Best Practice & Research Clinical Obstetrics & Gynaecology

Aims and Scope/Editorial Board

2009-12-01

IUGR: a contemporary review

Samina Mahsud-Dornan, James C. Dornan — 2009-09-02

Intrauterine growth restriction (IUGR) is associated with increased perinatal mortality and morbidity. When diagnosed antenatally in the third trimester in the developed world, the baby rarely dies. Although we may deliver too early at times, we rarely deliver too late. However, significant mortality is caused by ‘unexplained’ stillbirths, many of whom are small for gestational age, suggesting that we should consider re-classifying them as ‘unpredicted’ stillbirth, thereby significantly shifting the emphasis on potential prediction to the antenatal period, rather than leaving it as a post-partum diagnosis. Stillbirth brings tragedy for all concerned, and is often poignantly associated with the findings of a morphologically normal baby in an otherwise healthy pregnancy. So near, yet so far.

Intrauterine growth restriction: new standards for assessing adverse outcome

Jason Gardosi — 2009-10-09

The study of associations between intrauterine growth restriction (IUGR) and adverse outcome benefits from the use of a birthweight standard which is based on customised growth potential. Its application is able to retrospectively quantify the strength of the link with IUGR, whether fetal growth problems were identified antenatally or not. Furthermore, growth failure hitherto unrecognised by conventional standards, such as the average size but relatively small babies of mothers with high body mass index, identify IUGR as a cause of the increased perinatal mortality risk in obese pregnancies. Fetal growth restriction is found to be a frequent antecedent of perinatal morbidity and mortality, pointing to the need to improve its timely antenatal detection as a mainstay of management and prevention.

Pathological assessment of intrauterine growth restriction

Phillip Cox, Tamas Marton — 2009-07-06

Intrauterine growth restriction (IUGR) is a major cause of foetal and neonatal morbidity and mortality. During post mortem, the pathologist is well placed to diagnose the presence and cause of IUGR in a stillborn baby. This article describes the approach of the pathologist in diagnosing IUGR and some of the pitfalls. We distinguish between reduced growth potential (formerly symmetrical IUGR) and nutritional IUGR (formerly asymmetrical IUGR). Aetiologically, restricted growth can be of foetal, maternal and placental origin. We discuss the importance of identifying the cause of IUGR in a clinicopathological context and the pathological findings in some of the more frequent causes of IUGR presenting at post mortem.Based on an accurate gestational age, ideally determined by the obstetrician in early pregnancy, the pathologist can derive a birth weight centile. However, the pathologist is also able to identify other indicators of IUGR, such as an elevated brain/liver weight ratio, atrophic thymus and changes in other internal organs.Placental examination plays a major role in the investigation as the majority of IUGR cases have significant placental pathology. This includes pre-eclampsia-related changes, abnormalities of the villous parenchyma and pathology of the umbilical cord.The potential benefit of a meticulous workup of IUGR foetuses is to provide an explanation of the pathological condition and to identify avoidable causes.

Aetiology and Pathogenesis of IUGR

Srividhya Sankaran, Phillipa M. Kyle — 2009-07-13

Intrauterine growth restriction (IUGR) is a major cause of perinatal mortality and morbidity. A complex and dynamic interaction of maternal, placental and fetal environment is involved in ensuring normal fetal growth. An imbalance or lack of coordination in this complex system may lead to IUGR. Animal studies have given us an insight into some aspects of the basic pathophysiology of IUGR, and recent technologies such as Doppler studies of maternal and fetal vessels have added further information. The aetiologies of IUGR are diverse, involving multiple complex mechanisms, which make understanding of the pathophysiology difficult. However, particular focus is placed on the mechanisms involved in uteroplacental insufficiency as a cause of IUGR, as (1) it is common, (2) outcome can be good if timing of delivery is optimal and (3) it may be amenable to therapy in the future. While the research into the pathophysiology of IUGR continues, there have been interesting discoveries related to the genetic contribution to IUGR and the intrauterine programming of adult-onset diseases attributed to IUGR.

