Wear pattern of retrieved patellar implants.

The so-called "papillon" pattern of polyethylene wear of 17 patellar components from 5 Kinematic and 12 Total Condylar prostheses, retrieved after an average of 80 months in situ, was studied. The primary diagnosis was osteoarthritis in all cases. Four modes of damage were observed: polishing in 13 cases, delamination in 12, cold flow in 6 and scratching in 3. The median total area of polyethylene damage was 76.5% for polishing, 70.6% for delamination, 35.3% for cold flow and 17.6% for scratching. The importance of the conformity of the Kinematic patellar component in order to decrease contact stresses was confirmed. The average contact stresses on the nonconforming total Condylar patellar component (12.9 kgf/mm2), were significantly higher (p < 0.002) than the average contact stresses on the conforming Kinematic patellar component (2.9 kgf/mm2). The area of wear was smaller for the nonconforming Total Condylar (357.2 mm2) than for the conforming Kinematic patella (439.2 mm2). This difference, however, is not statistically significant. The average weight of the patients with a Kinematic Knee (74.5 kg) was higher than that of patients with a Total Condylar knee (66 kg), but the difference was not significant. The high incidence of significant wear of the patellar components indicates that a basic deficiency is present in the design of patellar implants, and calls for the improvement of two mechanical features: adequate thickness of the polyethylene implant and conforming articulating surfaces.

The relation between inter-twin birth weight discordance and total twin birth weight.

OBJECTIVE: We tested the hypothesis that the frequency of growth discordance among twins is not related to the uterine capacity for carrying twins. METHOD: We counted and compared the frequencies of birth weight discordance of more than 25% in an unlike-sexed twin cohort (n = 1244) and in a population-based twin cohort (n = 7570) across the deciles of the total twin birth weight (twin A + twin B) distribution. The birth order of the heavier twin was noted. RESULTS: Similar frequencies of discordant pairs were found in both cohorts (11% and 12%, respectively; Mantel-Haenszel chi2 test: P = .131, odds ratio (OR) 0.9, 99% confidence interval (CI) 0.67, 1.11; Woolf test for heterogeneity: two-tailed P = .472). In the discordant pairs, twin A was considerably more often the heavier twin in all birth weight deciles (unlike-sexed cohort: P < 10(-8), OR 5.9, 99% CI 3.0, 11.7; population-based cohort: P < 10(-8), OR 3.1, 99% CI 2.3, 4.0), and in both cohorts (inter-cohort difference: P = .109, OR 1.4, 99% CI 0.83, 2.32). Both cohorts showed a similar nonlinear trend: given that X = decile order, discordance decreased as a function of 22.0 - 6.54 ln[X] for the unlike-sexed twins cohort and 23.0 - 8.18 ln[X] for the population-based cohort, with r values of 0.967. CONCLUSION: The more favorable the uterine milieu for carrying twins, the smaller the likelihood of discordant twin growth. Birth order of the heavier twin appears to be an integral part of the discordance phenomenon. The similarity of the cohorts suggests that these conclusions are valid for both like and unlike-sexed twins.

Intra-amniotic bleeding and fetal echogenic bowel.

OBJECTIVE: To assess the relationship between intra-amniotic bleeding and fetal echogenic bowel. METHODS: Comprehensive fetal ultrasound examinations were done before and 12 hours after fetal transfusions. Follow-up ultrasound examinations were done weekly in 28 fetuses with intra-amniotic bleeding. Hyperechogenic bowel was diagnosed when the echogenicity of fetal bowel was similar to that of bone. Postpuncture bleeding was identified when a stream of echogenic material from the cord into the amniotic space was seen, lasting at least 60 seconds. RESULTS: None of the fetuses had echogenic bowel before initial transfusions. Intra-amniotic bleeding was followed by bowel echogenicity in seven of 28 fetuses within the first 12 hours after bleeding episodes. Echogenic bowel remained in five fetuses 2 weeks after the bleeding episodes. In three fetuses, echogenic bowel was still seen 4 weeks later. CONCLUSION: Intra-amniotic bleeding can lead to echogenic bowel.

