Venous Doppler velocimetry in relationship to central venous pressure and heart rate during hypoxia in the ovine fetus.

OBJECTIVE: Characteristic changes in ductus venosus (DV) blood velocity and pulsations in the umbilical vein (UV) have been described during imminent fetal asphyxia. The aim of this study was to examine fetal venous blood velocity in relationship to pressure gradient across the DV during hypoxia in a fetal lamb preparation. METHODS: In general anesthesia, a cesarean section was performed on seven pregnant ewes, the fetus was exteriorized and put into a heated waterbath with uninterrupted umbilical circulation. Pressure measurements in the UV and inferior vena cava (IVC) were performed with the catheter tips on both sides of the DV. Fetal hypoxemia was induced by giving the ewe 12% oxygen in inhaling air. Pressure across the DV and Doppler velocimetry were repeatedly measured during hypoxemia. Blood velocity was recorded in the DV and UV by Doppler ultrasound. RESULTS: Before hypoxia the median pressure gradient across the DV was in systole 1 mmHg and 0.31 mmHg in end-diastole and during hypoxemia 1.5 mmHg and zero, respectively. The pressure difference across the DV was constant during hypoxemia irrespective of the presence of umbilical venous pulsations or heart rate. IVC-pressure was greatly influenced by fetal heart rate (FHR). A small but linear fall in systolic IVC pressure was seen with increasing FHR. In end-diastole the IVC pressure changed in a parabolic fashion, with increasing pressure during brady- and tachycardia. Pulsations in the UV also showed a parabolic relationship to FHR and central venous pressure. DV end-systolic and end-diastolic blood velocity changed during hypoxemia in direct relationship to FHR and central venous pressure, but without direct relationship to fetal blood gases. CONCLUSION: The pressure gradient across the DV is constant during hypoxemia. Changes in central and umbilical venous pressure are directly related to FHR. Umbilical venous and DV blood velocity changed in direct relationship to FHR and central venous pressure.

Fetal urine production estimated with ultrasound. The lower limit of normality is illustrated in a case with severe hypoplasia of the kidneys.

Urine production and weight deviation in a growth-retarded fetus with oligohydramnios was estimated by ultrasound on four occasions between weeks 27 and 33 of gestational age. The fetus demonstrated facial features typical of Potter's syndrome. Although this syndrome is associated with bilateral renal agenesis, the fetus in the present case presented with hypoplastic kidneys. Urine production was reduced when measured on three occasions but was surprisingly normal at week 31. In this report, we describe a way to assess urine production in a fetus.

Power spectrum analysis of the fetal heart rate during noradrenaline infusion and acute hypoxemia in the chronic fetal lamb preparation.

In a chronically instrumented fetal lamb the effect on heart rate variability of noradrenaline as well as hypoxemia is studied by the use of power spectral analysis. Subsequent to both noradrenaline infusion and hypoxemia the very low frequency components of the variability are markedly decreased as compared with control conditions. After hypoxemia also a high frequency peak appears in the spectrum.

Successful DNA-based prenatal exclusion of juvenile neuronal ceroid lipofuscinosis.

A family with two siblings, 10 and 8 years old, both with clinical and ultrastructural evidence of juvenile neuronal ceroid lipofuscinosis is described. The family was found to be informative for the restriction fragment length polymorphisms (RFLPs) detected by the probes pCJ52-95M1 (locus D16S148) and pCJ52-94T1 (locus D16S159) flanking the juvenile neuronal ceroid lipofuscinosis locus, CLN3. The parents were both heterozygous using these probes, while their two children with juvenile neuronal ceroid lipofuscinosis were both homozygous. Chorionic villi analysis showed that the fetus was heterozygous and had inherited the one allele of the mother which was not found in the two siblings. This suggested that the fetus had derived one healthy allele from the mother, the risk for a double crossing-over being less than 1 per cent. Electron microscopy showed no fingerprint inclusions in chorionic villi. The child was investigated at 6 months of age and found to be healthy, as new fingerprint inclusions were found at electron microscopy and no vacuolated lymphocytes were found in the blood smear. Due to the risk of heterogeneity, both DNA-based analysis and electron microscopy on chorionic villi are recommended for prenatal examination for juvenile neuronal ceroid lipofuscinosis.

Megacystis-microcolon-intestinal hypoperistalsis syndrome. Antenatal appearance in two cases.

