The PAIR approach is now used - Puncture, Aspirate cyst, Injection of hypertonic saline solution or ethanol, and re-aspiration.
- Hydatis comes from Greek meaning watery cyst
- Hydatid cysts are caused by infection with the tapeworm Echinococcus
- E. granulosus → cystic disease
- E. multilocularis → lung disease
- Dogs are definitive hosts and release ova which infect cattle and sheep
- Seen in Central Europe, the Mediterranean countries, the Middle East
- South America,Australia, New Zealand, and South Africa
- Cysts May be present from childhood infection
- Remain subclinical until they enlarge
- Cysts in Brain → Epilepsy
- Cysts in Right (60%) lobe of Liver
- Cysts in Lung → haemoptysis, localised chest pain
- Cysts in Bone → localised pain and fracture
- Cysts in Kidney → localised pain and haematuria
- Cyst rupture → Fever and acute hypersensitivity reactions
- There is a blood eosinophilia
- Imaging e.g. CT/MRI or USS
- Serology with antibody testing is useful
- Percutaneous ultrasound guided cyst aspiration or biopsy shows reveal clear watery fluid containing scolices and have elevated pressure in active cysts. This procedure has very low rates of complications. Be alert to anaphylaxis and secondary spread. This is only done when the diagnosis is still unclear.
- Cysts may be excised or drained with the intent of avoiding spilling any of the contents which can cause anaphylaxis. The PAIR approach is now used - Puncture, Aspirate cyst, Injection of hypertonic saline solution or ethanol, and re-aspiration.
- Alternatively a laparotomy is performed and the liver and surrounding area is packed with hypertonic saline-soaked swabs and the cyst injected with 0.5% silver nitrate. The contents are then carefully aspirated. Alternatively, the cyst can be removed in its entirety.
- Treatment is with Albendazole and Praziquantel or Metronidazole usually begun preoperatively but some cases require aspiration of the cyst contents and injection of 100% alcohol especially if there is no biliary drainage.