Objective
We sought to provide evidence-based guidelines for utilization of Doppler studies for fetuses with intrauterine growth restriction (IUGR).
Methods
Relevant documents were identified using PubMed (US National Library of Medicine, 1983 through 2011) publications, written in English, which describe the peripartum outcomes of IUGR according to Doppler assessment of umbilical arterial, middle cerebral artery, and ductus venosus. Additionally, the Cochrane Library, organizational guidelines, and studies identified through review of the above were utilized to identify relevant articles. Consistent with US Preventive Task Force suggestions, references were evaluated for quality based on the highest level of evidence, and recommendations were graded.
Results and Recommendations
Summary of randomized and quasirandomized studies indicates that, among high-risk pregnancies with suspected IUGR, the use of umbilical arterial Doppler assessment significantly decreases the likelihood of labor induction, cesarean delivery, and perinatal deaths (1.2% vs 1.7%; relative risk, 0.71; 95% confidence interval, 0.52–0.98). Antepartum surveillance with Doppler of the umbilical artery should be started when the fetus is viable and IUGR is suspected. Although Doppler studies of the ductus venous, middle cerebral artery, and other vessels have some prognostic value for IUGR fetuses, currently there is a lack of randomized trials showing benefit. Thus, Doppler studies of vessels other than the umbilical artery, as part of assessment of fetal well-being in pregnancies complicated by IUGR, should be reserved for research protocols.
Intrauterine growth restriction (IUGR) is defined as sonographic estimated fetal weight <10th percentile for gestational age. According to the American College of Obstetricians and Gynecologists, IUGR is “one the most common and complex problems in modern obstetrics.” This characterization is understandable considering the various published definitions, poor detection rate, limited preventive or treatment options, multiple associated morbidities, and increased likelihood of perinatal mortality associated with IUGR. Suboptimal growth at birth is linked with impaired intellectual performance and diseases such as hypertension and obesity in adulthood.
The quality of evidence for each included article was evaluated according to the categories outlined by the US Preventative Services taskforce:
- I
Properly powered and conducted randomized controlled trial; well-conducted systematic review or metaanalysis of homogeneous randomized controlled trials.
- II-1
Well-designed controlled trial without randomization.
- II-2
Well-designed cohort or case-control analytic study.
- II-3
Multiple time series with or without the intervention; dramatic results from uncontrolled experiments.
- III
Opinions of respected authorities, based on clinical experience; descriptive studies or case reports; reports of expert committees.
Recommendations are graded in the following categories:
Level A
The recommendation is based on good and consistent scientific evidence.
Level B
The recommendation is based on limited or inconsistent scientific evidence.
Level C
The recommendation is based on expert opinion or consensus.
Current challenges in the clinical management of IUGR include accurate diagnosis of the truly growth-restricted fetus, selection of appropriate fetal surveillance, and optimizing the timing of delivery. Despite the potential for a complicated course, antenatal detection of IUGR and its antepartum surveillance can improve outcomes. The purpose of this document is to synthesize and assess the strength of evidence of the current literature regarding the use of Doppler velocimetry of the umbilical artery, middle cerebral artery, and ductus venosus for nonanomalous fetuses with suspected IUGR, and to provide recommendations regarding antepartum management of these pregnancies, in particular for singleton gestations. We acknowledge that defining small for gestational age (birthweight <10th percentile for gestational age) by general population charts vs customized charts is an important issue, but this is not the focus of this clinical opinion.
Umbilical artery Doppler
Doppler velocimetry of the umbilical artery assesses the resistance to blood perfusion of the fetoplacental unit ( Figure 1 , A) . As early as 14 weeks, low impedance in the umbilical artery permits continuous forward flow throughout the cardiac cycle. Maternal or placental conditions that obliterate small muscular arteries in the placental tertiary stem villi result in a progressive decrease in end-diastolic flow in the umbilical artery Doppler waveform until absent ( Figure 1 , B) and then reversed ( Figure 1 , C) flow during diastole are evident. Reversed end-diastolic flow in the umbilical arterial circulation represents an advanced stage of placental compromise and has been associated with obliteration of >70% of arteries in placental tertiary villi. Absent or reversed end-diastolic flow in the umbilical artery is commonly associated with severe (birthweight <3rd percentile for gestational age) IUGR and oligohydramnios.
