Adverse perinatal outcomes are strongly associated with degree of abnormality in uterine artery Doppler pulsatility index.

OBJECTIVES: To investigate the association between varying degrees of abnormality in the uterine artery Doppler pulsatility index (UtA-PI) and adverse perinatal outcomes. METHODS: Prospective study of 33,364 women who gave birth to singleton, non-anomalous babies in Oxford, following universal measurement of UtA-PI in mid-pregnancy. Relative risk ratios for the primary outcomes of extended perinatal mortality and live birth with severe small-for-gestational-age (SGA) were calculated by multinomial logistic regression, for early preterm birth (<34+0) and late preterm/term birth (≥34+0). The risks were also investigated for iatrogenic preterm birth or a composite adverse outcome before 34+0 weeks. RESULTS: Compared with women with normal UtA-PI, the risk of extended perinatal mortality before 34+0 weeks was higher in women with UtA-PI >90th centile (RRR 4.7, 95% CI 2.7-8.0, p<0.001), but this was not demonstrated in later births. The risk of severe SGA birth was strongly associated with abnormal UtA-PI for both early births (RRR 26.0, 95% CI 11.6-58.2, p<0.001), and later births (RRR 2.3, 95% CI 1.8-2.9, p<0.001). Women with a raised UtA-PI were more likely to undergo early iatrogenic birth (RRR 7.8, 95% CI 5.5-11.2, p<0.001). For each of the outcomes and the composite outcome, the risk increased significantly in association with the degree of abnormality, through the 90th, 90-94th, 95-99th and >99th centiles (ptrend<0.001). CONCLUSIONS: An elevated UtA-PI is a key predictor of iatrogenic preterm birth, severe SGA and perinatal loss up to 34+0 weeks. It is the 90th centile that should be used, and management should be further tailored to the degree of abnormality, as pregnancies with very raised UtA-PI measurements constitute a group at extreme risk. This article is protected by copyright. All rights reserved.

Perinatal outcome of fetuses predicted to be large-for-gestational age on universal third-trimester ultrasound in non-diabetic pregnancy.

OBJECTIVE: To describe the perinatal outcome of fetuses predicted to be large-for-gestational age (LGA) on universal third-trimester ultrasound in non-diabetic pregnancies of women attempting vaginal delivery. METHODS: This was a prospective population-based cohort study of patients from a single tertiary maternity unit in the UK offering universal third-trimester ultrasound and practicing expectant management of suspected LGA until 41-42 weeks. All women with a singleton pregnancy and an estimated due date between January 2014 and September 2019 were included. Women delivering before 37 weeks, those having a planned Cesarean delivery, those with pre-existing or gestational diabetes, those with fetal abnormalities and those who did not undergo a third-trimester scan were excluded from the assessment of perinatal outcome of cases with LGA predicted on ultrasound after implementation of the universal scan period. Association of LGA on universal third-trimester ultrasound screening and perinatal adverse outcome was assessed, with the exposures of interest being estimated fetal weight (EFW) at the 90th -95th , > 95th and > 99th percentile. The reference group was composed of fetuses with EFW at the 30th -70th percentile. Analysis was performed using multivariate logistic regression. The evaluated adverse perinatal outcomes included a composite outcome of admission to neonatal intensive care unit, Apgar score < 7 at 5 min and arterial cord pH < 7.1 (CAO1) and a composite outcome of stillbirth, neonatal death and hypoxic ischemic encephalopathy (CAO2). Secondary maternal outcomes were induction of labor, mode of delivery, postpartum hemorrhage, shoulder dystocia and obstetric anal sphincter injury. RESULTS: Cases with EFW > 95th percentile on universal third-trimester scan were at increased risk of CAO1 (adjusted odds ratio (aOR), 2.18 (95% CI, 1.69-2.80)) and CAO2 (aOR, 2.58 (95% CI, 1.05-6.34)). Cases with EFW at the 90th -95th percentile had a less pronounced increase in the risk of CAO1 (aOR, 1.35 (95% CI, 1.02-1.78)) and were not at increased risk of CAO2. All pregnancies with a fetus predicted to be LGA were at increased risk of all of the evaluated secondary maternal outcomes except for obstetric anal sphincter injury. The risk of adverse maternal outcome was typically higher with increasing EFW. Post-hoc exploration of data suggested that shoulder dystocia had a limited contribution to composite adverse perinatal outcomes in LGA cases (population attributable fraction of 10.8% for CAO1 and 29.1% for CAO2). CONCLUSIONS: Cases with EFW > 95th percentile are at increased risk of severe adverse perinatal outcome, such as death and hypoxic ischemic encephalopathy. These findings should aid antenatal counseling regarding the associated risk and delivery options. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Detection of small- and large-for-gestational age using different combinations of prenatal and postnatal charts.

