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Biomedical subjects

J C Birnholz

Publications and source records attributed to J C Birnholz.

At least 19 recordsLinked to original sources
PubMed1995

Amniotic fluid accumulation in the first trimester.

Amniotic fluid volume was estimated sonographically in 507 of 977 first trimester pregnancies with living fetuses and in 99 of 227 instances of missed abortion. Volume is correlated with fetal length, cross referenced by average heart rate for living fetuses. Fluid volume increases exponentially after 9 weeks, consistent with the onset of renal function. Fluid volume tends to be excessive with missed abortion. Free fluid volume is a physiologic variable, determined from morphologic features. Standards are proposed for amniotic fluid volume dynamics in the first trimester.

Abortion, Missed↗
PubMed1991

Human fetal upper respiratory tract function as revealed by ultrasonography.

The respiratory functions of the oropharynx, larynx, and trachea of normal human fetuses in utero were explored by means of real-time, two-dimensional ultrasonography combined with color-flow and spectral Doppler analysis. Coronal and transverse images revealed the maturation of coordinated respiratory activity of these structures in the late second and early third trimesters. Observation of the effects of these movements upon the flow of amniotic fluid in the fetal respiratory tract provides an appreciation of the early role of the upper airway in the modulation of fetal breathing.

Female↗
PubMed1990

Ecologic physiology of the fetus. Ultrasonography of supply-line deprivation syndromes.

Supply-line deprivation is a major source of developmental fetal pathology. Clinical surveys have tended to emphasize the role of placental failure, although the umbilical cord may also be a site of injury. Supply-line limitations are met by a series of active fetal compensatory maneuvers. These include growth retardation. The role of ultrasound is in detecting when these compensations are invoked, grading their effectiveness, and determining trends. Nuchal cord occurs in about a third of cases, conferring a risk of hypoxic injury in utero but also providing a unique physiologic test possibility. Clinical evaluation and management should be predicated upon pathophysiologic considerations, with examination technique and extent individualized for each case.

Embryonic and Fetal Development↗
PubMed1989

Fetal syndromes.

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Congenital Abnormalities↗
PubMed1988

Fetal hyaloid artery: timing of regression with US.

Large-aperture, dynamically focused ultrasonic imaging permits noninvasive, anatomic study of the eye at the millimeter level in the second and third trimesters of pregnancy. The authors report their observations of the hyaloid artery in 210 of 219 fetuses examined with this technique. This vessel is seen in fetuses of 20 weeks gestational age or less and regresses spontaneously at the start of the third trimester. The 210 subjects included 100 who were examined at gestational ages of 16-32 weeks or more and 85 healthy fetuses and 25 with pathologic findings at birth who were examined at 34 weeks gestational age to term. The presence of the hyaloid artery in the mid third trimester was uncommon in healthy subjects (less than 1%) and was not seen in any beyond 29.9 weeks gestational age. However, in nine of the 25 fetuses with abnormalities (five with trisomy syndromes), the vessel was seen at 30.8-36.8 weeks gestational age. The temporarily delayed regression of the hyaloid artery may occur with trisomy 21 syndrome and other forms of retarded brain development.

Eye↗
PubMed1988

Fetal ear length.

A prenatal standard for ear length was developed from ultrasonic images of 180 normal subjects. Length increased from about 6 mm at 15 weeks to 33 mm at term and was well fit by linear regression (r2 = .96). Short ears (greater than or equal to 1.5 SD below gestational age average) were associated strongly, and specifically, with chromosomal disorders.

Congenital Abnormalities↗
PubMed1987

The diagnosis of fetal hydrocephalus prior to 22 weeks.

The prenatal diagnosis of hydrocephalus is described in 11 cases between 17 and 21 weeks using two sonographic criteria. These sonographic findings involve the asymmetrical appearance of the choroid plexus and the size and configuration of the anterior horns of the lateral ventricles. We have found that these criteria can accurately diagnose fetal hydrocephalus in the first half of the second trimester.

Female↗
PubMed1986

An algorithmic approach to accurate ultrasonic fetal weight estimation.

A flexible model is proposed for estimation of fetal weight from biparietal, occipitofrontal, and average abdominal diameters and femoral shaft length. Individual formulas are selected by gestational age-independent decision rules that reflect fetal body proportions. The correlation coefficient for observed and predicted weight was .994 in a series of 96 fetuses studied within 36 hours of delivery, with 20% of cases having error less than 10 g/kg and 90% with error less than 80 g/kg.

Birth Weight↗
PubMed1986

Fetal lumbar spine: measuring axial growth with US.

Ultrasound (US) can be used to visualize vertebral segments, suggesting a quantitative means of studying vertebral column growth in utero and thus a means of detecting developmental abnormalities. US images of the lumbar spine were obtained in 128 clinically normal fetuses between the gestational age of 11 through 41 weeks. A large-aperture, dynamically focused US system capable of regional magnification was used. Average lumbar spacing was calculated from distance between centrums of at least four lumbar bodies. The average distance between lumbar centrums increased nearly linearly throughout the second and third trimesters (r2 = 0.98). Enhanced anatomic display implies new capabilities for recognizing developmental abnormalities antenatally.

Gestational Age↗
PubMed1986

Ultrasound guidance for selected dilatation and evacuation procedures.

Intraoperative ultrasound was used as an adjunct in difficult dilatation and evacuation (D&E) procedures for first-trimester abortions. This technique was useful in eight technically difficult D&Es in the presence of acute retroflexion, acute anteflexion, cervical stenosis and lower uterine segment fibroids.

Abortion, Therapeutic↗
PubMed1985

Ultrasonic fetal ophthalmology.

The fetal eye is studied ultrasonically during the second and third trimesters with a large aperture, dynamically focused imaging system. The globe, lens, iris, pupil, and cornea can be resolved separately, and extraocular structures including muscles, retro-orbital fat, and optic nerve may be visualized. The hyaloid artery is seen before 20 weeks and regresses by 25 weeks gestational age. Average vitreous diameter in 157 normal cases exhibits acclerations between 12 and 20 weeks, between 28 and 32 weeks, and near term with decelerations intervening. Associations between limited ocular growth and delayed cerebral development are reaffirmed.

Eye↗
PubMed1985

Management of an infant with prenatal ultrasound diagnosis of upper airway obstruction.

We report a case in which a cervical teratoma was diagnosed antenatally in the mid third trimester. In anticipation of potential upper airway obstruction, resources were mobilized to the operating room at the time of the planned cesarean section. The neonate was unable to breathe, but his airway was secured without delay. There was no evidence of cerebral anoxia initially or at one year follow-up. As prenatal diagnosis by ultrasound becomes more refined, the otolaryngologist will play an increasing role in perinatal decision making and anticipated emergencies at the time of delivery. Airway obstruction of various causes will be the most urgent problem.

Airway Obstruction↗