Dr Alexandra Stanislavsky and Dr Mohamed Refaey et al.


Polyhydramnios refers to a situation where the amniotic fluid volume is more than expected for gestational age.


It is generally defined as :



It can occur in approximately 1 - 1.5 % of pregnancies.

Clinical presentation

The patient may clinically present as a large for dates uterus


Polyhydramnios occurs as a result of either increased production or decreased removal of amniotic fluid. The aetiology of polyhydramnios can be due to a vast variety of maternal and fetal disorders. 

It is usually detected after 20 weeks (often 3rd trimester) due to the fetus not starting swallowing in early pregnancy. Fetal swallowing is a major route of removal of amniotic fluid.


The potential causes of polyhydramnios are protean


Polyhydramios is associated with poor outcome if present in combination with intra uterine growth restriction (IUGR).


Some classify the severity of polyhydramnios as 

  • mild : single deepest pocket at 8 - 11 cm
  • moderate : single deepest pocket at 12 - 15 cm
  • severe : single deepest pocket > 16 cm

Treatment and prognosis

The prognosis is variable dependent on associated conditions

Management options

Usually minimal or no interventional required for idiopathic mild uncomplicated cases. Options include


Ultrasound Obstet Gynecol. 2012 Jun;39(6):648-53. doi: 10.1002/uog.10093.

Maximal amniotic fluid index as a prognostic factor in pregnancies complicated by polyhydramnios.

Pri-Paz S, Khalek N, Fuchs KM, Simpson LL.


Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, New York 10032, USA. Αυτή η διεύθυνση ηλεκτρονικού ταχυδρομείου προστατεύεται από τους αυτοματισμούς αποστολέων ανεπιθύμητων μηνυμάτων. Χρειάζεται να ενεργοποιήσετε τη JavaScript για να μπορέσετε να τη δείτε.



Polyhydramnios is present in approximately 2% of pregnancies and has been associated with a variety of adverse pregnancy outcomes. Our aim was to evaluate the association between the maximal amniotic fluid index (AFI) and the frequency of specific adverse outcomes.


This was a retrospective chart review of 524 singleton pregnancies diagnosed with polyhydramnios and delivered in a single tertiary referral center between 2003 and 2008. Polyhydramnios was defined as either AFI ≥ 25 cm or a maximum vertical pocket (MVP) ≥ 8 cm even in the presence of AFI < 25 cm. The cohort was stratified into four groups based on the maximal AFI noted during the pregnancy: < 25 cm but with MVP ≥ 8 cm; 25-29.9 cm; 30-34.9 cm; and ≥ 35 cm. Data were collected to determine the frequency of the following adverse pregnancy outcomes: prenatally diagnosed congenital anomalies, fetal aneuploidy, preterm delivery, Cesarean delivery, low birth weight, 5-min Apgar score < 7 and perinatal mortality.


Higher AFI was associated with a statistically significant increase in the frequency of adverse pregnancy outcomes. The most severe form of polyhydramnios, as based on the maximal AFI (≥ 35 cm; n = 67), was associated with the highest rates of prenatally diagnosed congenital anomalies (79%), preterm delivery (46%), small-for-gestational-age neonate (16%), aneuploidy (13%) and perinatal mortality (27%). No significant association between degree of polyhydramnios and adverse outcome was demonstrated in cases of idiopathic polyhydramnios (n = 253).


There is an association between the frequencies of a variety of adverse pregnancy outcomes and the severity of polyhydramnios as reflected by the maximal AFI.

Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

Causes of polyhydramnios can include:
Multiple pregnancies
Rh incompatibility
Intrauterine infection
Gastrointestinal abnormalities
Maternal kidney or cardiac conditions
Maternal diabetes causing frequent fetal urination
Neurological abnormalities, including anencephaly
Annular pancreas due to malformation in pancreas development
Chromosomal abnormalities, including Down’s syndrome and Edwards syndrome
Fetal renal disorders that result in increased urine production, such as antenatal Bartter syndrome
Esophageal or duodenal astresia, or abnormal closing or absence of the esophagus or duodenum
Twin-twin transfusion syndrome, during which one twin receives excess blood flow and the other receives a shortage
  Gastrointestinal disorders, such as duodenal atresia, esophageal atresia, gastroschisis, and diaphragmatic hernia
  Brain and nervous system (neurological) problems, such as anencephaly and myotonic dystrophy
  A variety of other causes, such as poorly controlled diabetes,