Two cases with severe congenital megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) are presented. This is a rarely encountered syndrome in neonates and 45 cases have earlier been reported. The disease is usually lethal and it now seems clear that MMIHS is an autosomal recessive disorder. The enlarged bladder, typical of this syndrome, is however easy to define by ultrasound, sometimes even in early pregnancy. The concomitant finding of a dilatation of the urinary tract and the absence of oligohydramnios may lead the physician to suspect the diagnosis. Because of the information available from sonography, appropriate investigations can be undertaken immediately after delivery. Prenatal ultrasound examination in subsequent pregnancies is recommended.

Electrocardiographic waveform changes and catecholamine responses during acute hypoxia in the immature and mature fetal lamb.

The aim of the present study was to investigate the changes in electrocardiographic waveform and the release of catecholamines in the fetal lamb during nonacidemic fetal hypoxia. Chronically instrumented fetal lambs were subjected to reproducible hypoxia by reduction of the maternal placental blood flow. This was achieved by complete obstruction of the maternal aorta for 60 seconds. The fetuses were divided into an immature (119 to 126 days, n = 10) and a mature group (129 to 141 days, n = 6). Both groups of fetuses had a marked fall in oxygen tension (from 2.43 +/- 0.12 to 1.46 +/- 0.12 and 2.22 +/- 0.15 to 1.11 +/- 0.17 kilopascals [kPa] in the immature and mature groups, respectively) and in oxygen saturation (from 48% +/- 3% to 17% +/- 2% and 49% +/- 3% to 15% +/- 3%, respectively), but only modest changes occurred in pH and carbon dioxide tension. Basal fetal catecholamine concentrations did not differ between the groups but increased more significantly in the mature group with acute hypoxia. An increase in the T wave amplitude of the fetal electrocardiogram occurred in both groups during the latter part of occlusion with peak values shortly after removal of the occlusion. A linear correlation was found between the plasma epinephrine concentration and the T/QRS ratio in the mature group. Fetuses in both groups showed a marked bradycardia of similar magnitude during the occlusion but differed during the early phase of heart rate recovery by a slower acceleration of heart rate in the mature group. In connection with this marked bradycardia, the mature group showed a significant rise in mean arterial blood pressure at end of the occlusion. We suggest that fetal maturity has a significant influence no only on the release of catecholamines during nonacidemic hypoxia but also on the cardiovascular reaction pattern and changes in the ST waveform.

First-trimester diagnosis of juvenile neuronal ceroid lipofuscinosis by demonstration of fingerprint inclusions in chorionic villi.

One of the most common hereditary, progressive encephalopathies in children--juvenile neuronal ceroid lipofuscinosis (NCL)--lacks methods for carrier detection and prenatal diagnosis. A transcervical chorionic villus biopsy was performed at 9 completed weeks in a fetus at high risk of this disease. The syncytiotrophoblast of the chorionic villi contained fingerprint inclusions similar to those observed in various cells from children with this disease. Together with previous reports of second-trimester diagnosis in a case with late-infantile NCL (MacLeod et al., 1984, 1985), the presence of typical inclusions in placental tissue sampled at term in the infantile NCL (Rapola et al., 1987) and the lack of pathological alterations in one fetus at high risk of juvenile NCL and without clinical and morphological signs of disease at the age of 15 months (Kohlschutter et al., 1989), our findings strongly indicate that an early prenatal diagnosis of (juvenile) NCL is possible.

Prenatally diagnosed gastroschisis--a preliminary report advocating the use of elective caesarean section.

Seven cases of prenatally diagnosed gastroschisis were evaluated. All infants were delivered by elective Caesarean section and brought to the operating theatre immediately after birth where the abdominal wall defect was closed within one hour post partum. Primary closure was easy and successful in all cases without widening of the defect and with the umbilicus left intact, because of the total lack of oedema and bowel peel. The average duration of postoperative total parenteral nutrition (7 days) and hospital stay (18 days) was significantly shorter in this prenatally diagnosed group compared to traditionally treated cases.

Cesarean section and perinatal mortality in Sweden in 1981.

During the years 1973-81, the cesarean section (CS) birth rate increased from 5.5% to 12.4% in Sweden. During the same time, perinatal mortality declined from 12 to 7.1 per thousand children. The rates of CS and perinatal mortality, however, cannot be presented as reciprocally dependent variables without taking into consideration many of the other factors that have been at work during the same decade, e.g. improved results of the neonatologists in the lower weight groups, electronic fetal monitoring, use of steroids, introduction of tocolytic agents. The present study revealed that the incidence of CS could vary between 8% and 19% between different obstetric departments in Sweden during 1981. Despite this great difference in CS rate, no difference was noted in the rates of asphyxia or perinatal mortality. It is concluded that in the present study we have seen no indication that a marked increase in the CS rate would improve our present perinatal survival data and furthermore it still remains unproven that CS and perinatal mortality rates necessarily have a reciprocal relationship.

