Amniotic fluid

1. Amniotic fluid Normal & abnormal Dr. Abdalla H. Alsadig MD

2. IMPORTANT TOPICS • Amniotic fluid function • Clinical importance of AF • Volume and composition • Amniotic fluid abnormalities

3. Amniotic fluid function: • Allow 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 labour.

4. 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 labour. • Diagnosis of PROM(ferning test).

5. Amniotic fluid formation and composition: • First & early second trimester : Amount is 5-50 ml & arises from: - ultrafiltrate of Maternal plasma through the vascularized uterine decidua (in early pregnancy). - Transudation of fetal plasma through the fetal skin & umbilical cord (up to 20 weeks' gestation). * It is iso-osmolar with fetal & maternal plasma, though it is devoid of proteins.

6. 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 secretes 600-700ml of urine/day into AF. - Fetal respiratory tract secretes 250ml/day into AF. - Fluid transfers across the placenta. - Fetal oro-nasal secretions. • Secretion is controlled by: - Fetal swallowing at term removes 500ml/day. - Reabsorption into maternal plasma (osmotic gradient). • AF constituents: - urea, creatinine & uric acid + desquamated fetal cells, vernix, lanugo hair & others→ hypo-osmolar amniotic fluid….

7. Amniotic fluid volume : • About 500 mls enter and leave the amniotic sac each hour. • gradual ↑ up to 36 weeks toaround 600 to 1000 ml then↓ after that. • The normal range is wide but the approximate volumes are: - 500 ml at 18 weeks - 800 ml at 34 weeks. - 600 ml at term.

8. 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.

9. Amniotic fluid abnormalities • Oligohydramnios: Defined as reduced amniotic fluid i.e.amniotic fluid index of 5 cm orless 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) .

10. 1. Fetal causes: * Renal cause (57%): - Renal agenesis (Potter’s syndrome). - polycystic kidney. - Urethral obstruction (atresia/posterior urethral valve). * Fetal growth restriction. * Fetal death. * Postterm pregnancy. * Preterm premature rupture membranes Causes of oligohydramnios:

11. Causes of oligohydramnios: 2. Maternal causes: • Uteroplacental insufficiency. • Preeclampsia. 3. Placental causes: • twin-twin transfusion. 4. Drug causes: Prostaglandin synthase inhibitor as NSAID. • 5. Idiopathic

12. In early pregnancy: Amniotic adhesions or bands→ amputation/death. Pressure deformities (club feet). Pulmonary hypoplasia: - Thoracic compression. - No breathing movement. - No amniotic fluid retain. Flattened face. Postural deformities. Complications of oligohydramnios:

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

14. Oligohydramnios: • Diagnosis: - Fundal > date. - AF I < 5CM , DVP < 2. • IUGR: abdominal circumference < 10th centile. • Doppler abnormalities • Congenital fetal anomalies. • Management: • Treat the cause (pprom, preeclampsia). • Assess fatal wellbeing (U/S/CTG/Doppler/BPP). • Vesicoamniotic shunting (urethral obstruction). • Amnioinfusion (no↓ in fetal death).

15. Polyhydramnios

16. Polyhydramnios • types 1. Mild hydramnios (80%): a pocket of amniotic fluid measuring 8 to 11 cm. 2. moderate hydramnios (15%): a pocket of amniotic fluid measuring 12 to 15 cm. 3. Severe hydramnios (5%) - twin-twin transfusion syndrome : a pocket of amniotic fluid measuring 16 cm or more.

17. Fetal malformation: - GIT: esophageal/duodenal atresia, tracheoesophageal fistula. - CNS: anencephaly (↓swallowing, exposed meninges, no antidiuretic hormone). Twin-twin transfusion → fetal polyuria. Hydrops fetalis: congestive heart failure, severe anaemia or hypoproteinemia → placental transudation diabetes mellitus (osmotic diuresis). Idiopathic. Causes of polyhydramnios

18. 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. diagnosis of polyhydramnios

19. management • Minor degrees: no treatment. • Bed rest, diuretics, water and salt restriction: ineffective. • Hospitalization: dyspnea, abdominal pain or difficult ambulation. • Endomethacin 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 35 weeks • Amniocentesis: to relieve maternal distress and to test for fetal lung maturity. Complications: ruptured membrane, chorioamnionitis, placental abruption, preterm labour.

20. Thanks