Neonatal Proximal Bowel Obstruction

Steven J. Kraus, MD

DIFFERENTIAL DIAGNOSIS

Common

Esophageal Atresia (EA)
Duodenal Atresia (DA) or Stenosis (DS)
Duodenal Web (DW)
Jejunal Atresia

Less Common

Hiatal Hernia
Midgut Volvulus (MV)
Annular Pancreas
Preduodenal Portal Vein

Rare but Important

Gastric Atresia

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Many neonates diagnosed prenatally by US or MR
Inability to pass nasogastric tube suggests EA
- Neonate usually has difficulty swallowing secretions
- Look for other radiologic findings of VATER or VACTERL
  - Vertebral anomalies, anorectal malformation, renal anomalies, radial ray anomalies, congenital heart defects
- Radiographs can be diagnostic for duodenal atresia
- “Double bubble” (rounded duodenum)
- Air-filled duodenum without complete distention → immediate upper GI to exclude MV (surgical emergency)
- Look for signs of Down syndrome
  - 11 rib pairs
  - Cardiomegaly, shunt physiology
Duodenal dilation with distal gas in face of bilious emesis is suspicious for midgut volvulus
- Immediate upper GI required
Radiographs show “triple bubble” of jejunal atresia
- Contrast enema sometimes to assess for distal atresia (suggested by microcolon)
Radiograph showing retrocardiac lucency suggests hiatal hernia
- UGI can confirm
- Frequently associated with gastric volvulus
Annular pancreas almost always associated with DA
Preduodenal portal vein rarely found in isolation
Gastric atresia usually with other atresias, not isolated

Helpful Clues for Common Diagnoses

Esophageal Atresia (EA)
- Intermittent fluid distention of proximal esophagus on fetal imaging
  - High T2 signal in distended pouch on fetal MR
  - Anechoic fluid distention of pouch on fetal US
- Air-filled esophageal pouch on newborn chest radiograph
  - Nasogastric tube tip upper esophagus
- Sometimes associated tracheoesophageal fistula (TEF); preoperative esophagram
  - Lateral position esophagram to show fistula
  - Fistula usually just above carina; extends anterior and superior toward trachea
- Sometimes associated with laryngotracheal cleft
- Faulty division of foregut
- 50-75% have associated anomalies
- 5 types
  - Proximal EA with distal TEF (82%)
  - EA without TEF (10%)
  - Isolated TEF (H type) (4%)
  - EA with proximal and distal TEF (2%)
  - EA with proximal TEF (2%)
Duodenal Atresia (DA) or Stenosis (DS)
- Dilated, round proximal duodenum and stomach “double bubble” on fetal imaging
  - Anechoic, high T2 signal in round D1-2 segment on fetal US/MR
- Air-filled “double bubble”; no distal gas on neonatal radiograph
  - If duodenum initially not rounded (partially distended), cannot exclude MV; immediate upper GI indicated
- Most common upper bowel obstruction in neonate
- Failure of vacuolization (recanalization) during embryogenesis
- Up to 33% also have annular pancreas
- Up to 33% also have Down syndrome
- Up to 28% also have malrotation
Jejunal Atresia
- “Triple bubble” on neonatal radiographs
  - Dilated air-filled stomach, duodenum, and proximal jejunum without distal gas
  - No other imaging generally required
  - Microcolon on water-soluble enema suggests additional distal atresia
- Dilated fluid-filled proximal bowel loops on fetal sonography or MR
- Absence or complete occlusion of intestinal lumen of segment of jejunum
- Likely due to in utero ischemic event

Helpful Clues for Less Common Diagnoses

Hiatal Hernia
- Neonatal radiography shows retrocardiac density overlying mid to right heart
- Upper GI shows gastroesophageal junction and stomach above diaphragm
  - Sliding hiatal hernia does not usually cause bowel obstruction
- Traction or torsion (volvulus) of stomach is common
- Can be associated with congenital short esophagus
Midgut Volvulus (MV)
- Abnormal twisting of small bowel around superior mesenteric artery causing obstruction ± bowel ischemia/necrosis
- Most frequent finding on abdominal radiography is normal bowel pattern
  - Multiple dilated bowel loops is later finding, likely due to ischemic ileus
  - Late findings: Pneumatosis, portal venous gas, gasless abdomen, free intraperitoneal air
- UGI
  - Duodenal dilation to 2nd segment of duodenum
  - Cone-shaped appearance of D2 segment with decompressed D3 and distal bowel
  - Usually duodenojejunal junction (DJJ) low and not at, or to left of, left vertebral pedicle on AP image (malrotation)
  - Rare cases of MV with normal duodenal rotation
  - Corkscrew appearance of duodenum and proximal jejunum
  - If contrast obstructed at D2, cannot exclude MV; may indicate surgical exploration at surgeon’s discretion
  - If enema performed, may show nonrotation with spiral course of colon involved in volvulus
Annular Pancreas
- Similar radiographic and UGI findings as DA, DW, MV
- Band of pancreatic tissue surrounds D2
Preduodenal Portal Vein
- Radiographic and UGI findings similar to DA, DW, MV

Helpful Clues for Rare Diagnoses

Gastric Atresia
- No gas beyond stomach; UGI: Gastric outlet obstruction
- Usually with multiple intestinal atresias
- Enema: Usually microcolon due to distal atresias

Image Gallery

AP radiograph shows feeding tube tip overlying thoracic inlet

due to EA. The abdominal gas indicates a TEF. Ribs are gracile. No vertebral anomalies. Question congenital heart disease.

AP radiograph of the chest/abdomen in another patient shows EA pouch

without fistula; there is no gas beyond atretic esophagus.

(Left) Anteroposterior radiograph of a newborn shows a dilated, air-filled stomach and dilated, spherical proximal duodenum

with no distal gas, consistent with DA. The presence of cardiomegaly, pulmonary edema, and 11 rib pairs suggests Down syndrome. (Right) Anteroposterior radiograph shows a “double bubble” sign of duodenal atresia: Dilated, air-filled stomach and round, obstructed proximal duodenum