The history and physical examination may often be unhelpful in most cases of idiopathic polyhydramnios, which is discovered incidentally. In the patient with clinical symptoms consistent with or ultrasound findings diagnostic of polyhydramnios, however, the history obtained should focus on the presence of risk factors for polyhydramnios. Screening is recommended for impaired glucose intolerance, sexually transmitted diseases, congenital infections, risk factors for maternal or fetal anemia, and alloimmunization. The evaluation of the persistent decreased maternal perception of fetal movement may prompt a further workup for neurologic conditions that cause decreased neuromuscular function.[1][6][7] Patients diagnosed and affected by polyhydramnios may be asymptomatic or present with clinically significant maternal dyspnea secondary to excessive amniotic fluid resisting diaphragmatic movement.

Clinical exam findings present in symptomatic patients with severe polyhydramnios include the tightness of the maternal abdomen and swelling of the lower extremities. A fundal height > 3cm above expected gestational age or rapid uterine enlargement warrants fetal growth assessment and fluid assessment to rule out macrosomia or polyhydramnios. It is often in the context of fetal growth scans or ultrasound for the evaluation of other pregnancy-related conditions that the diagnosis of polyhydramnios is made.[1][6] The patient may present in preterm labor or premature rupture of membranes and excessive amniotic fluid may result in a non-vertex fetal presentation or cord prolapse.[2][3][4] Labor dystocia or fetal macrosomia may warrant the need for cesarean delivery.[15] The patient may demonstrate signs of postpartum hemorrhage as this risk is increased in polyhydramnios due to the overdistension of the uterus from excessive AFV.[2][6][16]

Ultrasound (US) is diagnostic for polyhydramnios and a useful diagnostic tool for fetal evaluation.[1][17] Amniotic fluid assessment is performed with a single deepest pocket (SDP) or amniotic fluid index (AFI) and can be used to determine the severity of polyhydramnios.[6][18]

SDP measurement is performed by dividing an abdomen into 4 imaginary quadrants bisecting the umbilicus and measuring the single largest vertical pocket with the probe placed perpendicularly to the maternal abdomen. Measurements less than 2 cm indicate oligohydramnios. Normal AFV ranges from 2 to 8 cm. Measurements greater than 8 cm indicate polyhydramnios with mild polyhydramnios defined as 8-11 cm, moderate polyhydramnios between 12-15 cm, and severe polyhydramnios greater than 16 cm. This is the more commonly practiced method due to its simplicity and comparability to the alternative method.[1][6][7][18]

AFI is the quantitative sum of the vertical amniotic fluid measurement in 4 abdominal quadrants. The US transducer is placed perpendicularly to the maternal abdomen. The measured fluid should be at least 0.5 cm in width and be devoid of the umbilical cord or fetal extremities. A measured AFV of 5-25 cm is within normal limits. Values of less than 5 cm indicate oligohydramnios. Polyhydramnios is defined as a value greater than or equal to 25 cm and can be further classified into mild (25-30 cm), moderate (30.1-35 cm), or severe (>35 cm). Color Doppler can be utilized to identify the presence of the umbilical cord.[1][6][7]

When polyhydramnios is diagnosed the evaluation should focus on identifying an underlying cause. The most common causes of polyhydramnios are gestational diabetes and fetal anomalies. Anatomy US is routinely performed for all patients between 18-22 weeks of fetal gestational age to assess for fetal abnormalities and identify multiple gestations. In severe polyhydramnios, a fetal US anatomy evaluation should screen for congenital abnormalities including oral, esophageal, tracheal, or intestinal deformities, central nervous system defects, cardiac septal defects, pulmonary masses, diaphragmatic hernia, urogenital abnormalities, evidence of hydrops fetalis, anatomic findings consistent with trisomies, and placental masses.[1][6][7] Patients with polyhydramnios should be evaluated for macrosomia or intrauterine growth restriction. Polyhydramnios is associated with fetal macrosomia >4000g in 15-30% of cases as larger fetuses have increased urine output.[6]

