Ascariasis may cause right abdominal pain.
When a roundworm burrows into the bile duct, it can lead to biliary ascariasis, which presents as a sudden onset of subxiphoid pain that is usually unbearable and causes the patient to toss and turn.
The pain can settle suddenly and recur suddenly and irregularly.
It is now less common, but can still occur in less developed areas and if suspected, the diagnosis can be ruled out or confirmed by observation of signs and ultrasound.