Cap assisted hysteroscopy enables retrograde catheter-ization and hydrotubation of the equine oviduct

Infertility in the brood mare with no clinically identifiable cause is of great concern for economic and emotional reasons. Diseases of the fallopian tube are a known cause of infertility in women; but due to the poor operational accessibility it is still an area with many unknowns in equine reproductive medicine. Previous studies indicate positive effects of catheterization and subsequent irrigation of the fallopian tube (hydrotubation) to remove cell debris and collagen masses that clog the lumen, preventing the oocyte from being fertilized or the embryos migration through the fallopian tube. As an alternative to flank laparoscopy, a hysteroscopic access using a catheter has been described, which led to increased pregnancy rates in supposedly sterile mares. With the technique described here, hysteroscopic access to the uterine papilla was possible in 22 standing, sedated mares in dioestrus. Use of an attachment cap for the endoscope and a specially developed, conical-tapered catheter with angiography guide wire made it possible to visualize the uterine papilla as well as secure access to the fallopian tube and subsequent hydrotubation. Of 22 papillae hysteroscopically controlled with a cap, 20 were successfully catheterized. The microbiological evaluation of endometrial swabs showed an increase in genital pathogens after the procedure. After completion of the hysteroscopy prostaglandin was always administered to induce oestrus. 7/9 (78 %) patient mares with unexplained sterility became pregnant in the breeding season following the fallopian tube irrigation. Endometrial biopsies from the two mares remaining barren were classified in category III (foaling probability < 10 %). The catheter system developed in this study in conjunction with the cap-assisted hysteroscopy enables safe targeting of the uterine papilla, as well as the subsequent catheterization and hydrotubation of the fallopian tube. To summarize, the minimally invasive technique described here can safely replace the surgical-operative flank access to the fallopian tube in mares with suspected obstruction of the fallopian tube lumen, and fertility was restored in 7 out of 9 mares.