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Biomedical subjects

J S Abramowicz

Publications and source records attributed to J S Abramowicz.

At least 19 recordsLinked to original sources
PubMed2001

Comparative sensitivity of human fetal and adult erythrocytes to hemolysis by pulsed 1 MHz ultrasound.

Human fetal and adult erythrocytes differ significantly in mean corpuscular volume (MCV), the fetal cells being larger than adult cells and diminishing in MCV as gestational age (GA) increases. Previous studies have shown that the sensitivity of erythrocytes from different species to lysis by mechanically applied shear stress increases as MCV increases. The tested hypotheses in the present project were: 1. fetal erythrocytes would be more sensitive to sonolysis than adult erythrocytes because of the former's larger size, and 2. erythrocyte sonolytic sensitivity would scale with MCV. Fetal and adult erythrocytes were resuspended to 40% hematocrit in oxygenated isotonic saline solution and 500 microL aliquots were exposed for 60 s to 200 micros bursts of 1-MHz ultrasound (US) (peak pressures: approximately 4.8 MPa positive, approximately 2.7 MPa negative; duty factor = 0.01), either with or without 3.6 volume % Albunex (ALX) present. Background-corrected hemolysis was indistinguishable from zero in sham-exposed fetal or adult erythrocyte suspensions. Without ALX, mean background-corrected US-induced hemolysis was significantly greater than zero for fetal and adult cells (0.42 +/- 0.15% vs. 0.62 +/- 0.15), but fetal cell lysis was not significantly greater than adult cell lysis. With ALX, US-induced hemolytic yields increased approximately 80-fold (fetal: 50.53 +/- 2.14; adult: 46.40 +/- 1.85%), and were significantly higher for fetal than for adult cells. There was also a statistically significant correlation between MCV and US-induced background-corrected hemolysis. Thus, the two hypotheses were supported.

Adult↗
PubMed1998

Obstetric ultrasonography: a biophysical consideration of patient safety--the "rules" have changed.

We address the issue of health and safety in relation to exposure to diagnostic ultrasound, with particular emphasis given to obstetrics. In terms of fetal and maternal outcomes, the epidemiologic record of diagnostic ultrasound is exemplary but is primarily made on the basis of data derived from clinical devices whose outputs were relatively low compared with what is now allowable and available. The power outputs of clinical devices have been increasing over the past decade such that the potential for thermal and nonthermal insults is increased. For obstetric devices that use these higher outputs, the Food and Drug Administration now requires the presentation of 2 on-screen indexes, the thermal index and the mechanical index, in recognition of the 2 major mechanisms by which ultrasonography is known to affect cells and tissues. Greater responsibility for patient safety is now placed on the diagnostician; for the new indexes to be meaningful the diagnostician must be cognizant of the health and safety implications. The purpose of this article is to provide some guidance to the obstetrician in interpreting the indexes and to review the current status of ultrasonography biophysics in relation to the use of diagnostic ultrasound in obstetrics.

Acoustic Stimulation↗
PubMed1997

Brachydactyly-short stature-hypertension (Bilginturan) syndrome: report on two families.

We report on two families with autosomal dominant brachydactyly of hands and feet and hypertension. All affected members of the first family had proportionate short stature. However, the propositus and the affected relatives in the second family were only short compared to unaffected relatives. The hypertension was medically responsive in all cases. The propositus in the second family had poor compliance and a striking generalized vasculopathy. All patients were of normal intelligence and had a normal facial appearance. The brachydactyly-short stature-hypertension syndrome was first reported by Bilginturan et al. [1973] in a Turkish family and the families reported by us are Caucasian and Hispanic. The gene causing this condition in the original Turkish family was recently mapped to 12p. Our report expands our existing knowledge and the ethnic diversity of this syndrome.

Adult↗
PubMed1997

Ultrasound contrast media and their use in obstetrics and gynecology.