X-ray pelvimetry and trial of labor after previous cesarean section. A prospective study.

The benefits of X-ray pelvimetry and electronic monitoring of fetal heart rate and intra-uterine pressure were studied prospectively in order to predict the likelihood of a successful vaginal birth after previous cesarean section (CS). In 1982, a total of 369 parturients (7% of all deliveries) who had previously undergone CS were studied. Trial of labor (TL) was allowed in 160 cases (43.4%) and planned repeat CS was performed in 209 patients (56.6%). Patients in the TL group were compared with a matched control group. One hundred and fifty patients (94%) in the TL group gave birth by the vaginal route. There were no differences in the duration of the first and second stage of labor, duration of ruptured membranes (ROM), maternal blood loss or the incidence of CS and vacuum extraction between the TL group and the control group. Rates of low Apgar score (less than 7) at 1 and 5 min were the same in both groups. Intensive fetal monitoring during the course of labor, together with X-ray pelvimetry in selected cases, markedly reduced the incidence of acute repeat CS with no change in the overall rate of successful vaginal delivery compared with our previous results.

Cesarean section and intraoperative surgical complications.

The incidence of surgical complications associated with cesarean section (CS) was studied prospectively in 1319 patients undergoing CS during the years 1978, 1979 and 1980 (18% of all deliveries). The overall complication rate was 11.6% (9.5% patients with minor complications and 2.1% with major complications). The complication rate for emergency operations was 18.9% and for elective CS, 4.2%--a highly significant difference. (p less than 0.001). Six risk factors were associated with the occurrence of surgical complications in emergency cases: Station of the presenting part of the fetus in relation to the spinal plane (p less than 0.001), labor prior to surgery (p less than 0.001), low gestational age (less than 32 weeks) (p less than 0.001), rupture of fetal membranes (with labor) prior to surgery (p less than 0.01), previous CS (p less than 0.01), and skill of the operator (p less than 0.05). However, no such risk factors were found in the elective group. The clinical relevance of these findings is summarized in two conclusions. Firstly, the proportion of emergency operations needs to be reduced, either in favor of elective procedures, or by allowing more patients to give birth by the vaginal route. Secondly, emergency CS requires great skill on the part of the surgeon, and should therefore not be entrusted to young, inexperienced obstetricians.

The incidence of acute neonatal respiratory disorders in relation to mode of delivery.

Over a 3-year period all infants (n = 7401) born at the Department of Obstetrics and Gynecology, Central Hospital, Borås Sweden, were studied for signs of respiratory disease. For all infants who developed signs of respiratory disorders the mode of delivery and the type of anesthesia used in cesarean section (CS) were analysed. The incidence of respiratory disorders in the whole material was 3.0% (n = 220) and the mortality rate for these disorders was 0.24%. There was a significantly higher incidence (p less than 0.001) of respiratory disorders in infants weighing greater than or equal to 2500 g born by CS vis-à-vis infants born by the vaginal route. The group born by elective CS under maternal general anesthesia had a higher (p less than 0.05) rate of respiratory disorders than those born by elective CS under maternal epidural anesthesia. It is concluded that the risk of respiratory disorders in infants delivered by CS is related to the mode of delivery per se. Consequently, a reduction in the proportion of such interventions ought to reduce the overall number of infants developing respiratory disease, as indicated in the present study.

The course of subsequent pregnancies after previous cesarean section.

The course of pregnancies subsequent to cesarean section (CS) was studied. During the years 1970-72, 543 women were delivered by CS at Borås Central Hospital. A questionnaire was sent to all 543 during the autumn of 1976 and the spring of 1977. The questions concerned further conceptions and the outcome of all subsequent pregnancies after CS. Of the 440 (81%) women who answered the questionnaire, 244 (55.5%) became pregnant, the total number of subsequent pregnancies being 306. The incidence of spontaneous abortion, extra-uterine pregnancy and legal abortion was not significantly higher than the corresponding rate for the total material for our department during the same period. Among the 215 women who completed a new pregnancy, an elective CS was performed in 81 cases (38%). Trial of labor occurred in 143 patients, 91 of whom (68%) gave birth per vaginam , while 43 (32%) were delivered by acute CS. In nearly half of the acute CS cases the indication was a narrow pelvis not detected until labor had started. This indicates that roentgenologic pelvimetry should be considered in certain cases, when planning delivery after a previous CS.

