Biomedical subjects

K Swenson

Publications and source records attributed to K Swenson.

43 records · Page 3Linked to original sources

PubMedDate not supplied

A study of to determine if limiting the contact of sperm with zona pellucida reduces the rate of spontaneous abortions.

A recent study suggested that oligoasthenozoospermia may be an etiologic factor for spontaneous abortion (SAB) after in vitro fertilization-embryo transfer (IVF-ET). However, IVF-ET with intracytoplasmic sperm injection (ICSI) did not seem to be associated with an increased SAB rate. The study presented herein compared the rate of SAB in pregnancies achieved by IVF-ET according to the type of oocyte insemination process. The 3 types evaluated were conventional insemination, which exposed the oocyte to 25,000 sperm with prolonged contact (16-24 h), intermediate contact with a short insemination protocol where contact with 25,000 sperm was limited to 2 h, and very limited contact with ICSI, where only 1 sperm was injected into the oocyte thus not exposing the zona pellucida to any sperm. The patients were further subdivided into age groups of < or =39 or > or =40. SAB rates after frozen ET were also evaluated. The clinical pregnancy and SAB rates following fresh or frozen ET for conventional, ICSI, and short insemination techniques for the 2 age groups were comparable. These data question whether oligoasthenozoospermia may be a factor in causing SAB, and whether avoidance of contact with the zona pellucida by using ICSI can negate this effect. A larger study is needed.

Abortion, Spontaneous↗

PubMedDate not supplied

A randomized study comparing the effect of standard versus short incubation of sperm and oocyte on subsequent pregnancy and implantation rates following in vitro fertilization embryo transfer.

Some data suggest that some sperm are associated with a toxic product that lowers embryo implantation rates when these sperm come in contact with the zona pellucida. The possibility exists that shortening the incubation time could improve pregnancy rates. A randomized prospective study was initiated to evaluate pregnancy and implantation rates with transfer of embryos formed by conventional overnight vs short (2-h) co-incubation of sperm and oocytes. The clinical and viable pregnancy rates were 41 and 29% for conventional co-incubation versus 30 and 30% for short co-incubation. Implantation rates were also similar (17.9 vs 17.8%). Short incubation does not seem to impact any advantage over conventional co-incubation techniques in couples undergoing in vitro fertilization where the male factor is normal.

Embryo Implantation↗

PubMedDate not supplied

Pregnancy/implantation rates as related to age following transfer of frozen embryos produced by ICSI.

A study has suggested that one drawback of ICSI is that if these embryos are cryopreserved they have lower implantation rates after thawing and transfer as compared to other frozen embryos derived from conventional oocyte insemination. Other studies have not shown such adverse effects on pregnancy rates following frozen embryo transfer (ET) of embryos formed by ICSI. The study presented here evaluated the largest number of frozen ET cycles of embryos following ICSI, which were compared to couples having frozen ET with embryos formed by conventional insemination. In women age 39 and younger, the clinical, viable, pregnancy rates and implantation rates were very similar. Similar rates were reached for the older group. These data convincingly demonstrate that fertilization by ICSI does not adversely effect the implanting capacity of frozen-thawed embryos.

Adult↗

PubMedDate not supplied

Cumulative probability of pregnancy following IVF with ICSI and fresh or frozen embryo transfer.

The authors studied the cumulative probability of pregnancy for up to 4 consecutive embryo transfer (ET) cycles with ICSI performed for male factor. Transfers could be either fresh or frozen. The clinical pregnancy rate (PR) for the first 4 cycles were similar [44% (61/366); 31% (44/138); 45% (14/31); 44% (4/9)]. Delivery rates were also similar. There was a lower PR on the second retrieval vs. the first retrieval (47% vs. 29%), but this may be related to most of the second retrievals occurring in the second transfer cycle (67%, 31/55); this may be explained by women who were poor responders and required another retrieval without a frozen ET. The majority of transfers in cycle 1 were fresh, whereas cycles 2-4 used primarily frozen-thawed embryos. These data should be helpful for patients requiring IVF with ICSI in deciding to continue with more IVF cycles or consider other

Cryopreservation↗

PubMedDate not supplied

Sperm toxicity evaluated by the overnight sperm survival test.

A subnormal sperm stress test has also been associated with implantation failure despite apparently normal fertilization; however, this test is cumbersome and time-consuming. The overnight sperm survival test has been considered to possibly demonstrate lipid peroxidation abnormalities similar to the sperm stress test. The present study evaluated whether lower overnight survival scores were associated with lower pregnancy and implantation rates following in vitro fertilization-embryo transfer. The results showed no adverse effect of poor overnight survival test scores. Possibly, the overnight survival test, though similar in some respects to the sperm stress test, is not similar for properties of predicting embryo implantation defects. Corroboration that subnormal stress tests predicts implantation disorders is needed.

Adult↗

PubMedDate not supplied

Evaluation of sperm nuclear morphology in specimens with abnormal sperm chromatin structural assays.

Two recent tests have claimed to identify the subfertile male even when other semen parameters were normal: the sperm chromatin structure assay (SCSA) and abnormal sperm nuclear morphology using much higher magnification. The present study attempted to determine if having a high (> 30%) DNA fragmentation index (DFI), thus resulting in an abnormal SCSA test, is associated with a greater likelihood of sperm with abnormal nuclei. Four males with high DFI scores (57.6%, 65.4%, 31.0%, and 35.3%) had their nuclei evaluated by a complex microscope set-up that magnifies the sperm at least 6000x. The corresponding % of normal nuclei was 0%, 20.0%, 23.7% and 40.0%. The mean and median % of normal nuclei was 20.9+/-16.43 and 21.8, respectively. More studies of similarly matched refractory in vitro fertilization cases, where males have normal DFI scores, are needed to determine if having a high DFI index is associated with a lower percentage of normal nuclei.

Cell Nucleus↗

PubMedDate not supplied

In vitro fertilization with intracytoplasmic sperm injection is an effective therapy for male factor infertility related to subnormal hypo-osmotic swelling test scores.

The aim of the study was to determine if intracytoplasmic sperm injection (ICSI) would be an effective therapy for mates with subnormal hypo-osmotic swelling test (HOST) scores, a condition known to prevent implantation of embryos despite allowing normal fertilization and embryo formation. Couples in whom the male partner had a HOST score of <50% and failed to achieve a pregnancy despite at least 3 cycles of intrauterine insemination with chymotrypsin-galactose-treated sperm were treated with in vitro fertilization (IVF) with ICSI. The clinical and viable pregnancy rates were 49.0% and 45.3% (n = 53). The implantation rate was 27.1%. These data thus demonstrate that ICSI is an effective therapy for infertile couples in whom the male partner has a subnormal hypo-osmotic swelling (HOS) score. Previous studies using conventional IVF without ICSI when HOS was subnormal found normal fertilization rates but a marked reduction in pregnancy and implantation rates. The very acceptable pregnancy and implantation rates demonstrated in this study with ICSI is consistent with the hypothesis that the defect associated with sperm that have subnormal HOST scores is not related to the single spermatozoon that is responsible for fertilizing the oocyte but may be related to a toxic factor associated with the supernumerary sperm attached to the zona pellucida.

Adult↗