Residual cavities after surgery for hepatic hydatid cysts--an ultrasonographic evaluation.

Ultrasonography has made it easier to diagnose precisely hepatic hydatid cysts, but the interpretation of images of residual cavities persisting long after the operation can be difficult. We reviewed the clinical histories of 22 children treated surgically for hepatic hydatid cysts at our hospital (1985-1992) to find clues to the proper attitude toward residual cavities. The children's mean age was 7.4 +/- 2.5 years. Fourteen children had single cysts (11 right and 3 left) and 8 children had multiple cysts, one of them 30 cysts (16 right and 14 left). The mean ultrasonographic diameter of the 44 cysts was 6.1 +/- 3 cm. Cystectomy with partial pericystectomy was performed in every case. Six months after operation, 29 cavities had disappeared, became calcified, or were substituted with fibrous scar tissue. The remaining 15 residual cavities had a mean diameter of 3 +/- 1 cm. The residual cavities exhibited little change at 12 months (2.8 +/- 1 cm), but at 18 months 9 had disappeared, 2 that increased in size and 4 remained the same size. Of these 4 stable lesions, surgery performed in 2 found no cysts and 2 have been followed-up ultrasonographically for 5 years. This short series shows that ultrasonography is useful in the diagnosis and follow-up of residual cavities after surgery for hepatic hydatid cysts. Most residual cavities disappeared by 18 months. In the cavities that persisted, our findings suggest that surgical treatment is justified only when the cyst becomes larger on ultrasonography.