Cephalhematoma and caput succedaneum: do they always occur in labor?

OBJECTIVE: Our purpose was to analyze our experience with cephalhematomas detected prenatally by ultrasonography. STUDY DESIGN: Seven cases of cephalhematomas were identified prenatally among 16,292 fetuses having comprehensive ultrasonographic examinations between 1993 and 1996. The course of pregnancy and the neonatal outcome were reviewed in each case. RESULTS: Cephalhematomas appeared as an echogenic bulge posterior to the occipital region (5 cases) or at the temporal region of the fetal head (2 cases). CONCLUSION: Cephalhematomas, which are believed to be a result of operative delivery, can also originate, in utero, antepartum. Premature rupture of membranes appears to be an associated factor.

How accurate is fetal biometry in the assessment of fetal age?

OBJECTIVE: The purpose of the study was to assess the accuracy of fetal biometry in the midtrimester of pregnancy in the assignment of fetal age. STUDY DESIGN: A total of 152 singleton, 67 twin, and 19 triplet gestations resulting from in vitro fertilization with ultrasonographic fetal biometry from 14 to 22 weeks made up the study population. A gestational age prediction equation was derived from singletons with the use of stepwise linear regression. This equation was compared with 38 previously published equations and then applied to the twin and triplet populations. RESULTS: Head circumference was the best predictor of gestational age (random error [SD] 3.77 days). Addition of abdominal circumference and femur length to head circumference improved the accuracy of the dating equation (random error 3.35 days). Most dating formulas had systematic errors of <1 week. The systematic error was -0.32 day for averaging the singleton-based predictions for twins and -1.26 days for triplets. CONCLUSIONS: Gestational age assessment with the use of fetal biometry from 14 to 22 weeks is accurate for singleton, twin, and triplet gestations.

Practical guidelines for antepartum fetal surveillance.

Antepartum fetal assessment is used in pregnancies at high risk for perinatal morbidity and mortality. Current testing options include the fetal movement count, the nonstress test, the contraction stress test and the biophysical profile. Vibroacoustic stimulation is a useful adjunctive procedure. All of these modalities have limitations. A strict protocol for antepartum fetal surveillance that is applicable to all patients is not possible. However, a testing approach based on general principles and guidelines can be followed.

Computed sonography: requiem to echogenicity assessment?

We studied the influence of changes in gain settings, log compression, persistence, preprocessing, and postprocessing on image density in the fetal liver model. Each parameter was studied while the others were held constant. The image density was objectively measured by electrooptical transmission densitometry using a transparent film output. Neither the persistence nor the preprocessing levels significantly changed image density. Postprocessing of sonographic images produced significant differences (p < 0.02) in mean image density of most of the various postprocessing curves and is a serious confounder of tissue echogenicity assessment. The data reconfirmed that there is a linear relationship (r = -0.94 to -0.997) between image density and gain setting. However, each log compression setting significantly changed (p < 0.0000001) this relationship, obviating possible image density calibration. Our data suggest that manipulation of image parameters by computed sonographic technology obviates accurate echogenicity assessment.

Quantitative assessment of gray-level perception: observers' accuracy is dependent on density differences.

Sonographic image density represents tissue echogenicity, or the acoustic nature of scanned tissue. It has the potential to distinguish normal from abnormal tissue. Humans are poor assessors of tissue echogenicity, yet their abilities have not been quantitatively compared to more objective methods. We compared the accuracy of image density differentiation by the human eye and by densitometry in the fetal liver model. A group of 60 observers was asked to compare the echogenicity of three pairs of images of a fetal liver. Twenty-three repeated the comparison several weeks later. Image density was measured by electro-optical densitometry. The two-tailed signed rank test was used to compare the observer's perceptions with the density values and the repeated observations with the original responses. The density of each fetal liver image in pair A was the same. Image B1 had a 12.3% lower density than image B2, and image C1 had a 6.3% greater density than image C2. Observers were accurate more often when comparing images with large density differences (pair B) than they were when comparing images with the same density (pair A) or with small density differences (pair C). Accuracy was not related to being medically qualified or from an obstetric or gynecological department. Intraobserver variation was not significant. We conclude that the human eye is extremely inaccurate at discerning differences in echogenicity when images have small or no differences in optical density. Densitometry is, therefore, indispensable for accurate image density assessment.

