Biliary ascariasis is caused by the migration of the nematode Ascaris lumbricoides from the duodenum into the biliary tract via the ampulla of Vater. It produces five major clinical syndromes: biliary colic, acute cholangitis, acute cholecystitis, acute pancreatitis, and hepatic abscess. [1-2] In endemic regions, it accounts for up to 37% of all biliary disease. [3] Approximately 90–97% of cases resolve with conservative medical therapy alone. [3-4]
1. History
- RUQ/epigastric colicky pain — often severe, episodic, and recurrent; mimics choledocholithiasis [3][5]
- History of vomiting or passing roundworms (per mouth or stool) — present in ~25–48% and highly suggestive [3][5]
- Timing: acute onset, may be recurrent over weeks to months with repeated worm migration [6]
- Associated symptoms: nausea, vomiting, anorexia, fever, jaundice [2][7]
- Travel/residence in endemic regions (South/Southeast Asia, sub-Saharan Africa, Central/South America) [2][8]
- Prior biliary interventions: cholecystectomy or sphincterotomy — 80% of patients in one large series had prior biliary surgery, which facilitates worm entry [5]
- Ask about prior anthelmintic treatment and stool examination
2. Alarm Features
- Charcot's triad (fever, jaundice, RUQ pain) → acute cholangitis [6]
- Reynolds' pentad (Charcot's triad + hypotension + altered mental status) → suppurative cholangitis/sepsis
- High fever with rigors → pyogenic cholangitis or hepatic abscess [6-7]
- Severe epigastric pain radiating to back → acute pancreatitis [1][6]
- Peritoneal signs → biliary perforation or peritonitis [7]
- Hemodynamic instability or sepsis [7]
- Persistent symptoms >3 weeks on medical therapy → trapped/dead worm, stone formation [1][6]
3. Medications
- Anthelmintics (first-line):
- Albendazole 400 mg PO single dose (most commonly used; high cure rate for ascariasis) [2][9]
- Higher dose of albendazole 800 mg PO has been used specifically for biliary ascariasis [4]
- Mebendazole 100 mg PO BID × 3 days or 500 mg single dose [9]
- Pyrantel pamoate 11 mg/kg (max 1 g) — alternative, especially in pregnancy (Category C vs albendazole Category C) [9]
- Supportive medications:
- IV analgesics (NSAIDs, opioids for colic)
- IV antispasmodics (hyoscine butylbromide) [4]
- IV antibiotics if cholangitis suspected (cover gram-negatives and anaerobes)
- IV fluids, NPO if pancreatitis
- Cautions:
- Anthelmintics should be given after acute symptoms subside to avoid worm agitation and further migration [3]
- Avoid piperazine (withdrawn from many markets due to toxicity) [9]
- Benzimidazoles are teratogenic in animals — use with caution in first trimester of pregnancy [2]
4. Diet
- NPO during acute biliary colic, cholangitis, or pancreatitis
- Advance to low-fat diet as symptoms improve
- Adequate hydration, especially if febrile or vomiting
- Long-term: food hygiene education — wash raw vegetables, avoid fecal-contaminated soil/water in endemic areas [2]
5. Review of Systems
- GI: abdominal pain character/location, nausea, vomiting (ask specifically about worms in vomitus), diarrhea, stool changes, passage of worms in stool
- Constitutional: fever, chills, rigors, weight loss, anorexia
- Hepatobiliary: jaundice, dark urine, pale stools, pruritus
- Pulmonary: cough, dyspnea, wheezing (Löffler syndrome from larval migration — may precede biliary symptoms by weeks) [2]
- Dermatologic: urticaria (associated with larval migration) [2]
6. Collateral History and Family History
- Household contacts with known ascariasis or helminth infections
- Sanitation conditions at home — open defecation, untreated water, soil contact [2]
- Immigration/travel history from endemic regions (South Asia, Latin America, sub-Saharan Africa) [8]
- Family history of biliary disease (gallstones, prior cholecystectomy) — increases risk of biliary migration [10]
- Occupational exposure (farming, soil contact)
7. Risk Factors
- Residence in or travel to endemic areas (tropical/subtropical regions with poor sanitation) [2]
- Female sex — 11.3× higher odds of hepatobiliary-pancreatic ascariasis compared to males [10]
- Prior biliary surgery — cholecystectomy or sphincterotomy dramatically increases risk of worm entry into the biliary tree (present in up to 77–80% of cases in some series) [5]
- Previous gallbladder disease — significantly associated with biliary ascariasis in adults [10]
- High worm burden — increases likelihood of aberrant migration [2]
- Adult age — biliary ascariasis is more common in adults than children (unlike intestinal obstruction, which predominates in children), as the adult biliary tree is large enough to accommodate worms [11]