Beckwith-Wiedemann syndrome




Source: http://www.umm.edu/ency/article/003267all.htm#ixzz2MDRKbQcM
Follow us: @UMMC on Twitter | MedCenter on Facebook - See more at: http://www.umm.edu/ency/article/003267all.htm#sthash.5t4FfehH.dpuf

Is polyhydramnios in an ultrasonographically
an indication for genetic evaluation?
normal fetus
Yoni Barnhard, MD, Itai Bar-Hava, MD, and Michael Y. Divon, MDBronx, New
CONCLUSIONS: (1) Polyhydramnios is associated with an increased incidence of congenital fetal
anomalies. (2) Growth-retarded fetuses with polyhydramnios warrant genetic evaluation. (3) A genetic
study is not absolutely indicated for patients with polyhydramnios and a sonographically normal fetus. (AM
J OBSTET GYNECOL 1995;173:1523-7.)
Barnhard Y, Bar-Hava I, Divon MY.
SourceDepartment of Obstetrics and Gynecology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

 Am J Med Genet A. 2009 Feb 15;149A(4):779-84. doi: 10.1002/ajmg.a.32778.
Polyhydramnios, fetal overgrowth, and macrocephaly: prenatal ultrasound findings of Costello syndrome.
Smith LP, Podraza J, Proud VK.

J Obstet Gynaecol Res. 2010 Aug;36(4):876-81. doi: 10.1111/j.1447-0756.2010.01257.x.
Case of polyhydramnios complicated by Opitz G/BBB syndrome.
Tajima H, Itoh H, Mochizuki A, Nakamura Y, Kobayashi Y, Hirai K, Suzuki K, Sugihara K, Ohishi A, Ohzeki T, Kanayama N.

Prenat Diagn. 1998 Jan;18(1):68-72.
Polyhydramnios as a prenatal symptom of the digeorge/velo-cardio-facial syndrome.
Devriendt K, Van Schoubroeck D, Eyskens B, Vantrappen G, Swillen A, Gewillig M, Dumoulin M, Moerman P, Vandenberghe K, Fryns

Pediatr Res. 2010 Mar;67(3):300-3. doi: 10.1203/PDR.0b013e3181ca038d.
Bartter syndrome prenatal diagnosis based on amniotic fluid biochemical analysis.
Garnier A, Dreux S, Vargas-Poussou R, Oury JF, Benachi A, Deschênes G, Muller F.
Bartter syndrome is an autosomic recessive disease characterized by severe polyuria and sodium renal loss. The responsible genes encode proteins involved in electrolyte tubular reabsorption. Prenatal manifestations, mainly recurrent polyhydramnios because of fetal polyuria, lead to premature delivery.

Prenat Diagn. 2008 Sep;28(9):796-9. doi: 10.1002/pd.1973.
Prader-Willi syndrome: is there a recognizable fetal phenotype?
Bigi N, Faure JM, Coubes C, Puechberty J, Lefort G, Sarda P, Blanchet P.
diminished fetal movement, polyhydramnios and oddly positioned hands and feet suggested PWS

Minerva Ginecol. 1997 Jan-Feb;49(1-2):49-52.
[A rare cause of polyhydramnios: Steinert's syndrome. A clinical case report].
Steinert's syndrome is a systemic disease with autosome mother-to-child transmission, characterized by myotonia and muscular dystrophia. The syndrome's clinical characteristics include: respiratory and alimentation diseases, facial diplegia, generalized hypotonia, areflexia, atrophy, arthrogryposis, hydramnios, retard in psychomotor development, cataract and genital disorders.

