intrauterine growth restriction (iugr) and large for gestational age (lga)

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INTRAUTERINE GROWTH RESTRICTION AND LARGE FOR GESTATIONAL AGE KEALEBOGA D. SMITH MBBS V DATE: 20/02/15

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INTRAUTERINE GROWTH RESTRICTION AND

LARGE FOR GESTATIONAL AGE

KEALEBOGA D. SMITHMBBS V

DATE: 20/02/15

PRESENTATION OUTLINE

1. Definitions

2. Incidence

3. Classification of IUGR

4. Pathogenesis

5. Diagnosis & clinical findings

6. Differentials

7. Complications

8. Management, prognosis & prevention

9. LARGE FOR GESTATIONAL AGE

10. Conclusion

Definition of terms

• IUGR-defined as estimated fetal weight (EFW) at or below the 10th percentile for gestational age.

• fetus is unable to achieve its genetically determined potential size.

• NB: SGA and IUGR are related but not synonymous

• SGA is a term that applies to the infant that is less than the 10th percentile at birth or having a birth weight >2 standard deviations below the mean for gestational age.

• Not all fetuses that are SGA are pathologically growth restricted and, in fact, may be constitutionally small

Incidence

• About 3-10% (up to 15%) of all pregnancies are associated with IUGR

• Perinatal mortality rate is 5-20 times higher for growth retarded fetuses

• IUGR estimated to be the predominant cause for low birth weight in developing countries

Classification of IUGRTYPE SYMMETRIC/TYPE 1 (20%) ASYMMETRIC/TYPE 2 (80%)

ONSET Early in utero Later onset

ETIOLOGY Congenital infections, genetic disorders Utero-placental insufficiency, maternal malnutrition, hypertension

PATHOPHYSIOLOGY • Impaired cell division• Decreased cell number• irreversible

• Impaired cellular hypertrophy• Decreased cell size• reversible

CLINICAL FEATURES • inadequate growth of head and body• head:abdomen ratio may be normal

• brain is spared, therefore head:abdomen ratio increased

PROGNOSIS Poor prognosis More favorable prognosis

Pathogenesis (Pathogenic classification of IUGR) FETOPLACENTAL CAUSES

GENETIC DISORDERS:

Autosomal: trisomy 13, 18, 21; ring chromosomes; chromosomal deletions; partial trisomiesSex chromosomes: Turner's syndrome, multiple chromosomes (XXX, XYY)Neural tube defectsSkeletal dysplasias: achondroplasia, chondrodystrophies, osteogenesis imperfectaAbdominal wall defects

CONGENITAL INFECTION: Viral: cytomegalovirus, rubella, herpes, varicella-zosterProtozoan: toxoplasmosis, malariaBacterial: listeriosis

PLACENTAL DISORDERS: placenta previa, placental infarction, chorionic villitis, chronic partial separation, placental malformations (circumvallate placenta, placental hemangioma, twin-twin transfusion syndrome)

MULTIPLE GESTATION

Pathogenesis continued……

MATERNAL FACTORS (assoc. with asymmetric IUGR)

Coexistent maternal disease:: hypertension, anemia, renal disease, DM, malnutrition ( pancreatitis, intestinal parasites, maternal eating d/os), cyanotic cardiopulmonary disease

Substance abuse/drugs: alcohol, cigarette smoking, cocaine, heroin, warfarin, folic acid antagonists (methotrexate, aminopterin), anticonvulsants

Small maternal stature

Risk of reccurence with previous IUGR

Diagnosis & Clinical findings

A. Establishing the gestational age is imperative:

Use the following to determine the gestational age:

1. LNMP

2. size of uterus (lagging fundal height)..if varying by >2cm from the

assigned GA, U/S indicated to assess EFW & amniotic fluid volume

3. time of quickening

4. early U/S measurements

NB: Any discrepancies should raise the suspicion of IUGR

Continued…..B. Detailed maternal hx for any evidence of recent infection, meds & drug exposure, any maternal medical conditions assoc. with IUGR or any hx of IUGR in a prior pregnancy

C. Investigationsguided by the history and physical exam

e.g FBC, LFT, RFT, TORCH screen, urine dipstick & cultures, blood sugar, fetal karyotyping via genetic amniocentesis if IUGR presents prior to 3rd trimester.

continued…E. Fetal assessment: ULTRASONOGRAPHY

• The diagnosis of IUGR is made when biometric parameters on U/Sindicate that the EFW is less than the 10th for GA

• Abdominal circumference (AC): most sensitive measurement. WHY?

• Head circumference(HC) to AC ratio: ratio changes as pregnancy progresses. In 2nd trimester, the HC>AC. At about 32-36 weeks’ gestation, ration is 1:1, and after 36 weeks the abdominal measurements become larger

NB: persistence of a head-to-abdomen ration <1 in gestation is predictive of ASYMMETRIC IUGR

• Femur length not useful in identifying IUGR but can identify skeletal dysplasia

...fetal assessment: Doppler measurements

Doppler studies more useful in diagnosing moderate to severe IUGR.

