Obstetrics - Abnormal fetal growth, Oligohydramnios and Polyhydramnios

Question 1

Fetal growth

• Determinants of growth
• Define SGA and IUGR

Answer 1

Overview on fetal growth:
- Determined by a complex interplay between fetal genetic and intrauterine environmental factors
- Intrauterine growth chart: influenced by racial and ethnic backgrounds

Terminology:
- Small for gestational age (SGA): BW <10th percentile (or >2SD below mean) for gestational age (pathological or constitutional)
- Intrauterine (or fetal) growth restriction (IUGR, FGR): BW <10th percentile (or >2SD below mean) for gestational age such that they do not fulfill their expected in-utero growth potential (pathological)

Question 2

Constitutionally small fetus

Cause
Trend on growth chart

Answer 2

Question 3

Symmetrical small fetus
Causes
Trend on growth chart

Answer 3

Question 4

Asymmetrically small fetus

Causes
Trend on growth chart

Answer 4

Head-sparing effect in the event of ↓nutrient supply (that limit glycogen/fat storage but allow continued brain growth)
- most IUGR result from ↓nutrient supply
- in order to ↑chance of survival, fetus respond to ↓nutrient supply by - ↓overall size, ↓total body fat, ↓lean mass, ↓bone mineral content → wasted baby appearance
- redirect blood flow from less vital organs to brain, heart, adrenal, placenta
- in the above situations, head circumference is relatively preserved with respect to abdominal circumference
- this disturbance of internal organ body proportion may have a life-long effect on organ structure and fx

These babies are asymmetrically small with HC relatively preserved to AC

The converse occur in DM babies due to increased glycogen and fat storage (as above charts)

These babies are at risk of wide range of Cx found in SGA babies

Question 5

Asymmetrical small fetus

Index to assess growth rate

Answer 5

Question 6

SGA

• Antenatal detection and diagnosis

Answer 6

Question 7

SGA

Post-natal clinical features

Answer 7

Question 8

Differentiating features between SGA and Pre-term babies

Answer 8

Question 9

Risks a/w SGA

Answer 9

Question 10

Clinical assessment of maturity scoring ststem

Answer 10

New Ballard Score

Question 11

Investigations for severe SGA

Answer 11

Question 12

Timing of delivery for SGA

Answer 12

Question 13

SGA

Mode of delivery
Neonatal management

Answer 13

Question 14

SGA

Clinical sequalae in development

Answer 14

Question 15

Define LGA and Macrosomia

Answer 15

Question 16

LGA

• Causes
• Clinical features

Answer 16

Cause:
- Gestational diabetes (not pre-existing DM)
- Genetic (constitutional) cause
- Syndromes a/w excessive intrauterine growth, e.g. Beckwith-Wiedemann syndrome, PallisterKillian syndrome

Clinical features:
- macrosomia
- facial plethora
- ↑hairiness
- hypotonic posture (behave relatively prematurely)

Question 17

LGA

Fetal complications of GDM and macrosomia

Answer 17

Complications of baby of DM mothers:
- Birth injury: shoulder dystocia, Erb’s palsy, fractured clavicle
- Perinatal asphyxia
- Metabolic disturbances: hypoglycemia, hypocalcemia (due to hyperinsulinism)
- ↑congenital malformation
- ↑susceptibility to infection
- ↑prematurity-related Cx: e.g. RDS, hypertrophic cardiomyopathy, wet lung disease
- Hyperviscosity syndrome: a/w polycythemia

Question 18

Pathophysiology of abnormal liquor volume

Answer 18

Question 19

Assessment of amniotic fluid volume

Answer 19

Question 20

Oligohydramnios

• Definition
• Causes

Answer 20

Question 21

Oligohydramnios

Clinical presentation

Answer 21

Question 22

Oligohydramnios

Complications

Answer 22

Question 23

Oligohydramnios

Investigations
Management

Answer 23

Question 24

Polyhydramnios

Definition
Causes

Answer 24

Question 25

Polyhydramnios

Clinical presentation
Complications

Answer 25

Clinical presentation:
- large for age uterus
- fetal poles hard to palpate
- severe abdominal swelling and discomfort in acute hydramnios

Question 26

Polyhydramnios

Management

Answer 26

Question 27

Signs of TORCH syndrome causing IUGR

Answer 27