Semen analysis is sometimes not enough to assess sperm ability to fertilise. Therefore, there are many other specific sperm tests to detect sperm function. Such a test is the Hyaluronan Binding Assay (HBA) which assesses sperm maturity and fertility. It is based on the principle that hyaluronic acid selectively binds to mature spermatozoa that carry an intact acrosome and normal morphology. Hyaluronic acid is normally found in the extracellular matrix of the granulosa cells which surround the ovum. It forms a layer which creates a natural obstacle, as it allows only mature spermatozoa, which have special receptors, to bind and cause lysis of hyaluronic acid. In this way they manage to reach and penetrate zona pellucida, in order to achieve the acrosome reaction and consequently the egg fertilization.

A low-binding HBA analysis corresponds to a low number of mature spermatozoa and is therefore a prognosis of infertility. Conversely, hyaluronic acid-binding spermatozoa are able to interact with the egg and  they have high integrity of their genome.

Thus, samples with > = 80% binding are considered to have normal maturity and function, whereas binding <80% indicates reduced maturity and function.

In case of an abnormal HBA test, fertilization can be done using the new technique PICSI.