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Biomedical subjects

T F Porter

Publications and source records attributed to T F Porter.

At least 19 recordsLinked to original sources
PubMed2006

Immunotherapy for recurrent miscarriage.

BACKGROUND: Because immunological aberrations might be the cause of miscarriage in some women, several immunotherapies have been used to treat women with otherwise unexplained recurrent pregnancy loss. OBJECTIVES: The objective of this review was to assess the effects of any immunotherapy, including paternal leukocyte immunization and intravenous immune globulin on the live birth rate in women with previous unexplained recurrent miscarriages. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (December 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2004, Issue 3), MEDLINE (1966 to September 2004) and EMBASE (1980 to September 2004). SELECTION CRITERIA: Randomized trials of immunotherapies used to treat women with three or more prior miscarriages and no more than one live birth after, in whom all recognised non-immunologic causes of recurrent miscarriage had been ruled out and no simultaneous treatment was given. DATA COLLECTION AND ANALYSIS: The review author and the two co-authors independently extracted data and assessed study quality for all studies considered for this review. MAIN RESULTS: Twenty trials of high quality were included. The various forms of immunotherapy did not show significant differences between treatment and control groups in terms of subsequent live births: paternal cell immunization (12 trials, 641 women), Peto odds ratio (Peto OR) 1.23, 95% confidence interval (CI) 0.89 to 1.70; third party donor cell immunization (three trials, 156 women), Peto OR 1.39, 95% CI 0.68 to 2.82; trophoblast membrane infusion (one trial, 37 women), Peto OR 0.40, 95% CI 0.11 to 1.45; intravenous immune globulin, Peto OR 0.98, 95% CI 0.61 to 1.58. AUTHORS' CONCLUSIONS: Paternal cell immunization, third party donor leukocytes, trophoblast membranes, and intravenous immune globulin provide no significant beneficial effect over placebo in improving the live birth rate.

Abortion, Habitual↗
PubMed2001

Obstetric uses of intravenous immunoglobulin: successes, failures, and promises.

Intravenous immune globulin (IVIG) is approved for use in a number of conditions that may occur in obstetrical patients, including autoimmune thrombocytopenia and immune deficiency syndromes. IVIG also is widely used in obstetrics for nonapproved indications, such as fetal-neonatal alloimmune thrombocytopenia, antiphospholipid syndrome, and recurrent miscarriage. This review critically analyzes the use of IVIG for these indications based on the best available information. The authors conclude IVIG is effective in the management of fetal-neonatal alloimmune thrombocytopenia. IVIG appears promising as a treatment for severe fetal-neonatal alloimmune hemolysis due to antierythrocyte antibodies. A prospective multicenter trial should be undertaken. IVIG is no more effective than heparin and low-dose aspirin in the treatment of pregnancies complicated by antiphospholipid syndrome but has not been adequately evaluated in refractory cases. Finally, pending convincing studies, IVIG is not effective and should not be used for the management of recurrent miscarriage.

Abortion, Habitual↗
PubMed2001

Antiphospholipid antibodies in women at risk for preeclampsia.

OBJECTIVE: The aim of this study was to determine whether positive results of tests for any of 5 antiphospholipid antibodies are associated with recurrent preeclampsia among women with a history of preeclampsia in a previous pregnancy. STUDY DESIGN: Second-trimester serum samples were obtained from 317 women with preeclampsia in a previous pregnancy who were being followed up in a prospective treatment trial. The serum samples were measured by enzyme-linked immunoassay for immunoglobulin G and immunoglobulin M antibodies against 5 phospholipids. Positive results were analyzed with regard to preeclampsia, severe preeclampsia, intrauterine growth restriction, and preterm delivery. RESULTS: Sixty-two of the 317 women (20%) had recurrent preeclampsia develop, 19 (6%) had severe preeclampsia, and 18 (5.8%) were delivered of infants with growth restriction. Positive results of tests for immunoglobulin G or immunoglobulin M antiphospholipid antibodies were not associated with recurrent preeclampsia. Positive results for immunoglobulin G or immunoglobulin M antibodies at the 99th percentile were also not associated with preterm delivery. Positive results at the 99th percentile for immunoglobulin G antiphosphatidylserine antibody were associated with severe preeclampsia, and positive results at the 99th percentile for immunoglobulin G anticardiolipin, antiphosphatidylinositol, and antiphosphatidylglycerol antibodies were associated with intrauterine growth restriction. The positive predictive values for these outcomes all were approximately 30%. CONCLUSION: Positive results of testing for antiphospholipid antibodies in the second trimester were not associated with recurrent preeclampsia among women at risk because of a history of preeclampsia. Positive results for immunoglobulin G antiphosphatidylserine antibody were associated with severe preeclampsia, and positive results for immunoglobulin G anticardiolipin, antiphosphatidylinositol, and antiphosphatidylglycerol antibodies were associated with intrauterine growth restriction. However, the positive predictive values for all these associations were modest. Testing for antiphospholipid antibodies during pregnancy is of little prognostic value in the assessment of the risk for recurrent preeclampsia among women with a history of preeclampsia.

