P.W. Soothill

Effect of Gestational Age on Fetal and Intervillous Blood Gas and Acid-Base Values in Human Pregnancy

Intervillous, umbilical venous and umbilical arterial blood samples were obtained by cordocentesis or fetoscopically from 200 pregnancies at 16-38 weeks gestation. The fetuses were either not affected by the condition under investigation or it was one which would not affect blood gas and acid-base status. Blood pH, pO2, pCO2, bicarbonate, base excess and plasma lactate concentration were determined and ranges for each parameter are presented. Samples obtained fetoscopically were more acidotic, hypercapnic and had a greater base deficit than those obtained by cordocentesis. In the umbilical venous samples, the pO2 decreased, while the bicarbonate, base excess and lactate increased with gestation. In the umbilical arterial samples the pO2 decreased and pCO2 increased; there were no other significant changes with gestation. Similarly, in the intervillous samples the only significant change with gestation was that of a decrease in pO2.

ULTRASOUND-GUIDED SAMPLING OF UMBILICAL CORD AND PLACENTAL BLOOD TO ASSESS FETAL WELLBEING

Fetal and maternal placental (intervillous) blood samples were obtained by means of an outpatient ultrasound-guided technique from a 33-week pregnancy with symmetrical intrauterine growth retardation. The baby was delivered by emergency caesarean section because blood gas, pH, and lactate measurements showed severe hypoxic acidosis, due to inadequate placental transfer.

Prediction of morbidity in small and normally grown fetuses by fetal heart rate variability, biophysical profile score and umbilical artery Doppler studies

Objective To assess the ability of noninvasive tests of fetal wellbeing to predict hypoxic morbidity independent of fetal size.

The effect of replacing fetal hemoglobin with adult hemoglobin on blood gas and acid-base parameters in human fetuses

In order to determine whether the differences between fetal and adult hemoglobins are important to fetal oxygenation, pH, PO2, PCO2, bicarbonate, and base excess were measured in umbilical venous and arterial blood samples obtained from fetuses with erythroblastosis fetalis. The values from fetuses that had previously been transfused and had predominantly adult hemoglobins were compared with those that had not been transfused and had predominantly fetal hemoglobin. Umbilical arterial blood was more acidotic and had a greater base deficit, while the umbilical venous PO2 was 4.8 mm Hg higher in the samples with adult hemoglobins than in those with fetal hemoglobin. The results suggest that oxygenation of fetal tissue is better with fetal hemoglobin but that adult hemoglobin can be compensated by an increase in oxygen transfer.

A comparison between computerised (mean range) and clinical visual cardiotocographic assessment

Objective To compare Computer cardiotocographic (CTG) analysis with clinical visual analysis.

Effect of a fetal surveillance unit on admission of antenatal patients to hospital

OBJECTIVE--To analyse the effect of a fetal surveillance unit, which undertakes a wide range of maternal and fetal tests on an outpatient or inpatient basis, on the number and length of antenatal hospital admissions. DESIGN--A comparison of the number and length of antenatal admissions six months before and five months after the opening of the unit on 1 July 1990. MAIN OUTCOME MEASURES--Admission rate, antenatal bed occupancy, and interval from admission to discharge or delivery. RESULTS--The antenatal bed occupancy rate fell by 22% from 174/100 deliveries during the six months before the unit was opened to 136/100 deliveries in the five months after it was opened. The difference in distribution of lengths of admission after the unit was opened from before was highly significant (Mann-Whitney test = 5.14, n = 752 and 679; p less than 0.0001), and this was due to shorter intervals from admission to discharge and from admission to delivery. In contrast, the antenatal admission rate did not change significantly (50/100 deliveries v 49/100 deliveries). There was no significant change in the stillbirth rate (6/1294 births v 8/1372 births; difference between rates = 0.0012, 95% confidence interval-0.0043 to 0.0067). CONCLUSION--Obstetricians are more prepared to discharge antenatal patients from hospital and, similarly, admit patients for delivery rather than for assessment if the patients are reliably monitored on an outpatient basis. If this change in practice is sustained substantial financial and social benefits will result as well as improvements in organisation, audit, teaching, and research.

Antenatal testing to predict outcome in pregnancies with unexplained antepartum haemorrhage

Objective To investigate whether Doppler studies of placental perfusion and antenatal tests for fetal hypoxia can identify reduced placental functional reserve in women with unexplained antepartum haemorrhage (APH).