Pneumoperitoneum



Pneumoperitoneum


Alexander J. Towbin, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Postoperative


  • Necrotizing Enterocolitis (NEC)


Less Common



  • Traumatic Bowel Injury


  • Dissection from Pneumothorax or Pneumomediastinum


  • Medications


  • Appendicitis


  • Iatrogenic


  • Infection


Rare but Important



  • Spontaneous Gastric Perforation


  • Distal Intestinal Obstruction


  • Lymphoma


  • Perforated Peptic Ulcer


  • Ehlers-Danlos Syndrome


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • CT is most sensitive modality



    • Air rises to nondependent location


  • Left lateral decubitus and cross table lateral views are most sensitive radiographic views


  • In neonates, “football” sign may be present



    • Falciform ligament appears as laces of football due to massive pneumoperitoneum


    • Less common in older children and adults


  • Other radiographic signs



    • Air under diaphragm


    • Triangular lucencies


    • Air outlining both sides of bowel wall


Helpful Clues for Common Diagnoses



  • Postoperative



    • Residual pneumoperitoneum is common after abdominal surgery



      • Duration of free air is determined by its initial volume and absorption rate


      • Usually resolves within 1 week


      • May last as long as 10-24 days


    • Laparoscopy uses carbon dioxide to distend abdomen during surgery



      • CO2 is absorbed faster than room air


    • Amount and duration of postoperative air is proportional to age in pediatric patients



      • Older children have larger volume of free air → lasts longer


    • If greater than expected air is present, evaluate for perforation or dehiscence


  • Necrotizing Enterocolitis (NEC)



    • 1 of most common surgical emergencies in infants


    • Disease of prematurity



      • > 90% occur in children born < 36 weeks


      • Occurs in 3-7% of NICU patients


    • Rate is inversely related to birth weight


    • ↑ incidence in African-Americans and males


    • May present with feeding intolerance, bilious aspirates, or abdominal distension


    • Radiographic findings include fixed dilated loops of bowel, pneumatosis, portal venous gas, and free air



      • If clinical suspicion for NEC exists, abdominal radiographs should be performed every 6 hours


    • Treatment can be medical or surgical



      • Indications for surgical treatment include pneumoperitoneum or other signs of bowel perforation


      • 20-40% with NEC require surgery


Helpful Clues for Less Common Diagnoses



  • Traumatic Bowel Injury



    • Incidence of small bowel injury has increased with increased seat belt use


    • ˜ 5% of patients admitted with major trauma suffer small bowel injury


    • Jejunal injuries may be most common


    • Delay in diagnosis of bowel injury can lead to ↑ morbidity and mortality


    • Often associated with other injuries


    • Radiologic findings of bowel injury include free fluid, bowel wall thickening, and pneumoperitoneum


    • CT can be useful to predict site of perforation



      • Findings include concentration of extraluminal gas, segmental bowel wall thickening, and focal defect


    • In infants and neonates, penetrating trauma can be caused by thermometer placement


    • Sexual abuse can cause colonic perforation


  • Dissection from Pneumothorax or Pneumomediastinum




    • Free air from pneumothorax or pneumomediastinum can dissect into abdomen


    • Air enters through diaphragmatic crus or rents in diaphragm


  • Medications



    • Indomethacin



      • Used to help close patent ductus arteriosus


      • Also can ↓ GI blood flow and lead to intestinal perforation


  • Appendicitis



    • Pneumoperitoneum is rare with perforated appendicitis


    • If present, usually only a few locules of air


  • Iatrogenic



    • Bowel perforation can be caused by tube placement or endoscopy


    • Air enema for intussusception reduction



      • Incidence of perforation is very low


      • With air enema, perforation can lead to tension pneumoperitoneum


      • Tension pneumoperitoneum should be treated with needle decompression


  • Infection



    • Most common cause of nontraumatic colonic perforation



      • Salmonella is most common bacteria that causes perforation


Helpful Clues for Rare Diagnoses



  • Spontaneous Gastric Perforation



    • Usually occurs at 2-7 days of life in term infants


    • More common in African-Americans and males


    • Prenatal risk factors



      • Premature rupture of membranes, toxemia, breech delivery, diabetic mother, group B Streptococcus positive mother, placenta previa, abruption, and emergent cesarean delivery


    • Postnatal risk factors



      • Prematurity, low birth weight, small for gestational age, low Apgar scores, respiratory distress, exchange transfusion, and indomethacin treatment


    • Presents with sudden onset of abdominal distension


    • Large volume of pneumoperitoneum



      • Most common cause of “football” sign


  • Distal Intestinal Obstruction



    • In neonate, causes can include Hirschsprung disease, meconium ileus, atresias, or malrotation with midgut volvulus


  • Lymphoma



    • Primary bowel lymphoma manifests as focal bowel wall thickening


    • With chemotherapy, perforation can occur


  • Perforated Peptic Ulcer



    • Now rare with treatment of H. pylori


  • Ehlers-Danlos Syndrome

Tags:
Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Pneumoperitoneum

Full access? Get Clinical Tree
Get Clinical Tree app for offline access