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R T Geirsson

Publications and source records attributed to R T Geirsson.

63 records · Page 4Linked to original sources
PubMed1984

In-vivo accuracy of ultrasound measurements of intrauterine volume in pregnancy.

The accuracy of ultrasonic measurements of intra-amniotic volume using a parallel planimetric area method was assessed in 18 women by comparison against different measures of the same volume space. In nine patients undergoing second-trimester termination of pregnancy amniotic fluid volume was measured using a dye dilution method and fetal volume was measured by either water displacement or calculated from fetal weight. The estimated intra-amniotic volume by this method was not significantly different from the ultrasonic measurement. In one patient who had a hysterotomy, fetal and amniotic fluid volumes showed a difference of 1.01% between ultrasonically-measured and actual intra-amniotic volume. In eight patients studied in the third trimester the mean difference between ultrasonic and estimated intra-amniotic volume at delivery was 6.2%.

Amnion↗
PubMed1984

Longitudinal and transverse uterine area measurements (LTUA) are not representative of intrauterine volume.

A midline longitudinal area and the maximum transverse area of the pregnant uterus were used to compute the intrauterine volumes of 37 women in the third trimester of pregnancy. The results were compared with measurements done simultaneously using a parallel planimetric area method. The use of only two areas caused significant underestimation of total intrauterine volume, by 14-36 per cent. Because of the variable shape of the uterine cavity in pregnancy, the product of longitudinal and transverse intrauterine area measurements cannot give reliable information about intrauterine volume.

Female↗
PubMed1984

Diagnosis of intrauterine growth retardation using ultrasound.

Ultrasound has been developed in the last twenty years to become the major instrument for diagnosis of intrauterine growth retardation. However, currently available commercial instruments cannot be used to their full advantage without accurate early ultrasonic measurement of gestational length and without at the same time screening for multiple pregnancy and fetal malformation. Once this has been done, methods that take account of changes in body proportion become less important in the diagnosis of IUGR in later pregnancy and formulas that allow accurate weight categorization can be used with advantage. If an ultrasonic method for screening a whole population is required, then weight-categorization formulas are now well researched and provide an acceptable margin of low false positive rates. The formula should, however, be adapted to give a measure of weight deviation rather than absolute weight so that it can be used over a period of time in pregnancy and not only in a specific week. If a non-ultrasound method is to be used for selecting a population at higher risk, conventional risk criteria (Hobel et al, 1973) and symphysisfundus measurements are valuable. Ultrasound fetometry may then be used with very high sensitivity to improve the identification of those fetuses at risk, but critical evaluation of the use of ultrasound in this situation is still needed. The basic measurement techniques of BPD and fetal trunk measurements singly or combined into weight prediction formulas could then, in larger reference laboratories, be supplemented by ancillary ultrasonic means of investigating fetal growth and fetal well-being. An adverse fetal environment preceding measurable growth retardation of the fetus itself can possibly be reflected in a decrease of intrauterine volume and amniotic fluid and changes of fetal well-being could be investigated by means of changes in volume parameters, fetal activity or fetal blood flow. The next steps towards improved ultrasonic evaluation of IUGR fetuses are likely to be in this direction, while increased IUGR detection will mainly result from better screening techniques.

Body Weight↗
PubMed1983

Concentrations of hypoxanthine, xanthine, uridine and urate in amniotic fluid at caesarean section and the association of raised levels with prenatal risk factors and fetal distress.

Samples of amniotic fluid were obtained at caesarean section from 33 of 80 consecutive unselected patients in whom the membranes were intact. Concentrations of the ATP metabolites, hypoxanthine and xanthine, as well as uridine and urate were determined using high pressure liquid chromatography. Independent 'clinical' factors associated with reduced fetal growth and well-being were identified and the patients were assigned to one of three groups: those with no recognized risk, those with moderate risk and a small group of four patients with high risk. The mean hypoxanthine concentration was higher in the moderate-risk group than in the group with no risk. Two of the three patients with proteinuric hypertension in the high-risk group had normal hypoxanthine concentrations. There were seven patients with fetal distress, and concentrations of hypoxanthine, xanthine, uridine and urate were significantly higher in the three patients who had meconium stained amniotic fluid in addition to abnormal fetal heart rate tracings than in the remaining four who had fetal heart rate abnormalities only. It is suggested that fetal distress at emergency caesarean sections might be quantitated by such analysis.

Amniotic Fluid↗