Noonan Syndrome
Includes: BRAF-Related Noonan Syndrome, KRAS-Related Noonan Syndrome, MAP2K1- Related Noonan Syndrome, NRAS-Related Noonan Syndrome, PTPN11-Related Noonan Syndrome, RAF1-Related Noonan Syndrome, SOS1-Related Noonan Syndrome
Disease characteristics. Noonan syndrome (NS) is characterized by short stature, congenital heart defect, and developmental delay of variable degree. Other findings can include broad or webbed neck, unusual chest shape with superior pectus carinatum and inferior pectus excavatum, cryptorchidism, characteristic facies, varied coagulation defects, lymphatic dysplasias, and ocular abnormalities. Although birth length is usually normal, final adult height approaches the lower limit of normal. Congenital heart disease occurs in 50%-80% of individuals. Pulmonary valve stenosis, often with dysplasia, is the most common heart defect and is found in 20%-50% of individuals. Hypertrophic cardiomyopathy, found in 20%-30% of individuals, may be present at birth or develop in infancy or childhood. Other structural defects include atrial and ventricular septal defects, branch pulmonary artery stenosis, and tetralogy of Fallot. Up to one third of affected individuals have mild intellectual disability.
Am J Med Genet. 2000 May 29;92(3):159-65.
Noonan syndrome: a cryptic condition in early gestation.
Achiron R, Heggesh J, Grisaru D, Goldman B, Lipitz S, Yagel S, Frydman M.
Department of Obstetrics and Gynecology, The Chaim Sheba Medical Center, Tel Hashomer, Israel.
Noonan syndrome is one of the most common of genetic syndromes and manifests at birth, yet it is usually diagnosed during childhood. Although prenatal diagnosis of Noonan syndrome is usually not possible, in a few cases the ultrasonographic findings suggested the diagnosis in utero. Reported sonographic clues include septated cystic hygroma, hydrothorax, polyhydramnios, and cardiac defects, such as pulmonic stenosis and hypertrophic cardiomyopathy. During a 6-year period, 46,224 live-born infants were delivered at the Chaim Sheba Medical Center. Seven newborn infants and four fetuses were found to have Noonan syndrome. One fetus showed transient nuchal translucency of 4 mm and bilateral neck cysts at the 13th gestational week. Both findings resolved spontaneously by the 18th gestational week, but during the third trimester this fetus developed hydrothorax, skin edema, and polyhydramnios. In the three other fetuses, first- and second-trimester ultrasonographic findings were normal, and the diagnosis of Noonan syndrome was suggested only during the third trimester. All three fetuses had polyhydramnios and skin edema. A cardiac malformation, hydrothorax, and a large head were present in one fetus. Sonographic facial findings were investigated. In all four fetuses posteriorly angulated, apparently low-set ears and depressed nasal bridge were identified. Wide nasal base was seen in two fetuses. In two fetuses, persistent opening of the fetal mouth was interpreted as fetal hypotonia. One fetus developed progressive postnatal hypertrophic cardiomyopathy and in one case, pulmonic stenosis became apparent at age 6 months. This small series suggests that Noonan syndrome has an evolving phenotype during in utero and postnatal life. Amelioration of early nuchal region findings and late onset of the more "typical" ultrasonographic changes may limit early prenatal detectability.
Children with Noonan syndrome are afflicted with cardiovascular,
hematological, and muscular problems, in addition to a distinct physical
appearance and, in most cases, learning disabilities. The majority,
however, will grow up and function quite normally in the adult world.
There is still much to learn about the natural history of Noonan
syndrome. Close follow-up of patients with the neuro-cardio-faciocutaneous
syndromes as they age may be helpful in our understanding
of how the RAS-MAPK pathway affects the development and aging
process of these patients. With continued research, it is hopeful that we
may someday be able to alleviate or at least modify the adverse effects
these germline mutations play in development.


Magann EF, Dajani NK. How do we evaluate amniotic fluid volume

How do we evaluate amniotic fluid volume in twins?


EF Magann, NK Dajan


Twin pregnancies are at increased risk, compared to singleton pregnancies, for spontaneous abortions, malformations, low birth weight neonates, and preterm deliveries. Additionally the pregnancies are at greater risk for gestational diabetes, hypertension/ preeclampsia, acute fatty liver, and placental abruption. Because of these increased risks for pregnancy complications and adverse pregnancy outcomes, the assessment of amniotic fluid volume is even more important in twin pregnancies during the fetal anatomic survey, growth assessment, and as a component of antenatal testing.


