Polyhydramnios and

Oligohyramnios

Prepared by:Ayman Al-Jaafry.

Qassim UnivesityFaculty of Medicine

Obstetrics and Gynecology

Objectives: Physiological aspects of amniotic fluid Techniques for assessing AFV Amniotic fluid disorders: Polyhydramnios.

Oligohydramnios.

Post-term pregnancy

Defintion: ‘42 completed weeks or more (294 days or

more) from last menstrual period (LMP)‘.

dIncidence:

Removal:

via fetal swallowing and absorption by the amniotic-chorionic surface.

Composition: Nature: - It is a clear pale, slightly alkaline pH 7.2 fluid. Normally the amniotic fluid volume is around 500-

1500 ml Water (98-99%) carbohydrates ( glucose and fructose) proteins ( albumin and globulins), lipids,

hormones (estrogen and progesterone), enzymes ( alkaline phosphatase).

Minerals (sodium, potassium and chloride) Suspended materials ; desquamated epithelial

cells and meconium.

Functions:

During pregnancy: Protects the fetus against injury. A medium for free fetal movement.. Maintains the fetal temperature. Source for nutrition of the fetus. A medium for fetal excretion. Essential for lung development .

During Labour: The fore-bag of water helps the dilatation of

the cervix. Antiseptic for the birth canal .

Techniques for Assessing AFV

Techniques for Assessing AFV By measurement at time of

hysterotomy . Dye dilution techniques.

Most accurate techniques but they are invasive .

Ultrasound : Commonly used , less invasive .

US methods for assessment of AFV:

Single deepest pocket Normal 2- 8 Cm. Oligohydramnios <2 Cm. Ployhydrmnios > 8 Cm. Less Accurate for low AFV.

Amniotic fluid index (AFI) Measurement and summation of deepest pocket in each of four quadrants Normal = 5.1-25 cm. Oligo ≤ 5 cm. Poly ≥ 25 cm. Hight false positive rates.

Amniotic Fluid Disorders

Polyhydramnios

Polyhydramnios Pathologic accumulation of amniotic

fluid. Defined as more than 2,000 mL at any

gestational age, more than the 95th percentile for gestational age, or an amniotic fluid index (AFI) greater than 25 cm at term.

Prevalence:• In 0.9% to 1.6% of women, some increase

in amniotic fluid is seen during pregnancy (80% mild, 5% severe).

Causes: Idiopathic (two thirds). Maternal diabetes. Multiple gestation. Fetal anomalies .

Risk Factors:

Fetal anomalies that impair swallowing or alter urine production.

Multiple gestation (twin–twin transfusion).

Maternal diabetes. Erythroblastosis.

a)Fetal Structural Malformations : Acrania or anencephaly due to : Impairment of the swallowing

mechanism. Lack of antidiuretic hormone with

resultant polyuria. Transudation of fluid across the

exposed fetal meninges

Fetal Structural Malformations:

Gastrointestinal malformations : Obstructions of the GI tract, such as

esophageal and duodenal atresia due to decreased absorption, as swallowing in these fetuses is usually normal.

Ventral wall defects : may result in increased AFV due to

transudation of fluid across the peritoneal surface or bowel wall .

B) Chromosomal and genetic abnormalities :

The most common abnormalities are trisomies 13, 18, and 21

C) Neuromuscular disorders : May cause excess AFV, likely due to

impaired swallowing .

D) Abruptio placentae : Is associated with polyhydramnios at

the time of rupture of membranes, due to rapid decompression of the overdistended uterus.

E) Isoimmunization : Can result in polyhydramnios

associated with hydrops fetalisF) Congenital infections : Such as toxoplasmosis,

cytomegalovirus, and syphilis Are rare causes of polyhydramniosG) Twin-to-twin transfusion syndrome

(TTTS): The recipient twin develops polyhydramnios

and, occasionally, hydrops fetalis, whereas the donor twin develops growth retardation and oligohydramnios.

H) Diabetes mellitus common cause of polyhydramnios , is

often associated with poor glycemic control or fetal malformations.

Fetal hyperglycemia may increase oncotic pressure, causing transudation of fluid across the placental interface to the amniotic cavity , as well as increased glomerular filtration rate.

I) Multiple Gestation:- Occurs in 5% to 8% of multiple

pregnancies, particularly with monoamniotic twins.