Pregnancy following gastric bypass surgery for morbid obesity.

BACKGROUND: Surgical treatment for severe obesity is sometimes recommended. Many long-term risks, particularly to adolescents and to subsequent pregnancies, are still being determined. CASE: A 23-year-old woman, gravida 6, para 2, treated for morbid obesity during adolescence with gastric bypass surgery, presented at 6 weeks' gestation with severe microcytic anemia. Significant iron and cobalamin deficiencies were found. Although the vitamin B12 deficiency responded to parenteral treatment, the iron deficiency was refractory to oral supplementation because of malabsorption. By 30 weeks' gestation, the patient required blood transfusions to correct the progressive anemia. Subsequently, she delivered a healthy male infant at term. CONCLUSION: Severe iron deficiency anemia resulting from malabsorption can complicate pregnancy following gastric bypass surgery for morbid obesity. For women of childbearing age, this potential adverse effect must be considered.

Selective reduction of multifetal pregnancies to twins improves outcome over nonreduced triplet gestations.

OBJECTIVE: Our purpose was to evaluate effects of multifetal pregnancy reduction on pregnancy complications and birth weights of remaining twin fetuses compared with expectantly managed triplets and nonreduced twins. STUDY DESIGN: Medical records of 54 triplet pregnancies, 59 twin pregnancies resulting from multifetal pregnancy reduction, and 88 sets of twins conceived with assisted reproductive techniques and delivered at New York Hospital after 24 weeks were retrospectively reviewed. Birth weights were corrected for gestational age at delivery by use of a formula derived from composite standardized growth curves. Statistical analysis was performed with chi(2) analysis and Student t test. RESULTS: Twins remaining after reduction and nonreduced twins were less likely to have preeclampsia than were triplets (14% and 23% vs 30%) and to be delivered before 36 weeks (39% and 27% vs 72%). They had birth weights that were > 100 gm larger than those of triplets even when corrected for gestational age. Reduced twins were similar to nonreduced twins in all parameters studied. CONCLUSIONS: Multifetal pregnancy reduction results in pregnancy complications, gestational age, and birth weights closer to those of nonreduced twins than to expectantly managed triplets.

Multiple gestations from in vitro fertilization: successful implantation alone is not associated with subsequent preeclampsia.

OBJECTIVE: Our purpose was to compare the risk for preeclampsia and severe preeclampsia in triplet and twin gestations and to evaluate the effect of successful implantation on the development of preeclampsia and on perinatal outcome in triplet pregnancies conceived by means of in vitro fertilization. STUDY DESIGN: A case control study was conducted of triplet pregnancies (n = 38) matched for maternal age, parity, race, and delivery date with twin pregnancies (n = 38) resulting from a single fetal reduction (spontaneously or by means of multifetal pregnancy reduction) after successful implantation of triplets. All pregnancies were conceived by means of in vitro fertilization. Rates of preeclampsia and other maternal complications, factors affecting implantation, and perinatal outcomes were compared. Preeclampsia and severe preeclampsia were defined by The American College of Obstetricians and Gynecologists criteria. The Student t test and the chi(2) test were used for statistical analysis. RESULTS: The triplet group had a higher rate of severe preeclampsia (26.3%) than the twin (reduced triplet) group (7.9%). The prevalence of preeclampsia (mild and severe combined) also was higher among the triplet group (44.7%) than among the twin group (15.8%). There was no difference in other maternal complications of pregnancy or in factors potentially affecting implantation, such as assisted hatching. Mean fetal weight was lower among the triplet group, but gestational age at delivery was not significantly different. CONCLUSIONS: The rate of preeclampsia is higher among triplets conceived by means of in vitro fertilization than among triplets conceived by means of in vitro fertilization and reduced to twins. This finding suggests that fetal number, placental mass, or factors unrelated to the success of implantation are more important to the development of preeclampsia than is successful implantation alone.