Normal amniotic fluid volume in twins

In Order to be able to evaluate abnormal amniotic fluid volume in twin pregnancies, normal volume must first be defined. The only study that was embarked upon to address this question, evaluated amniotic fluid volume between 27-38 weeks in diamniotic twin pregnancies. 1 The investigators observed that the volumes per individual amniotic fluid sac ranged from 155 – 5430 ml with a mean of 877 ml which is similar to that observed in singleton pregnancies. The volumes of each sac were determined by the validated dye-determined volume techniques of Charles and Jacoby. 2 This technique is invasive and requires laboratory support and is not practical for the day to day assessment of amniotic fluid volume. The need for a more viable alternative has led to the ultrasound estimate of amniotic fluid volume. Several ultrasound methods have been used to estimate the amniotic fluid volume in twins including the amniotic fluid index, single deepest pocket (SDP), two diameter pocket (2DP) and the subjective assessment of the amniotic fluid volume.

Ultrasound estimate of amniotic fluid volume in twin


Amniotic Fluid Index (AFI)


In singleton pregnancies, the estimation of the amniotic fluid volume by the AFI is customarily done by the technique described by Phelan. 3 The uterus is divided into 4 quadrants: by the umbilicus transversely into upper and lower quadrants and by the linea nigra into right and left halves. With the ultrasound transducer held perpendicular to the floor, the largest vertical pocket of fluid within each quadrant without an aggregate of cord or fetal small parts is measured in centimeters. To be a measurable pocket, the pocket must be at least 1 cm in the horizontal measurement throughout the pocket. (Figure 1 and 2) A depth of 0-5 is labelled as oligohydramnios, 5-24 or 5-25 as normal, and ≥ 24 or ≥ 25 as hydramnios. In twin pregnancies, the summated AFI has been used by a number of investigators to estimate the amniotic fluid volume. 4-6 This estimate is done in a manner similar to the technique used in singleton pregnancies by dividing the abdomen into four quadrants. The largest pocket in each quadrant is measured and summed giving the summated AFI. Membrane placement is not taken into consideration in measuring the summated AFI. (Figure 3) When the accuracy of the summated AFI was evaluated by dye-dilution techniques; the summated AFI identified 94% of twin pairs as having normal amniotic fluid volume when only 52% had normal volumes. In 20 of the 62 twin pairs with discordant amniotic fluid volume by dye-determination, the summated AFI identified the discordant volumes as normal in 90%. The summated AFI identified 8 of the 10 twin pregnancies with low volumes in both sacs by dye-determination as normal amniotic fluid volume.7 High and low volumes of amniotic fluid may well co-exist in twin pregnanciesas summated AFI poorly detects discordant volumes by not taking membrane placement into consideration. (Figure 4) A number of other techniques have been used under the category of AFI to determine the amniotic fluid volume in twins. Gerson et al 8 estimated the amniotic fluid volume by identifying the dividing membrane between the twins and, using the fetal diaphragm, divided the amniotic fluid sac into upper and lower halves measuring the largest pocket free of umbilical cord in centimetres and summed the measurement providing a two quadrant AFI. (Figure 5) Hill et al 9 detected each fetus and its surrounding amniotic sac and, using the fetus as the vertical axis in the sac, measured the largest vertical pocket in the 4 quadrants of the sac surrounding the fetus. The AFI was the summation of these 4 measurements. (Figure 6) Neither of these techniques has been validated by a dye-determined amniotic fluid volume. Magann et al 10 identified the separating membrane between the twins and measured the largest vertical pocket of fluid in each quadrant that the fetus and the sac occupied. Figure 7) The fetus and sac occupied two quadrants and the summed measurement was the sum of the largest vertical pocket in those two quadrants. An AFI of ≤ 5cm was regarded as oligohydramnios, 5-20 as normal, and ≥ 20 as hydramnios. The AFI was then compared with dye determined fluid volume, the AFI technique was able to correctly classify fluid volumes between 500 – 2000 ml in 47 of 48 cases (98%), but poorly identifies volume < 500 ml in 7 of 35 cases (20%) or > 2000 ml in 0 of 7 cases (0%). 10

Single Deepest Pocket (SDP)

