Cystic Echinococcosis in the Liver: Evaluation of Percutaneous Treatment

António Menezes Silva, Henrique Vasconcelos Dias, Isabel Iria, Marco Aurélio Fonseca, Morais Valente


Aim: The objective of this manuscript is to demonstrate the efficacy of PAIR in the treatment of liver echinococcal cysts, and to present the method to define the cysts inactivity after therapy, based on US images of the cyst during the post intervention evaluation. methods: We report the results of 62 liver cysts, type 1, 2 and 3a (WHO-IWGE US classification) treated by PAIR combined with Albendazole therapy, between 2003 and 2008, in the General Surgery Department and Radiology Department of the Pulido Valente Hospital (Lisbon-Portugal). All cysts were submitted to a final evaluation at five years follow-up. To evaluate the therapeutic efficacy we based in the US images. The US criteria for the therapeutic efficacy evaluation are: the parasite’s layers detachment immediately after PAIR; the diminution of the liquid area and its substitution by a solid pattern giving the cyst a pseudotumoral aspect; the modification of the US pattern of the cyst with the progressive solidification of the cyst content; and, sometimes, the cyst vanishing or observation of a linear echoic scare (vestiges). The percentage of the solidified area was determined by Computer Assisted Design (CAD) program. The cyst inactivity was defined if the cyst content solidification was total or almost total (> 90%). Results: The final evaluation of the 62 cysts showed a therapeutic efficacy of 87.1% (54 cysts), from which 48 (77.4%) reached a solidified pattern greater than 90% and six (9.7%) vanished. From the remaining nine cysts, three (4.8%) were referred to surgery in the second and third evaluations due to no alteration of its pattern (all cysts type 2); two (3.2%) reached solidification lower than 90%; and three (4.8%) relapsed (cysts type 2). No major complications or mortality were observed, neither secondary echinococcosis after PAIR. Conclusion: PAIR is an effective and safe method to treat cysts type 1 and 3a of the WHO-IWGE US classification. The efficacy was 96.2% in cysts type 1 and 95.8% in cysts type 3a. It is not indicated in multivesicular cysts (type 2), in which the therapeutic failure was 50%.


Cystic Echinococcosis; Multivesicular cysts; PAIR; Cyst solidification; Inactive cyst

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