The equine oviduct is essential for fertilization and early embryonic development and is thus an important part of the genital tract. The interaction between the oviduct and the spermatozoa, the oocyte and the embryo have been well described as well as a range of pathologies that occur in the equine oviduct.

Despite this knowledge the oviduct remains inaccessible to our routine diagnostic tools such as rectal palpation and ultrasonography. Thus, diagnosis of oviductal pathology is extremely difficult and in a first stage is done by elimination of other causes of infertility resulting in a tentative diagnosis of oviductal pathology.

Oviduct pathologies can be categorized in adhesions and cysts around the infundibulum, inflammation (salpingitis), hydrosalpinx, congenital abnormalities, tumors and occlusion or obstruction.

Retrospective studies on slaughterhouse material clearly demonstrate that inflammation of the oviduct occurs in mares but the association with bacterial endometritis is unclear. It has been reported that salpingitis has a higher (double) incidence in mares with endometritis. This seems in contradiction with the statement that the uterine tubal junction (UTJ) forms a very tight sphincter that isolates the oviduct from the uterine lumen. Presently, we still have no technique to diagnose salpingitis nor are there treatments described. Constrictions leading to occlusion, accumulation of fluid in the oviduct (hydrosalpinx), para-ovarian cysts and adhesions (primarily around the infundibulum) have also been described on slaughterhouse surveys but the diagnosis is equally difficult.

The presence of collagen-type masses in the lumen of the oviduct has also been proposed as a possible cause for sub- or infertility. These oviductal plugs hinder the migration of the oocyte and/or embryo towards the UTJ.
Obstructions are mainly found in older mares that were barren for a longer period of time. The embryo produces PGE2 to facilitate its own transport towards the uterus. This PGE2 production also results in a clearance of unfertilized oocytes and other material accumulating in the oviduct thereby preventing oviductal blockage.

There are several methods to diagnose oviductal blockage but all are (semi-)invasive and not very reliable. Consequently presumptive oviductal blockages are treated without previous diagnosis. One treatment strategy is to flush the oviduct either by flushing the oviduct from the infundibulum side via laparotomy or retrograde through the UTJ via hysteroscopy.
The catheterization of the infundibulum and the UTJ are technically challenging and there is a risk of damaging the oviduct. Therefore, the current treatment of choice for presumed blocked oviducts is dripping prostaglandin-E2 on to the oviduct in situ via laparoscopy. This stimulates relaxation of the UTJ and stimulation of oviductal contractions resulting in passage of any inspissated material and restoration of fertility. In conclusion, oviduct pathology should be included in the list of differential diagnoses in case of unexplained sub- or infertility.

Disciplines : Fertilité, Médecine interne, Chirurgie
Mots clés : Oviducte, salpingite, obstruction, hydrosalpinx, infertilité, subfertilité, jument