In singleton pregnancies, the estimation of the amniotic fluid volume by the SDP is usually done by the technique as described by Chamberlain. 11 With the ultrasound transducer held at a right angle to the uterine contour, the vertical and transverse diameters of the largest pocket of fluid were measured. The width of the largest pocket of amniotic fluid was measured at a right angle to the depth of the measurement. In all cases except for those with severe oligohydramnios (vertical pocket of < 1 cm) the width of the pocket was ≥ 1 cm. A depth of < 1 cm was severe oligohydramnios, 1-2 cm as oligohydramnios and > 2cm to < 8 cm was labelled as normal. It was in a companion article in the same journal that a largest vertical pocket of ≥ 8 was labelled as polyhydramnios. 12 In neither article were the issues of fetal small parts or umbilical cord in the pocket addressed. Chamberlain did not address how the amniotic fluid volume in twins should be estimated. Currently many clinicians measure the largest pocket without umbilical cord or fetal small parts or only if their appearance is transient. In the estimation of amniotic fluid volume using the SDP in twins, the separating membrane is located and the largest vertical pocket of amniotic fluid volume in each sac is measured in centimetres. (Figure 8) A measurement of ≤ 2 cm is classified as oligohydramnios, 2-8 cm as normal, and > 8 cm as hydramnios, the same measurement thresholds that are used in singletons. A comparison of the SDP to a dye determined fluid volume revealed that the SDP was able to correctly classify fluid volumes between 500 – 2000 ml in 47 of 48 cases (98%), but poorly identifies volume < 500 ml in 1 of 35 cases (3%) or > 2000 ml in 0 of 7 cases (0%). 10

2-Diameter Pocket

In singleton pregnancies, the 2-dameter pocket technique is the vertical measurement multiplied by the horizontal measurement of the largest identified pocket of amniotic fluid. A two-diameter pocket of ≤ 15 cm2 was classified as oligohydramnios, 15 – 50 cm2 as normal fluid volume and ≥ 50 cm2 as polyhydramnios. 13 In twin pregnancies, the separating membrane is identified and the largest pocket of fluid in each sac without fetal small parts or umbilical cord is identified and the horizontal measurement is multiplied by the vertical measurement. (Figure 9) The same values used for oligohydramnios, normal and polyhydramnios in singletons are also used for twins. A comparison of the 2DP to a dye-determined fluid volume revealed that the 2DP was able to correctly classify fluid volumes between 500 – 2000 ml in 39 of 48 cases (81%), identified volume < 500 ml in 20 of 35 cases (57%)and > 2000 ml in 1 of 7 cases (14%). 10

Subjective Assessment


The subjective assessment of amniotic fluid volume is the visualization of the amniotic fluid volume by an experienced sonographer and estimating if the fluid volume is low, normal or high based on visualization alone, without measurements. 10 In an investigation evaluating the subjective assessment of amniotic fluid volume in singleton pregnancies with multiple ultrasound estimates including the SDP, 2DP, and the AFI, the subjective assessments were similar in accuracy with the objective ultrasound measurements in classifying volumes of fluid as oligohydramnios, normal and polyhydramnios with those volumes validated by dye-determination techniques. A similar study was carried out in twin pregnancies and the subjective and objective evaluation were found to be similar in the identification of amniotic fluid volumes in each sac of a twin pregnancy, the volume validated by dye-dilution techniques. The recognition of low volumes was poor, ranging from 7-29%.


Twin pregnancies are at significantly higher risk for pregnancy complications, perinatal morbidity and mortality compared to singleton pregnancies. Amniotic fluid volume in normal diamniotic twin pregnancies in the third trimester of pregnancy is similar to the normal volumes in singleton pregnancies in the third trimester. The amniotic fluid volume can be measured accurately in each sac but the techniques to measure those fluid volumes are impractical for everyday use. The summated AFI, by not considering membrane placement, is not able to recognize individual low or high sac volumes and shouldn’t be used to estimate amniotic fluid volume. The other techniques evaluating individual sac volume; AFI, SDP, 2DP, and subjective assessment are all able to reasonably identify normal amniotic fluid volume, but poorly recognize oligohydramnios and polyhydramnios.