The various groups of vessels used are as follows:

1. Uterine artery flow abnormalities-predict IUGR as early as 12-14 wks

2. Umbilical artery (UA) flow abnormalities- Placental resistance> umbilical artery blood flow. UA Doppler studies recommended as the primary method of surveillance for IUGR fetuses

3. Others: fetal cerebral arterial flow, Doppler venous flow studies, aortic isthmus

Biophysical profile also used in assessing fetal well being

Neonatal assessment1. Reduced birthweight for gestational age

2. Physical appearance (thin, with loose peeling skin, scaphoid abdomen, disproportionately large head)

3. Use of growth charts to plot e.g Lubchencho & Olsen charts

4. Ballard score

Differentials

• Oligohydramnios

• Healthy pregnancy with wrong due dates

• Constitutionally small fetus

Complications of IUGR

Management

1. Treatment is individualized

2. Goal of management is to deliver the most mature fetus in the best physiological condition possible

3. Management of pregnancy depends on a surveillance plan that maximizes gestational age while minimizing the risks of neonatal morbidity and mortality

4. Administer glucocorticoids to women likely to deliver before 34wks

5. Optimal timing for delivery of IUGR is still controversial

6. C/S indicated when there is evidence of fetal compromise, malpresentation, or when traumatic delivery is anticipated

7. Labor is particularly stressful to IUGR fetus, therefore C/S preferred

8. Continuous electronic FHR monitoring should be done during labor

Prognosis

• Term infants with birthweights <3rd percentile have higher morbidity and mortality

• IUGR have lower IQs, higher incidence of learning & behavioral problems.

• Adults who were IUGR at birth are at a higher risk of developing ischemic heart diseases & related disorders (e.g HTN, DM, stroke, hypercholesterolemia)

• IUGR infants appear to catch in weight in the first 6 months of life

Prevention

Many causes of IUGR are not preventable but few interventions proved to be effective:

• Smoking cessation

• Balanced protein & energy supplementation

• immunizations

• Optimizing pre-existing maternal conditions e.g HTN, DM

• Low dose aspirin & dipyridamole to prevent idiopathic uteroplacental insufficiency (no reliable evidence)

LARGE FOR GESTATIONAL AGE (LGA)• defined as above the 90th percentile of weight for any

specific gestational age.

• Macrosomia generally refers to fetuses with an EFW of at least 4500 g regardless of the gestational age

• Fetuses that are >4500g are >95th percentile at any gestational age and therefore represent an extreme subset of LGA fetuses

• LGA not well documented in literature and often discussed along with macrosomia because of similar risk factors and complications

Factors predisposing to LGA

Maternal factors Fetal factors

• Diabetes• Obesity• Postdatism (GA >42WKS)• Multiparity• Advanced age• Previous LGA infant• Large stature

• genetic or congenital disorders

• Male gender• Congenital heart disease esp

TGA (“happy chubby blue male infant”

Pathogenesis

• In most cases etiology is unknown

• Maternal diabetes is the most recognized risk factor.

• Beckwith-Wiedemann syndrome frequently assoc. with fetal macrosomia because of pancreatic islet cell hyperplasia

• Carpenter’s syndrome and fragile X syndrome may be assoc. with increased incidence of LGA

Clinical findings

• Fundal height measurement exceeds margin of error (>3cm) for that gestational age

• Excessive maternal weight gain

• U/S is used to make a diagnosis by assessing EFW.

• It must be kept in mind that U/S assessment of fetal weight has a larger margin of error at later gestational ages

DDX include: polyhydramnios, fetal structural abnormalities, multiple gestation, molar pregnancy, incorrect dates

Complications of LGA

Management • A consensus has not been reached regarding management strategies to

reduce the risk of assoc. with LGA/macrosomia

• Management strategies for suspected fetal macrosomia include elective C/S and early induction of labor

• Early induction not shown to reduce risk of C/S or shoulder dystocia

• Obstetricians must be familiar with procedures that release a shoulder dystocia at delivery

• Delivery should occur in a setting where immediate operation can be accomplished

• C/S in fetus with EFW ≥4500g

• Manage maternal complications accordingly e.g perineal trauma

Conclusion

• IUGR remains a challenging problem to clinicians

• Antenatal diagnosis is the key to proper management of IUGR

• Optimal timing for delivery of IUGR fetuses is still debated

• In general, outcomes are more favorable with C/S delivery

• Early identification of risk factors of LGA/macrosomia is important to reduce morbidity

• Maternal diabetes and obesity substantially increase the risk of LGA/macrosomia

References 1. Decherney, A.H et al. Current Diagnosis & Treatment: Obstetrics &

Gynecology. 11th ed (2013) chapter 16

2. Hacker, N.F et al. Hacker and Moore’s Essentials of Obstetrics and gynecology. 5th ed (2010) pg153-157

3. Gomella, T.L et al. Neonatology: Management, Procedures, On-call Problems, Diseases, and Drugs. 7th ed (2013) pg732-742

4. Management of suspected macrosomia: http://www.aafp.org/afp/2001/0115/p302.html#sec-4

5. Macrosomia treatment and management: http://emedicine.medscape.com/article/262679-treatment

THANK YOU