[A postpartum woman with toxic shock syndrome: group A streptococcal infection, a much feared postpartum complication.] / Een kraamvrouw met toxische-shocksyndroom.

BACKGROUND: The development of toxic shock syndrome (TSS) after an invasive group A streptococcal (GAS) infection in the postpartum period is a much feared complication. The mortality rate of TSS with necrotizing fasciitis is 30 to 50%. CASE DESCRIPTION: We present the case of a woman with atypical pelvic pain which was the first symptom of toxic shock syndrome as a consequence of a GAS infection. Clinical deterioration necessitated a hysterectomy. Also a fasciotomy was performed as consequence of lower extremity compartment syndrome. After this, multiple debridement operations were necessary, followed by split skin grafts. CONCLUSION: This case illustrates the extremely serious complications of GAS infection. In some cases aggressive surgical intervention is necessary, in addition to an optimal antibiotic treatment regime. Ideally, the treatment of a GAS-induced TSS should be managed by a multidisciplinary medical team.

Increased maternal TSH and decreased maternal FT4 are associated with a higher operative delivery rate in low-risk pregnancies: A prospective cohort study.

BACKGROUND: The increasing number of operative deliveries is a topic of major concern in modern obstetrics. Maternal thyroid function is of known influence on many obstetric parameters. Our objective was to investigate a possible relation between maternal thyroid function, and operative deliveries. Secondary aim was to explore whether thyroid function was related to specific reasons for operative deliveries. METHODS: In this prospective cohort study, low-risk Caucasian women, pregnant of a single cephalic fetus were included. Women with known auto-immune disease, a pre-labour Caesarean section, induction of labour, breech presentation or preterm delivery were excluded. In all trimesters of pregnancy the thyroid function was assessed. Differences in mean TSH and FT4 were assessed using t-test. Mean TSH and FT4 levels for operative deliveries were determined by one way ANOVA. Repeated measurement analyses were performed (ANOVA), adjusting for BMI, partiy, maternal age and gestational age at delivery. RESULTS: In total 872 women were included, of which 699 (80.2%) had a spontaneous delivery. At 36 weeks gestation women who had an operative delivery had a significantly higher mean TSH (1.63 mIU/L versus 1.46 mIU/L, p = 0.025) and lower mean FT4 (12.9 pmol/L versus 13.3 pmol/L, p = 0.007)) compared to women who had a spontaneous delivery. Mean TSH was significantly higher (p = 0.026) and mean FT4 significantly lower (p = 0.030) throughout pregnancy for women with an operative delivery due to failure to progress in second stage of labour, compared to women with a spontaneous delivery or operative delivery for other reasons. CONCLUSIONS: Increased TSH and decreased FT4 seem to be associated with more operative vaginal deliveries and Caesarean sections. After adjusting for several confounders the association remained for operative deliveries due to failure to progress in second stage of labour, possibly to be explained by less efficient uterine action.

Maternal thyrotropin is independently related to small for gestational age neonates at term.

OBJECTIVE: Small for gestational age (SGA) newborns constitute still a major cause of perinatal morbidity and mortality. Overt thyroid disease is a known cause of preterm birth and low birthweight but in its untreated condition it is rare today. In this study, we investigated the possible relation between maternal thyroid function assessed in euthyroid women at each trimester and the incidence of term born SGA neonates. DESIGN: A prospective cohort study was performed. PATIENTS: Thyroid function was assessed at 12, 24 and 36 weeks gestation in 1051 healthy Caucasian women who delivered at ≥ 37 weeks gestation. MEASUREMENTS: One-way anova was used to compare mean TSH and FT4 levels between women with SGA neonates and controls. Multiple logistic regression analysis was performed to adjust for known risk factors of SGA. RESULTS: Seventy (6·7%) SGA neonates were identified and they were significantly more often born to women with a TSH ≥ 97·5th at first and third trimester. Multiple logistic regression analysis showed that smoking (OR: 4·4, 95% CI: 2·49-7·64), pre-eclampsia (OR: 2·8, 95% CI: 1·19-6·78) and TSH ≥ 97·5th percentile (OR 3·3, 95% CI 1·39-7·53) were significantly related to SGA. Maternal FT4 levels and TPO-Ab status were not associated with SGA offspring. CONCLUSIONS: Our data show that TSH levels in the upper range of the reference interval at different trimesters (3·0-3·29 mIU/l) are independently related to an increased risk of delivering SGA neonates at term.

