Small Intestine
Ascarid Impaction
Basic Information 
Epidemiology
Risk Factors
Clinical Presentation
Physical Exam Findings
Physical examination findings consistent with abdominal discomfort (colic)
• Heart rate: Normal to tachycardic (60–120 beats/min)
• Respiratory rate: Normal to tachypneic (24–60 breaths/min)
• Rectal temperature: May have mild pyrexia (>38.5° C)
• Reduced or absent borborygmi
• Progressive signs of dehydration
• Abdominal palpation: May be normal to exhibiting resentment on palpation with or without abdominal distension
Etiology and Pathophysiology
• Direct life cycle. Free-living stage (development of the infective second-stage larva in the egg) ranges from 9 to 14 days depending on environmental conditions. Egg development is arrested during the winter period (eggs can survive for several years outside the host). Temperatures above 39° C (102° F) destroy the eggs unless protected from desiccation in organic matter.
• Ingested eggs containing the second-stage larvae hatch in the small intestine and penetrate the intestinal wall to enter the portal blood vessels. Larvae migrate to the liver within 48 hours of ingestion and can be seen in the lung by day 14. Larvae are coughed up and swallowed, where they continue development in the duodenum and proximal jejunum. Mature worms reach a length of 10 to 50 cm and a diameter of 3 to 5 mm in 6 to 12 weeks.
• Rapid increase in size and over burden cause impaction of intestinal lumen.
• Deworming with a paralytic anthelmintic potentially causes immobilization and death of parasite-causing impaction.
• There is some suggestion that release of potent allergens may cause subsequent intestinal damage and necrotizing enteritis and peritonitis (report of intradermal injection of P. equorum somatic extract causing severe systemic response and colic).
Diagnosis 
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