oviduct plays a critical role during fertilization and early embryonic development. Consequently, pathologic conditions of the oviduct such as salpingitis, hydrosalpinx, and occlusion can adversely affect fertility of mares.
Blockage of the oviducts by masses of collagen, fibroblast cells, and other cellular and non‐cellular debris has been described. These oviductal masses can become a physical obstruction to both the upward passage of sperm and the downward passage of an embryo after fertilization. Diagnosis, however, of a blocked oviduct may be difficult and is sometimes suspected after exclusion of other possibilities for infertility in a mare.
This chapter describes the starch granule test for the diagnosis of oviductal patency. The starch granule test involves the deposition of a starch suspension onto the ovarian surface (through a transabdominal approach with a long needle) and the subsequent recovery of starch from the uterus or cervix. One oviduct can be tested at a time.
Equipment and Supplies
Surgical scrub, clippers, sterile soluble starch powder (1 g), sterile water (10 ml), sterile saline, 2% lidocaine, 2% Lugol’s iodine, microscope slides, coverslips, microscope, 14 gauge 5 cm (2 inch) needle, 18 gauge 12.5 cm (5 inch) spinal needle, syringes, obstetrical sleeve, obstetrical lubricant, sterile lavage tubing (optional).
Technique
The mare should be in diestrus for the procedure. Estrual mares may have a delay in oviductal transport.
A suspension of starch granules is made by mixing 1 g of sterile soluble starch powder in 10 ml of sterile water.
The flank of the mare is clipped and a sterile prep performed.
5 ml of 2% lidocaine is infiltrated subcutaneously and into deeper muscle layers in the flank area corresponding to the needle puncture for starch deposition.
As an optional procedure, one can create a puncture hole through the skin with either a small scalpel blade or a 14 gauge needle.
The ovary is held per rectum against the ipsilateral flank and a percutaneous needle puncture is made through the skin, or the previous puncture hole, with an 18 gauge 12.5 cm (5 inch) spinal needle to deposit 5 ml of starch solution on the ovarian surface.
The external cervical os and vagina are flushed with 10 ml of sterile saline beginning 24 hours after application of the starch solution (original description of the test). The fluid is recovered by aspiration back into the syringe.
Alternatively, the uterus of the mare could be lavaged with sterile saline through a catheter and inflatable cuff. The recovered fluid is allowed to sediment or is centrifuged.
An aliquot of the recovered fluid is placed onto a microscope slide and stained using a few drops of 2% Lugol’s iodine. A coverslip is then placed over the admixture.
The solution is examined with conventional light microscopy with the 10× objective for the presence of stained starch granules (dark blue granules).
The presence of starch granules in the uterine fluid suggests that the oviduct is patent.
Another option for deposition of the starch granules onto the surface of the ovary would be via laparoscopy or a transvaginal needle.
Additional Comments
The starch granule procedure is relatively easy to perform and does not require specialized equipment, technology, or training. However, the starch granule test requires individual testing of each oviduct on separate estrous cycles. The rate of transport through the oviduct is decreased significantly if the starch granules are applied at the time of ovulation. In the original report, granules were evident in the vagina of all mares by 24 hours, except when applied onto an ovulating ovary, in which case granules were not identified until at least 4 days later. The starch mixture contains granules of varying size (4–120 μm diameter), but only small granules (6–56 μm) are usually recovered from the uterus or cervix. These granules are significantly smaller than an early equine embryo (150–250 μm). There is considerable variability in the transport and recovery of all markers. As with other tests evaluating natural oviductal transport of markers, the starch granule test is not considered to be highly reliable or accurate in the detection of oviductal blockage.
Further Reading
1 Allen WE, Kessy BM, Noakes DE. 1979. Evaluation of uterine tube function in pony mares. Vet Rec 105: 364–6.
2 Kenney RM. 1993. A review of the pathology of the equine oviduct. Eq Vet J Suppl 15: 42–6.
3 Liu IKM, Lantz KC, Schalafke S, et al. 1990. Clinical observations of oviductal masses in the mare. Proc Annu Conv Am Assoc Eq Pract 36: 41–5.
4 Tsutsumi Y, Suzuki H, Takeda T, Terami Y. 1979. Evidence of the origin of the gelatinous masses in the oviducts of mares. J Reprod Fertil 57: 287–90.
28 Fluorescent Microspheres Test for Evaluation of Oviductal Patency
Sofie Sitters1 and John J. Dascanio2
1 Amsterday, The Netherlands
2 School of Veterinary Medicine, Texas Tech University, USA
Introduction
Blockage of one or both oviducts with intraluminal gelatinous masses can result in reduction of fertility in the mare. The starch granule test has limitations for evaluation of oviductal patency in the mare. One limitation is the inability to evaluate both oviducts simultaneously. A second concern is the size variation of the starch granules that typically seem to pass through the tested oviducts and that these granules are significantly smaller than the diameter of an early equine embryo.
Consequently, fluorescent microspheres have been used as an alternative to evaluate oviductal patency. The clear advantage of using fluorescent microspheres over the starch granule test is that use of two colors of beads can discriminate between patency of the left and right oviduct, making it possible to demonstrate patency of both the mare’s oviducts in a single procedure. A solution containing fluorescent microspheres is deposited onto the surface of the ovary using a transvaginal ultrasound probe and needle or applied into the proximal oviductal lumen via a laparoscope. This technique requires access to either a fluorescent microscope or a flow cytometer.
Equipment and Supplies
Examination gloves, tail wrap, tail rope, non‐irritant soap, bucket, disposable bucket liner, roll cotton, obstetrical sleeves, obstetrical lubricant, twitch, sedation, fluorescent microspheres (15 μm in diameter) in two colors (i.e., red and green). Option 1: ultrasound with transvaginal probe and 60 cm (24 inch) 18 gauge single channel needle. Option 2: laparoscope and 8 Fr catheter. Uterine lavage catheter, 0.9% sterile saline or lactated Ringer's solution, flow cytometer or fluorescent microscope.
Transvaginal Ultrasound Technique
The mare should be in