The aetiology of meconium-stained amniotic fluid: pathologic hypoxia or physiologic foetal ripening? (Review).

INTRODUCTION: Despite the many efforts to study the (patho)physiology of meconium release before delivery, it still remains an indistinct subject. Some studies have reported a relationship between hypoxia and MSAF, whilst others have not. The most common association found however, is between MSAF and the term of gestation. METHODS: MEDLINE, EMBASE and the Cochrane library were electronically searched. Papers about the (patho)physiology of meconium-stained amniotic fluid in English were included. Papers about management strategies were excluded (see elsewhere this issue). RESULTS: Different theories have been proposed including acute or chronic hypoxia, physiologic foetal ripening and peripartum infection. CONCLUSION: We suggest that meconium-stained amniotic fluid should be regarded as a symptom rather than a syndrome becoming more prevalent with increasing term and which might be associated with higher levels of infection or asphyxia.

Maternal thyrotrophin in euthyroid women is related to meconium stained amniotic fluid in women who deliver at or over 41 weeks of gestation.

BACKGROUND: Maternal thyroid dysfunction is of known influence on pregnancies in the preterm period. However little is known about its effect on term and post term pregnancies. Meconium stained amniotic fluid (MSAF) is known to occur preferentially in (post)term pregnancies. AIMS: To assess a possible independent relation between maternal thyroid function and MSAF. STUDY DESIGN AND SUBJECTS: 1051 women, in whom thyroid function was assessed at each trimester, were followed prospectively (delivery ≥37weeks). We compared the difference in mean TSH and FT4 between women with (152) and without (899) MSAF using one way ANOVA. Thyroid function was assessed in subgroups regarding gestational age. Finally we performed multiple logistic regression analysis with MSAF as dependent variable and TSH as independent variable adjusting for various confounders. RESULTS: Maternal thyroid function was not associated with the incidence of MSAF when analysing all deliveries ≥37weeks. However, in the "at-risk" group for MSAF (>41weeks), multiple logistic regression showed an independent relation between MSAF and TSH (O.R.: 1.61, 95% CI: 1.10-2.43). CONCLUSIONS: The present study shows that in women delivering ≥41weeks of gestation, higher TSH is independently related to MSAF.

Involving women in personalised decision-making on mode of delivery after caesarean section: the development and pilot testing of a patient decision aid.

OBJECTIVE: To develop a patient decision aid (PtDA) for mode of delivery after caesarean section that integrates personalised prediction of vaginal birth after caesarean (VBAC) with the elicitation of patient preferences and evidence-based information. DESIGN: A PtDA was developed and pilot tested using the International Patients Decision Aid Standards (IPDAS) criteria. SETTING: Obstetric health care in the Netherlands. POPULATION: A multidisciplinary steering group, an expert panel, and 25 future users of the PtDA, i.e. women with a previous caesarean section. METHODS: The development consisted of a construction phase (definition of scope and purpose, and selection of content, framework, and format) and a pilot testing phase by interview. The process was supervised by a multidisciplinary steering group. MAIN OUTCOME MEASURES: Usability, clarity, and relevance. RESULTS: The construction phase resulted in a booklet including unbiased balanced information on mode of birth after caesarean section, a preference elicitation exercise, and tailored risk information, including a prediction model for successful VBAC. During pilot testing, visualisation of risks and clarity formed the main basis for revisions. Pilot testing showed the availability of tailored structured information to be the main factor involving women in decision-making. The PtDA meets 39 out of 50 IPDAS criteria (78%): 23 out of 23 criteria for content (100%) and 16 out of 20 criteria for the development process (80%). Criteria for effectiveness (n = 7) were not evaluated. CONCLUSIONS: An evidence-based PtDA was developed, with the probability of successful VBAC and the availability of structured information as key items. It is likely that the PtDA enhances the quality of decision-making on mode of birth after caesarean section.

Does the method of dissecting in anterior colporraphy lead to a difference in thickness of removed vaginal tissue?

