A Case Of Intra Uterine Growth Retardation

A 32-year-old primigravida is seen in your office at 33 weeks gestation for a routine prenatal visit. Her gestational age was calculated by her last normal menstrual period which was consistent with an ultrasound performed at 8 weeks gestation. Her pregnancy has been uneventful to date, although she has continued to smokeone pack or more of cigarettes daily. She states that she has been feeling normal fetal movement and no uterine contractions.
On examination, her height is 5 ft 6 in., her weight is 118 lb (53.5 kg), and her BP is 90/60 mm Hg. Her fundal height is 26 cm. On ultrasound, you note a single pregnancy with an estimated fetal weight of 900 g, which is at the 3rd percentile for gestational age.

1. What is the most likely diagnosis?
2. What other important items should be noted on the ultrasound?
3.  What is the next step in the management of this patient?
4. What are potential complications of the patient’s disorder?

Answers And Case Discussion: 

1. What is the most likely diagnosis?

Answer:  Intrauterine growth restriction (IUGR), likely due to cigarette smoking.

2. What other important items should be noted on the ultrasound?

Answer: Other ultrasound items: 

(a) Determine whether this is symmetric or asymmetric IUGR, and 

(b) assess the amniotic fluid.

3. What is the next step in the management of this patient?

Answer:  Next step: Evaluate fetal well-being.

4. What are potential complications of the patient’s disorder?

Answer:  Potential complications: Preterm birth; fetal stress; intrauterine demise.

Risk Factors For IUGR :

Maternal factors:

• Hypertensive disease (chronic hypertension or preeclampsia)

• Renal disease

• Cardiac and respiratory disease

• Underweight and/or poor pregnancy weight gain

• Significant anemia

• Substances: cocaine, tobacco

Uterine/placental factors:

• Abruptio placenta

• Placenta previa

• Infection

Fetal factors:

• Multiple gestation

• Aneuploidy

• Congenital syndromes

• Structural fetal malformations

• Infection

Approach To IUGR:

DEFINITIONS

1. IUGR: The most commonly used definition is a birthweight less than the 10th percentile for gestational age (GA).

2. ASSYMETRIC IUGR: Preservation of the HC while the AC and FL lag behind.

3. SYMMETRIC IUGR: All parameters including the HC are small.

4. BIOPHYSICAL PROFILE: Combination of ultrasound criteria and NST to assess for fetal well being conducted over 30 minutes. Fetal breathing, movement, tone, and amniotic fluid are assessed.

5. DOPPLER FLOW STUDIES: Using ultrasound to assess for flow through vessels. With IUGR, Doppler flow in the umbilical artery is helpful.

6. END-DIASTOLIC FLOW: The flow through the umbilical artery measured by Doppler ultrasound. Reverse end-diastolic flow is associated with a high stillbirth rate within 48 hours. Absent end-diastolic flow has a moderately high stillbirth risk, and in some settings can be closely observed.

Diagnosis

By definition, 10% of infants in a population will have a birth weight less than the 10th percentile. This designation notes that while defining a pathologic condition using a 10th-percentile cutoff makes statistical sense, it may not be clinically relevant.

The clinical challenge of greatest relevance is distinguishing the small-but healthy

fetus from the one who is compromised.  

When a patient has had an early ultrasound establishing the gestational age, then a “dating error” is not a consideration. In those patients who present with late prenatal care, the possibility of wrong dates is likely (for example, menstrual history suggests 36 weeks but ultrasound measures 30 weeks). A repeat ultrasound in 2 to 3 weeks showing adequate interval growth is highly suggestive of

a dating error, whereas lagging growth suggests IUGR.

Symmetric or Asymmetric

Early insults to fetal growth are thought to more commonly manifest as symmetric IUGR. Symmetric IUGR may be caused by aneuploidy or early transplacental infection.

On the other hand, asymmetric IUGR describes a pattern with a relatively smaller abdominal circumference in comparison to the fetal head circumference, and is thought to reflect a more recent insult to fetal growth. An example of this type of situation occurs in association with hypertension developing late in the pregnancy.

Neonatal Morbidity Associated With IUGR:

Some of the neonatal morbidities associated with IUGR include: 

• increased meconium aspiration,
• necrotizing enterocolitis, 
• hypoglycemia, 
• respiratory distress,
• hypothermia, and 
• thrombocytopenia.

It has been suggested that IUGR has long-term consequences, beyond those seen

in the immediate postnatal period. 

Management

Treatment of the fetus with suspected IUGR will depend upon the clinical circumstances, particularly the gestational age. In general, pregnancies less than 34 weeks’ GA should receive a course of antenatal corticosteroids to enhance lung maturation since preterm delivery is commonly encountered. Doppler studies are very useful. Antenatal testing with BPP or modified BPP—along with a repeat growth scan in 2 to 4 weeks—is suggested