The Huhner test is a type of fertility test in which the compatibility of sperm and cervical mucus is evaluated. This is an important test because up to 8% of infertility cases are related to incompatibility between cervical mucus and sperm. The Huhner test, also known as the Sims-Huhner test or the postcoital test, is carried out by an infertility diagnostician, who examines these fluids several hours after intercourse has taken place.
Cervical cells secrete mucus which changes in consistency according to different phases of the menstrual cycle. As the cycle approaches the time of ovulation, cervical cells produce larger quantities of mucus. The mucus also changes qualitatively, to approximate a pH and viscosity that is more compatible with sperm migration. For sperm to travel past the cervix and into the uterus, the mucus present in the cervix must generally be of pH 7 to 8.5, and have a certain degree of viscosity and stretch. Infertility may result if the cervical mucus and sperm are incompatible.
To determine whether cervical mucus has the required pH and viscosity, the Huhner test is carried out several hours after intercourse, on a date close to the woman’s time of ovulation. Generally, a couple undergoing the test is asked to avoid intercourse for 48 hours prior to the test, and to then have intercourse four to eight hours before the test appointment is scheduled. During the test appointment, mucus samples are collected from the woman’s cervix and are then examined in a diagnostic lab.
Several different aspects of the cervical mucus are evaluated during a Huhner test. First, the mucus is examined for clarity and viscosity. Mucus obtained from the cervix at the time of ovulation should be clear and watery, and viscous enough that a portion of the mucus can be stretched at least 3.15 inches (8 cm) before breaking. The pH of the mucus is also recorded; the optimal level is pH 7 to 8.5.
The next part of the Huhner test involves the microscopic examination of the mucus to check how many sperm are present. A drop of mucus should contain a dozen or more sperm, which should swim with a strong forward motion. If there are too few sperm, this may indicate that the pH of the mucus is too low for sperm to survive. If sperm are unable to swim strongly, the mucus may be too thick.
The presence of other types of cells, including immune cells and yeast cells, is also noted. If larger than normal numbers of immune cells are present an infection may be affecting the quality of cervical mucus. Similarly, the presence of yeast cells indicates an infection that may also affect survival and motility of sperm. In some cases, resolving the infection will improve mucus quality enough to allow the woman to conceive.
If the quality of a woman’s cervical mucus is reducing her ability to conceive, and this problem has no other underlying cause, she may be prescribed hormonal medication that can improve the quality of the mucus. When medication does not resolve the problem, artificial insemination may be recommended. This procedure enables sperm to bypass the cervical mucus, improving the chances of conception.