Risk factors for small for gestational age infants

Lesley McCowan, Richard P. Horgan — 2009-07-01

There are many established risk factors for babies who are small for gestational age (SGA) by population birth weight centiles (usually defined as <10th centile). The confirmed maternal risk factors include short stature, low weight, Indian or Asian ethnicity, nulliparity, mother born SGA, cigarette smoking and cocaine use. Maternal medical history of: chronic hypertension, renal disease, anti-phospholipid syndrome and malaria are associated with increased SGA. Risk factors developing in pregnancy include heavy bleeding in early pregnancy, placental abruption, pre-eclampsia and gestational hypertension.A short or very long inter-pregnancy interval, previous SGA infant or previous stillbirth are also risk factors. Paternal factors including changed paternity, short stature and father born SGA also contribute.Factors associated with reduced risk of SGA or increased birth weight include high maternal milk consumption and high intakes of green leafy vegetables and fruit.Future studies need to investigate risk factors for babies SGA by customised centiles as these babies have greater morbidity and mortality than babies defined as SGA by population centiles.

The prevention and treatment of intrauterine growth restriction

Rosalie Grivell, Jodie Dodd, Jeffrey Robinson — 2009-07-06

Foetal growth restriction is an important and often under-diagnosed complication of pregnancy with important implications for maternal, infant, child and later health. The key to prevention of foetal growth restriction is the recognition of those women at risk and implementation of effective interventions. Ideally, all women should plan pregnancy, providing an opportunity for lifestyle change, reduction of risk factors and optimisation of medical conditions. Failing adequate preconception care, antenatal care should include an assessment of risk factors in early pregnancy, so appropriate interventions may be instituted. Effective interventions are available for women with HIV and also those living in malaria-endemic areas. Antiplatelet agents reduce the risk of pre-eclampsia and small-for-gestational age (SGA) babies in women at risk. Intrauterine treatments offer limited benefit to the baby with foetal growth restriction. The key to management is likely to be optimising the conditions of delivery and minimising neonatal morbidity as much as possible.

Fetal growth screening by fundal height measurement

Kate Morse, Amanda Williams, Jason Gardosi — 2009-10-12

Fundal height assessment is an inexpensive method for screening for fetal growth restriction. It has had mixed results in the literature, which is likely to be because of a wide variety of methods used. A standardised protocol of measurement by tape and plotting on customised charts is presented, which in routine practice has shown to be able to significantly increase detection rates, while reducing unnecessary referral for further investigation. Fundal height measurement needs to be part of a comprehensive protocol and care pathway, which includes serial assessment, referral for ultrasound biometry and additional investigation by Doppler as required.

Biometric assessment

Torvid Kiserud, Synnøve Lian Johnsen — 2009-07-08

Ultrasound is used to assess foetal age, foetal weight and growth. The error of such measurements is considerable, but the technique of averaging repeat measurements restricts random error. The use of customised foetal weight charts, that is, adjusting for ethnicity and maternal and foetal factors helps in classifying foetal weight appropriately. Commonly used cross-sectional reference ranges are useful for the foetal weight assessment at any stage of pregnancy, but not for foetal growth. Growth assessment requires serial measurements and longitudinal reference ranges, which provide conditional terms for individual foetuses. That is, an initial measurement is used for calculating individual ranges for the rest of pregnancy. Compared to the ranges for the entire population, the conditional ranges for a small foetus are narrower and skewed in the direction of the initial measurement. Quality control is recommended to ensure that such methods work when applied to the local population.

Detection of foetal growth restriction using third trimester ultrasound

Leanne Bricker, Samina Mahsud-Dornan, James C. Dornan — 2009-09-01

Foetal growth restriction is an important contributor to perinatal mortality, being responsible for up to 50% of stillbirths. Optimal prevention and accurate detection enabling timely intervention remain elusive, particularly in presumed low-risk pregnancy. Third trimester ultrasound seems a logical solution, but systematic review of evidence from randomised trials has shown that third trimester ultrasound does not have a significant impact on perinatal mortality but may increase interventions such as caesarean delivery. However, the evidence is difficult to interpret in the context of current obstetric practice as the evolution of ultrasound technology and rapid assimilation of newer techniques has resulted in questionable validity of the findings. If third trimester ultrasound were introduced routinely, there is a need to decide the optimal timing and number of examinations and what ultrasound parameters should be used to identify the foetus at risk.

