Pocket ObGyn – Intrauterine Growth Restriction
See Abbreviations
Definition and Epidemiology (Obstet Gynecol 2013;121:1122)
- Defined as sonographic EFW <10th percentile
- By definition is present in 10% of all Often, not signif until EFW <5%
Etiology
- Mat factors:
Behavioral: Smoking, substance use, decreased nutritional intake
Medical: Extremes of reproductive age, HTN, renal dz, lung dz, lupus, cyanotic heart dz, collagen vascular dz, viral or protozoal illness
• Fetal factors:
Congen d/o (eg, aneuploidy), constitutional
Clinical Manifestation
- Small for gestational age infant (<10%)
- Neonat morbidity: Dependent on cause; infants born constitutionally small generally have no sequelae & those w/ congen anomalies have poorer outcomes
- Perinatal morbidity & mortality is increased, particularly below 3%ile EFW
Physical Exam
- Lagging fundal height compared to gestational Nml fundal height measurements from 20–36 w are defined as 1 cm per week of gest ±2 cm.
Diagnostic Workup/Studies
- Goal: Identify true placental insufficiency causing IUGR constitutional or other
- Clinical dx:
Screening is accomplished via fundal height measurements Lagging fundal height (³3 cm) ® US eval for growth
- US:
Eval after identifying lagging fundal height includes EFW using fetal biometry
Fetal biometry: Head circumference, biparietal diameter, abdominal circumference, & femur length
EFW <10% = IUGR
AFI should be performed for prog
Oligohydramnios (AFI <5 cm) correlates w/ an increased risk of fetal death
- Umbilical artery Doppler:
Measurement of velocity of flow through umbilical artery during systole & diastole Peak systolic velocity is elevated in IUGR ® indicates placental resistance
W/ progression of IUGR, diastolic flow ¯ as placental resistance ® AEDF or REDF AEDF: Risks of continuing Preg begin to outweigh the risks of prematurity REDF: Move toward deliv
Management (Am J Obstet Gynecol 2011;204:34.e1)
- Initial US is performed after lagging fundal height is found (65–85% sens and 96% spec). Growth US repeated in 3–4 w
- At least weekly antenatal testing is indicated & may include: NST, BPP, modified BPP + umbilical artery Doppler
Negative predictive values are >99% for each of the above tests – ie, a negative test is highly reassuring that IUFD will not occur w/i 1 w
- Deliv: (Obstet Gynecol 2011;118:323)
38–39 w6d gest w/ nml testing and isolated IUGR; Deliv plan tailored to individual risks and ongoing eval
34–37 w6d gest w/ abnormal umbilical artery Dopplers or other risk factors (eg, oligo, maternal comorbities)
Earlier delivery (£34 w) considered for the most severe cases (eg, REDF), after steroids for FLM and with MgSO4 for fetal neuroprotection (for £32 w GA)