Browsing by Author "Van der Merwe, Elrike"
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- ItemThe incidence and clinical characteristics of placental insufficiency among high-risk pregnancies with normal umbilical artery resistance index after 32 weeks gestation : a cross-sectional study(Stellenbosch : Stellenbosch University, 2015-12) Van der Merwe, Elrike; Geerts, L. T. G. M.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Obstetrics and Gynaecology.ENGLISH ABSTRACT: Introduction: Intrauterine fetal growth restriction (FGR) due to placental insufficiency (PI) is an important cause of perinatal morbidity and mortality. There is also evidence that FGR is associated with neurodevelopmental delay, as well as the development of insulin resistance, obesity, hypertension and diabetes mellitus type 2 as an adult. It is therefore of the utmost importance to develop surveillance strategies and management protocols to reduce the incidence of FGR or, failing that, improving their outcome. Traditionally fetal wellbeing in suspected SGA was assessed by umbilical artery Doppler (UAD) resistance index (RI) or pulsatility index (PI) and if found to be within the normal range, it was seen as a reassuring sign that no significant placental disease is present. However, studies have shown that the pathophysiology of early- and late onset FGR are different and that late onset placental insufficiency (LOPI) may be present even in the presence of a normal umbilical artery Doppler result. The aim of this prospective study was to determine the incidence of LOPI in high risk women with a normal UA RI and assess which clinical variables are associated with this. Method: The study was a prospective, descriptive study conducted from 11 February 2013 till 21 October 2013 at Tygerberg Hospital (TBH), a secondary and tertiary referral centre in the Western Cape Province, South Africa, responsible for the Eastern half of the Cape Town Metropole and surrounding areas. The study population consisted of all women referred by the clinical (nursing or medical) staff to the Fetal Evaluation Clinic (FEC) or ultrasound unit at TBH for UA RI assessment according the current Western Cape Ultrasound policy. Exclusion criteria included known fetal anomalies, multiple pregnancies and proven pre-eclampsia. Recruited patients received an ultrasound examination by senior staff and the ultrasound data were captured in Astraia© database. Based on the ultrasound data the women were divided into 4 subgroups for comparison. Results: A total of 228 patients were recruited. Eight were excluded from the study for various reasons (incomplete consent (2), no ultrasound data (3), too early GA after redating (2), known LOPI at time of recruitment (1)). In 10 cases fetal anomalies were noted on ultrasound and these were also excluded – 6 of these had evidence of late onset placental insufficiency and 4 were small for gestational age. This left 210 study participants for the final analysis, with 76 classified as likely LOPI (36.2%) and 134 in the non LOPI group (63.8%). The likely LOPI group was equally divided with 38 (18%) patients each in the average for gestational age (AGA) and small for gestational age (SGA) groups. In the normal placenta group the majority of patients (112 (53%)) were AGA with 22 (11%) being SGA. There were no clinically significant differences between the groups when the baseline characteristics, Doppler and non-Doppler findings were compared. Conclusion: LOPI is a condition that affects a significant proportion of our population. This does not only have consequences for the short term pregnancy outcome, but also for the long term outcomes, with regards to neurodevelopment and the development of metabolic diseases. In settings where pregnancy dating is far less accurate than in developed countries and where customised growth charts are not available, it may not be appropriate to base management algorithms on the expected fetal weight (EFW) centile as inaccurate clinical or relatively late ultrasound dating (after 20 weeks) may not have allowed the EFW to drop below the 10th centile for the assumed (and perhaps underestimated) gestation. This study shows that relying on a distinction between AGA and SGA would seriously underestimate the magnitude of the problem of placental pathology and also illustrates the poor sensitivity of traditional clinical risk factors and grey scale ultrasound findings in identifying the pregnancies at risk of LOPI-associated complications. Further studies are needed to assess feasibility and impact of the proposed policy change.