Postoperative Recurrence of Hydatid Cyst According to World Health Organization (WHO) Classification

Hydatid cyst is one of the most common diseases of humans and animals, which its most common involved site is liver. Despite various treatments, hydatid cyst recurrence is still a serious problem in areas with high prevalence. Therefore, in this study, we aimed to investigate the recurrence rate of hydatid cyst, and also the association of recurrence with the characteristics and manifestations of sonography according to the classification of hydatid cyst by World Health Organization (WHO). In this cross-sectional study, all patients with hydatid cyst, who underwent surgery during 2011-2014 were evaluated for demographic characteristics, cyst features, and types of surgical methods. After surgery, all the patients were followed up for 3 years, and increase of size in repeated sonographies was considered as recurrence. Findings: Based on WHO classification, the most common types of cysts included 23 cases (35.4%) of cystic echinococcosis type 1 (CE1), 12 cases (18.5%) of CE3b, 11 cases (16.9%) of CE3a, 7 cases (10.8%) of CE2, 3 cases (4.6%) of CE4, and 2 cases (3.1%) of CE5. Three cases (4.6%) of the patients had hydatid cyst recurrence. There was no significant association between demographic characteristics, cyst features, cyst classification according to WHO, and surgical methods with recurrence rate (P > 0.05). Hydatid cysts types of CE1, CE3b and CE3a are the most common types based on the WHO classification, and there is no association between their frequencies and the recurrence rate of hydatid cyst. Therefore, the use of this method of hydatid cyst classification is not recommended in order to determine the probability of recurrence of patients. However, more extensive studies in this field are recommended to determine the efficacy of this classification method to determine the risk of recurrence of hydatid cyst