A 5-year-old boy was referred to the radiology department for ultrasound examination with clinical suspicion of acute appendicitis based on his symptoms of abdominal pain, nausea and vomiting for two days.
Ultrasound was performed which revealed a blind-ending distended loop in the right iliac fossa, most likely the appendix. A linear tubular-shaped echogenic structure visualized within the lumen of the appendix most likely represented an ascaris worm (Fig. 1a, b).The appendix showed signs of inflammation evident by luminal distension, surrounding hyperechoic mesenteric fatty infiltration and few prominent lymph nodes in the meso-appendix. Based on ultrasound features the child was sent back to the referring surgeon with the suspicion of acute appendicitis secondary to ascaris in the lumen.
Intra-operative exploration revealed distended inflamed appendix with a large ascaris in the lumen (Fig. 2a, b), thus confirming the ultrasound diagnosis.
There was no evidence of echogenic focus with posterior shadowing in the lumen of the appendix or focal mass to raise the possibility of other causes such as appendicolith or appendicitis due to tumours. Also, no abnormal collection was seen in the vicinity of the inflamed appendix to suggest perforation of appendix and abscess formation.
Appendicitis is the inflammation of the appendix, commonly presents with right iliac region pain, nausea, vomiting, and decreased appetite. It is caused by blockage of the hollow portion of the appendix, most commonly by a calcified "stone" made of faeces. However, inflamed lymphoid tissue from a viral infection, parasites or tumours may also cause the blockage. This blockage leads to increased pressures within the appendix, decreased blood flow, bacterial growth inside the appendix with subsequent inflammation and luminal distention resulting in injury and death .
Ascariasis is a parasitic infection distributed worldwide but mostly occurring in developing countries. Infection happens by the ingestion of embryonated eggs in raw vegetables, water or soil-contaminated hands .
Ascariasis may cause intestinal obstruction, perforation, cholangitis, cholangiohepatitis, biliary obstruction, liver abscess, appendicitis, pancreatitis and granulomatous peritonitis [3, 4].
Acute appendicitis by an adult worm is a well-known complication. The ascaris may result in obstruction of the lumen .
In cases where the diagnosis cannot be made based on the clinical history and physical examination, close observation, radiologic imaging and laboratory tests can often be helpful.
Ultrasound and CT may help lower the rate of false-negative appendicitis diagnosis, reduce morbidity from perforation, and lower hospital expenses.
Ultrasound is safe and readily available, with accuracy rates between 71 and 97 percent .
Graded compression ultrasound using a linear high frequency 5-12 MHz transducer is a non-invasive technique which is particularly suitable for children, young and pregnant women with suspected appendicitis . However, ultrasound has limitations, especially in the obese patients where tissue penetration is reduced and in the presence of a retrocaecal appendix surrounded by bowel gas which prevents sound transmission.
Sonographically, the identification of a non-compressible, thickened appendix greater than 6-7 mm in diameter is diagnostic of appendicitis. Other associated findings can be the presence of a hyperechoic appendicolith with posterior acoustic shadowing, anechoic fluid or an abscess in the right lower quadrant .
Sometimes the cause for acute appendicitis like ascaris can be visualized.
In our case there was no evidence of echogenic focus with posterior shadowing in the lumen of the appendix or focal mass to raise the possibility of other causes such as appendicolith or tumours.
Also, no abnormal collection was seen in the vicinity of the appendix to suggest perforation of appendix and abscess formation.
Acute appendicitis caused by ascaris is an uncommon entity especially in children. Transabdominal ultrasound with high frequency linear transducer by expert hands can be the first and highly sensitive modality for an early diagnosis.
Differential Diagnosis List
Ascaris lumbricoides and acute appendicitis
Ascaris worm within small bowels
Appendicolith causing appendicitis
Tumours causing appendicitis
Ascaris lumbricoides and acute appendicitis