Partial small bowel obstruction in a traveler.

Figure 1. Contrast-enhanced abdominal CT scan showing a long tubular filling defect (arrow) in the jejunum Figure 2. Contrast-enhanced abdominal and pelvic CT scan showing a long tubular filling defect (arrow) in the jejunum Diagnosis: Partial small bowel obstruction due to intestinal ascariasis. Multiple tubular-shaped filling defects in the jejunum were seen on CT scan, consistent with ascarides in the small bowel (figures 1 and 2). Ova and parasite evaluation of the patient's stool samples revealed numerous fertilized and unfertilized eggs. Ascaris lumbricoides is one of the most common nematodes to infect man. The prevalence of infection due to this organism can be as high as 80% in developing countries, especially in China and Southeast Asia [1]. With an estimated 4 million individuals infected in the United States, it is the third most common nematode infection in the United States and is most prevalent among the immigrant population [1]. Infection occurs via fecal-oral route after ingestion of the fertilized ova from contaminated food or water. Clinically, as-cariasis can present in various ways, depending on the phase of infestation. Pulmonary ascariasis occurs when larvae released from ingested ova in the stomach migrate to the jejunum, cross the intestinal wall, enter the portal system, and eventually reach the pulmonary circulation and airways. As the larvae undergo further development in the pulmonary alveoli, the patient can present with symptoms of pneumonitis and peripheral eosin-ophilia. The larvae migrate from the lower respiratory tract to the tracheobronchial tree. When the host coughs, the larvae are swallowed and re-enter the gastrointestinal tract. Intestinal ascariasis begins when the larvae reach the jejunum, where they undergo final development into full-grown nematodes [1]. Most patients with intestinal ascariasis have mild symptoms that include nausea and intermittent abdominal discomfort. Some patients remain asymptomatic, with ascarides found incidentally on radiographic examination or ova found in stool samples [1]. The most common complication of intestinal as-cariasis is small bowel obstruction, which is typically due to a physical obstruction caused by a large number of entangled worms. Other mechanisms of small bowel obstruction due to a worm bolus include volvulus and intussusception, which may lead to bowel ischemia or infarction. These mechanisms of small bowel obstruction are typically seen in children with large worm burdens [1]. The mortality rate among children with complicated intestinal obstruction may be as high as 24%; this high rate is attributable to delay in presentation [2]. Intestinal obstruction …