Cesarean section and maternal mortality in Sweden 1973-1979.

During the years 1973-79, 704732 births took place in Sweden and 63 075 cesarean sections (CS) were performed. Within the study period there were 20 maternal deaths associated with delivery or puerperium. Thirteen of these patients were delivered by CS and 7 by the vaginal route. The hospital records of the 13 deaths associated with CS were closely analysed and it was found that 5 of the patients were critically ill before the beginning of surgery, and the CS per se was not responsible for these deaths. The 8 remaining maternal deaths gave a corrected (cesarean-attributed) maternal mortality rate of 12.7/100 000 cesarean deliveries. For vaginal deliveries the mortality rate was 1.1/100 000 deliveries. Thus, the risk of maternal death from CS in Sweden was twelve times as high as that from vaginal parturition. All maternal deaths except one, associated with CS, occurred after emergency operation. No deaths were ascribable to anesthesia complications. The most common causes of death after CS were pulmonary embolism, amniotic fluid embolism, coagulopathy and peritonitis. Time trends in the causes of maternal death in Sweden are discussed.

Postoperative cesarean section morbidity: a prospective study.

During a 3-year period, 1,319 women delivered of their infants by cesarean section were prospectively studied to determine the type and rate of postcesarean complications and to identify risk factors which predispose to postoperative morbidity. The overall complication rate was 14.5% and the most common complication was infection (13.3%), in particular, endometritis (6.6%), urinary tract infection (3.1%), and wound infection (1.6%). A lower complication rate was seen in elective operations (4.7%) compared with emergency operations (24.2%). Four significant factors that predispose to postoperative morbidity were identified: duration of ruptured membranes prior to operation (p less than 0.001), duration of labor prior to operation (p less than 0.001), anemia (p less than 0.01), and obesity (p less than 0.01). Patients with a combination of risk factors had an increased complication rate, in some cases as high as 91%. The clinical relevance of these findings in trying to decide possible ways to reduce the complication rate by changing the delivery routines is discussed.

Myocardial metabolism in relation to electrocardiographic changes and cardiac function during graded hypoxia in the fetal lamb.

Previous studies from this laboratory have demonstrated early and progressive alterations in the ST-T period of the fetal and neonatal electrocardiogram in relation to asphyxia. The aims of the present study were to investigate the metabolic background of these hypoxic ECG changes by means of serial myocardial biopsies in fetal lambs, relating these changes to the hypoxic depletion of glycogen, ATP and creatine phosphate stores in the heart and to the altered myocardial performance as measured by heart rate, mean arterial blood pressure, combined cardiac output and max. dP/dt. The experiments were performed on 21 fetal lambs, acutely exteriorized and subjected to graded hypoxia. During hypoxia there was a significant relationship between the degree of changes in the ST-T period according to a scoring system and the depletion of myocardial glycogen and ATP, a highly significant correlation between the rate of myocardial glycogenolysis and the rate of increase in T wave amplitude, and a parallelism between the amount of glycogen available and fetal cardiovascular function. The myocardium was capable of regenerating its glycogen stores under conditions of adequate oxygenation and in the absence of acidosis and hypoglycaemia.

Alterations in the electrocardiogram of the fetal lamb as a sign of fetal asphyxia. A comparison between the scalp lead and the precordial lead.

Progressive changes in the ST-T period of the fetal electrocardiogram (FECG) were studied in 18 lamb fetuses, acutely exteriorized and subjected to graded hypoxia. The aim of the study was to compare the bipolar precordial lead (CR-lead) with the unipolar scalp lead, and to correlate the alterations in the FECG to blood-gas and acid-base status. The scalp lead gave less information regarding fetal condition and was more difficult to interpret than the precordial lead. This might be one factor in the controversy regarding the significance of alterations in the FECG during asphyxia and labor, since the scalp lead is used mainly in clinical situations. Our previous results demonstrating progressive changes in the ST-T period of the FECG during hypoxia in experimental animals and showing the same ECG changes in newborn human infants immediately after birth, were registered with the bipolar precordial lead. It is possible that a bipolar scalp lead might give more information regarding the fetal condition than the unipolar scalp lead mainly used in clinical practice.