8. Differential Diagnosis
- Choledocholithiasis / cholelithiasis — most important mimic; distinguished by ultrasound (stones produce acoustic shadowing; worms do not) [8][12]
- Acute cholangitis (bacterial, non-parasitic)
- Acute cholecystitis (calculous)
- Gallstone pancreatitis
- Hepatic abscess (amebic or pyogenic)
- Cholangiocarcinoma / periampullary tumors — if obstructive jaundice without clear etiology
- Clonorchis/Opisthorchis infection — other parasitic causes of biliary obstruction [13]
- Choledochal cyst
- Acute appendicitis (if worm in appendix) [11]
9. Past Medical History
- Prior episodes of biliary colic or ascariasis
- Previous cholecystectomy or endoscopic sphincterotomy — critical risk factor [5]
- History of helminth infections or deworming
- HIV/immunosuppression — increases risk of severe bacterial complications [7]
- Chronic liver disease
- Prior ERCP or biliary interventions
10. Physical Exam
- Vital signs: fever (cholangitis, abscess), tachycardia, hypotension (sepsis)
- Abdominal exam:
- RUQ tenderness, positive Murphy's sign (cholecystitis)
- Epigastric tenderness (pancreatitis)
- Guarding/rigidity (peritonitis — suggests perforation) [7]
- Hepatomegaly (hepatic abscess) [14]
- Abdominal distension
- Skin/sclera: jaundice (obstructive) [2]
- Note: Physical exam may be unremarkable in early or uncomplicated biliary migration [8]
- Inspect vomitus and stool for worms
11. Lab Studies
- CBC: leukocytosis (infection), eosinophilia (suggestive of helminthic infection, though may be absent in acute biliary disease)
- LFTs: elevated ALP, GGT, direct bilirubin (obstructive pattern); transaminases may be mildly elevated
- Lipase/amylase: elevated if pancreatitis [5]
- Blood cultures: if cholangitis or sepsis suspected [13]
- Stool ova and parasites: may identify Ascaris eggs (each female produces ~200,000 eggs/day), though sensitivity is imperfect [11]
- CRP/procalcitonin: markers of systemic infection
- Coagulation studies: if obstructive jaundice (vitamin K malabsorption)
12. Imaging
- First-line: Abdominal ultrasound — diagnostic tool of choice [1][12]
- Sensitivity ~86% for biliary worms [12]
- Classic findings: long, linear, echogenic structure without acoustic shadowing in the CBD; may show characteristic movement [12]
- "Inner tube sign" — central anechoic tube within the echogenic strip (representing the worm's digestive tract) [12]
- Biliary dilatation, gallbladder distension, wall edema, sludge [12]
- MRCP: confirms intraductal worms extending into intrahepatic ducts; excellent for surgical planning [8]
- ERCP: both diagnostic and therapeutic — visualizes worms in CBD/intrahepatic ducts and allows extraction [3][6]
- CT abdomen: can support diagnosis; useful for identifying complications (abscess, pancreatitis) [2]
- Plain abdominal X-ray: may show worm outlines in bowel; less useful for biliary disease specifically [2]
- Imaging is unnecessary if uncomplicated intestinal ascariasis without biliary symptoms
13. Special Tests
- Stool microscopy (Kato-Katz technique): quantifies egg burden [11]
- ERCP with basket extraction: both diagnostic and therapeutic gold standard for refractory cases [1][6]
- Upper endoscopy: may visualize worms at the ampulla of Vater or in the duodenum [2]
- Capsule endoscopy: case reports suggest utility for small intestinal ascariasis [2]
14. ECG
- Not routinely indicated unless:
- Hemodynamic instability or sepsis (evaluate for tachyarrhythmias)
- Pre-procedural assessment before ERCP or surgery
- Elderly patients with comorbidities presenting with acute abdominal pain
15. Assessment
Biliary ascariasis presents along a severity spectrum: [1][6]
- Mild: Biliary colic alone — episodic RUQ pain, no systemic signs. Most common presentation (56% of cases in large series) [6]
- Moderate: Acute cholecystitis or uncomplicated cholangitis — fever, jaundice, localized tenderness
- Severe: Pyogenic cholangitis, acute pancreatitis, hepatic abscess, sepsis, or biliary perforation — carries mortality risk (~0.8–3.8%) [6][10]
Atypical presentations include isolated pancreatitis without biliary colic, or hepatic abscess as the initial presentation. [7][14] Worms may traverse the ducts repeatedly, and dead worms serve as a nidus for hepatolithiasis. [1][6]
16. Treatment Plan
Initial stabilization
- IV fluids, NPO, IV analgesics and antispasmodics [4]
- IV antibiotics if cholangitis (e.g., piperacillin-tazobactam or ciprofloxacin + metronidazole)
Conservative medical therapy (first-line for most cases)
- Symptom management → once acute symptoms subside, administer albendazole 400–800 mg PO [4][9]
