• Zelop C, Fleischer AC, Andreotti RF, Angtuaco TL, Horrow MM, Lee S, Javitt MC, Lev-Toaff AS, Scoutt LM, Expert Panel on Women's Imaging. Growth disturbance--risk of intrauterine growth restriction. [online publication]. Reston (VA): American College of Radiology (ACR); 2007. 10 p. [23 references]

This is the current release of the guideline.

This guideline updates a previous version: Zelop C, Fleischer AC, Andreotti RF, Bohm-Velez M, Horrow MM, Hricak H, Javitt MC, Thurmond A, Expert Panel on Women's Imaging. Growth disturbances: risk of intrauterine growth restriction. [online publication]. Reston (VA): American College of Radiology (ACR); 2005. 10 p. [20 references]

The appropriateness criteria are reviewed annually and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

ACR Appropriateness Criteria®

Clinical Condition: Growth Disturbances–Risk of Intrauterine Growth Restriction (IUGR)

Variant 1: Risk of IUGR justifies evaluation.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 2: Risk of IUGR: initial evaluation.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 3: Small fetus, low or low normal fluid, follow-up studies.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 4: Very small fetus, normal fluid, follow-up studies.

Variant 5: Normal sized fetus, low or absent fluid, follow-up studies.

Summary of Literature Review

Intrauterine growth restriction (IUGR) is an important complication of pregnancy. It can be associated with significant risks of perinatal morbidity and mortality. One of the primary mechanisms of IUGR is uteroplacental insufficiency, which may occur in a variety of maternal or placental conditions. The major concern in IUGR is not the small size of the fetus, per se, but the possibility of life-threatening fetal compromise.

When clinically suspected, IUGR can be confirmed as probably present by sonographic fetal measurements and weight estimation, but both false-negative and false-positive cases can be anticipated. Findings that should prompt an ultrasound (US) examination include: maternal size smaller than dates or otherwise anticipated from a prior US, poor maternal weight gain, maternal hypertension, or pre-eclampsia. Other maternal conditions such as lupus erythematosus or a history of previous birth of a growth-restricted infant may also warrant evaluation. The greater the risk of IUGR based on the clinical findings, the greater is the positive predictive value of US, but the likelihood of IUGR also increases even when US predicts a normal weight. Estimated fetal weight and abdominal circumference are equivalently better than the ration between femur length and abdominal circumference in predicting IUGR, and biometry performed within 2 weeks of delivery is more predictive than when performed at 26–34 weeks. One study found that among small-for-gestational-age (SGA) fetuses with no anatomic abnormalities, only those that were asymmetric (abdomen small in proportion to head) were associated with increased pregnancy-induced maternal hypertension before 32 weeks and cesarean delivery for abnormal heart rate patterns when compared with those of fetuses average for gestational age (AGA). Additionally, asymmetric SGA fetuses sustained higher adverse neonatal composite outcomes compared to symmetric SGA or AGA fetuses.

Once a probability of IUGR has been established, and uteroplacental insufficiency is considered to be a likely mechanism based on US findings and clinical setting, there are a series of possible therapeutic interventions that can be used to improve fetal growth and prevent the development of fetal compromise. Assessment of fetal well-being is essential to the management of such pregnancies. This testing is aimed at determining if there is life-threatening fetal compromise, and whether urgent premature delivery offers a better chance at survival and avoidance of morbidity than does continued exposure to an increasingly hostile intrauterine environment.

Periodic fetal biometry, evaluation of amniotic fluid volume, use of the BPP or a selected subset of its component tests, Doppler ultrasound, fetal heart rate monitoring, and fetal movement counting can all contribute to the determination of fetal compensation or compromise. It is beyond the scope of this guideline to compare these methods and rate the relative effectiveness of the many individual parameters testable alone or in various combinations. Instead, the guideline ranks the relative utility of these broad categories of fetal assessment once a risk of IUGR and potential fetal compromise has been established.