OBJECTIVE: To evaluate the difference in thickness of the anterior vaginal wall removed after different surgical dissecting techniques of anterior colporrhaphy. STUDY DESIGN: In patients undergoing primary anterior colporrhaphy, trimmed vaginal tissue was taken following different surgical techniques of vaginal wall dissection. Tissues were preserved in formalin and stained with hematoxylin-eosin and elastica-van Giesen stains. The examiner was an experienced pathologist blinded to the surgical technique. The specimens were examined for the epithelial thickness (ET), lamina propria thickness (LPT), muscular layer thickness (MT) and total thickness (TT). RESULTS: Tissue was analysed in 93 women who underwent anterior compartment pelvic organ prolapse surgery. There was no difference between the different surgical techniques in thickness measured in the three histological layers and for the total thickness. The use of hydrodissection was the only independent factor leading to thicker removed vaginal tissue. CONCLUSIONS: Dissecting the vaginal wall as thin as possible does not result in a thinner vaginal layer than dissecting in the most optimal surgical plane. The use of hydrodissection provides a thicker trimmed tissue.

Effect of 17-alpha hydroxyprogesterone caproate on cervical length in twin pregnancies.

OBJECTIVES: Previous studies on singleton pregnancies have indicated that progestogens may reduce the rate of cervical shortening during pregnancy. The aim of this study was to investigate whether treatment with 17-alpha hydroxyprogesterone caproate (17-OHPC) has an effect on cervical shortening in twin pregnancies. METHODS: This was a secondary analysis of patients who had participated in a multicenter randomized clinical trial on the effectiveness of 17-OHPC in preventing preterm birth in multiple pregnancies (the AMPHIA-trial). We included all trial participants with a twin gestation who had undergone repeat cervical length measurements during pregnancy. We performed a separate analysis of women with repeat measurements in centers where this was standard protocol for multiple pregnancies. The rate of cervical shortening for both the 17-OHPC group and the placebo group was analyzed using a linear mixed model. RESULTS: Of the 671 patients who participated in the trial, 282 (42%) had a twin pregnancy and underwent two or more cervical length measurements. Of these women, 140 were monitored in centers where repeat measurements were standard protocol. We observed an overall reduction of cervical length from 44.3 mm at 14-18 weeks to 30.0 mm at 30-34 weeks' gestation. In the 17-OHPC group, cervical length decreased by 1.04 mm each gestational week, while this was 1.11 mm per week for the placebo group (P = 0.6). For the overall group, each 10% decrease in cervical length led to an increase in the risk of preterm birth (hazard ratio, 1.14; 95% CI, 1.08-1.21). CONCLUSION: In women with a twin pregnancy, there is progressive shortening of the cervix during pregnancy, regardless of 17-OHPC use.

Neonatal thyroid screening results are related to gestational maternal thyroid function.

OBJECTIVE: To study the relationship between maternal thyroid function at each pregnancy trimester and neonatal screening results. BACKGROUND: Overt maternal thyroid dysfunction during gestation is associated with poor neonatal thyroid function. However, research on the relationship between suboptimal maternal thyroid function (assessed at three trimesters) and neonatal thyroid screening outcome is scarce. DESIGN/PATIENTS: Prospective follow-up study during three trimesters of gestation in 886 Dutch Caucasian healthy pregnant women followed from 12-week gestation until term delivery (>37 weeks) and their neonates. MEASUREMENTS: The relation between neonatal data from the Congenital Hypothyroidism (CH) screening and maternal thyroid determinants [TSH, FT4 and thyroid peroxidase (TPO)-Ab] assessed at 12-, 24- and 36-week gestation. RESULTS: Boys have lower screening TT4 levels and their mothers have higher TSH levels at 24- and 36-week gestation. Higher maternal TSH levels (>97·5th percentile, as defined in 810 women without TPO-Ab at 12 weeks) at one or more times during pregnancy (O.R: 2·26, 95% CI: 1·20-4·29) and lower gestational age (O.R: 1·22, 95% CI: 1·05-1·41) are independently related to lower screening TT4 levels. CONCLUSIONS: Maternal thyroid function during gestation is related to neonatal TT4 at screening. The finding of both lower neonatal TT4 levels in boys and higher TSH levels in mothers carrying boys is worthy of further investigation, as both observations may be meaningfully related.

Induction versus expectant monitoring for intrauterine growth restriction at term: randomised equivalence trial (DIGITAT).