Contrast media have gained acceptance to enhance ultrasonography in many fields of medicine; in particular, cardiology. Several agents have been described and many more are being manufactured and tested. By increasing the number of strong sound scatterers, these agents improve images by increasing the amount of echoes. This is true both for grey-scale and color or Doppler imaging. Their use in obstetrics is very limited at the moment because of safety issues. In a laboratory setup, they have been shown to markedly enhance placental imaging. In gynecology, imaging of the uterine cavity and Fallopian tubes is greatly improved. A potential area where ultrasound contrast may find a role is gynecological oncology. Vascularity is increased in many tumors, but usually vessel diameter is small and velocity low. One can therefore expect future use of the ultrasound contrast agents in ovarian or other gynecological neoplasms.

Contrast Media↗
PubMed1997

Incorporating sonographic cheek-to-cheek diameter, biparietal diameter and abdominal circumference improves weight estimation in the macrosomic fetus.

The objective of this study was to improve the accuracy of sonographic fetal weight estimation in macrosomic (> 4000 g) fetuses by combining the cheek-to-cheek diameter (CCD), an indicator of subcutaneous tissue mass, with the biparietal diameter (BPD) and abdominal circumference (AC) in generating a new weight formula. Three hundred well-dated, uncomplicated singleton pregnancies > 32 weeks' gestational age (GA) were analyzed. Sonographic fetal measurements obtained in every case included BPD, head circumference, AC, femur length and CCD. Sonographic estimation of fetal weight (EFW) was derived by using BPD and AC. Actual birth weights (BW) of fetuses delivered within 7 days of the last sonographic examination and weighing over 1500 g (n = 123) were compared to EFW. A formula was derived by correlating BPD, AC and CCD with BW in these 123 fetuses using multiple regression analysis. A second formula was derived from the data of 39 macrosomic fetuses. The two formulae were then tested for accuracy of prediction of fetal weight in 157 other fetuses delivered within 7 days and grouped by birth weight, 44 of them weighing > 4000 g. The new formula for macrosomic fetuses was: EFW (g) = 1065 + 84.5 BPD (cm) + 41.29 AC (cm) + 111.0 CCD (cm). In the macrosomic fetuses, a difference of < 10% between EFW and BW was demonstrated in 72.7% by the BPD-AC formula and 95.5% when incorporating CCD. In this group, the mean percentage error was significantly smaller: 4.14 vs. 7.97% (p = 0.0005). In the regression analysis, the contributions of BPD, AC and CCD to the variance in BW were 5.5%, 16%, and 18.3%, respectively (p = 0.008). In the non-macrosomic fetuses, CCD improved prediction of BW, but the trend did not reach statistical significance. Our results demonstrate that, in the macrosomic fetus, CCD explains more of the variance in BW than other parameters and incorporating it in the sonographic weight estimation greatly improves its accuracy.

Abdomen↗
PubMed1996

Maternal posture influences the extent of sensory block produced by intrathecal dextrose-free bupivacaine with fentanyl for labor analgesia.

The cephalad extent of sensory block produced by intrathecal (IT) dextrose-free local anesthetics and opioids has been reported to be quite variable. Most reports describing the effects of IT analgesics do not control for patients posture. Because these medications are hypobaric relative to cerebrospinal fluid (CSF), parturients in a sitting position may develop greater cephalad extents of sensory block than those in a lateral position during IT injection. Parturients in labor were randomized to sitting or lateral position during IT administration of dextrose-free bupivacaine 0.25% with fentanyl 0.005%. Extent of sensory block was evaluated at intervals thereafter. Free flow of CSF was obtained in 20 parturients. Those in a sitting position during IT injection had significantly higher maximal cephalad extent of block than those in a lateral position (mean +/- SD, T-3.1 +/- 2.9 vs T-6.3 +/- 3.4, P = 0.036). Mean cephalad extent of block was greater in the sitting group at 20 and 30 min. When sensory block asymmetry was observed, the extent of block was greater on the nondependent side. Posture during IT injection of this dextrose-free analgesic combination affects extent of sensory block in laboring parturients.