OBJECTIVE: To determine the extent to which the detection rate of small-for-gestational age (SGA) and large-for-gestational age (LGA) at birth is influenced by the use of different combinations of estimated-fetal-weight (EFW) and birth-weight (BW) charts. METHODS: This was a cohort study of all pregnant women with a singleton term birth receiving care in a university hospital during a 3-year period. All participants underwent a universal 36-week ultrasound scan for EFW measurement and had BW recorded at delivery. Five different reference charts were used for EFW and BW centile calculation. Two-by-two contingency tables were constructed using EFW as the screening test variable and BW as the outcome variable in order to calculate sensitivity, specificity, positive predictive value (PPV) and negative predictive value for all possible chart combinations. RESULTS: The cohort included 17 678 pregnancies. The sensitivity of EFW < 10th centile for the detection of BW < 10th centile ranged from 10.8% to 66.8% and the sensitivity of EFW < 3rd centile for the detection of BW < 3rd centile ranged from 4.1% to 66.8%, depending on the charts used. The sensitivity of EFW > 90th centile for BW > 90th centile ranged between 22.9% and 68.3%. When locally derived charts for EFW and BW were used, the sensitivity of detection of BW < 10th centile using EFW < 10th centile was 43.7% (PPV, 45.5%); for the detection of BW < 3rd centile using EFW < 3rd centile, the sensitivity was 25.6% (PPV, 26.7%) and, for the detection of BW > 90th centile using EFW > 90th centile, it was 49.6% (PPV, 49.0%). CONCLUSIONS: Different combinations of EFW and BW charts can yield vastly different detection rates (sensitivity) in the same population cohort and time period. If SGA and LGA detection rates are to be used as a meaningful performance indicator, healthcare systems should follow a clear and predefined methodology that includes explicit definitions of common reference standards. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

How often do we identify fetal abnormalities during routine third-trimester ultrasound? A systematic review and meta-analysis.

BACKGROUND: Routine third-trimester ultrasound is frequently offered to pregnant women to identify fetuses with abnormal growth. Infrequently, a congenital anomaly is incidentally detected. OBJECTIVE: To establish the prevalence and type of fetal anomalies detected during routine third-trimester scans using a systematic review and meta-analysis. SEARCH STRATEGY: Electronic databases (MEDLINE, Embase and the Cochrane library) from inception until August 2019. SELECTION CRITERIA: Population-based studies (randomised control trials, prospective and retrospective cohorts) reporting abnormalities detected at the routine third-trimester ultrasound performed in unselected populations with prior screening. Case reports, case series, case-control studies and reviews without original data were excluded. DATA COLLECTION AND ANALYSIS: Prevalence and type of anomalies detected in the third trimester. We calculated pooled prevalence as the number of anomalies per 1000 scans with 95% confidence intervals. Publication bias was assessed. MAIN RESULTS: The literature search identified 9594 citations: 13 studies were eligible representing 141 717 women; 643 were diagnosed with an unexpected abnormality. The pooled prevalence of a new abnormality diagnosed was 3.68 per 1000 women scanned (95% CI 2.72-4.78). The largest groups of abnormalities were urogenital (55%), central nervous system abnormalities (18%) and cardiac abnormalities (14%). CONCLUSION: Combining data from 13 studies and over 140 000 women, we show that during routine third-trimester ultrasound, an incidental fetal anomaly will be found in about 1 in 300 scanned women. This information should be taken into account when taking consent from women for third-trimester ultrasound and when designing and assessing cost of third-trimester ultrasound screening programmes. TWEETABLE ABSTRACT: One in 300 women attending a third-trimester scan will have a finding of a fetal abnormality.

