Oligohydramniosand

Polyhydramnios

IMPORTANT TOPICS

Amniotic fluid functionAmniotic fluid function Clinical importance of AF Volume and compositionVolume and composition Amniotic fluid abnormalitiesAmniotic fluid abnormalities

Amniotic fluid function:

Allows room for fetal growth, movement and development.

Ingestion into GIT→ growth and maturation. Fetal pulmonary development (20 weeks). Protects the fetus from trauma. Maintains temperature. Contains antibacterial activity. Aids dilatation of the cervix during labor. Protects cord and placenta from compression in

labor

Clinical importance of AF:

Screening for fetal malformationScreening for fetal malformation (amniotc fluid (amniotc fluid αα--fetoprotein).fetoprotein).

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

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

Diagnosis and follow up of labour.Diagnosis and follow up of labour.

Diagnosis of PROMDiagnosis of PROM (ferning test).(ferning test).

Amniotic fluid formation and composition:

First & early second trimester :First & early second trimester : Amount is 5-50 ml & arises from:Amount is 5-50 ml & arises from:

- ultrafiltrate of Maternal plasma through the vascularized - ultrafiltrate of Maternal plasma through the vascularized uterine decidua (uterine decidua (in early pregnancyin early pregnancy).).

- Transudation of fetal plasma through the fetal skin & - Transudation of fetal plasma through the fetal skin & umbilical cord (umbilical cord (up to 20 weeks' gestationup to 20 weeks' gestation).).

Volume and composition

From 20 weeks up to term (mainly fetal urine):- At 18th week, the fetus voids 7-14ml/day; at term fetal

kidneys secrete 600-700ml of urine/day into AF. - Fetal respiratory tract secretes 250ml/day into AF. - Fluid transfer across the placenta. - Fetal oro-nasal secretions. Secretion is controlled by: - Fetal swallowing at term removes 500ml/day. - Resorption into maternal plasma AF constituents: - urea, creatinine & uric acid + desquamated fetal cells,

vernix, lanugo hair

Amniotic fluid volume : About 500 mls enter and leave the amniotic sac each About 500 mls enter and leave the amniotic sac each

hour.hour. gradual gradual ↑ ↑ up to 36 weeks up to 36 weeks toto around 600 to 1000 ml around 600 to 1000 ml

thenthen↓ after that.↓ after that. The normal range is wide but the approximate The normal range is wide but the approximate

volumes are:volumes are:

- 500 ml at 18 weeks- 500 ml at 18 weeks

- 800 ml at 34 weeks.- 800 ml at 34 weeks.

- 600 ml at term.- 600 ml at term.

Amniotic fluid volume assessment

Clinical assessment is unreliable.Clinical assessment is unreliable.

Objective assessment depends on U/S to measure:Objective assessment depends on U/S to measure:

- deepest vertical pocket (DVP).- deepest vertical pocket (DVP).

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

Amniotic fluid abnormalities

Oligohydramnios:Oligohydramnios:

Defined as reduced amniotic fluid i.e. amniotic fluid index of 5 cm or less or the deepest vertical pool < 2 cm.

Polyhydramnios:Polyhydramnios:

Defined as Defined as excessive amount of amniotic fluid of 2000 ml or more (AFI of > 25 cm or the deepest vertical pool of > 8 cm) .

Causes of oligohydramnios:Causes of oligohydramnios:

1.1. Fetal causes:Fetal causes:

* * Renal causesRenal causes:: - Renal agenesis (Potter’s syndrome).- Renal agenesis (Potter’s syndrome). - polycystic kidney.- polycystic kidney. - Urethral obstruction (atresia/posterior urethral valve).- Urethral obstruction (atresia/posterior urethral valve). * Fetal growth restriction.* Fetal growth restriction. * Fetal death.* Fetal death. * Postterm pregnancy.* Postterm pregnancy. * Preterm premature rupture membranes.* Preterm premature rupture membranes.

Causes of oligohydramnios (cont’):Causes of oligohydramnios (cont’):

2. Maternal causes:2. Maternal causes:• Uteroplacental insufficiency.Uteroplacental insufficiency.• Preeclampsia.Preeclampsia.• Connective tissue disorders.Connective tissue disorders.

3. Placental causes:3. Placental causes:• twin-twin transfusion.twin-twin transfusion.

4. Drug causes:4. Drug causes: Prostaglandin synthase inhibitors as NSAID.Prostaglandin synthase inhibitors as NSAID.

5. Idiopathic5. Idiopathic

Complications of oligohydramnios:Complications of oligohydramnios:

In early pregnancy:In early pregnancy:• Amniotic adhesions or bandsAmniotic adhesions or bands→ amputation/death→ amputation/death..• Pressure deformities (Flattened face).Pressure deformities (Flattened face).• Pulmonary hypoplasia:Pulmonary hypoplasia:

- Thoracic compression.- Thoracic compression.

- No breathing movement.- No breathing movement.

- No amniotic fluid retained in the lungs.- No amniotic fluid retained in the lungs.• Postural deformities (Talipes Equino Varus). Postural deformities (Talipes Equino Varus).

Complications of oligohydramnios:Complications of oligohydramnios:

In late pregnancyIn late pregnancy::• Fetal growth restriction.Fetal growth restriction.• Preterm labour.Preterm labour.• Fetal distress.Fetal distress.• Fetal death.Fetal death.• Meconium aspiration.Meconium aspiration.• Labour induction/CS.Labour induction/CS.

