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KEY QUESTIONS
What fetal risks are associated with intrauterine growth restriction (IUGR)?
How do you determine the etiology of IUGR once it is diagnosed?
What are risk factors for the development of IUGR?
What are the most reliable methods to diagnose IUGR?
What are the best methods for fetal surveillance for IUGR?
When are antenatal corticosteroids indicated?
When should patients be considered for inpatient vs. outpatient management?
When should patients with IUGR be delivered?
What is the optimal route of delivery for patients with IUGR?
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CASE 36-1
A 25 y.o. G2P1 presents at 33 weeks gestation complaining of decreased fetal movement. She reports some occasional contractions but denies bleeding or leakage of fluid. She also denies symptoms of preeclampsia. She has no significant past medical history. Her pregnancy has been uncomplicated. The initial FHR tracing is Category 2, with moderate variability but occasional late decelerations. A bedside ultrasound is performed and is notable for mildly decreased fluid with an AFI of 6.5, and fetal biometry demonstrates an EFW in the 20th percentile, but the abdominal circumference is at the 5th percentile.
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Intrauterine growth restriction (IUGR), which is also known as fetal growth restriction, is an important diagnosis to detect in pregnancy due to the high risk of perinatal morbidity and mortality.1 In fact, a high percentage of stillbirths, both term and preterm, are due to undiagnosed IUGR. Undetected IUGR accounts for a much higher proportion of stillbirth than cases of IUGR detected in the antenatal period.2 It is, however, important to understand that not all small fetuses are growth restricted, as they may have in fact met their true growth potential despite their small size. This chapter will attempt to help differentiate constitutionally small fetuses from those that are truly growth restricted and at risk for perinatal morbidity and mortality. It will discuss strategies for the diagnosis and management of IUGR as it pertains to an obstetrics and gynecology (OB/GYN) hospitalist.
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ETIOLOGY, PATHOPHYSIOLOGY, AND RISK FACTORS
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IUGR has numerous causes, including maternal, fetal, and placental factors. In many cases, these factors overlap (Table 36-1). The underlying pathophysiology for IUGR is multifactorial and largely dependent on the precipitating etiology. Although most cases are related to placental insufficiency, a careful assessment for fetal conditions, including structural malformations, genetic conditions, and maternal disorders, should be performed. There are relatively few interventions once IUGR has been diagnosed, but careful attention to improving fetal growth through optimizing maternal medical conditions should be considered.
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