An objective scoring method to evaluate image quality of middle cerebral artery Doppler.

Objective: To validate an objective scoring system for middle cerebral artery (MCA) pulsed wave Doppler images.Method: From an image database of routine 36-week scans, a random sample of MCA Doppler images was selected. Two reviewers rated the images subjectively as acceptable or unacceptable. Subsequently they used an objective 6-point image scoring system and awarded one point for each of the following: (1) anatomical site, (2) magnification, (3) angle of insonation, (4) image clarity, (5) sweep speed adjustment, and (6) velocity scale and baseline adjustment. Image scores 4-6 were defined as good quality whereas 0-3 as poor. The subjective and objective agreement between the two reviewers was compared using the adjusted Kappa statistic.Results: A total of 124 images were assessed. Using objective scoring the agreement rate between reviewers increased to 91.9% (κ = 0.839) compared to subjective agreement 75.8% (κ = 0.516). The agreement for each criterion was: anatomical site 91.1% (κ = 0.823), magnification 95.2% (κ = 0.903), clarity 83.9% (κ = 0.677), angle 96.0% (κ = 0.919), sweep speed 98.4% (κ = 0.968), and velocity scale and baseline 94.4% (κ = 0.887).Conclusion: Objective assessment of MCA Doppler images using a 6-point scoring system has greater interobserver agreement than subjective assessment and could be used for MCA Doppler quality assurance.

External cephalic version at term: a cohort study of 18 years' experience.

OBJECTIVE: To analyse the outcome of referrals for external cephalic version (ECV). DESIGN: Retrospective cohort study of prospectively collected data. SETTING: Major university hospital, UK. SAMPLE: Women with non-cephalic presentation at term and no prior caesarean, referred to a specialist clinic. METHODS: Details of referrals, ECV attempts, and perinatal outcomes were prospectively collected and analysed. Multivariate binary logistic regression models were created to determine independent predictors of ECV success, reversion, and spontaneous version. MAIN OUTCOME MEASURES: External cephalic version success rates, predictors of success and cephalic presentation at birth, and perinatal outcomes. RESULTS: Three thousand eight had confirmed breech presentation; 2614 women underwent ECV. Ineligibility for ECV occurred in 117 breech presentations (3.9%), and 297 eligible women (10.2%) declined it. ECV was successful in 1280 (49.0%, 95% CI 47.0-50.9%) (40% in nulliparous women; 64% in others); 1234 (97.3%) were cephalic at birth. Spontaneous version after failure occurred in 4.3% and was more common in multiparas (aOR 2.47, 95% CI 1.43-4.26) and those with a posterior fetal back (aOR 6.09, 95% CI 1.90-19.53). Reversion after successful ECV occurred in 2.2%. In women with a successful ECV whose fetus remained cephalic at birth, 85.7% delivered vaginally. The corrected perinatal mortality of the ECV cohort was 0.12%. CONCLUSION: External cephalic version has a low complication rate and is effective for most breech presentations, enabling vaginal birth and avoiding caesarean section. TWEETABLE ABSTRACT: External cephalic version can safely be performed with most breech presentations.

Using fetal abdominal circumference growth velocity in the prediction of adverse outcome in near-term small-for-gestational-age fetuses.