The role of Doppler and placental screening

Rogelio Cruz-Martinez, Francesc Figueras — 2009-09-03

Placental-associated diseases account for most cases of adverse perinatal outcome in developing countries. Uterine Doppler evaluation predicts most instances of early-onset preeclampsia and intrauterine growth restriction, but there is no evidence in favour of any prophylactic strategy in cases of an abnormal screening result. Umbilical artery Doppler investigation allows identifying those small-for-gestational-age foetuses at higher risk, and its use in these pregnancies improves a number of perinatal outcomes. Middle cerebral artery Doppler investigation reflects brain redistribution, and its use in combination with the umbilical artery in a cerebroplacental ratio seems to improve prediction of adverse outcome, mainly in near-term pregnancies, where most instances of adverse outcome occur in foetuses with normal umbilical artery. Ductus venosus Doppler waveform is a surrogate parameter of the foetal acid–base status. However, the benefits of its use in the management of early-onset growth restriction needs further evidence.

Obstetric management of intrauterine growth restriction

Karel Maršál — 2009-10-09

The aim of obstetric management is to identify growth-restricted foetuses at risk of severe intrauterine hypoxia, to monitor their health and to deliver when the adverse outcome is imminent. After 30–32 gestational weeks, a Doppler finding of absent or reverse end-diastolic flow in the umbilical artery of a small-for-gestational age foetus is in itself an indication for delivery. In very preterm foetuses, the intrauterine risks have to be balanced against the risk of prematurity. All available diagnostic information (e.g., Doppler velocimetry of umbilical artery, foetal central arteries and veins and of maternal uterine arteries; foetal heart rate with computerised analysis of short-term variability; amniotic fluid amount; and foetal gestational age-related weight) should be collected to support the timing of delivery. If possible, the delivery should optimally take place before the onset of late signs of foetal hypoxia (pathological foetal heart rate pattern, severely abnormal ductus venosus blood velocity waveform, pulsations in the umbilical vein).

Neonatal management and long-term sequelae

Henry L. Halliday — 2009-06-29

Intrauterine or fetal growth restriction is best defined by using customised birth weight percentiles based upon the growth potential for an individual infant. Growth restriction in utero may be classified as asymmetric or symmetric depending upon the duration of the process. Asymmetric growth restriction is caused by placental insufficiency, maternal hypertensive conditions, long-standing maternal diabetes, smoking, living at altitude or multiple gestation. Symmetric growth restriction may be due to congenital infections, chromosomal or other abnormalities, fetal alcohol syndrome, low socioeconomic status or be constitutional. The underlying cause of growth restriction often predicts the potential adverse effects on the foetus and newborn and later effects in childhood and adulthood. With placental insufficiency, there may be chronic or acute on chronic fetal hypoxia with birth asphyxia and hypothermia, neonatal hypoglycaemia, polycythaemia and coagulopathy. Management is directed at prevention or early treatment of these conditions. In contrast, symmetrically growth-restricted infants should be examined carefully to look for congenital infections and malformations that may need specific interventions. Infants with constitutional short stature generally do not need any specific management. Feeding of growth-restricted infants is important to overcome deficiencies incurred in utero. Most infants show catch-up growth although about 10% do not. Those with excessive catch-up growth may be at greatest risk of developing insulin resistance in adulthood leading to diabetes, obesity and heart disease. The so-called fetal origins of disease may actually have a postnatal onset related more to excessive weight gain in infancy. There is still controversy over the indications for growth hormone treatment in growth-restricted infants who remain of short stature in early childhood. Intrauterine growth restriction is also associated with a five- to seven-fold increased risk of cerebral palsy probably due to chronic placental insufficiency.

Index

2009-12-01

Intrauterine Growth Restriction: A Contemporary Review Multiple Choice Questions for Vol. 23, No. 6

2009-12-01

Regarding the role of umbilical artery Doppler in the management of intrauterine growth restriction, which answers are true:

Acute Gynaecology Volume 2: Infection, uterine and ovarian pathology Answers to Multiple Choice Questions for Vol. 23, No. 5

2009-12-01

1.a) Fb) Fc) Fd) Te) T Explanations: