Teaching Case

A 30-year-old patient of South Asian origin was referred for an ultrasound examination of the abdomen and pelvis by her general practitioner as she had been having symptoms of bloating and dysmenorrhoea. Her blood tests were within normal limits.

The US examination demonstrated normal appearance of the uterus and the ovaries, however, there were complex cystic lesions detected in both the liver (Fig. 1) and the spleen (Fig. 2) and a CT examination of the abdomen and pelvis was recommended as the next test for evaluation of these findings. The CT scan confirmed low attenuation lesions in both the liver and the spleen (axial and coronal images – Figs. 3, 4) with no enhancement or wall calcification demonstrated. There was also a long tubular filling defect demonstrated in a jejunal loop (coronal reformatted image – Fig. 5), which stood out against the positive oral contrast the patient had received as bowel preparation for the CT examination. The patient was treated with antihelminthics and a follow up CT demonstrated stable appearance of the hepatic and splenic cysts and the worms had been cleared and no longer visible.

Combined helminthic infestation is more common in tropical countries and with the changing economic climate and population migration awareness of parasitic infestations and imaging characteristics would definitely guide the clinicians in treating these conditions.
Hydatid cyst, caused by echinococcus is diagnosed with a combination of epidemiologic data, radiological demonstration of cysts and combined immunologic and other laboratory tests, sometimes including cyst aspiration and analysis if no contraindications exist. E-Granulosus and E-Multilocularis are the most prevalent species encountered. In humans, hydatid disease involves the liver in approximately 75% of cases, the lung in 15%, and other anatomic locations in 10% [1–3].The liver is the most common organ involved and patients may remain asymptomatic for a long time and the usual presenting symptoms is with a palpable abdominal mass or pain related to cyst enlargement. Classification systems exist based on imaging characteristics [4-5]. Imaging features vary depending on the stage of cyst development, appearing as low attenuation well defined round or oval simple cysts in the early stages and a multiseptate complex appearance after daughter cysts develop, which also suggest viability. In the later stages the septa can disintegrate and partial calcification of the cyst does not always indicate the death of the parasite; nevertheless, densely calcified cysts may be assumed to be inactive [6-7]. Complications include bile duct compression, biliary fistulation, peritoneal seeding and rupture, leading to fever, pruritis and anaphylaxis [5].
Ascaris is the commonest and the largest roundworm parasite of the human intestine with a global distribution but being more common in tropical countries.
Again most patients are asymptomatic or present with nonspecific abdominal symptoms. However, because of the high prevalence of Ascaris infection, complications and mortality are frequent [8]. Definitive diagnosis is achieved when worms or eggs are identified in stool samples. However, imaging findings are highly specific and may point toward the diagnosis.
On images from barium studies, Ascaris worms may be depicted as elongated filling defects with opacification of the intestinal lumen of the worm by contrast material. It may be possible to distinguish the worm’s digestive tract on ultrasound in slim patients as two echogenic parallel lines in the bowel lumen. On CT again the worms are demonstrated as long filling defects incidentally, made more prominent if the patient has a positive bowel preparation.
Complications such as bowel obstruction are usually related to a massive infestation [9]. Intestinal obstruction due to ascariasis is not an uncommon complication in children. Other complications include biliary colic, gallstone formation, liver abscess and pancreatitis [9-12].