OBJECTIVE: To compare the effect of induction of labour with a policy of expectant monitoring for intrauterine growth restriction near term. DESIGN: Multicentre randomised equivalence trial (the Disproportionate Intrauterine Growth Intervention Trial At Term (DIGITAT)). SETTING: Eight academic and 44 non-academic hospitals in the Netherlands between November 2004 and November 2008. PARTICIPANTS: Pregnant women who had a singleton pregnancy beyond 36+0 weeks' gestation with suspected intrauterine growth restriction. INTERVENTIONS: Induction of labour or expectant monitoring. MAIN OUTCOME MEASURES: The primary outcome was a composite measure of adverse neonatal outcome, defined as death before hospital discharge, five minute Apgar score of less than 7, umbilical artery pH of less than 7.05, or admission to the intensive care unit. Operative delivery (vaginal instrumental delivery or caesarean section) was a secondary outcome. Analysis was by intention to treat, with confidence intervals calculated for the differences in percentages or means. RESULTS: 321 pregnant women were randomly allocated to induction and 329 to expectant monitoring. Induction group infants were delivered 10 days earlier (mean difference -9.9 days, 95% CI -11.3 to -8.6) and weighed 130 g less (mean difference -130 g, 95% CI -188 g to -71 g) than babies in the expectant monitoring group. A total of 17 (5.3%) infants in the induction group experienced the composite adverse neonatal outcome, compared with 20 (6.1%) in the expectant monitoring group (difference -0.8%, 95% CI -4.3% to 3.2%). Caesarean sections were performed on 45 (14.0%) mothers in the induction group and 45 (13.7%) in the expectant monitoring group (difference 0.3%, 95% CI -5.0% to 5.6%). CONCLUSIONS: In women with suspected intrauterine growth restriction at term, we found no important differences in adverse outcomes between induction of labour and expectant monitoring. Patients who are keen on non-intervention can safely choose expectant management with intensive maternal and fetal monitoring; however, it is rational to choose induction to prevent possible neonatal morbidity and stillbirth. TRIAL REGISTRATION: International Standard Randomised Controlled Trial number ISRCTN10363217.

High thyrotrophin levels at end term increase the risk of breech presentation.

OBJECTIVE: To study the relationship between maternal thyrotrophin (TSH) and breech presentation at term. DESIGN: Combined data sets of two prospective studies to obtain adequate epidemiological power. PATIENTS: One thousand and fifty-eight healthy pregnant women (58 breech, 1000 cephalic) and 131 women who presented in breech at an obstetrical outpatient clinic. MEASUREMENTS: Maternal thyroid parameters [TSH, free thyroid hormone (FT4), thyroid peroxidase antibody (TPO-Ab)] and foetal presentation were assessed in both groups between 35 and 38 weeks gestation. Power calculations suggested that at least 148 breech cases were required. RESULTS: The characteristics of the women in breech in both samples were similar. Women in breech (n = 58 + 131) had significantly higher TSH (but not FT4) than those (n = 1000) with cephalic presentation (Mann-Whitney U-test, P = 0·003). Different cut-offs were used to define high TSH in the 916 TPO-Ab-negative women with cephalic presentation: the 90th, 95th and 97·5th percentiles were 2·4 mIU/l (n = 149), 2·7 mIU/l (n = 77) and 3·2 mIU/l (n = 37). The prevalence rates of breech presentation in these women were all higher compared to the prevalence of breech in women below these cut-offs (df = 1, P < 0·01). The relative risk of the 149 women with a TSH >90th percentile (>2·4 mIU/l) to present in breech was 1·82 (95% CI: 1·30-2·56). CONCLUSIONS: Women with high TSH at end term are at risk for breech presentation. Substantial evidence for a relation between breech presentation and neurodevelopmental delay exists. As high TSH during gestation has also been linked to poor neurodevelopment, the relation between breech presentation and poor neurodevelopment might be thyroid-related.

Maternal thyroid function during gestation is related to breech presentation at term.

OBJECTIVE: To study the relationship between suboptimal maternal thyroid function during gestation and breech presentation at term. DESIGN: Prospective follow-up study during three trimesters of gestation. PATIENTS: A total of 1058 Dutch Caucasian healthy pregnant women were prospectively followed from 12 weeks gestation until term (>or=37 weeks) delivery. MEASUREMENTS: Maternal thyroid parameters [TSH, free T4 (FT4) and auto-antibodies to thyroid peroxidase] were assessed at 12, 24 and 36 weeks gestation as well as foetal presentation at term. RESULTS: At term, 58 women (5.5%) presented in breech. Compared with women with foetuses in the cephalic position, those women who presented in breech at term had significantly higher TSH concentrations, but only at 36 weeks gestation (P = 0.007). No between group differences were obtained for FT4 level at any assessment. The prevalence of breech presentation in the subgroup of women with TSH >or= 2.5 mIU/l (90th percentile) at 36 weeks gestation was 11%, compared with 4.8% in the women with TSH < 2.50 mIU/l (P = 0.006). Women with TSH below the 5th percentile had no breech presentations. Breech position was significantly and independently related to high maternal TSH concentration (>or=2.5 mIU/l) at 36 weeks gestation (O.R.: 2.23, 95% CI: 1.14-4.39), but not at 12 and 24 weeks gestation. CONCLUSIONS: Women with TSH levels above 2.5 mIU/l during end gestation are at risk for breech presentation, and as such for obstetric complications.

[Fewer caesarean sections for breech presentation following external cephalic version according to a protocol in a special office visit]. / Minder keizersneden wegens stuitligging dankzij geprotocolleerde uitwendige versie in een speciaal spreekuur.

OBJECTIVE: Identification of determinants affecting the outcome of external cephalic version (ECV) in breech presentation, and investigation of the impact of ECV--performed according to a standardized protocol in an outpatient clinic--on the mode of delivery. DESIGN: Retrospective analysis. METHOD: In 2003 a standardized protocol of ECV was developed in the outpatient clinic for obstetrics of the Catharina Hospital in Eindhoven, the Netherlands; it was tested in 'version office visits'. Obstetric characteristics of all pregnant women who underwent attempts of ECV in the clinic from January 2004 until June 2006 during these sessions, and the subsequent births, were analysed. 85% of all ECVs were performed by the same hospital midwife and gynaecologist, in accordance with the protocol. RESULTS: ECV was successful in 96 of 209 pregnant women (46%). In 1 pregnant woman an emergency caesarean section was performed after ECV because of partial abruptio placentae. Nulliparity, incomplete breech presentation and low birth weight of the baby were associated with a lower success rate of ECV in this study. In the group with a successful ECV the percentage of caesarean deliveries was substantially lower (9 versus 83%; odds ratio: 0.21; 95% CI: 0.09-0.51). CONCLUSION: A regular team consisting of a hospital midwife and a gynaecologist working according to a standardized protocol for ECV in a case of breech presentation proved successful: the number of term breech presentations substantially diminished and therefore the percentage of caesarean sections was lower in the group in which ECV had been successful. This could have considerable impact on health care in the Netherlands in terms of reduced maternal morbidity and cost savings.

The effects of low-dose endotoxin on the umbilicoplacental circulation in preterm sheep.

OBJECTIVE: In the present study we examined the effects of low-dose endotoxin (lipopolysaccharides, LPS) on continuously recorded umbilical blood flow. METHODS: Twenty fetal sheep were catheterized at a gestational age of 107 +/- 1 days. A flow probe was placed around either the common umbilical artery or one single umbilical artery. Three days later fetuses received either 100 or 500 nanograms of LPS (n = 14) or 2 mL saline (n = 6) intravenously. Six fetuses died within 12 hours after LPS. Fetal heart rate (FHR), mean arterial pressure (MAP), and umbilical blood flow (Q(umb)) were monitored for 3 days. RESULTS: FHR increased by 25 +/- 4% at 4-5 hours after LPS (P <.01) and was elevated for 15 hours after LPS. MAP increased by 18 +/- 5% 1 hour after LPS (P <.01) and returned to control value 4-5 hours after LPS. Q(umb) began to decrease 1 hour after LPS and was minimal (-30 +/- 7%, P <.001) at 4-5 hours after LPS. Q(umb) slowly returned to the control value at 12 hours after LPS. Placental vascular resistance increased by 73 +/- 37% (P <.01), whereas pH did not appreciably change. CONCLUSION: Intravenous application of endotoxin caused a substantial and long-lasting decrease in umbilical blood flow resulting in fetal hypoxemia without acidemia. These effects may be of significance in the development of fetal brain damage associated with intrauterine infection.

The role of nitric oxide on fetal cardiovascular control during normoxia and acute hypoxia in 0.75 gestation sheep.