Chorioamniotic Separation



The amnion and chorion are seen as separate membranes early in pregnancy. The images below show the normal appearance of the membranes at 8 and 12 weeks. By about 18 weeks into the pregnancy, the membranes fuse together, against the wall of the uterus. Sometimes, however, the membranes do not fuse on schedule, and this persistent chorioamniotic separation has importance implications for pregnancy outcomes.


Drs. Ulm and colleagues (Ulm: Unfused Amnion and Chorion After 14 Weeks of Gestation: Associated Fetal Structural and Chromosomal Abnormalities) have suggested that failure of the membranes to fuse after 14 weeks may flag pregnancies at increased risk for chromosomal aneuploidy and/or structural malformations. We typically expect the membranes to be fused by 16 to 17 weeks.


A key article regarding chorioamnionic separation is: Bromley: Amnion-Chorion Separation After 17 Weeks Gestation. Obstetrics and Gynecology, 1999; 99:1024-6. This is the largest single series of patients with chorioamnionic separation, and Drs. Bromley, Shipp, and Benacerraf drew the conclusion that “Complete amnion-chorion separation that persisted after 17 weeks gestation is associated with a variety of adverse perinatal outcomes, including aneuploidy.” Specifically, among the 15 reported pregnancies, 10 had membrane separation only after amniocentesis. Their conclusions were similar to what we see in other series. Among their 15 patients, 10 resulted in live newborns (1 with Down syndrome). Five of the ten delivered preterm, and there were two babies with IUGR.



Levine and colleagues reviewed the literature specifically regarding chorioamnionic separation after second trimester genetic amniocentesis (Levine, et al.: Radiology, 1998; 209-:75-81). In cases reported prior to their study, and included in their literature review, there were 25 patients with complete separation, 8 of whom had term deliveries, 11 were born prematurely, and there were 5 fetal demises. Among the seven new cases reported by Dr. Levine and colleagues, there were three deaths, and two preterm deliveries.


The picture at the left shows the ultrasound appearance of chorioamniotic separation. The ultrasound picture shows a slice through the wall of the uterus. The small arrows indicate the amnion, the inner membrane. The larger arrows indicate the chorion, the outer membrane. (The arrow facing down is on the baby)

It is very difficult to make prognostications about any individual pregnancy with chorioamnionic separation because of the relatively small numbers of patients in the public series. There are individual cases that highlight potential concerns. For example, Barak (Journal of Ultrasound and Medicine, 2003; 22:1283-88) reported a case in which apparent chorioamnionic separation was due to a large clot between the membranes, and this differentiation vs chorioamniotic separation must be borne in mind-. Graf and colleagues (Chorioamnionic Membrane Separation: A Potentially Lethal Finding. Fetal Diagnosis and Therapy, 1997; 12:81-4) reported fetal demise in utero due to a twisting of the separated membranes about the cord, an observation that has been made in other reports and series as well. There is one case report of a serious fetal skin condition occurring in relation to chorioamnionic separation in two pregnancies of one woman (Kim: Complete Chorioamnionic Membrane Separation with Fetal Restrictive Dermopathy in Two Consecutive Pregnancies. Prenatal Diagnosis, 2007; 27:352-5)


What can we offer in terms of reducing the chance for an adverse perinatal outcome in a pregnancy affected with chorioamnionic separation?

1. First, there is, at least in theory, the potential for evolution of chorioamnionic separation to bands or limb entanglement by membrane. This can be monitored by ultrasound.

2. The association with preterm birth may be due to relative weakening of the membranes due to the separation. In this regard, we would recommend maternal education regarding signs and symptoms of preterm labor, and also consideration of monitoring of cervical length by scan.

3. Because of the possible association with IUGR, monthly scans to assess fetal growth would be recommended.

4. With respect to the association with fetal demise in utero, unfortunately, the mechanism seems to be due to twisting of the membranes around the base of the cord,

which would not necessarily be predictable/preventable. To reduce the risk of fetal demise we typically recommend:

a. Scrupulous daily kick counts starting at 26 weeks gestation, and

b. initiation of twice-weekly nonstress tests and fluid checks, possibly as early as 28 weeks gestation, for ongoing assurance regarding fetal health.