- Acute polyhydramnios before 28 weeks' gestation has been reported to occur in 1.7% of all twin pregnancies; the perinatal mortality in these cases approaches 90%.

Symptoms: There may be abdominal pain. Discomfort and dyspnoea. Indigestion. Oedema, increase of varicose veins and haemorrhoids.

Signs: The uterus is bigger than expected. Identification of the fetus and fetal parts is

difficult. The fetal heart is difficult to hear. Ballottement of the fetus is easy. Abdominal girth at the umbilicus is more than

100 cm before term. The abdominal girth varies a little — an ebb and flow.

Investigations:Ultrasonographic Examination

Necessary to both quantify amniotic fluid volume and identify multiple fetuses and fetal abnormalities .

Amniocentesis To obtain karyotype and fluid for viral

studies.

Treatment: Minor and moderate degrees of

polyhydramnios can be managed expectantly until the onset of labor or spontaneous rupture of membranes.

If the patient develops dyspnea, abdominal pain, or difficulty ambulating, treatment becomes necessary

A) Amnioreduction the most common treatment If performed, the rate of withdrawal

should be about 500 mL/hour and limited to 1500 to 2000 mL total volume or until the SDP < 8cm)

is less often associated with preterm labor than less frequent removal of larger volumes. Amnioreduction is repeated every 1 to 3 weeks as needed. Antibiotic prophylaxis is not necessary.

B) Pharmacologic treatment:

Indomethacin. Decrease fetal renal blood flow and

therefore fetal urine production. The greatest drawback of indomethacin

use is the potential closure of the fetal ductus arteriosus which has been detected as early as 48 hours after initiating therapy. Ductal closure is uncommon before 27 weeks.

Treatment is limited to pregnancies less than 32 weeks, and the duration of therapy is <48 hours.

Oilgohydramnios

Definition : AFI of less than the fifth percentile

for gestational age or less than 5 cm at term.

Risks of perinatal morbidity and mortality are particularly high when it is detected during the second trimester.

Perinatal mortality may approach 80% to 90% when it is detected during the second trimester .

Pulmonary hypoplasia.Lack expansion and Failure of

growth. Prolonged oligohydramnios in the

2nd and 3rd trimester can lead to deformation sequence in 10 - 15% characterized by facial , cranial and skeletal abnormalities .

Etiology : Ruptured membranes (most common) at any

gestational age. Fetal urinary tract malformations(renal

agenesis, dysgnesis outlet obstruction , NSAIDs , IUGR)

Placental insufficiency Postdate pregnancy : may be due to deterioration in placental

function causing a less efficient transfer of water from the mother to the fetus

Diagnosis History: ruptured membrane Examination: Fundal height less than expected for

gestational age. Rupture of membranes should be ruled

out via a sterile speculum exam. US examination: is necessary to

quantify amniotic fluid and to identify fetuses with IUGR or abnormalities.

Treatment Hydration of the mother : (transient

effect ) In cases in which oligohydramnios is caused

by obstructive genitourinary defect, in utero surgical diversion of urine flow has produced promising results.

Urinary diversion must be accomplished before the development of renal dysplasia and early enough in gestation to allow for lung development.

Until near term, oligohydramnios should be managed with frequent fetal surveillance.

Amnioinfusion. Induction of labor at 38 wks of gestation or

if nonreassuring fetal tests after 34 w.

Johns Hopkins Manual of Gynecology and Obstetrics. Oligohydramnios and. Polyhydramnios: Mechanisms and.

Therapy. Michael G. Ross, M.D., M.P.H.. Harbor-UCLA Medical Center. UCLA School of Medicine.

www.medscape.com J Matern Fetal Neonatal Med. 2002 Mar;11(3):167-70. Dye-

dilution techniques using aminohippurate sodium: do they accurately reflect amniotic fluid volume? Magann EF, Whitworth NS, Files JC, Terrone DA, Chauhan SP, Morrison JC. Source Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson, USA.

Am J Obstet Gynecol. 1992 Oct;167(4 Pt 1):986-94. Amniotic fluid volume assessment: comparison of ultrasonographic estimates versus direct measurements with a dye-dilution technique in human pregnancy. Dildy GA 3rd, Lira N, Moise KJ Jr, Riddle GD, Deter RL. Source Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas.

Netter, Obstetrics and Gynecology Second_Edition.