OBJECTIVE: The role of nitric oxide in control of fetal cardiovascular functions and of cerebral blood flow during normoxia and acute hypoxia is only partially known. We studied the effects of nitric oxide synthase inhibition on the distribution of cardiac output in preterm sheep using N(omega)-nitro-L-arginine methyl ester (L-NAME). METHODS: Thirteen fetal sheep were instrumented at a gestational age of 107 days. Three days later fetuses received L-NAME (n = 7) or vehicle infusion (n = 6). At 0 minutes, acute hypoxia was induced by occlusion of the maternal aorta for 2 minutes. Organ blood flows (microsphere method) and physiologic variables (fetal heart rate, mean arterial pressure [MAP], oxygen saturation, and pH) were measured at -75, -1, +2, +4, and +30 minutes. RESULTS: L-NAME caused bradycardia and an increase in MAP. A significant decrease in cardiac output by 32% occurred in the control group during the control period, which was consequently reflected in organ blood flows. L-NAME injection reduced cardiac output by 64% during normoxia. Blood flow to the fetal body, placenta, and cerebrum decreased by 62%, 66%, and 55%, respectively. During acute hypoxia, L-NAME did not change the redistribution of cardiac output toward the central organs. In the L-NAME group MAP increased, and fetal heart rate was maintained; in contrast, in controls MAP initially decreased and then returned to control values while fetal heart rate decreased. After hypoxia L-NAME delayed the recovery of cardiac output and blunted the increase in blood flow to the brain and heart. CONCLUSIONS: Although influenced by fetal stress after extensive instrumentation, the results of this study indicate that nitric oxide plays a role in fetal cardiovascular control during normoxia and acute hypoxia. Nitric oxide also mediates the increase in blood flow to the brain and heart immediately after hypoxia.

The ex utero intrapartum treatment (EXIT) procedure in fetal neck masses: a case report and review of the literature.

Large fetal neck masses can cause airway obstructions with potential fetal demise after delivery. The relationship of the neck mass to airway structures can be defined prenatally with ultrasound and magnetic resonance imaging (MRI). The ex utero intrapartum treatment (EXIT) procedure can be used to obtain a fetal airway while feto-maternal circulation is preserved to optimise fetal outcome. We present a case in which prenatally a large fetal neck mass was diagnosed on ultrasound and a successful EXIT procedure was performed. A review of the literature is given and the prenatal use of ultrasonography and MRI in case of fetal neck masses is discussed.

Endotoxemia severely affects circulation during normoxia and asphyxia in immature fetal sheep.

OBJECTIVE: The purpose of the present study was to determine whether endotoxins (lipopolysaccharides, LPS) affect the fetal cardiovascular system in a way likely to cause brain damage. METHODS: Thirteen fetal sheep were chronically instrumented at a mean gestational age of 107 +/- 1 days. After control measurements of organ blood flow (microsphere method), blood gases, and acid base balance were obtained, seven of 13 fetuses received LPS (53 +/- 3 microg/kg fetal weight) intravenously. Sixty minutes later, asphyxia was induced by occlusion of the maternal aorta for 2 minutes. Measurements of organ blood flows were made at -60, -1, +2, +4, +30, and +60 minutes. RESULTS: Unlike in the control group, after LPS infusion there was a significant decrease in arterial oxygen saturation (-46%; P <.001) and pH (P <.001). In LPS-treated fetuses the portion of combined ventricular output directed to the placenta decreased significantly (-76%; P <.001), whereas output to the fetal body (+60%; P <.001), heart (+167%; P <.05), and adrenals (+229%; P <.01) increased. Furthermore, during asphyxia circulatory centralization was impaired considerably in LPS-treated fetuses, and there was clear evidence of circulatory decentralization. This decentralization caused a severe decrease in cerebral oxygen delivery by 70%. Within 30 minutes after induction of asphyxia five of seven LPS-treated fetuses died, whereas all control fetuses recovered completely. CONCLUSIONS: Endotoxemia severely impaired fetal cardiovascular control during normoxia and asphyxia, resulting in a considerable decrease in cerebral oxygen delivery. These effects might have important effects in the development of fetal brain damage associated with intrauterine infection.

Effect of repetitive umbilical cord occlusions on neuronal brain activity measured by the cerebral function analyzing monitor and histologic outcome in immature fetal sheep.