Adult↗
PubMed1995

Color Doppler imaging of the uteroplacental circulation in the first trimester: value in predicting pregnancy failure or complication.

OBJECTIVE: The purpose of this study was to determine the utility of color duplex Doppler sonography of the uteroplacental circulation in predicting the outcome of first-trimester gestations. SUBJECTS AND METHODS: One hundred women with viable pregnancies of 7 to 12 weeks' gestational age were prospectively evaluated. Color Doppler imaging was used to identify the location of blood flow within the uteroplacental circulation, and spectral Doppler imaging was used to analyze waveforms obtained from the decidual spiral arteries. RESULTS: Abnormal color Doppler findings were associated with a significantly higher prevalence of complicated pregnancies. Among women with abnormal Doppler findings, 12 (43%) of 28 pregnancies ended in miscarriage, whereas among women with normal findings only one (1.4%) of 72 women miscarried (p < .005). CONCLUSIONS: This study indicates that abnormal blood flow patterns of the early uteroplacental circulation are associated with an increased prevalence of pregnancy complications and that color Doppler imaging may be used to predict pregnancy outcome.

Abortion, Spontaneous↗
PubMed1994

Amnioinfusion during labor complicated by particulate meconium-stained amniotic fluid decreases neonatal morbidity.

OBJECTIVE: Our purpose was to evaluate the efficacy of prophylactic amnioinfusion in decreasing neonatal morbidity associated with labor complicated by particulate meconium-stained amniotic fluid and to assess potential complications of this procedure. STUDY DESIGN: One hundred five laboring pregnant women with particulate (moderate or thick) meconium by subjective clinical analysis were randomly assigned to receive amnioinfusion or to receive standard obstetric care without amnioinfusion. Patients with any antepartum complications, other than the presence of meconium, were excluded from the study. Statistical analyses consisted of the two-tailed and paired Student t tests, Pearson chi 2 test, and Wilcoxon nonparametric test. Significance was set at p < 0.05. RESULTS: The study included 47 patients in the study group and 58 patients in the control group. A significantly greater proportion of study patients demonstrated decreased meconium concentration between rupture of membranes and delivery (46 of 46 vs 15 of 58, p < 0.001). The relative dilution of meconium consistency by objective analysis was significantly different between the study group and the control group (77.1% decrease vs 9.3% increase, p < 0.001). The proportion of neonates with meconium below the vocal cords was reduced in the study group (two of 47 vs 36 of 58, p < 0.001). Umbilical artery pH was increased in the study group neonates (7.29 +/- 0.01 vs 7.25 +/- 0.009, p < 0.05). The rate of neonatal acidemia was reduced in the study group (4 of 45 vs 12 of 50, p < 0.05). The rate of meconium aspiration syndrome was reduced in the study group (1 of 47 vs 8 of 58, p < 0.05). Maternal and neonatal morbidity rates were similar. CONCLUSION: Prophylactic amnioinfusion should be considered a possible addition to the intrapartum management of patients with particulate meconium-stained amniotic fluid.

Acidosis↗
PubMed1994

Significance of idiopathic midtrimester polyhydramnios.

It is uncertain whether idiopathic midtrimester polyhydramnios is associated with adverse perinatal outcome. Fifty patients with midtrimester polyhydramnios without apparent etiology were compared to 85 control patients. Demographic, obstetric, and neonatal data were recorded and compared using chi-square, Fisher's exact, and Student t tests. Comparisons were also made within the study group between those patients with resolution of the polyhydramnios and those with persistence. Demographic and obstetric data were similar in both groups. Of study patients, 94% had mild polyhydramnios, which resolved in 75.6% of those having follow-up scans. There were no differences in neonatal outcome between study and control groups. Fetal aneuploidy was increased in the persistent polyhydramnios group (2 of 10, 20%) compared to the group with spontaneous resolution (none of 33, 0%), P = 0.049. Mild idiopathic midtrimester polyhydramnios resolves frequently and, if so, is not associated with adverse perinatal outcome. However, persistence of polyhydramnios is associated with an increased risk of fetal aneuploidy, and fetal karyotyping should be considered.