OBJECTIVE: To investigate whether abdominal circumference growth velocity (ACGV) improves the prediction of perinatal outcome in small-for-gestational-age (SGA) fetuses beyond that afforded by estimated fetal weight (EFW) and cerebroplacental ratio (CPR). METHODS: A cohort of 235 singleton SGA fetuses at 36-38 weeks' gestation was examined. ACGV, EFW and CPR centiles were calculated. ACGV centile was determined using data from a large database of 19-21- and 36-38-week scans in an unselected population. Binary variables of ACGV < 10th , EFW < 3rd and CPR < 5th centiles were defined as abnormal. Two composite adverse outcomes (CAO) were explored: CAO-1 defined as at least one of umbilical artery pH < 7.10, 5-min Apgar score < 7 or neonatal unit admission, and CAO-2 that included in addition hypoglycemia, intrapartum fetal distress and perinatal death. Univariate and multivariate logistic regression analyses were performed to analyze the relationship between the three risk factors and their predictive value for CAO. The change in screening performance afforded by adding ACGV to EFW and CPR was assessed and receiver-operating characteristics (ROC) curves were calculated. RESULTS: ACGV < 10th centile was an independent risk factor for CAO. The sensitivity, specificity, positive and negative likelihood ratios of a predictive model based on EFW < 3rd centile and CPR < 5th centile were, respectively, 51%, 70%, 1.71 and 0.69 for CAO-1 and 41%, 70%, 1.39 and 0.83 for CAO-2. After addition of ACGV < 10th centile to the model, the respective values were 82%, 46%, 1.54 and 0.38 for CAO-1 and 71%, 47%, 1.34 and 0.62 for CAO-2. Using continuous variables, the areas under the ROC curves improved marginally from 0.669 (95% CI, 0.604-0.729) to 0.741 (95% CI, 0.677-0.798) for CAO-1 and from 0.646 (95% CI, 0.580-0.707) to 0.700 (95% CI, 0.633-0.759) for CAO-2 after addition of ACGV to the model. CONCLUSIONS: ACGV is a risk factor for adverse neonatal outcome that is independent of EFW and of CPR, although any improvement in the prediction of adverse outcome is not statistically significant. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Small-for-gestational-age babies after 37 weeks: impact study of risk-stratification protocol.

OBJECTIVE: Although no clear evidence exists, many international guidelines advocate early-term delivery of small-for-gestational-age (SGA) fetuses. The aim of this study was to determine whether a risk-stratification protocol in which low-risk SGA fetuses are managed expectantly beyond 37 weeks affects perinatal and maternal outcomes. METHODS: This was an impact study examining data collected over a 39-month period (1 January 2013 to 30 April 2016) at a tertiary referral unit. The study included women who were referred to the fetal medicine unit with a singleton non-anomalous fetus diagnosed antenatally as SGA (estimated fetal weight < 10th centile) from 36 + 0 weeks' gestation. In 2014, a protocol for management of SGA was introduced, which included risk stratification with surveillance and expectant management after 37 weeks for lower-risk babies (protocol group). This was compared with the previous strategy, which recommended delivery at around 37 weeks (pre-protocol group). Primary outcome was neonatal composite adverse outcome. RESULTS: In the pre-protocol group, there were 138 SGA babies; in the protocol group there were 143. Mean gestational ages at delivery were 37.4 weeks in the pre-protocol group and 38.2 weeks in the protocol group (P = 0.04). The incidence of neonatal composite adverse outcome was lower in the protocol group (9% vs 22%; P < 0.01), as was neonatal unit admission (13% vs 39%; P < 0.01). Induction of labor and Cesarean section rates were lower, and vaginal delivery rate (83% vs 60%; P < 0.01) was higher, in the protocol group. Most of the differences were as a result of delayed delivery of SGA babies that were stratified as low risk. CONCLUSIONS: The findings of this study suggest that protocol-based management of SGA babies may improve outcome, and that identification of moderate SGA should not in isolation prompt delivery. Larger numbers are required to assess any impact on perinatal mortality. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Post-natal outcomes of antenatally diagnosed intra-abdominal cysts: a 22-year single-institution series.