OBJECTIVE: To examine the effect of repetitive total umbilical cord occlusions on electrocortical brain activity as measured by cerebral function analyzing monitoring (CAFM) and the histologic outcome in immature sheep fetuses. STUDY DESIGN: We performed brief repeated total umbilical cord occlusions, two every 5 minutes, in 12 immature sheep fetuses (at 90 days of gestation, term 147 days) until fetal mean arterial pressure dropped below 50% of baseline value during two successive occlusions. A pair of electrodes was inserted on the parietal dura for recording of electrocortical brain activity (ECoG). Off-line ECoG signal processing consisted of amplitude integrated analysis (CFAM) and spectral analysis. Fetal blood gas analyses were performed at regular intervals just before subsequent umbilical cord occlusions. Three days after the occlusion neuronal damage was evaluated histologically in three regions of the fetal brain. RESULTS: CFAM amplitide parameters decreased significantly during the first occlusion and remained so during the entire repetitive occlusion period (analysis of variance [ANOVA]; P <.05). Spectral analysis of the ECoG signal demonstrated no changes in the distribution of frequency bands. Progressive acidemia and hypotension developed with ongoing occlusions. Five fetuses died at the end or shortly after the entire repetitive occlusion period. No neuronal damage or macroscopic intraventricular and/or germinal matrix hemorrhage was observed in the surviving fetuses. CONCLUSION: Repetitive umbilical cord occlusions in immature sheep fetuses resulted in functional, not structural changes of the fetal brain in surviving fetuses. At this gestational age, amplitude analysis is more sensitive than spectral analysis of the ECoG signal to functional changes of the compromised fetal brain.

The PR interval-fetal heart rate relationship during repetitive umbilical cord occlusions in immature fetal sheep.

OBJECTIVE: To evaluate the relationship of the PR interval and fetal heart rate during repetitive umbilical cord occlusions in immature sheep fetuses. STUDY DESIGN: In seven chronically cannulated immature sheep fetuses [gestational age 90.6 days (mean)], we analyzed continuous fetal electrocardiogram recordings during repetitive cord occlusions for 2 out of every 5 min until fetal mean arterial pressure dropped to 50% of baseline value. PR interval-fetal heart rate correlation coefficients (Pearson) was measured on consecutive blocks of 2.5 min. R-values of the baseline and the repetitive occlusion period were compared by Fisher's exact test. RESULTS: Repetitive cord occlusions resulted in acidosis and hypotension. Two fetuses died at the end of the repetitive occlusion period. Four out of seven fetuses showed a significant change from a negative relationship between the PR interval and fetal heart rate during baseline to a predominantly positive relationship during the repetitive occlusion period. CONCLUSION: In immature fetal sheep, a change from a negative relationship between the PR interval and fetal heart rate to a predominantly positive relationship between the PR interval and fetal heart rate was observed in four out of seven fetuses following the initiation of repetitive umbilical cord occlusions.

Fetal arterial pressure and heart rate changes in surviving and non-surviving immature fetal sheep following brief repeated total umbilical cord occlusions.

OBJECTIVES: To describe the changes in fetal heart rate and mean arterial pressure during repetitive total umbilical cord occlusions in immature sheep fetuses, resulting in severe asphyxia or fetal death. To describe the relationship between these changes and concurrent changes in acid-base status. STUDY DESIGN: We performed brief repeated total umbilical cord occlusions, two out of every five min, in 14 immature sheep fetuses (at 90 days of gestation), until fetal mean arterial pressure dropped below 50% of baseline value during two successive occlusions. Fetal blood gas analyses were performed at regular intervals just before cord occlusions. RESULTS: Progressive acidemia and hypotension developed with ongoing occlusions. The degree of hypotension during occlusions increased with ongoing occlusions. The minimum fetal arterial blood pressure during occlusions correlated well with the progressive acidemia. Six fetuses died at the end of the repetitive occlusion period. In the non-survivors, acidemia was more severe and paCO2 gradually increased during the entire repetitive occlusion period. In the survivors group, a period of transient hypoxia and hypotension was observed with a nadir at +60 min following the final occlusion. CONCLUSION: Repetitive umbilical cord occlusions in immature sheep fetuses resulted in repetitive periods of hypotension, bradycardia, progressive fetal acidemia and ultimately fetal demise. Minimum fetal arterial blood pressure during occlusions correlated well with the progressive fetal acidemia.