Ascariasis (Biliary)
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: bili…
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:
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:
- 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.