covering parts of the intestine.

70-90% of cases are diagnosed within the first year of life.

• Complications of malrotation and volvulus
  • Intestinal obstruction: d/t Ladd’s bands
  • Midgut volvulus: volvulus involving the SMA; resulting in severe bowel ischemia and further complications
• Signs and symptoms
  • Bilious vomiting
  • Bloating
  • Abdominal distention
  • Fever
  • Blood-streaked stool or melena
  • Dehydration (hydration status may vary)
• Investigations
  • Abdominal XR:
    • Double bubble sign
    • Distal air-fluid levels
  • Upper GI contrast series OR Contrast enema
    • Dilated bowel on the right side only (Malrotation w/o volvulus)
    • “Corckscrew” or “beked” like appearance w/scant contrast distally (Malrotation and volvulus = IO → vomiting, distension + fever, bloody stools etc.)
• Treatment
  • Admit to PICU/NICU
  • IV antibiotics
  • Emergency paediatric consultation
  • Emergency surgical correction w/resection of dead bowel
    • Ladd’s procedure
    • Second look in 24-48 hrs

Omphalocele

Omphalocele is a defect of the abdominal wall musculature, resulting in protrusion of the abdominal viscera through the umbilical cord. Visceral organs are visible but are covered with a protective sack. Dx antenatally via sonography

• Associations
  • Trisomies
  • Beckwidth-Weidman syndrome
  • NTDs
  • Cardiac defects
  • Other congenital anomalies
• Treatment
  • Admit to NICU
  • Cover exposed viscera w/moistened sterile gauze (prevents fluid loss and infetion)
  • NG decompression
  • IV fluids/nutrition
  • Staged closure
• Complications of omphalocele
  • Respiratory compromise
  • Compression of IVC

Gastroschisis

This is a bigger problem. Gastroschisis is an incomplete fusion of the abdominal wall resulting in free herniation. Gastroschisis does not have a protective sac and the viscera are in acute danger (infection, peritonitis, bowel necrosis…, needs to be covered up ASAP). Dx antenatally via sonography

• Associations
  • Trisomies
  • SGA (50%)
• Complications
  • Chemical peritonitis
  • Sepsis
  • Bowel desruction
• Treatment
  • Admit to NICU
  • Cover abdominal contents w/moistened sterile gauze
  • NG decomression
  • IV fluids/nutrition
  • Broad spectrum IV antibiotics (prevent peritonitis)
  • Urgent surgery within 24-48 hours; staged closure

Meconium ileus

Meconium ileus is an impaction of meconium (overly thick and tenacious) in the distal small bowel. Common in babies with Cystic fibrosis (13-17% of patient swith CF)

• Patient History
  • Cystic fibrosis
• Signs and Symptoms
  • Abdominal distention
  • Bilious vomiting
  • FPM
  • Respiratory distress (resulting from severe distension)
• Investigations
  • Abdominal X-ray
    • Multiple loops of smal bowel (distal obstruction) in a “soap-bubble appearance”
  • Upper GI contrast Study
  • Contrast enema
    • Microcolon
    • Insippated w/meconium at the terminal ileum
• Treatment
  • Contrast enema w/N-acetylcysteine (NAC) added to fluid to dissolve the meconium (successful 50% of the time)
  • Laparotomy

Meconium plug syndrome

Not the same as meconium ileus. In meconium plug syndrome, the meconium is normal, but the intestine is functionally immature. The meconium becomes backed up and forms a plug.

• Patient History
  • Infants of Diabetic moms
  • Mother on Magnesium sulphate (d/t pre-eclampsia)
• Differentials
  • Meconium ileus: contrast enema shows normal colon in meconium plug, but microcolon in meconium ileus
  • Hirschprung’s disease: affects rectosigmoid area. Anorectal manometry and/or rectal biopsy for definitive r/o
• Investigations
  • Contrast enema
    • Filling defects
• Treatment
  • Contrast enema w/N-acetylcysteine added to the fluid to dissolve the meconium
  • Anorectal manometry (10-30% of meconium plug cases coexist w/Hirschprung’s disease

Hirschprung’s disease

Hirschprung’s disease involves abscence of ganglion cells in the mucosa and muscularis layer of a segment of colon.

Incidence of 1/5000. Boys: Girls 4:1.

80% = rectosigmoidal disease (short-segment disease)

15-20% = extends proximal to the sigmoid (long-segment disease)

<5% = involves the entire colon*

• Associations
  • Genetic abnormalities (esp. Down syndrome)
• Signs and symptoms
  • Failure to pass meconium
  • Abdominal distention
  • Reluctance to fed
  • Enterocolitis (fever, bloody stool, explosive diarrhoea(
  • DRE
    • Empty rectal vault
    • Release of stool/flatus
  • Bouts of alternnating constipation and diarrhea
  • Primarily constipation (in older children)
• Investigations
  • Abdominal Xray
    • Multiple loops of dilated bowel (distal obstruction)
  • Contrast enema
    • Transition zone (occurs later in life)
  • Manometry
  • Rectal biopsy: most accurate test
• Treatment
  • Peds surgical consult
  • Surgical resection of aganglioni segment
    • Diverting colostomy/ileostomy followed by secondary take-down, or by primary repair
• Complications
  • Fecal retention
  • Incontinence
  • Anastomotic breakdown
  • Stricture

Necrotizing enterocolitis

Necrotizing enterocolitis has an unclear etiology; but is most likely d/t bacterial dyscolonization causing hypoxic injury to the bowel.

• Pathophysiology
  • Hypoxia → Intestinal sloughing → bacterial invasion into the wall (pneumatosis intestinalis) and inflammation → gangrene and perforation
• Patient History
  • Premature
• Signs and symptoms
  • Abdominal distention
  • Abdominal pain
  • Blood in stool
  • Intolerance to feeds
  • Vomiting
  • Diarrhea
  • Decreased bowel sounds
  • Erythema over the abdomen
  • Shock
• Investigations
  • AP and LLD Abdominal X-ray: best initial test
    • Dilated bowel
    • Edematous walls
    • Intramural air (pneumatosis intestinalis; an ominous sign)
    • Sx of perforation in LLD view (absolute indication for emergent Sx)
  • CBC: thrombocytopenia, abnormal white cell count (leukocytosis followed by leukopenia), low Hct
  • U/E/Cs: hyponatremia
  • BGA: metabolic acidosis
• Treatment
  • Peds surgical consult
  • NPO (do not resume PO feeds until disease resolves, subjectively and objectively)
  • NG decompression
  • Supplemental O2; closely monitor pulse Ox
  • IV fluids and TPN
  • Broad spectrum Abx (Amp/gent, pip/taz)
  • Repeat AXR, BGA (to look for improvement)
• Indications for emergent surgery
  • Evidence of perforation on XR
  • Fixed dilated loop of bowel
  • Abdominal cellulitis
  • Deterioration despite maximal medical support

Imperforate anus

An imperforate anus is an abnormal termination of the anorectum. Includes fistulas opening into the vaginal vault or perineum (esp. girls), colourethral fistulas (esp. boys), or blind rectum. Dx is via px, UA, and pelvic radiographs.

• Signs and symptoms
  • Imperforate anus
  • Failure to pass meconium
  • UTI (esp in boys d/t colourethral fistula)
  • VACTERL associations
• Treatment
  • NPO
  • IV fluids, nutrition
  • Echocardioraphy (to r/o cardiac defects
  • Surgical repair
    • Immediate surgical repair for supralevator type
    • May delay surgical repair if there is an external opening