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Biomedical subjects

R D Robertson

Publications and source records attributed to R D Robertson.

35 records · Page 2Linked to original sources
PubMed1981

Constriction of the umbilical cord as a cause of fetal demise following midtrimester amniocentesis.

Two cases of constriction of the umbilical cord resulting in fetal demise following midtrimester amniocentesis are presented. In both cases, real-time ultrasonography prior to amniocentesis revealed a viable fetus. Fetal demise was identified immediately following the procedure in the first case and one month later in the other. A localized constriction at the fetal end of the umbilical cord in both, with torsion of the constricted segment in the second case, was observed. Wharton's jelly was noted to be deficient in this segment of the cord in the first case. The mechanism of fetal demise is discussed. It is suggested that this abnormality should be considered when fetal demise follows midtrimester amniocentesis.

Adult↗
PubMed1980

Chromosome findings in 2,500 second trimester amniocenteses.

We have analyzed the chromosome abnormalities found in 2,500 amniocenteses for prenatal diagnosis; 1,887 (75%) were performed because the maternal age was 34 years or more. Chromosome abnormalities were detected in 1.80% of those referred for advanced maternal age, 1.2% between ages 34 and 39 years and 4.6% 40 years and over. Of these, four occurred in women who would have been 34 years at delivery (2.9%). Trisomy 21 accounted for 50% of the chromosome abnormalities; sex chromosome abnormalities, for 25%; the remaining 25% was divided equally between trisomy 18 and partial trisomies and mosaics. Unexpected translocations were found in 0.4%, of which two-thirds were balanced and identified in one parent. The accuracy was 99.6%.

Amniocentesis↗
PubMed1980

The prenatal determination of fetal sex: amniotic fluid testosterone as a preliminary screening test.

Amniotic fluid testosterone levels were measured by radioimmunoassay without chromatography on 101 specimens obtained at amniocenteses between 15 and 19 wk gestation. For the male fetus, the amniotic fluid testosterone level of 553 +/- 23 pmol/l (mean +/- SE) was significantly higher (P less than 0.0005) than the concentration found for the female fetus (206 +/- 9 pmol/l). There was an overlap of the ranges 74-1120 pmol/l for the male and 122-399 pmol/l for the female fetuses. Amniotic fluid testosterone levels above 400 pmol/l were observed in 84% of the male and in none of the female fetuses. The method allowed determination of testosterone levels within 8 h. It is concluded that amniotic fluid testosterone measured by radioimmunoassay without chromatography is a rapid and effective preliminary screening test for the prenatal diagnosis of fetal sex.

Amniocentesis↗
PubMed1979

Maturity of fetal lungs tested by production of stable microbubbles in amniotic fluid.

Lung surfactant in amniotic fluid, and hence the maturity of the fetal lungs, can be assessed by observation of stable microbubbles (less than 15 micron diameter). Bubbles are formed by agitation with a Pasteur pipette and examined in hanging drops under the 10 x power of a microscope. Either after a count of bubbles, or after a general survey of hanging drops, the fluid is given a stable microbubble rating. A 'strong' rating indicates that the idiopathic respiratory distress syndrome will not occur after delivery, and that the lecithin/sphingomyelin ratio will indicate maturity. Complete absence of stable microbubbles suggests a high risk of respiratory trouble for the newborn infant, as does a weak or lower rating in the 30 to 37 week gestational age group. The test takes 5 to 10 minutes to perform, is cheap and easy, is not affected by blood, but may be affected by meconium. If a 'strong' rating is found, measurement of the L/S ratio can safely be omitted.

Amniotic Fluid↗
PubMed1979

Assessment of ovulation by ultrasound and plasma estradiol determinations.

The timing of ovulation was studied daily during the periovular period in 19 women attending an artificial insemination clinic during 24 menstrual cycles; B-mode ultrasound examination and plasma estradiol (E2) determinations were used. The maximum diameters of the ovarian follicles and the peak plasma E2 determinations all occurred within 2 days prior to and including the day of ovulation, as determined by conventional means, in the 12 normal cycles studied. The average values on the day prior to ovulation (day -1) for maximum follicle size and peak E2 determination were 2.5 cm and 1660 pmole/liter, respectively. Two definite ultrasonic patterns were noted after ovulation: The follicle either disappeared or filled with internal echoes. It is concluded from the preliminary study that ultrasound examination and plasma E2 determinations are equally effective in predicting the time of ovulation.

Estradiol↗
PubMed1976

A safe method of amniocentesis for lecithin/sphingomyelin determination in late pregnancy using ultrasound.

Two hundred consecutive amniocenteses for lecithin/sphingomyelin (L/S) determination in late pregnancy are reviewed. These procedures were performed under ultrasonic control before induction of labor or elective cesarean section in a prospective study to determine a safe method for aminocentesis. Complications included 3 failures, 14 blood-stained samples, 2 cases of labor occuring within 24 hours after amniocentesis, and 1 maternal abdominal wall hematoma. There was no cases of perinatal morbidity or mortality. It is proposed that this is a safe method of abdominal amniocentesis for L/S determination in late pregnancy.

Amniocentesis↗