Adult↗
PubMed2000

Coumarin derivatives and breast-feeding.

Coumarin derivatives are the anticoagulants most widely used in the United States. These agents are relatively contraindicated during pregnancy, and the use of these drugs in breast-feeding women remains controversial. Much of the confusion regarding the passage of these agents into breast milk might stem from the fact that different agents possess significantly different chemical properties. A review of the chemical structure of different coumarin derivatives, as well as available clinical evidence, suggests that warfarin sodium is not excreted into breast milk, and can be safely given to women requiring therapeutic anticoagulation postpartum. For the rare patient who cannot tolerate warfarin sodium, the use of dicumarol, rather than anisindione, is preferred.

Anticoagulants↗
PubMed2000

Alloimmune causes of recurrent pregnancy loss.

Recurrent pregnancy loss is a vexing problem facing many couples. Some authorities have suggested that idiopathic recurrent pregnancy loss is alloimmune in nature. Suggested mechanisms include the presence of cytotoxic antibodies, absence of maternal blocking antibodies, inappropriate sharing of human leukocyte antigens, and disturbances in natural killer cell function and distribution. Proposed therapies for so-called alloimmune-related pregnancy loss include leukocyte immunization and intravenous immune globulin. Unfortunately, neither has been successful in well-designed trials and both are expensive. Although alloimmune disturbances may be responsible for some idiopathic recurrent pregnancy loss, the pathophysiology is far from certain and there is currently no clinical indication for immunotherapy.

Abortion, Habitual↗
PubMed2000

Is vaginal birth after cesarean less expensive than repeat cesarean delivery?

OBJECTIVE: This study was undertaken to compare total medical costs of trial of labor after cesarean with those of elective repeat cesarean without labor, with both short- and long-term neonatal costs associated with such procedures taken into account. STUDY DESIGN: Costs associated with All Patient Refined diagnosis-related groups and Current Procedural Terminology for a large not-for-profit health care system were applied to an algorithm describing maternal and neonatal outcomes of trial of labor. Perinatal morbidity rates and cost estimates for long-term neurologic damage associated with uterine rupture were derived from published literature. RESULTS: If a 70% vaginal birth rate for women undergoing a trial of labor and delivery in a tertiary center with a mean uterine rupture to delivery time of 13 minutes is assumed, the net cost differential ranged from a saving of $149 to a loss of $217, depending on morbidity assumptions. For vaginal birth after cesarean success rates <70%, trial of labor in the presence of two previous scars, and institutional factors increasing the perinatal morbidity rate by just 4% with respect to that seen in tertiary centers, trial of labor resulted in a net financial loss to the health care system regardless of all other assumptions made. CONCLUSIONS: When costs as opposed to charges are considered and the cost of long-term care for neurologically injured infants is taken into account, trial of labor after previous cesarean is unlikely to be associated with a significant cost saving for the health care system. Recent government-mandated length-of-stay requirements are likely to make the economic benefit of vaginal birth after cesarean even less favorable. Factors other than cost must govern decisions regarding trial of labor or repeat cesarean.

Algorithms↗
PubMed2000

Neonatal alloimmune thrombocytopenia: antenatal management.

OBJECTIVE: The optimal management of pregnancies at risk for neonatal alloimmune thrombocytopenia is debated. Proposed management includes the administration of intravenous immunoglobulin and serial determination of the fetal platelet count. The aims of our study were to determine the effectiveness and likely mechanism of action of intravenous immunoglobulin and to evaluate the safety of cordocentesis in cases of neonatal alloimmune thrombocytopenia. STUDY DESIGN: Eighteen mother-infant pairs were studied. All were at risk for neonatal alloimmune thrombocytopenia on the basis of delivery of a previously affected infant and confirmation of specific maternal antiplatelet antibodies. The pertinent antigen was HPA-1a in 13 cases, HPA-3a in 2 cases, and undetermined in 3 cases. Serial cordocenteses were used to determine fetal platelet counts. If the platelet count was <50,000/microL before 37 weeks' gestation, treatment was initiated with intravenous immunoglobulin administered to either the fetus (n = 2) or the mother (n = 8). In 3 cases fetal and maternal immunoglobulin G levels were determined before and after treatment. RESULTS: Seven (39%) fetuses had adequate platelet counts, were not treated, and were delivered of infants with normal platelet counts. Eleven (61%) fetuses were thrombocytopenic. Eight thrombocytopenic infants were treated with maternally administered intravenous immunoglobulin. In 6 (75%) of 8 cases the fetal platelet count increased after administration of intravenous immunoglobulin, but 2 fetuses remained severely thrombocytopenic. Two thrombocytopenic fetuses were treated with intravenous immunoglobulin infusion directly into the umbilical vein; both remained thrombocytopenic. Moreover, fetal immunoglobulin G levels did not correlate well with the response to intravenous immunoglobulin. Two (5.3%) of 38 cordocenteses were complicated by hemorrhagic complications, necessitating immediate cesarean delivery despite the use of prophylactic platelet transfusion in one case. CONCLUSION: Severe fetal alloimmune thrombocytopenia does not always occur in subsequent fetuses. Thus either fetal antigen status or platelet counts or both of these are necessary to determine whether treatment is needed. The effect of intravenous immunoglobulin on raising the fetal platelet count is inconsistent and appears to be caused by maternal or placental factors rather than a direct inhibition of fetal platelet destruction by immunoglobulin. The risk of hemorrhagic complications from cordocentesis in pregnancies complicated by neonatal alloimmune thrombocytopenia is higher than generally appreciated and is not always avoided by platelet transfusion at the time of the procedure.

Antigens, Human Platelet↗
PubMed1999

Vibroacoustic and scalp stimulation.

Both VAS and scalp stimulation are useful in the evaluation of fetal compromise by decreasing the number of falsely abnormal FHR tests and limiting the number of unnecessary interventions, thus improving the efficiency of antepartum and intrapartum FHR monitoring. As is true for all types of fetal assessment using FHR monitoring, VAS and scalp stimulation have limitations, and a lack of response to these methodologies does not necessarily indicate fetal acidemia. When either VAS or scalp stimulation is employed, one must take into consideration their respective predictive values (see Table 1). Fetal VAS or scalp stimulation should be considered as one facet of comprehensive fetal evaluation. When these techniques are used in this manner, the clinician evaluating the fetus in the antepartum or intrapartum period may prevent unnecessary intervention and improve maternal and neonatal outcome.

Acoustic Stimulation↗
PubMed1999

Deep venous thrombosis: prophylaxis in gynecology.

Thromboembolism remains a serious concern for women undergoing surgery for benign and malignant gynecologic conditions. Attempts at perioperative thromboprophylaxis have probably reduced the incidence of DVT considerably. Both heparin and mechanical devices offer effective and safe treatment. However, even though unfractionated heparin and LMWH compounds are easy to administer and are well tolerated by patients, mechanical compression devices avoid the bleeding complications that may be encountered with anticoagulation therapy. Individual patient risks and circumstances should be taken into consideration when choosing which therapy to use (Table 1). Those patients at greatest risk may benefit from aggressive combination therapy.

Adult↗
PubMed1998

Institutional influences on the primary cesarean section rate in Utah, 1992 to 1995.

OBJECTIVES: Our purpose was to evaluate institutional and organizational influences on cesarean section rates in Utah and to adjust such rates for differences in patient acuity. STUDY DESIGN: Data on cesarean section rates were derived from the Utah Hospital Discharge Database and adjusted for patient acuity by correcting raw cesarean rates for those patients undergoing cesarean section meeting regional gestational age transport criteria. RESULTS: When analyzed by means of 1-way analysis of variance, the following factors had a significant negative correlation (P < .05) with cesarean section rate: presence of a newborn intensive care unit and maternal-fetal medicine subspecialists, presence on the medical staff of obstetrician-gynecologist(s) as opposed to family physicians only, delivery volume >1500/y, urban location, and 24-hour in-house anesthesiology. When cesarean rates were corrected for acuity, facilities with maternal-fetal medicine specialists and a newborn intensive care unit had significantly lower rates (P < .001) and more uniform rates than otherwise similar institutions. CONCLUSIONS: More medically sophisticated physicians and institutions have lower cesarean rates when patient acuity is taken into account.

Cesarean Section↗
PubMed1997

The risk of preterm birth across generations.

OBJECTIVE: To examine the risk of preterm birth for mothers who themselves were born before term. METHODS: Data were taken from a linked data base of birth certificates composed of two cohorts: 1) a parental cohort of women born between 1947 and 1957 and 2) their offspring born between 1970 and 1992. "Preterm mothers" were women in the parental cohort who were born at less than 37 weeks' gestation. "Term mothers" were women in the parental cohort born at or after 38 weeks' gestation. Preterm mothers and term mothers were matched for birth year, county of birth, marital status, parity, and age. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for the risk of preterm delivery in preterm mothers. Multiple logistic regression was used to assess the interaction of concomitant variables with the risk of premature delivery. RESULTS: The risk of preterm birth was significantly higher in preterm mothers than in term mothers (OR 1.18; 95% CI 1.02, 1.37). The risk increased as the gestational age at the mothers' birth decreased (less than 30 weeks'; OR 2.38; 95% CI 1.37, 4.16). The interaction between maternal age and parity increased the risk of preterm delivery at less than 34 weeks in some age and parity strata. CONCLUSION: An increased risk of preterm delivery exists for women who themselves were born before 37 weeks' gestation. The risk is inversely correlated with the maternal gestational age at birth and is influenced by maternal age and parity.

Adolescent↗
PubMed1997

Current status of the multicenter randomized clinical trial on fetal oxygen saturation monitoring in the United States.

Current clinical methods of intrapartum fetal assessment are sensitive but poorly specific in detecting fetal compromise during labor. These limitations have substantially contributed to the escalating cesarean section rate which occurred in the US during the last several decades. Experimental and clinical research efforts directed towards application of the oxygen saturation monitor (pulse oximeter) to intrapartum fetal assessment have produced encouraging results. If this new method of fetal assessment is to enter the clinical arena, safety and efficacy issues must first be properly evaluated via randomized clinical trials. The purpose of this report is to describe the design of a multicenter randomized clinical trial of intrapartum fetal oxygen saturation monitoring recently begun in the US. Specific aspects of the trial, including purpose, study design, sample size estimates, control and test groups, inclusion and exclusion criteria, fetal heart rate classification, definition of normal fetal arterial oxygen saturation (SpO2), clinical management protocol, and assessment of maternal-fetal outcomes will be addressed.

Female↗
PubMed1997

Intravenous immune globulin in the management of severe Rh D hemolytic disease.

Although intrauterine fetal transfusion has improved dramatically perinatal outcome in Rh D alloimmunization, in some cases the fetus is affected before transfusion is possible. Immune globulin (IVIG) administration is being increasingly used to successfully treat a variety of immune-mediated diseases, such as pregnancies affected by platelet alloimmunization. Although only a limited number of pregnancies have been reported, favorable outcomes with IVIG treatment of severe Rh disease have been described. We present a case report, review the published experience with IVIG treatment in severe, early-onset anti-D sensitization, and propose that IVIG may have an adjunctive role in the treatment of severe Rh isoimmunization.

Adult↗
PubMed1996

Anticardiolipin antibodies: clinical consequences of "low titers".

OBJECTIVE: To clarify the implications of low levels of immunoglobulin (Ig)-G or IgM anticardiolipin antibodies. METHODS: Women who underwent clinically indicated testing for antiphospholipid antibodies were divided into four groups based on results: 1) high-positive (lupus anticoagulant or more than 19 IgG binding units of anticardiolipin antibodies; N = 131), 2) low-positive IgG (fewer than 20 IgG binding units; N 93), 3) IgM only (more than nine IgM binding units; N 97), and 4) negative (N = 153). The development of antiphospholipid antibody-related disorders was assessed for the time interval from initial antibody testing to patient interview. The median study interval for each group was at least 4 years. Forty-five percent of women had repeat testing at the time of interview. RESULTS: Women in the high-positive group were more likely to develop at least one new medical complication than those in the low-positive IgG (odds ratio [OR] 4.49, 95% confidence interval [CI] 2.01-10.03), IgM only (OR 6.00, 95% CI 2.65-13.59), and negative (OR 9.11, 95% CI 3.92-21.2) groups. In contrast, the low-positive IgG, IgM only, and negative groups had similar risks for the development of new disorders. Twelve of 129 (9.3%) women in the low-positive IgG, IgM only, or negative groups had lupus anticoagulant or more than 19 IgG binding units on retesting. Half of these women developed at least one new disorder. CONCLUSION: Women with IgM or low levels of IgG anticardiolipin antibodies comprise distinct populations from those with lupus anticoagulant or moderate to high levels of anticardiolipin antibodies. These women are not at risk for antiphospholipid antibody-related disorders beyond the risk conferred by their medical histories. However, repeat testing is warranted with new or recurrent clinical symptoms.

Adult↗
PubMed1996

Normal values for amniotic fluid index during uncomplicated twin pregnancy.

OBJECTIVE: To establish the gestational age trends of amniotic fluid index (AFI) in uncomplicated twin pregnancies. METHODS: Amniotic fluid index was measured in uncomplicated twin pregnancies seen between 1985 and 1993 and meeting the following criteria: 1) no maternal medical or obstetric complications, 2) normal growth of both twins by serial ultrasound, and 3) normal amniotic fluid volume by ultrasound. Amniotic fluid index was measured by adding the deepest vertical pockets in four quadrants, defined by the umbilicus and linea nigra. The relation between gestational age and AFI was evaluated using linear regression analysis. RESULTS: Two hundred eighty-two sets of twins were considered uncomplicated; 1101 AFI measurements were performed on these pregnancies between 25.5 and 40.5 weeks' gestation. Percentile values for AFI were determined according to gestational age. The regression equation relating the median AFI to gestational age was: AFI = 19.4 - 0.12 x gestational age (P = .03). The R2 value was 0.04. CONCLUSION: Gestational age trends in normative AFI measurements for twin pregnancies have been established. Their use will facilitate a more reproducible, quantitative diagnosis of oligohydramnios in twins, compared with subjective, qualitative approaches to amniotic fluid volume assessment.

Adult↗
PubMed1995

Amniotic fluid embolism: analysis of the national registry.

OBJECTIVE: We analyzed the clinical course and investigated possible pathophysiologic mechanisms of amniotic fluid embolism. STUDY DESIGN: We carried out a retrospective review of medical records. Forty-six charts were analyzed for 121 separate clinical variables. RESULTS: Amniotic fluid embolism occurred during labor in 70% of the women, after vaginal delivery in 11%, and during cesarean section after delivery of the infant in 19%. No correlation was seen with prolonged labor or oxytocin use. A significant relation was seen between amniotic fluid embolism and male fetal sex. Forty-one percent of patients gave a history of allergy or atopy. Maternal mortality was 61%, with neurologically intact survival seen in 15% of women. Of fetuses in utero at the time of the event, only 39% survived. Clinical and hemodynamic manifestations were similar to those manifest in anaphylaxis and septic shock. CONCLUSIONS: Intact maternal or fetal survival with amniotic fluid embolism is rare. The striking similarities between clinical and hemodynamic findings in amniotic fluid embolism and both anaphylaxis and septic shock suggest a common pathophysiologic mechanism for all these conditions. Thus the term amniotic fluid embolism appears to be a misnomer.

Adolescent↗