Learning Objectives

• Character of A.F

• Functions of A.F

• Oligo-Poly-Hydramnios

Definition

Etiology

Diagnosis

Treatment

The Fetal Membranes

Definition:

Fetal membranes are all the structures that develop from the

zygote and do not share in the formation of the embryo (extraembryonic structures from the primitive blastomeres).

Fetal membranes are:

a. Chorion.

b. Amnion.

c. Yolk sac.

d. The umbilical cord including allantois and body stalk.

Amnion & Amniotic cavity

- It is a membrane which bounds the amniotic

cavity.

- It is continuous with the ectoderm of the embryo.

- It contains about 800-1000 ml of watery and clear

fluid at full term.

Amniotic Fluid The amniotic fluid is that fluid surrounding the developing fetus

that is found within the amniotic sac contained in the mother's womb.

• Physical characteristics ;

- It is clear pale yellow fluid. - pH of is around 7.2. - Specific gravity of 1.0069 – 1.008. -

-

Composition of amniotic fluid

- 98% water, 2% solid substances like inorganic & organic salts, fetal epithelium, protein & enzymes.

Origin: The following forms the amniotic fluid:

1- Amniotic membrane

2- Maternal tissue (interstitial) fluid by diffusion across the amnio-chorionic membrane from the deciduas parietalis.

3- Filtrated from maternal blood.

4- Fluid is also secreted by the fetal respiratory tract (300 – 400 ml daily) and enters the amniotic cavity.

5-Fetal urine.

Circulation

- The amniotic fluid, formed by amniotic membrane & filtrated from maternal blood accumulates in the amniotic cavity,

- Then, it is swallowed by the embryo.

- Lastly, it passes as fetal urine to accumulate again in the amniotic cavity.

Volume of the amniotic fluid: The volume of amniotic fluid increases slowly

from 30 ml at 10 weeks gestation to 350 ml at 20 weeks to 700 – 1000 ml by 37 weeks.

NORMAL AMNIOTIC FLUID VOLUME

Weeks Gestation

Fetus Amniotic Fluid Placenta (g) (ml) (g)

16 28 36 40

100 200 100 1000 1000 200 2500 900 400 3300 800 500

Function

Before labour: 1-It forms an isolating bag around the embryo protecting him

from external trauma, shock & temperature.

2-It prevents adhesion of the embryo to its membranes.

3-It allows homogenous media needed for the growth of the embryo.

4-It permits the free movement of the embryo needed for muscular exercise.

Function

During labor:

1- It forms the bags of fore water and hind water.

2-The bag of fore water allows regular dilatation of the cervix.

3-After rupture of membrane the amniotic fluid serves as a lubricant for fetus descent.

4-Also the amniotic fluid is bacteriostatic.

Clinical importance of AF:

• Screening for fetal malformation (serum α-fetoprotien).

• Assessment of fetal well-being (amniotic fluid index).

• Assessment of fetal lung maturity (L/S ratio).

• Diagnosis and follow up of labor.

• Diagnosis of PROM (ferning test).

• Diagnosis of fetal chromosomal abnormalities ( Down

syndrome, Edward syndrome, and others), and for DNA studies for diagnosis of some single gene disorders.

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Summary of the routine chemical tests performed on

amniotic fluid

• Tests for the Well-being and Maturity • __________________________________________________________ • Test Normal values at term Significance • __________________________________________________________ • Bilirubin scan 0.025 mg/dl Hemolytic disease

of the newborn

• L/S ratio 2.0 Fetal lung maturity

• Phosphatidyl- Present Fetal lung maturity

Glycerol

• Creatinine 1.3 – 4.0 mg/dl Fetal age

• Alpha fetal protein 4.0 mg/dl Neural tube disorders • __________________________________________________________

Amniotic fluid volume assessment

• Clinical assessment is unreliable.

• Objective assessment depends on U/S to measure:

- Deepest vertical pool (DVP).

- Amniotic fluid index (AFI). It is a total of the DVPs in each four quadrants of the uterus. it is a more sensitive indicator of AFV throughout pregnancy.

AFI

Amniotic fluid abnormalities

Oligohydramnios:

Defined as reduced amniotic fluid i.e. amniotic fluid index of 5 cm or less

or the deepest vertical pool < 2 cm.

Polyhydramnios:

Defined as excessive amount of amniotic fluid of 2000 ml or more

AFI of > 25 cm

or the deepest vertical pool of > 8 cm) .

ETIOLOGY OF POLYHYDRAMNIOS

• Idiopathic

• Fetal Anomalies

• Diabetes

• Multifetal gestation

• Immune/Non-immune hydrops

• Fetal infection

• Placental haemangiomas

Etiology of Polyhydramnios: Fetal Anomalies

• Problems with swallowing and GI absorption

• Increased transudation of fluid:

anencephaly, spina bifida

• Increased urination: anencephaly (lack of ADH, stimulation of urination centers)

• Decreased inspiration

SYMPTOMS

• Dyspnea

• Abdominal pain

• Contractions preterm labor

• Decreased Perception of Fetal

Movements

diagnosis of polyhydramnios

• Symptoms:

- dyspnea.

- edema.

- abdominal distention

- preterm labour.

• Abdominal examination:

- ↑uterus than expected.

- difficult to palpate fetal parts.

- difficult to hear fetal heart sound.

- ballotable fetus.

• Ultrasound:

- excessive amniotic fluid.

