Estimation of intraocular pressure in rabbits with commonly used tonometers.

BACKGROUND AND OBJECTIVES: To validate accuracy and reproducibility of the Perkins tonometer, pneumatonometer, and Tono-Pen XL (Medtronic Solan, Jacksonville, FL) in estimating intraocular pressure (IOP) in rabbits. MATERIALS AND METHODS: IOP was increased from 5 to 50 mm Hg in 5-mm increments. Measurements were compared to readings of two digital manometers simultaneously measuring real IOP in the anterior chamber and vitreous cavity. Interobserver accuracy was evaluated using 4 eyes with the Perkins tonometer. RESULTS: The Perkins tonometer and Tono-Pen XL underestimated IOP and were more accurate at pressures less than 30 mm Hg. No statistically significant difference was found between real IOP and Tono-Pen XL readings. The pneumatonometer overestimated pressures in the low ranges but was accurate at pressures greater than 40 mm Hg. The Tono-Pen XL had more variability than the Perkins tonometer and pneumatonometer at high IOP. CONCLUSIONS: None of the tonometers are accurate or reproducible in estimating IOP in rabbits over the tested range. Pneumatonometry, although not very accurate, has the advantage of having acceptable variability.     

Hemizona assay: assessment of sperm dysfunction and prediction of in vitro fertilization outcome

The hemizona assay (HZA) was used in a prospective, blinded study to assess the relationship between tight sperm binding in the HZA and sperm fertilizing ability in in vitro fertilization (IVF). In each controlled assay, the authors compared sperm binding of proven fertile men with that of patients undergoing IVF. Human oocytes stored in a salt solution were used in the study, and binding results were correlated with the fertilization rate of preovulatory oocytes during IVF. Patients with poor fertilization rates in IVF had significantly lower binding than those cases with successful fertilization (7.3 +/- 1.4 versus 62.1 +/- 10.9, respectively; mean +/- standard error, P less than 0.02). Based on current standards, the HZA was able to predict fertilization accurately in 26 of 28 cases (sensitivity of 83%, specificity of 95%, positive predictive value of 83%). The authors conclude that the HZA is a valuable tool for evaluating dysfunctional sperm-zona pellucida binding, with good predictive value for fertilization in vitro.     

Preclinical abortions: incidence and significance in the Norfolk in vitro fertilization program

Clinical and prognostic significance of preclinical abortions in assisted reproduction is ill defined. Strict diagnostic criteria include a transient and synchronous elevation of serum beta-human chorionic gonadotropin (hCG), estradiol, and progesterone levels 13 days after hCG administration, ending in a bleeding episode no more than 14 days after the missed period. The preclinical abortion study group (54 patients, 178 cycles) was compared with matched control groups A (54 patients, 132 cycles) and B (54 patients, 155 cycles), representing normal term pregnancies and all outcomes, respectively. Control group C included the overall population during the study period. The abortion rate per transfer (preclinical abortion and total miscarriage rates) and total pregnancy wastage in the study group were significantly higher; the ongoing pregnancy rate was significantly lower. Preclinical abortion should be considered as a true reproductive failure with similar implications.     

The perimenopausal patient in in vitro fertilization: the use of gonadotropin-releasing hormone

The perimenopause, incipient ovarian failure, is a major problem in stimulation failures during an in vitro fertilization program. This must be recognized as not necessarily related to age but also associated with adnexal inflammatory and operative processes. Although ovulation occurs uninterruptedly, the follicle-stimulating hormone in the early follicular phase is elevated and the luteinizing hormone is normal. Characteristically, there is no estradiol response to human menopausal gonadotropin therapy or a rapid response with a premature luteinizing hormone surge. These problems sometimes may be overcome with pulsatile intravenous gonadotropin-releasing hormone therapy, 5 or 10 micrograms/90 or 120 minutes. The major therapeutic problem is in the identification of a luteinizing hormone surge in these patients. Of eight women who were treated, two failed to respond with follicular maturation, three either had no oocytes aspirated from apparently postmature follicles or had postmature oocytes; and one had treatment cancelled due to ovulation. The four latter patients may have failed because of unrecognized ovulation. In the remaining two patients, one oocyte was fertilized and transferred, and one pregnancy occurred.     