Adult↗
PubMed1994

Acute maternal obstructive renal failure in a twin gestation despite normal physiological pregnancy-induced urinary tract dilation.

Obstructive renal failure due to an overdistended uterus is a very rare complication of pregnancy. Most previously reported cases have involved twin gestations, the majority occurring in the presence of polyhydramnios. We describe a patient with a twin gestation who developed acute obstructive renal failure despite only very mild physiological pregnancy-induced dilation of the urinary collecting system in the absence of polyhydramnios. This case suggests that acute obstructive uropathy should be considered as a rare cause of acute renal failure even in cases with seemingly normal pregnancy-induced physiological urinary tract dilation.

Acute Kidney Injury↗
PubMed1993

Cleft palate: confirmation of prenatal diagnosis by colour Doppler ultrasound.

We present a case of a twin with trisomy 47,XX+i(9p) in whom the diagnosis of cleft palate was confirmed by colour Doppler imaging demonstrating abnormal fluid flow across the fetal pharyngeal bone defect. Application of this technique in cases predisposed for this congenital lesion may prove beneficial in the diagnosis of the more subtle types of isolated cleft palate.

Abnormalities, Multiple↗
PubMed1993

Prenatal sonographic assessment of early, rapidly growing fetal cervical teratoma.

Although malignant transformation of fetal cervical teratoma is extremely rare, perinatal morbidity is high and usually related to the size of the tumour, which may compromise fetal swallowing and subsequently lead to upper airway obstruction. We present a case in which mid-trimester serial sonography demonstrated markedly rapid early growth of a lesion of this type between 17 and 19 weeks' gestation indicating the aggressive nature of this tumour, assisting parental decision to terminate the pregnancy. Histopathology confirmed grade 3 immaturity of the lesion.

Adult↗
PubMed1993

Ultrasonographic measurement of cheek-to-cheek diameter in fetal growth disturbances.

OBJECTIVE: Our purpose was to assess the value of the cheek-to-cheek diameter and the cheek-to-cheek diameter/biparietal diameter ratio in the ultrasonographic detection of abnormal fetal growth. STUDY DESIGN: The cheek-to-cheek diameter and cheek-to-cheek diameter/biparietal diameter ratio were examined in 21 small-for-gestational-age (< 10th percentile for estimated weight) and 87 large-for-gestational-age (> 90th percentile) fetuses. Statistical analysis consisted of Student's t test comparison between means and analysis of covariance for comparison of regression lines slope between these 108 fetuses and previously published nomograms of appropriate-for-gestational-age fetuses. RESULTS: The mean cheek-to-cheek diameters in small-for-gestational-age fetuses were significantly smaller than in appropriate-for-gestational-age fetuses (p < 0.0001). In large-for-gestational-age fetuses the mean cheek-to-cheek diameters were significantly larger (p < 0.005). Although large-for-gestational-age fetuses of diabetic mothers exhibited higher cheek-to-cheek diameter/biparietal diameter ratios than did appropriate-for-gestational-age fetuses (p < 0.0001), in fetuses of nondiabetic mothers this ratio was only minimally larger (p < 0.05). CONCLUSION: The cheek-to-cheek diameter and cheek-to-cheek diameter/biparietal diameter ratio are innovative ultrasonographic parameters for detecting abnormal fetal growth. Furthermore, the cheek-to-cheek diameter/biparietal diameter ratio permits insight into the possible underlying pathophysiologic mechanisms of fetal macrosomia.

Cephalometry↗