Filarial Hydrocele Workup

Updated: Feb 17, 2017
  • Author: Bradley Fields Schwartz, DO, FACS; Chief Editor: Edward David Kim, MD, FACS  more...
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Laboratory Studies

Laboratory tests and findings in filarial hydrocele are as follows:

  • Complete blood cell count (CBC): Patients with patent filarial infection commonly have marked eosinophilia

  • Serum immunoglobulins: Elevated serum levels of immunoglobulin E (IgE) and immunoglobulin G4 (IgG4) are seen with microfilarial infection

  • Enzyme-linked immunoassay (ELISA): Og4C3 monoclonal antibody–based ELISA provides a quantitative measure of circulating filarial antigen (CFA)

  • Immunochromatographic testing (ICT): Dipstick testing of whole blood with ICT cards, which utilize monoclonal antibody AD.12, is a qualitative test for CFA that is widely used in the field as a screening test for lymphatic filariasis [7, 8]

  • Hydrocele fluid examination: CFA may be detected in hydrocele fluid, [9] and microfilariae may be found on cytology

  • Urine examination: Chyluria may be detected macroscopically, and microfilariae may be detected via microscopic examination of voided urine; proteinuria and hematuria may also be seen with microfilarial infection with renal involvement

  • Peripheral blood examination: Microfilariae may be detected via microscopic examination of peripheral blood; microfilariae demonstrate a circadian pattern that varies by endemic region, necessitating serum sampling that coincides with periods of activity; activity may be provoked with administration of DEC



Lymphatic obstruction can be demonstrated on ultrasonography. Motile adult worms may be seen in symptomatic and subclinical filarial hydroceles. The characteristic movements of adult filarial worms are called the filarial dance sign (FDS) and are a reliable diagnostic finding. Ultrasonography may also be used to monitor response to treatment.