- 97% of cases resolve with medical therapy alone [4]
- Serial ultrasound to confirm worm exit from the biliary tree [12]
Endoscopic intervention (if medical therapy fails)
- Indicated if symptoms persist or worms remain in ducts at 3 weeks [1]
- ERCP with basket/balloon extraction — successful in most patients [6]
- Endoscopic extraction at the ampulla without sphincterotomy is preferred when worm is visible [4]
- Nasobiliary catheter drainage if cholangitis [6]
Surgical intervention (last resort)
- Indicated for: trapped dead worms with stone formation, biliary perforation, hepatic abscess not amenable to drainage, failed endotherapy [3][15]
- Laparoscopic CBD exploration with worm extraction and T-tube placement [15]
17. Disposition
- Admit if:
- Cholangitis, sepsis, or hemodynamic instability
- Acute pancreatitis
- Hepatic abscess
- Inability to tolerate oral medications
- Need for ERCP or surgical intervention
- Peritoneal signs
- Observation if:
- Discharge if:
- Mild biliary colic that resolves with treatment
- Tolerating oral medications
- Ultrasound shows no complications
- Reliable follow-up ensured
- Consult GI/surgery for: refractory symptoms, cholangitis, pancreatitis, hepatic abscess, or worms persisting >3 weeks [1][6]
18. Follow Up / Return Precautions
- Follow-up ultrasound to confirm worm exit from the biliary tree (typically within 1–3 weeks) [2][12]
- Stool O&P at 2 weeks post-treatment (up to 3 samples) to confirm parasitological cure [2]
- Re-invasion rate is significant — 76/500 patients (15%) had recurrent biliary invasion during 4-year follow-up due to reinfection [6]
- Treat household contacts and address sanitation/hygiene to prevent reinfection [2]
Return precautions — instruct patients to return immediately for:
- Recurrent severe abdominal pain
- Fever, chills, or rigors
- Jaundice or dark urine
- Persistent vomiting or inability to eat
- Passage of worms in vomitus or stool (indicates ongoing infection)
Expected course: Most patients improve within 48–72 hours of conservative therapy. Worms typically migrate out of the biliary tree spontaneously within days to weeks. [4][6]
References
1. Hepatobiliary and Pancreatic Ascariasis. — Khuroo MS, Rather AA, Khuroo NS, Khuroo MS. World Journal of Gastroenterology. 2016.
2. Soil-Transmitted Helminth Infections. — Jourdan PM, Lamberton PHL, Fenwick A, Addiss DG. Lancet. 2018.
3. Biliary Ascariasis. A Common Cause of Biliary and Pancreatic Disease in an Endemic Area. — Khuroo MS, Zargar SA. Gastroenterology. 1985.
4. Non-Invasive Management of Ascaris Lumbricoides Biliary Tact Migration: A Prospective Study in 69 Patients From Ecuador. — González AH, Regalado VC, Van den Ende J. Tropical Medicine & International Health : TM & IH. 2001.
5. Pancreatic-Biliary Ascariasis: Experience of 300 Cases. — Sandouk F, Haffar S, Zada MM, Graham DY, Anand BS. The American Journal of Gastroenterology. 1997.
6. Hepatobiliary and Pancreatic Ascariasis in India. — Khuroo MS, Zargar SA, Mahajan R. Lancet. 1990.
7. Biliary Ascariasis and Severe Bacterial Outcomes: Report of Three Cases From a Paediatric Hospital in Brazil. — de Almeida BL, Silva DV, do Rosário MS, et al. International Journal of Infectious Diseases : IJID : Official Publication of the International Society for Infectious Diseases. 2020.
8. Biliary Ascariasis in a Non-Endemic Region: A Case Report. — Alsubhi R, Bakhsh N. Parasitology International. 2025.
9. Anthelmintic Drugs for Treating Ascariasis. — Conterno LO, Turchi MD, Corrêa I, Monteiro de Barros Almeida RA. The Cochrane Database of Systematic Reviews. 2020.
10. Extra-Intestinal Complications of Ascaris Lumbricoides Infections in India: A Systematic Review and Meta-Analysis. — Mewara A, Kanaujia R, Malla N. Transactions of the Royal Society of Tropical Medicine and Hygiene. 2023.
11. Soil-Transmitted Helminth Infections: Ascariasis, Trichuriasis, and Hookworm. — Bethony J, Brooker S, Albonico M, et al. Lancet. 2006.
12. Sonographic Appearances in Biliary Ascariasis. — Khuroo MS, Zargar SA, Mahajan R, Bhat RL, Javid G. Gastroenterology. 1987.
13. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). — Miller JM, Binnicker MJ, Campbell S, et al. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2024.
14. Hepatobiliary and Pancreatic Complications of Ascariasis in Children: A Study of Seven Cases. — Bahú Mda G, Baldisserotto M, Baldisseroto M, et al. Journal of Pediatric Gastroenterology and Nutrition. 2001.
15. Ascariasis in the Hepatobiliary System: Laparoscopic Management. — Astudillo JA, Sporn E, Serrano B, Astudillo R. Journal of the American College of Surgeons. 2008.