- fetal abnormalities.

(fetus)?

• Fetal prognosis worsens with more severe hydramnios and congenital anomalies

• 15-20% fetal malformations

• Preterm delivery

• Suspect diabetes

• Prolapse of cord

• Abruption

(Mother)?

• Placental abruption

• Uterine dysfunction

• Post-partum hemorrhage

• Abnormal presentation -- C/S

TREATMENT

• Mild to Moderate hydramnios: rarely requires treatment

• Hospitalization, bed rest

• Amniocentesis: to relieve maternal distress and to test for

fetal lung maturity. Complications: ruptured membrane, chorioamnionitis, placental abruption, preterm labour

• Non-steroidal anti-inflammatory analgesia

• Blood sugar control

management

• Indomethacin therapy: .

- impairs lung liquid production/enhances absorption.

- ↓fluid movement across fetal membranes.

* complications: premature closure of ductus arteriosus, impairment of renal function, and cerebral vasoconstriction. So not used after 34 weeks

OLIGOHYDRAMNIOS

AETIOLOGY FETAL • PROM (50%)

• CHROMOSOMAL ANOMALIES

• CONGENITAL ANOMALIES

• IUGR

• IUFD

• POSTTERM PREGNANCY

MATERNAL • PREECLAMPSIA

• CHRONIC HT

PLACENTAL • CHRONIC ABRUPTION

• TTTS

• CVS

DRUGS • PG SYNTHETASE

INHIBITORS

• ACE INHIBITORS

IDIOPATHIC

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ETIOLOGY

• Postdate

• Fetal Anomalies: obstruction of fetal

urinary tract/renal agenesis

• IUGR

• ROM

• Twin/Twin transfusion

• Exposure to ACE inhibitors, and

• Non-steroidal anti-inflammatory

DIAGNOSIS

SYMPTOMS NO SPECIFIC

SYMPTOMS H/O leaking p/v Postterm s/o preeclampsia Drugs Less fetal movements

SIGNS Uterus – small for

date Malpresentations IUGR

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USG

METHODS

DVP <2 cms

(<1 severe)

AFI <5 cms

(5-8 borderline)

2D pocket <15 sq cms

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COMPLICATIONS

FETAL Abortion

Prematurity

IUFD

Deformities –contractures

Potters syndrome

pulmonary hypoplasia

Malpresentations

Fetal distress

Low APGAR

MATERNAL

Increased morbidity

Prolonged labour: uterine inertia

Increased operative intervention

(malformations,

distres)

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MANAGEMENT

DEPENDS UPON

• AETIOLOGY

• GESTATIONAL AGE

• SEVERITY

• FETAL STATUS & WELL BEING

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DETERMINE AETIOLOGY

• R/O PROM

• TARGETED USG FOR ANOMALIES

• R/O IUGR ,IUFD when suspected

• Amniocentesis if chromosomal anomalies suspected – early symmetric IUGR

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TREATMENT • ADEQUATE REST – decreases dehydration • HYDRATION – Oral/IV Hypotonic fluids(2 Lit/d) temperory increase helpful during labour,prior to ECV, USG • SERIAL USG – Monitor growth,AFI,BPP • INDUCTION OF LABOUR/ LSCS Lung maturity attained Lethal malformation Fetal jeopardy Sev IUGR Severe oligo

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• AMNIOINFUSION Decreases cord

compression Dilutes meconium

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TREATMENT ACC. TO CAUSE

• Drug induced – OMIT DRUG

• PROM – INDUCTION

• PPROM – Antibiotics,steroid – Induction

• FETAL SURGERY

VESICO AMNIOTIC SHUNT-PUV

Laser photocoagulation for TTTS

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Amniocentesis • Amniocentesis is the

removal of a small amount of amniotic fluid from the sac around the baby.

• This is usually performed at 16 weeks in pregnancy.

• A fine needle is inserted under ultrasound guidance through the mothers' abdomen into a pool of amniotic fluid.

Amniocentesis

Amniocentesis Studies of the cells obtained from the amniotic fluid permit: 1- Chromosomal analysis of the cells which can be performed to investigate the

following; Diagnosis of sex of the fetus

Detection of chromosomal abnormalities e.g. trisomy 21 (Down’s syndrome)

DNA studies

2- The cells may indicate genetically transmitted diseases( Inherited disorders e.g Cystic Fibrosis).

3-To check for developmental problems e.g. Spina Bifida .

4- Other studies can be done directly on the amniotic fluid including measurement of

alpha-fetoprotein where high levels of alpha-fetoproteins in the amniotic fluid indicate the presence of a severe neural tube defect whereas low levels of alpha-fetoproteins may indicate chromosomal abnormalities .

Amniocentesis

Who is the proper candidate for an Amniocentesis investigation?

1-Those whom are suspected to have possible problems indicated by certain tests conducted previously,(e.g If pregnancy is complicated by a condition such as Rh-incombatibility,the doctor can use amniocentesis to find out if the baby's lungs are developed enough to endure an early delivery).

2- Family history of genetic abnormalities (in this case would be advisable to seek genetic counseling before becoming pregnant)

3-Those that have been exposed to certain risk enviromental factors that might lead to fetal abnormalities .

Amniocentesis

What are the risks of amniocentesis?

• - Abortion: about 1 in 200 to 400 women aborted (higher risk if done in the first quarter)

• - Uterine infection: 1 in 1000