Diagnosis:Diagnosis:

- Fundal level- Fundal level < date. < date.

- - AF I < 5CMAF I < 5CM , , DVP < 2.DVP < 2.

- IUGR: abdominal circumference < 10- IUGR: abdominal circumference < 10thth centile.centile.

- Doppler abnormalities- Doppler abnormalities

- Congenital fetal anomalies. - Congenital fetal anomalies.

Management:

-Treat the cause (pprom, preeclampsia).-Treat the cause (pprom, preeclampsia).

-Assess fatal wellbeing (U/S/CTG/Doppler/BPP).-Assess fatal wellbeing (U/S/CTG/Doppler/BPP).

-Vesicoamniotic shunting (urethral obstruction).-Vesicoamniotic shunting (urethral obstruction).

-Amnioinfusion:-Amnioinfusion: Indications of amnioinfusion:Indications of amnioinfusion:1.1. Meconium stained amniotic fluidMeconium stained amniotic fluid2.2. Variable decelerationsVariable decelerations3.3. Prophylactic for severe degreesProphylactic for severe degrees

Polyhydramnios

Incidence: 1% of all pregnancies Degrees

1. Mild hydramnios (80%):

a pocket of amniotic fluid measuring 8 to 11 cm.a pocket of amniotic fluid measuring 8 to 11 cm.

2.2. moderate hydramnios (15%): moderate hydramnios (15%):

a pocket of amniotic fluid measuring 12 to 15 cm.a pocket of amniotic fluid measuring 12 to 15 cm.

3.3. Severe hydramnios (5%) - Severe hydramnios (5%) - twin-twin transfusion twin-twin transfusion syndrome syndrome ::

a pocket of amniotic fluid measuring 16 cm or morea pocket of amniotic fluid measuring 16 cm or more..

Causes of polyhydramnios

Fetal malformation:Fetal malformation:

- GIT: esophageal/duodenal atresia, - GIT: esophageal/duodenal atresia, tracheoesophageal fistula.tracheoesophageal fistula.

- CNS: anencephaly (- CNS: anencephaly (↓swallowing, exposed ↓swallowing, exposed meninges, no antidiuretic hormone)meninges, no antidiuretic hormone). .

Twin-twin transfusion Twin-twin transfusion → fetal polyuria→ fetal polyuria..

Causes of polyhydramnios (cont’)

Hydrops fetalis: congestive heart failure, Hydrops fetalis: congestive heart failure, severe anaemia or hypoproteinemia severe anaemia or hypoproteinemia → → placental transudation placental transudation

Placental tumors e.g. chorioangiomaPlacental tumors e.g. chorioangioma diabetes mellitus (osmotic diuresis).diabetes mellitus (osmotic diuresis). Idiopathic 60%.Idiopathic 60%.

Types:Types:

Acute:Acute: usually develops in the first half of usually develops in the first half of pregnancy with rapid expansion to huge pregnancy with rapid expansion to huge dimensions.dimensions.

Usually ends in abortion, or termination Usually ends in abortion, or termination becomes mandatorybecomes mandatory

Chronic:Chronic: develops gradually so a much develops gradually so a much larger size can be tolerated.larger size can be tolerated.

Diagnosis of Polyhydramnios Symptoms:Symptoms:- dyspnea.- dyspnea. - edema.- edema. - abdominal distention- abdominal distention - preterm labour.- preterm labour. Abdominal examination:Abdominal examination: - - ↑uterus than expected.↑uterus than expected. - difficult to palpate fetal - difficult to palpate fetal

parts.parts. - difficult to hear fetal heart - difficult to hear fetal heart

sound.sound. - ballotable fetus- ballotable fetus..

Ultrasound:Ultrasound:

- excessive amniotic fluid.- excessive amniotic fluid.

- fetal abnormalities.- fetal abnormalities.

Complications of Polyhydramnios

PreeclampsiaPreeclampsia UTIUTI Preterm laborPreterm labor PROMPROM Accidental hemorrhageAccidental hemorrhage Cord prolapseCord prolapse Abnormal presentationsAbnormal presentations Increased risk for C.S.Increased risk for C.S. Post-partum hemorrhagePost-partum hemorrhage

Management Minor degrees: no treatment.Minor degrees: no treatment. Bed rest, diuretics, water and salt restriction: ineffective.Bed rest, diuretics, water and salt restriction: ineffective. HospitalizationHospitalization: dyspnea, abdominal pain or difficult : dyspnea, abdominal pain or difficult

ambulation.ambulation. Endomethacin therapy: Endomethacin therapy: - Decreases urine production- Decreases urine production - impairs lung liquid production/enhances absorption.- impairs lung liquid production/enhances absorption. - - ↑↑fluid movement across fetal membranes.fluid movement across fetal membranes. * complications: * complications: premature closure of ductus arteriosus, premature closure of ductus arteriosus,

impairment of renal function, and cerebral impairment of renal function, and cerebral vasoconstriction. So not used after 35 weeksvasoconstriction. So not used after 35 weeks

AmniocentesisAmniocentesis: to relieve maternal distress and to test : to relieve maternal distress and to test for fetal lung maturity. Complications: ruptured for fetal lung maturity. Complications: ruptured membrane, chorioamnionitis, placental abruption, membrane, chorioamnionitis, placental abruption, preterm labourpreterm labour. . Amniocentesis may be done Amniocentesis may be done repeatedly.repeatedly.