The biophysical profile has been and remains the mainstay of fetal well-being evaluation. It consists of four parameters variably sensitive to the acute exposure of the fetus to hypoxemia: fetal breathing movements, fetal limb and body movement, fetal tone, and amniotic fluid volume as an indicator of chronic hypoxemia. The nonstress test (NST), which is sometimes included with the BPP as a fifth component, can be used alone as a test of acute status, but it is often coupled with amniotic fluid measurement, a valuable reflection of fetal hypoxemic exposure over the previous week. Alternatively, the four sonographic BPP components can be used without the NST. Scores of 8 to 10 on the BPP are strong indicators of a well-compensated fetus, but there are many false-positives when the fetus fails one or two of the acute marker tests. Reduced amniotic fluid volume is an important predictor of intrapartum fetal distress, much of which is attributable to umbilical cord compression events, and the fluid should be periodically checked in pregnancies suspected to have IUGR. Testing strategies usually evaluate one or more of the acute status parameters at least weekly, and often twice weekly, from the point of potential postnatal viability onward. Amniotic fluid is usually assessed weekly, but more often if it is approaching severely low levels. Daily or even more frequent testing by BPP or NST may be indicated in critical situations.

Extensive research on Doppler analysis of uterine, umbilical, and various intrafetal vessels confirms a strong correlation between high-resistance arterial wave form patterns (e.g., low, absent, or reversed diastolic flow in the umbilical artery) and subsequent IUGR, hypoxemic fetal morbidity, and mortality. The correlation is greatest in high-risk pregnancies but insufficiently predictive in general, low-risk populations to be useful as a primary screening test.

Some have argued that since Doppler appears to be applicable primarily in a population already defined as high risk, the clinical decisions as to when a fetus is compromised and requires emergent delivery will be based on the BPP and heart-rate monitoring, making the Doppler superfluous. A recently published meta-analysis of 20 controlled trials of Doppler ultrasonography, however, found "compelling evidence" that knowledge of the Doppler findings improved perinatal outcome in high-risk pregnancies, reducing antenatal admissions, inductions of labor, and cesarean sections for fetal distress, and reducing the odds of perinatal death by 38%.

Studies correlating Doppler findings with the BPP, amniotic fluid volume, NST, US fetal weight estimates, and maternal blood pressure have shown that predictabilities of IUGR and fetal compromise are, to some extent, additive. Doppler waveform abnormalities may precede clinical recognition of less-than-expected abdominal enlargement, with abnormal BPP an even later finding. A review by one group of investigators summarizes many of these concepts about the sonographic assessment of IUGR. Another group found that decreased amniotic fluid and abnormal umbilical cord arterial Doppler waveforms were independent predictors of poor neonatal outcomes. A retrospective study by another group found that SGA singleton pregnancies with abnormal umbilical artery blood flow patterns had higher cesarean section rates for fetal nonreassuring status, increased neonatal intensive care unit stays, and increased neonatal morbidity. Those SGA fetuses with normal umbilical Doppler patterns were unassociated with these complications, suggesting that these were constitutionally small babies rather than being growth-restricted. In addition to arterial Doppler, the fetal venous system can also be interrogated as a surrogate for forward cardiac blood flow. In a recent study of fetuses with early-onset placental dysfunction, another group demonstrated that ductus venous Doppler parameters emerge as the primary cardiovascular factor in predicting neonatal outcome.

An additional test of value in IUGR and other high-risk pregnancies is daily (or even more frequent) fetal movement counting by the mother. Frequent and vigorous fetal movements are evidence of well-being, providing reassurance to the mother, while diminishing fetal activity can provide an early warning of a deteriorating fetal status. The testing is easy and inexpensive but provides benefit in addition to the formal fetal surveillance protocols.

The specific variant conditions included in this Appropriateness Criteria require several additional comments.

A fetus small for dates compared with an earlier US study in which amniotic fluid volume was low or low normal, is the typical setting in which uteroplacental insufficiency is the most likely mechanism for IUGR. Repeat US for biometry is indicated, with the frequency adjusted by the severity of the growth restriction and the gestational age. Mild growth lag prior to 28 to 30 weeks can be remeasured in 4 weeks, while severe IUGR after 33 weeks may be best remeasured in 2 weeks. Some formal testing protocol for fetal well-being should be initiated on a weekly or twice-weekly schedule. Daily fetal movement counts are indicated.