Safety, efficacy and cost of three cervical cytology sampling devices in a prenatal clinic.

OBJECTIVE: To evaluate and compare the safety, efficacy and cost of three cervical cytology sampling devices in pregnant women presenting for prenatal care to the obstetrics clinic, at Medical College of Pennsylvania Hospital. STUDY DESIGN: From September 7, 1993, to November 5, 1993, 61 cervical cytologic smears were obtained using the Cell-Sweep. From November 8, 1993, to January 7, 1994, 66 smears were obtained using the Ayre spatula/Cytobrush, and from January 10, 1994, to February 18, 1994, 55 smears were obtained using the Ayre spatula/cotton swab. The rate of smears with no endocervical component or with epithelial cell abnormality was determined for each group. The patients' medical records were reviewed retrospectively to determine complications occurring within two weeks of smear collection. RESULTS: Fifteen (25%) smears in the Cell-Sweep group, one (1.5%) in the Cytobrush group and nine (16%) in the cotton swab group were satisfactory but limited by absence of an endocervical component (P < .0006). None of the smears were unsatisfactory. Eleven (18%) smears in the Cell-Sweep group, eight (12%) in the Cytobrush group and nine (16%) in the cotton swab group revealed an epithelial cell abnormality (P = .643). For all three groups there was a low rate of spontaneous abortion, preterm spontaneous rupture of membranes or preterm labor occurring within two weeks of collection. There was no statistically significant difference in these complications between the three groups (P = .7). The Ayre spatula/cotton swab is the least expensive device. CONCLUSION: The Ayre spatula/cotton swab was the most satisfactory of the three methods tested for obtaining cervical cytology during pregnancy. It is safe and cost-effective and identifies the same proportion of epithelial cell abnormalities as the Ayre spatula/Cytobrush and the Cell-Sweep.

Multifetal pregnancies.

The incidence of multifetal pregnancies has been increasing steadily. Fetal complications such as prematurity, discordant growth, intrauterine fetal demise, twin-twin transfusion, and congenital anomalies account for a large share of perinatal morbidity and mortality. Maternal complications from multiple gestations are also significant. Recent trends in antepartum management such as multifetal pregnancy reduction, specialized prenatal care, and well-timed delivery have improved outcomes. Intrapartum management, including the possibility of asynchronous birth and critical assessment of mode of delivery, has also led to better outcomes. This review provides a brief summary of each of these topics with, a particular focus on the recent literature.

Antepartum mastitis: a case report.

BACKGROUND: Acute mastitis commonly occurs in the postpartum period. It has been reported only rarely in the antepartum period. CASE: A 14-year-old patient presented at 29 weeks gestation with her symptoms and examination consistent with bilateral mastitis that had worsened over 2 months. She had evidence of systemic infection. She was treated with parenteral antibiotics and local skin care. She gradually improved and delivered a healthy infant at term. CONCLUSION: The management of antepartum mastitis can be derived from experience with puerperal mastitis. It must include early recognition, a search for predisposing factors and causative organisms, and aggressive treatment. Such an approach can lead to successful pregnancy outcome with minimal fetal or maternal morbidity.

Trichloroethanol potentiates synaptic transmission mediated by gamma-aminobutyric acidA receptors in hippocampal neurons.

