Similar to blocked fallopian tubes pregnancy cannot occur, if there are cervical mucus abnormalities, which functions as a rigid block within the cervical canal that sperm cannot penetrate.
Normally this mucous has a complex chemistry, which is modulated by hormonal changes throughout the cycle. The purpose of the mucus block is to keep vaginal bacteria outside of the cervical canal and the uterine cavity.
However, at the end of the first part of the menstrual cycle (thanks to en.wikipedia.org for this link) following menstruation there is a predominant higher influence of estrogens. This changes the physical attributes around mid cycle to allow the now more fluid mucus in the cervical canal to be specifically penetrated by sperm, which has the right biochemistry to dissolve the mucus. The function of this mechanism is like “a lock and key” and for some couples there are biochemical incompatibility problems in this area.
In infertility clinics the gynecologist will often obtain a mucus sample during the mid cycle time of the woman and about 3 to 6 hours after intercourse. This sample can be tested in a number of ways. Essentially, it shows whether sperm is present or not, what viscosity the mucus has and other qualities (“spinnbarkeit” and “ferning test” are just a few technical buzz words to describe this). In about 5 to 10% of such infertility clinic work-ups clotting of sperm and cervical mucus (called “agglutination”) can be seen under the microscope, which may be due to sperm-antibodies in the woman’s cervical mucus (Ref. 5).
Ref.6 shows that there is an excellent association between two blood tests and this microscopic agglutination test and that this testing showed rates of approximately 20% positive patients in their fertility clinic. They also reported some success with reproductive technology (also called “assisted reproduction technologies” (=ART) where women could be fertilized with their husband’s semen to bypass the cervical mucus abnormality doing in vitro fertilization. Also, anti-sperm antibodies can be found in males who had a vasectomy in the past, then had a vasectomy reversal and are now attempting to father a child. More research is needed in this relatively new immunological reproduction technology field.
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