In vitro fertilization and embryo transfer (IVF/ET): An established and successful therapy for endometriosis

The purpose of this report is to present a 6-year experience in the management of endometriosis with in vitro fertilization and embryo transfer (IVF/ET). We divided 136 patients who underwent 280 cycles into three groups: (1) previous history of endometriosis but normal pelvis at the time of oocyte retrieval, (2) stages I–II endometriosis (revised AFS classification), and (3) stages III–IV endometriosis. The stimulation protocols, estradiol (E₂) responses, and distribution of terminal E₂ patterns were similar in all groups. Group 3 had significantly fewer preovulatory and immature oocytes retrieved and fewer embryos transferred. The fertilization rate and the per cycle/per transfer pregnancy rates were similar in all groups. The miscarriage rate was higher in group 3, and the on-going pregnancy rate per cycle was lower, Luteal phase E₂ and progesterone levels were comparable in all groups. No differences were found when groups 2 and 3 were analyzed for the presence of one or two ovaries or the presencelabsence of ovarian endometriosis. The overall fertilization rate, the per cycle/per transfer pregnancy rates, and the miscarriage rate were similar to those of tubal factor patients. We underscore the excellent out-come of patients with minimal or mild endometriosis in IVF/ET. We conclude that patients with moderate or severe endometriosis have a compromised reproductive potential, probably because of a reduced oocyte recovery rate and poor embryo quality.     

Predictive value of abnormal sperm morphology in in vitro fertilization

In patients with acceptable sperm count and motility, two patterns of abnormal morphology, judged with strict criteria, were identified and described. Patients with less than 4% normal forms and less than 30% morphology index (summation of normal and slightly amorphous forms) had a fertilization rate of 7.6% of the oocytes (P pattern, poor prognosis). Patients with normal morphology between 4 and 14% had a significantly better fertilization rate of 63.9% of the oocytes (P less than 0.0001). Cases with greater than 14% normal forms fertilized within the normal range for the laboratory. By evaluating sperm morphology with the proposed strict criteria, its predictive value in in vitro fertilization is enhanced.     

Male antisperm antibodies: association with a modified sperm stress test and lipid peroxidation

We previously reported a modified sperm stress test (MOST), low scores (< 0.39) in which were associated with sperm-related abnormal in vitro fertilization. Preliminary observations suggested that the presence of male sperm antibodies (ASA) could give low MOST scores. It was therefore decided to undertake a study to verify this possible association and also to ascertain if such a relationship was causal in nature. Six hundred and fifty semen samples from patients consulting for infertility were assessed for basic seminal characteristics, motion parameters (CASA), ASA and MOST. Thirty-nine samples (6%) were ASA-positive. Samples with and without ASA showed similar characteristics, except for percentage of normal forms and MOST scores (0.35 +/- 0.03 vs. 0.67 +/- 0.01, P < 0.001, for ASA-positive and -negative, respectively). There was a strong statistical association between presence of ASA and low MOST scores (P < 0.0001). One-hundred per cent of ASA-positive samples displayed low MOST scores. To verify the nature of this relationship, we incubated ASA-free spermatozoa with ASA-positive and -negative (control) sera. Despite an increase in the percentage of ASA-bearing spermatozoa in those aliquots incubated with ASA-positive serum, their original (pre-incubation) MOST scores remained unchanged. Furthermore, the rate of lipid peroxidation, indirectly reflected in MOST scores, was not different in the aliquots incubated with ASA. In conclusion, there seems to be a strong association between presence of ASA and low MOST values in semen samples of infertile patients; however, the relationship does not appear to be causal.