Intestinal intussusception and obstruction due to entrapped Ascaris

Ascariasis is an infection caused by a giant roundworm named Ascaris lumbricoides which is the most common intestinal nematode affecting human beings. It is endemic in underdeveloped areas and particularly affects children [1]. Infestation could be silent or may lead to serious complications like intestinal obstruction, volvulus, and intussusception [2]. Intestinal intussusception is idiopathic in over 90% of cases. Uncommon etiologies such as Merkel's diverticulum, polyp, lymphoma, and parasitosis are found in 6–8% of cases [3]. We report a case of small bowel obstruction by acute intussusception due to impacted Ascaris in a 3-year-old child.

A 3-year-old child erred to the emergency department for vomiting, diffuse abdominal pain, and cessation of passage of flatus and feces. The clinical symptoms had progressed for approximately 24 hours. On physical examination vitals were stable, abdomen was distended without any palpable mass. Mild eosinophilia (12.6%) was reported. Ultrasound showed in the right peri-umbilical region a dilated bowel loops with a doughnut like bowel mass in transverse section (Figure 1A) and sandwich like bowel mass in longitudinal section (Figure 1B) compatible with an intestinal intussusception. There were multiple “bull's eye” and “railway track” images (Figure 1A and Figure 1B) suggestive of intestinal ascariasis in the mass and beside it. Surgical intervention by laparotomy found an ileo-ileal intussusception with impacted Ascaris without sign of necrosis or intestinal perforation (Figure 2). Intussusception relief was done followed by an enterotomy for the evacuation of most roundworms and leaving the rest to medical treatment with albendazole. The patient was discharged 5th day postoperatively without complication.

Intussusception most often affects children between 6 months and 3 years old and is rare over the age of 6 [4]. In the majority of cases (more than 90%) no cause is found. Exceptionally, an underlying condition, constituting a lead point for intussusception, is found in 6–8% of cases [3]. The most commonly encountered lead points are Merkel's diverticulum, polyps, lymphomas, vascular malformations, worms, and Henoch–Schönlein's purpura [3],[5]. Ascariasis is the most common helminthiasis in humans. It can occur at any age but most often in preschool children. The clinical and biological manifestations are not specific. The most serious complications of this parasitosis are intestinal obstruction and perforation. Partial occlusion often resolves on its own with medical treatment. On the other hand, when the mechanical obstacle persists, the roundworm bolus acts as a fixed point and leads to intussusception and volvulus [6].

Ultrasound is a simple and reliable method for both positive and etiological diagnosis of intussusception with high sensitivity (98–100%) and specificity (88–100%) [7]. Indeed, it often shows a typical appearance of intussusceptions in the form of a target or doughnut sign in transverse section in which hypo-echoic outer ring corresponding to the wall of the recipient intestinal segment and a central hyperechoic zone corresponding to the interfaces of the invaginated segment. In longitudinal section, sandwich sign, hayfork sign, pseudokidney sign can be seen. Three parallel hypo-echoic bands with interposing two hyper-echoic band give sandwich sign [7]. Hayfork sign is a variant of sandwich sign seen at apex where three hypo-echoic bands go to join. Pseudokidney sign seen in oblique scan or curved intussusceptions in which hyper-echoic mesentery is seen on only one side of central limb of intussusceptum [8]. Ultrasound can also help visualize roundworms. They appear as a double echogenic tubular structure (“railway track”) in longitudinal section and as a target in transverse section (“bull's eye”) [9],[10]. These tubular structures can be mobile, making the diagnosis easier [9] as shown in our example.

Treatment of bowel obstruction by roundworm is usually surgical, but in the absence of signs of peritonitis, medical treatment may give good results, even with complete obstruction [11],[12]. In our patient, the management was surgical and consisted of an intussusception relief followed by an enterotomy for the evacuation of the round worm. All roundworms could not be milked to the colon because of the extension of the infestation, reason why an ileum enterotomy was done. The post-operative course was uneventful. Medical treatment with albendazole was started after the resumption of intestinal transit.

This case illustrates a rare cause of intussusception and intestinal obstruction in children. Ultrasound remains the best imaging modality for the management of pediatric abdominal emergency. It plays a key role for positive and etiological diagnosis of intestinal intussusception.