THESE INDIVIDUALS HAVE A GREATER PREDISPOSITION TO DEVELOP METABOLIC SYNDROME LATER IN LIFE MANIFESTING AS OBESITY, HYPERTENSION, HYPERCHOLESTEROLEMIA, CARDIOVASCULAR DISEASE & TYPE-2 DIABETES.
Once IUGR has been detected, the management of the pregnancy should depend on a surveillance plan that maximizes gestational age while minimizing the risks of neonatal morbidity and mortality. This should include steroid administration when at all feasible, based on the monitoring and delivery strategies discussed below (see Image 2 and Harman and Baschat's integrated fetal testing for IUGR). Fetal lung maturity studies by amniocentesis, in fetuses greater than 34 weeks', may additionally influence delivery timing.
The goal in the management of IUGR, because no effective treatments are known, is to deliver the most mature fetus in the best physiological condition possible while minimizing the risk to the mother. Such a goal requires the use of antenatal testing with the hope of identifying the fetus with IUGR before it becomes acidotic. Developing a testing scheme, following it, and having a high index of suspicion in this population when results of testing are abnormal is important. The positive predictive value of an abnormal antenatal test result in fetuses with IUGR is relatively high because the prevalence of acidemia and chronic hypoxemia is relatively high.
The protocol for antenatal testing suggested by Kramer and Weiner (see Image 2) is one example. It relies heavily on the use of UA Doppler testing because severely abnormal Doppler findings (absent or reversed end-diastolic flow) can precede an abnormal fetal heart rate by several weeks. Harman and Baschat suggested a different proposed antenatal testing strategy. This protocol integrates multiple venous and arterial Doppler measurements and the biophysical profile score (BPS); this strategy may be used at institutions where these measurements are routinely obtained by qualified technicians.
Harman and Baschat's integrated fetal testing for IUGR, in increasing order of severity from 1 (least severe) to 5 (most severe), is as follows:
Situation No. 1
Test results β AC less than fifth percentile, low AC growth rate, high ratio of head circumference to AC; BPS greater than or equal to 8 and AFV normal; abnormal UV and/or cerebroplacental ratio; normal MCA
Interpretation β IUGR diagnosed, asphyxia extremely rare, increased risk for intrapartum distress
Recommended management β Intervention for obstetric or maternal factors only, weekly BPS, multivessel Doppler every 2 weeks
Situation No. 2
Test results β IUGR criteria met, BPS greater than or equal to 8, AFV normal, UA with absent or reversed end-diastolic velocities, decreased MCA
Interpretation β IUGR with brain sparing, hypoxemia possible and asphyxia rare, at risk for intrapartum distress
Recommended management β Intervention for obstetric or maternal factors only; BPS 3 times a week; weekly UA, MCA, and venous Doppler
Situation No. 3
Test results β IUGR with low MCA PI; oligohydramnios; BPS greater than or equal to 6; normal IVC, DV, and UV flow
Interpretation β IUGR with significant brain sparing, onset of fetal compromise, hypoxemia common, acidemia/asphyxia possible
Recommended management β If at more than 34 weeks' gestation, deliver (route determined by obstetric factors). If at less than 34 weeks' gestation, administer steroids to achieve lung maturity and repeat all testing in 24 hours.
Situation No. 4
Test results β IUGR with brain sparing, oligohydramnios, BPS greater than or equal to 6, increased IVC and DV indices, UV flow normal
Interpretation β IUGR with brain sparing, proven fetal compromise, hypoxemia common, acidemia/asphyxia likely
Recommended management β If at more than 34 weeks' gestation, deliver (route determined by obstetric factors and oxytocin challenge test [OCT] results). If at less than 34 weeks' gestation, individualize treatment with admission, continuous cardiotocography, steroids, maternal oxygen, and/or amnioinfusion and then repeat all testing up to 3 times a day depending on status.
Situation No. 5
Test results β IUGR with accelerating compromise, BPS less than or equal to 6, abnormal IVC and DV indices, pulsatile UV flow
Interpretation β IUGR with decompensation, cardiovascular instability, hypoxemia certain, acidemia/asphyxia common, high perinatal mortality, death imminent
Recommended management β If fetus is considered viable by size, deliver as soon as possible at tertiary center. Route determined by obstetric factors and OCT results. Fetus requires highest level of natal ICU care.
The diagnosis of severe IUGR before 32 weeks' gestation is associated with a poor prognosis, and therapy must be highly individualized. Once a decision has been made to effect delivery, the mode of delivery is governed by evidence of acidemia, gestational age, and Bishop score. Cesarean delivery without a trial of labor is appropriate (1) in the presence of evidence of fetal distress by nonstress testing or reversed diastolic flow or (2) for traditional obstetrical indications for cesarean delivery (ie, malpresentation, prior cesarean delivery).
Li et al investigated the success rate of induction of labor in IUGR fetuses with and without UA blood flow changes and the neonatal outcomes of induced fetuses with a negative result after an OCT. They found that fetuses with abnormal (but not absent or reversed) UA blood flow who had a normal OCT result had similar success in induction of labor, without indications of detrimental fetal hypoxia or distress. This suggests that in fetuses with altered UA blood flow, an OCT may be appropriate to select fetuses that will tolerate labor induction.
When a trial of labor is undertaken, continuous heart rate monitoring with maternal left lateral decubitus positioning should optimize the success of the induction. Recent literature by Siristatidis et al suggests that fetal pulse oximetry is reassuring of fetal well-being when the oxygen saturation as measured using pulse oximetry is greater than 35% and may provide clinicians with additional options for management in labor.
FUTURE DIRECTIONS - PREVENTION :
Prevention of IUGR is highly desirable, and several studies have addressed this potential. Investigators have looked at altering the thromboxane-to-prostacyclin ratio by administering aspirin with or without dipyridamole to mothers of fetuses with IUGR. The studies examining these agents for prevention of IUGR are difficult to compare. Different doses of aspirin, different times of administration in pregnancy, and different indications for use make comparisons difficult; however, the following is a summary of the studies:
Wallenburg et al studied a population of women at high risk for IUGR in a nonrandomized trial using historic controls. They noted a decline in the rate of IUGR from 61.5% in the historic controls to 13.3% in those treated with aspirin and dipyridamole.
Despite the theoretical benefit of aspirin in many studies, the role of aspirin, if any, in the prevention of IUGR is still unclear. A large randomized controlled trial using a standardized high-risk population with a standardized treatment regimen could serve to better answer this question.
CONCLUSION : IUGR remains a challenging problem for clinicians. Most cases of IUGR occur in pregnancies in which no risk factors are present; therefore, the clinician must be alert to the possibility of a growth disturbance in all pregnancies. No single measurement helps secure the diagnosis; thus, a complex strategy for diagnosis and assessment is necessary. The ability to diagnose the disorder and understand its pathophysiology still outpaces the ability to prevent or treat its complications. The current therapeutic goals are to optimize the timing of delivery to minimize hypoxemia and maximize gestational age and maternal outcome. Further study may elucidate preventive or treatment strategies to assist the growth-restricted fetus.