PURPOSE: The aim of this study was to establish the post-natal diagnosis and outcome of antenatally diagnosed intra-abdominal cysts between 1991 and 2013 at our institution. METHODS: All antenatally diagnosed intra-abdominal cysts between 1991 and 2013 were identified using a foetal anomaly database. The cysts were monitored for resolution. In all cases where the cyst had not resolved antenatally, additional post-natal scans were conducted. Antenatal diagnosis, post-natal diagnosis and outcomes were also recorded. RESULTS: 118 cases of antenatal intra-abdominal cysts were identified over the 22-year study period with a 98 % live birth rate. The overall accuracy of an antenatal diagnosis at our institution was 92 %. 26 cases (22 %) resolved spontaneously in utero, the majority of which (77 %) were ovarian in nature. Four tumour cases were identified in the series, which included two neuroblastomas, one yolk sac tumour and one teratoma. 90 cysts persisted post-natally with 52 % requiring surgery. These primarily included choledochal and enteric duplication cysts as well as symptomatic solid organ cysts. Diagnostic revision was limited to 8 % of cases over the study period with an overall improvement over the last decade. Overall, 40 % of all antenatally diagnosed cysts required surgical intervention. In those cysts that persisted post-natally, 52 % required surgery. CONCLUSIONS: A fifth of prenatally diagnosed intra-abdominal cysts will resolve with most ovarian cysts regressing in utero. Half of all persistent cysts will, however, require surgical intervention. These data are useful for prenatal counselling and demonstrates the important role played by the paediatric surgeon in the overall management of intra-abdominal cysts.

Elsevier Trophoblast Research Award Lecture: Searching for an early pregnancy 3-D morphometric ultrasound marker to predict fetal growth restriction.

Fetal growth restriction (FGR) is a major cause of perinatal morbidity and mortality, even in term babies. An effective screening test to identify pregnancies at risk of FGR, leading to increased antenatal surveillance with timely delivery, could decrease perinatal mortality and morbidity. Placental volume, measured with commercially available packages and a novel, semi-automated technique, has been shown to predict small for gestational age babies. Placental morphology measured in 2-D in the second trimester and ex-vivo post delivery, correlates with FGR. This has also been investigated using 2-D estimates of diameter and site of cord insertion obtained using the Virtual Organ Computer-aided AnaLysis (VOCAL) software. Data is presented describing a pilot study of a novel 3-D method for defining compactness of placental shape. We prospectively recruited women with a singleton pregnancy and BMI of <35. A 3-D ultrasound scan was performed between 11 and 13 + 6 weeks' gestation. The placental volume, total placental surface area and the area of the utero-placental interface were calculated using our validated technique. From these we generated dimensionless indices including sphericity (ψ), standardised placental volume (sPlaV) and standardised functional area (sFA) using Buckingham π theorem. The marker for FGR used was small for gestational age, defined as <10th customised birth weight centile (cSGA). Regression analysis examined which of the morphometric indices were independent predictors of cSGA. Data were collected for 143 women, 20 had cSGA babies. Only sPlaV and sFA were significantly correlated to birth weight (p < 0.001). Regression demonstrated all dimensionless indices were inter-dependent co-factors. ROC curves showed no advantage for using sFA over the simpler sPlaV. The generated placental indices are not independent of placental volume this early in gestation. It is hoped that another placental ultrasound marker based on vascularity can improve the prediction of FGR offered by a model based on placental volume.

Developmental changes in spiral artery blood flow in the human placenta observed with colour Doppler ultrasonography.

OBJECTIVES: Our current knowledge of the physiological dilatation of spiral arteries in pregnancy, is based on histology. Real-time ultrasound visualisation of these changes may aid understanding of abnormal placentation. This study aimed to investigate if changes in the spiral artery blood flow can be followed 'in vivo' and explore the novel phenomenon of the larger 'mega-jets'. METHODS: Colour Doppler ultrasonography was used to identify the most prominent jets at blood from the spiral artery into the intervillous space. Their velocity, width and length were recorded seven set time points during pregnancy. RESULTS: Fifty two uncomplicated, term normotensive pregnancies were studied. Width and length of the jets' Doppler signals increased with gestation, the velocity decreased. The length of the jets shows a bi-modal frequency distribution. The width of the signals of longer ('mega') jets was significantly greater (p = 0.001) than that of the jets (mean 4.3 mm (3.1-5.9) versus 3.8 mm (1.8-5.8) respectively) at 34 weeks. However, there was no significant difference in the peak systolic velocity (p = 0.2). CONCLUSION: This study confirms that ultrasound can be used to study the gestation dependent changes in the haemodynamics of the placental basal plate predicted, but not proven, by histologic data. The bi-modal distribution of jet lengths suggests that mega-jets are a separate entity to 'normal' jets. That they are significantly wider than 'normal' jets and yet maintain the same velocity of blood flow suggests that they have a greater volume of blood flow. The mechanism for this is hypothesised and their apparent relationship with simple placental lakes discussed.

The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: analysis of 51,519 consecutive validated samples.

OBJECTIVE: To examine the relationship between umbilical cord pH at term and serious neonatal outcomes. DESIGN: Observational cohort study. SETTINGS: Deliveries within the Oxford Radcliffe Hospital NHS Trust between 1991 and 2009. POPULATION: In all, 51,519 singleton, term, nonanomalous live neonates with validated umbilical cord arterial pH values. METHODS: Absolute risks, relative risks with 95% confidence intervals, and numbers needed to harm were calculated for different levels of arterial pH across the entire range. MAIN OUTCOME MEASURES: Neonatal encephalopathy with seizures and/or death, encephalopathy within 24 hours of birth, 5-minute Apgar scores and neonatal unit admission. RESULTS: The median arterial pH was 7.22, interquartile range 7.17-7.27. The absolute risk of an adverse neurological outcome was significantly increased below 7.10 (0.36%) and was lowest between 7.26 and 7.30 (0.16%). Even below 7.00, the risk was only 2.95%. However, more than 75% of neonates with neurological outcomes examined, including seizures within 24 hours of birth, had a pH above 7.10. A small increase in risk was evident at higher pH levels. CONCLUSION: The threshold pH for adverse neurological outcomes is 7.10 and the 'ideal' cord pH is 7.26-7.30. Above 7.00, however, neonatal acidaemia is weakly associated with adverse outcomes. Most neonates with neurological morbidity have normal cord pH values. Other variables must influence adverse outcomes and account for more of these than acidaemia. A better understanding of these is required before intrapartum fetal monitoring can improve.

Inapplicability of fractional moving blood volume technique to standardize Virtual Organ Computer-aided AnaLysis indices for quantified three-dimensional power Doppler.

OBJECTIVE: To determine whether the technique of fractional moving blood volume (FMBV) is applicable to Virtual Organ Computer-aided AnaLysis II (VOCAL II™)-based indices to quantify three-dimensional power Doppler ultrasound (3D-PDU) by investigating the effect of gain level on the indices measured at a possible reference point for standardization. METHODS: Ten women with singleton pregnancy between 33+3 and 37+5 weeks' gestation were recruited. The optimal position for 3D acquisition of cord insertion into the placenta was identified and static 3D-PDU volumes were acquired using consistent machine configurations. Without moving the probe or the participant changing position, successive 3D volumes were stored at -3, -5, -7 and -9 dB and at the individualized sub-noise gain (SNG) level. Volumes were excluded if flash artifact was present, in which case all five volumes were reacquired. Using 4D View software, the cord insertion was magnified and the smallest sphere possible was used to measure vascularization index (VI), flow index (FI) and vascularization flow index (VFI). The associations between VOCAL indices and gain level were assessed using Pearson's correlation coefficient. RESULTS: VOCAL indices for cord insertion correlated poorly with gain level, whether fundamental or relative to SNG level (R(2) = 0.07 and 0.04, respectively). VI was consistently 100% and mean FI and VFI were 99.5 (SD, 0.57), with all values > 97 irrespective of gain level. CONCLUSIONS: Whilst previous work has shown that gain correlates well with placental tissue VOCAL indices, the correlation between gain level and VOCAL indices in an area of 100% vascularity at the cord insertion is poor. Regions of 100% vascularity appear to be artificially assigned a value approaching 100% for all VOCAL indices irrespective of gain level. This precludes using the technique of VOCAL indices from large vessels to standardize power Doppler measurements and the FMBV index is therefore not applicable to image analysis using VOCAL.

Influence of power Doppler gain setting on Virtual Organ Computer-aided AnaLysis indices in vivo: can use of the individual sub-noise gain level optimize information?

OBJECTIVES: To demonstrate the influence of gain setting on the calculated Virtual Organ Computer-aided AnaLysis (VOCAL(™)) three-dimensional (3D) indices and define a point, the sub-noise gain (SNG), at which maximum information is available without noise artifact. METHODS: Pregnant women were recruited at the time of their pregnancy-dating scan. Five identical static 3D power Doppler volumes of the placenta were acquired using identical machine settings apart from altering the power Doppler gain setting. The gain settings included the individualized SNG setting (determined by increasing gain until noise artifact was visible, then reducing it until the artifact just disappeared). The data were analyzed using VOCAL II. Vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were calculated for the same sample at five different power Doppler gain levels. The relationship between the values calculated for the VOCAL indices and the gain value was explored using linear regression analysis. RESULTS: Results from 50 women were analyzed. The percentage difference in VI and VFI from that observed at the SNG level in each woman was significantly linearly related to the gain setting relative to that at the SNG point (VI: r(2) = 0.68, P < 0.0001; VFI: r(2) = 0.72, P < 0.0001), with the values produced for VI and VFI decreasing as the gain was turned down. There was a distinct 'turning point' at the SNG level with linear relationships above and below, but with significantly different gradients (P ≤ 0.001). This relationship was not demonstrated for FI. CONCLUSION: The SNG setting appears to represent each individual's optimum gain level. Using this may improve meaningful comparisons of VI and VFI between patients.

Prenatal diagnosis: types and techniques.

Up to 3% of UK pregnancies will be affected by congenital abnormality. Prenatal diagnosis allows the parents to make informed decisions about their pregnancy, healthcare professionals to optimise the antenatal care and families prepare for the birth of the baby. There are many techniques employed which range from the non-invasive ultrasonography to the highly invasive amniocentesis. This review explores the methods currently available in the UK as well as considering the newer minimally-invasive technologies available including cell-free fetal DNA and pre-implantation genetic diagnosis.

Measurement of spiral artery jets: general principles and differences observed in small-for-gestational-age pregnancies.

OBJECTIVE: To investigate whether the jets of blood from the mouths of the spiral arteries could be measured reliably, as well as their relationship with the uterine artery (UtA) and any differences in small-for-gestational-age (SGA) pregnancies. METHODS: Participants underwent serial ultrasound scans, from 11 weeks' gestation. Pulsatility index (PI) and resistance index (RI) of jets into the intervillous space (IVS) and UtA were recorded at every visit. Intra- and interobserver variability studies were performed. Customized birth weight centiles were calculated and SGA was defined as < 10(th) centile. Linear mixed model analysis was used to allow for the longitudinal nature of the data. RESULTS: Sixty-six women were recruited; 58 remained normotensive and delivered at term. Of these, six women delivered SGA newborns and 52 delivered appropriate-for-gestational-age newborns. All had pulsatile jets until 20 weeks' gestation. The PI and RI of the jets decreased with advancing gestation, following a trend similar to that of the UtAs. There was no correlation between the jets and UtA waveforms when gestational age was controlled for. For intraobserver variability the intraclass correlation coefficient was 0.9. The interobserver study showed no significant difference between the observers. Mixed model analysis demonstrated that PI and RI of jets were different in SGA pregnancies (P < 0.06). This difference was not seen for the UtAs (P = 0.8). CONCLUSION: This technique enables examination of characteristics of the jets of blood flowing from spiral arteries into the IVS. It is both precise and reproducible, with biologically plausible results. Further work is required to assess differences in pregnancies with adverse outcomes.

Abdominal pregnancy: a perfusion confusion?

BACKGROUND: The uteroplacental blood supply is usually portrayed as a 'series' circuit. Differences seen in the uterine artery (UA) waveform in pregnancies destined to develop pre-eclampsia are often attributed to back pressure effects from the downstream flow through the spiral arteries of the placental bed. CASE: A third trimester abdominal pregnancy was successfully delivered by laparotomy at 30 weeks gestation. The UA waveforms of were recorded at 27 weeks. Both were 'normal' for the gestation, despite limited blood supply from the right uterine and the left not supplying the placenta at all. CONCLUSION: In the absence of pre-eclampsia, UAs can convert to a 'low resistance' waveform even when not directly connected to the placental bed. This case report adds to the evidence against the 'cause and effect' mechanism often used to explain the correlation between trophoblastic invasion and the UA waveform. Both may independently develop in response to a common underlying mechanism.

Neonatal survival of prenatally diagnosed exomphalos.

PURPOSE: Exomphalos is a midline defect, with a viable sac composed of amnion and peritoneum containing herniated abdominal contents with an incidence of about 1 in 4,000 live births. Associated major abnormalities can be karyotypic, syndromic or structural in up to 70% of cases. The aim of this study is to determine the factors that influence survival of antenatally diagnosed exomphalos. METHODS: All antenatally diagnosed and postnatally confirmed exomphalos registered with our fetal medicine unit, during 2002-2007, were reviewed. Both prenatal and postnatal outcomes were analysed. RESULTS: Of 88 cases identified with exomphalos, 85 were prenatally diagnosed. Fifty-five of them died in utero (45 terminations, 5 spontaneous abortions and 5 still births). There were 33 live births (37.5%), 7 of which were premature (30-35/40 gestation). Five babies died before coming to surgery (all with major exomphalos as well as abnormal karyotype) while 28 were operated upon. Fourteen cases with minor exomphalos, all isolated, were primarily closed and all survived to discharge. Of 14 babies with major exomphalos, 4 were closed primarily. Nine required silo formation and six successfully underwent secondary closure (one of which had a prenatal diagnosis of giant ruptured exomphalos). Three died before closure, two from sepsis and multi-organ failure, and one from an undiagnosed tracheo-oesophalgeal cleft. All three deaths had antenatally diagnosed giant ruptured exomphalos and were less than 34/40 weeks gestation. One baby was managed conservatively with antiseptic solution applied to the sac and left to heal by secondary intention. There were 17 cases of isolated exomphalos (with no other structural abnormalities), all of which survived. CONCLUSION: Antenatal diagnosis of exomphalos is 96% sensitive. Severe karyotypic and structural abnormalities were present in all intra-uterine and early postnatal deaths. Overall survival to discharge was 28%. Both minor and isolated exomphalos carried a good prognosis. Isolated exomphalos was a better prognostic factor than severity of the exomphalos itself. Ruptured giant exomphalos were associated with a poorer outcome especially in premature babies.