IUGR caused by uteroplacental insufficiency is unusual when a normal amniotic fluid volume is present with a small or very small fetus. A first consideration should be the possibility of inaccurate dating of the pregnancy. This can be confirmed by follow-up US biometry that demonstrates appropriate interval growth of the fetal measurement parameters for the number of weeks intervening between the first and second examination. With a symmetrically very small fetus for dates, however, particularly if detected in the second or even first trimester the possibility of aneuploidy, especially trisomy 18, trisomy 13, and triploidy, must be considered. Needless to say, the presence of fetal anomalies will raise the concern for chromosomal abnormality considerably. Diagnosis is generally accomplished by amniocentesis, but if a rapid karyotype is needed (e.g., to avoid a cesarean section for fetal compromise of a fetus with a lethal condition) cordocentesis or placental biopsy can often provide an answer in 48 to 72 hours.

When there is low or absent amniotic fluid with a normally grown fetus, causes of oligohydramnios other than IUGR must be considered. These include obstruction or nonfunction of the fetal urinary tract, premature rupture of membranes, and tocolysis of preterm labor by nonsteriodals. Regardless of its etiology, oligohydramnios is an important risk factor for perinatal morbidity and mortality, due largely to umbilical cord compression but also, in cases of early and long-standing oligohydramnios, to the possible occurrence of pulmonary hypoplasia. Close monitoring of fetal condition is indicated along with periodic imaging evaluation of the fetus to check growth and chest configuration for degree of lung compression.

In summary, intrauterine growth restriction, with its inherent risks of fetal morbidity and mortality from the hypoxemia of inadequate uteroplacental function, must be considered a major abnormality of pregnancy. When it is suspected on the basis of clinical and sonographic findings, urgent management decisions may be necessary, including the possibility of emergent preterm delivery. A protocol of frequent fetal surveillance is indicated to guide patient management and the timing of delivery.

Abbreviations

• BPP, biophysical profile
• IUGR, intrauterine growth restriction
• LMP, last menstrual period
• US, ultrasound

An algorithm for growth disturbances/growth restriction is provided in Appendix II of the original guideline document.

The recommendations are based on analysis of the current literature and expert panel consensus.

• Zelop C, Fleischer AC, Andreotti RF, Angtuaco TL, Horrow MM, Lee S, Javitt MC, Lev-Toaff AS, Scoutt LM, Expert Panel on Women's Imaging. Growth disturbance--risk of intrauterine growth restriction. [online publication]. Reston (VA): American College of Radiology (ACR); 2007. 10 p. [23 references]

Not applicable: The guideline was not adapted from another source.

1996 (revised 2007)

American College of Radiology - Medical Specialty Society

The American College of Radiology (ACR) provided the funding and the resources for these ACR Appropriateness Criteria®.

Committee on Appropriateness Criteria, Expert Panel on Women's Imaging

Panel Members: Carolyn Zelop, MD; Arthur C. Fleischer, MD; Rochelle F. Andreotti, MD; Teresita L. Angtuaco, MD; Mindy M. Horrow, MD; Susanna In-Sun Lee, MD, PhD; Marcia C. Javitt, MD; Anna S. Lev-Toaff, MD; Leslie M. Scoutt, MD

Not stated

This is the current release of the guideline.

This guideline updates a previous version: Zelop C, Fleischer AC, Andreotti RF, Bohm-Velez M, Horrow MM, Hricak H, Javitt MC, Thurmond A, Expert Panel on Women's Imaging. Growth disturbances: risk of intrauterine growth restriction. [online publication]. Reston (VA): American College of Radiology (ACR); 2005. 10 p. [20 references]

The appropriateness criteria are reviewed annually and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

None available

This summary was completed by ECRI on June 28, 2002. The information was verified by the guideline developer on October 1, 2002. This summary was updated on March 24, 2006. This NGC summary was updated by ECRI Institute on December 14, 2007.