We have examined the actions of trichloroethanol (TCEt), the active metabolite of the general anesthetic chloral hydrate, on responses mediated by gamma-aminobutyric acid (GABA)A receptors in response to application of exogenous GABA and activation of endogenous GABAergic transmission, by using hippocampal neurons in cell culture and in brain slices. In the presence of TCEt, Cl- current activated by exogenous GABA was both enhanced in amplitude and prolonged, leading to a net increase in total charge passing through GABAA receptor channels. Prolongation of GABA-activated current increased in magnitude in a concentration-dependent manner from 0.2 to 10 mM TCEt. Inhibitory postsynaptic currents produced at synapses between pairs of cultured GABAergic neurons or by activation of interneurons in hippocampal slices were also prolonged by TCEt, at concentrations from 0.5 to 10 mM. Application of TCEt at concentrations of 1 mM and above produced a small amplitude current which was directed outwardly at -40 mV in neurons in which methylsulfate or gluconate was the major intracellular anion and directed inwardly in neurons filled with Cl-. Our observations indicate that TCEt potentiates GABAergic transmission; presumably by potentiating the function of GABAA receptors in a manner similar to barbiturate or steroid anesthetics. This action is likely to contribute to the general anesthetic effect of TCEt which occurs after chloral hydrate administration.

Opposite effects of prefrontal cortex and nucleus accumbens infusions of flupenthixol on stimulant-induced locomotion and brain stimulation reward.

Ventral tegmental area (VTA) stimulation produced conditioned place preferences for stimulation-paired environments the magnitudes of which were dose-dependently reduced by systemic application of the dopamine antagonist, haloperidol (0.0, 0.15, 0.3 mg/kg). Bilateral microinjections of cis-flupenthixol (FLU) into the nucleus accumbens (0.0, 1.0, 5.0 or 10.0 micrograms) also resulted in reductions in the size of stimulation-induced place preferences as well as reductions in the magnitude of the hyperlocomotor response to 1.5 mg/kg (s.c.) D-amphetamine. Comparable microinjections of FLU into the medial prefrontal cortex (PFC) produced diametrically opposite effects: the size of VTA stimulation-induced place preferences was either unaffected (1.0 and 5.0 microgram groups) or slightly increased (10 micrograms group) and amphetamine-stimulated hyperlocomotion was dose-dependently potentiated. These behavioral findings suggest a dopamine-mediated modulatory role for the PFC over reward relevant elements within the nucleus accumbens.

Induction of giant depolarizing potentials by zinc in area CA1 of the rat hippocampus does not result from block of GABAB receptors.

The possibility that zinc (Zn2+) induces giant depolarizing potentials (GDPs) by blocking pre- and postsynaptic gamma-aminobutyric acidB (GABAB) receptors in area CA1 of rat hippocampal slices was investigated. Monosynaptic GABAA receptor-mediated fast and GABAB receptor-mediated late inhibitory postsynaptic potentials (IPSPs) were evoked in the presence of the excitatory amino acid (EAA) receptor antagonists 6,7-dinitroquinoxaline-2,3-dione (DNQX) and D,L-amino-5-phosphonovalerate (APV). Addition of Zn2+ (0.3 mM) resulted in the appearance of long-lasting GDPs which obscured monosynaptic late IPSPs. The GABAA receptor antagonist bicuculline methiodide (BMI; 30 microM) blocked fast monosynaptic IPSPs and GDPs, revealing a monosynaptic late IPSP that was prolonged in the presence of Zn2+ and blocked by the GABAB receptor antagonist CGP 35,348 (100 microM). The selective GABAB receptor agonist baclofen (10 microM) depressed monosynaptic IPSPs and population excitatory postsynaptic potentials (pEPSPs) by acting at presynaptic GABAB receptors. Depression of synaptic potentials by baclofen was unaffected by Zn2+. These results suggest that induction of GDPs in area CA1 does not result from an action of Zn2+ at GABAB receptors. We suggest instead that Zn2+ induces GDPs by inducing synchronized discharge of GABAergic interneurons.