There is no consensus regarding the frequency and interval of growth scans but interval growth scan and antepartum testing in the third trimester may direct delivery timing.[6][7] Antenatal testing in the third trimester with nonstress tests and serial ultrasounds to assess fluid levels is indicated in mild and severe polyhydramnios due to increased perinatal morbidity and mortality. Additionally, the progression of amniotic fluid may be assessed with serial ultrasounds to determine whether reductive amniocentesis is indicated in the symptomatic patient.[1][6] For suspected fetal anemia due to hydrops fetalis middle cerebral artery peak systolic velocity measurement can assist with diagnosis as a peak systolic velocity > 1.5 MoM correlates with fetal anemia. US is also useful in determining fetal presentation as polyhydramnios is associated with breech presentation.[1][6][7]  

Laboratory studies may help identify an underlying cause for severe polyhydramnios. All pregnant patients are tested for impaired glucose tolerance at 28 weeks gestations or earlier if at increased risk for gestational diabetes (i.e. primary family history, previous history of diabetes, or obesity with BMI > 30 kg/m2). Diabetes screening should be assessed to rule out maternal hyperglycemia as this is a common cause for polyhydramnios. In severe polyhydramnios screening for congenital infections includes a VDRL for syphilis, IgM and IgG for rubella, and labs for other TORCH infections including HIV, hepatitis, CMV, and toxoplasmosis. Additionally, amniocentesis and karyotyping may help diagnose genetic abnormalities including trisomy 21, 18, and 13 but are not recommended for mild cases.[1][6][7]

In the setting of maternal hemorrhage or risk for fetal anemia maternal blood type should be assessed to identify for risk for alloimmunization. The Rosette test can detect maternal-fetal hemorrhage by the presence of fetal D+ cells in maternal Rh-negative cells. Rh immunoglobulin should be administered for a positive Rossette test and the dose is determined by the Kleihauer-Betke test. Fetal hydrops should prompt maternal antibody screening for D, C, Lewis, Kell, Duffy, and Kidd antibodies, which cause hemolytic disease of the newborn. In unclear etiologies of fetal anemia maternal screening should also be performed for maternal hemolytic anemia risk factors including Barts hemoglobin for alpha thalassemia.[1][6]

The treatment varies based on the severity of polyhydramnios and its underlying cause. Idiopathic and mild polyhydramnios rarely require any treatment.[1][6] A maternal-fetal medicine consult is recommended in severe and symptomatic polyhydramnios or in the setting of a known fetal anomaly to initiate interval ultrasounds for growth and fetal assessment to determine delivery timing and mode. Delivery is recommended at a tertiary facility due to potential maternal and neonatal morbidity and mortality associated with severe polyhydramnios.[1][6] Additionally, the consultation of a maternal-fetal medicine specialist is indicated for symptomatic severe polyhydramnios for reductive amniocentesis and treatment for twin-twin transfusion syndrome. Selective fetoscopic laser photocoagulation or laser therapy is indicated in severe cases of twin-twin transfusion syndrome to ablate placental anastomosis and is performed at specialized pediatric centers by fetal surgeons.[19]

Reductive amniocentesis is beneficial and recommended only as a symptomatic treatment for patients with significant respiratory complaints associated with restricted diaphragmatic movement and for those with significant discomfort associated with excessive amniotic fluid.[1][6] The procedure timing varies based on maternal symptoms and on average 1.5 to 3L of amniotic fluid may be withdrawn.[20][21] [20]Significant adverse events post amniocentesis are uncommon but include preterm labor, placental abruption, and premature rupture of membranes.[21][22] Polyhydramnios usually recurs after amnioreduction making the efficacy of amnioreduction limited.[6] Serial AFV monitoring is indicated every 1 to 3 weeks post-procedure.[1][6] 

Indomethacin, a prostaglandin synthetase inhibitor, has demonstrated the ability to decrease amniotic fluid volumes and is useful as a tocolytic in preterm labor.[6][23] The dose is 2.2 to 3mg/kg/day and started at 24 weeks and discontinued at 35 weeks.[24] Moise postulated that a dose of 25mg Q6hrs was adequate for the treatment of fluid reduction in polyhydramnios.[25] Indomethacin use results in a transient decrease in fetal urine output but is also associated with neonatal complications including premature closure of the ductus arteriosus, oligohydramnios, periventricular leukomalacia, and necrotizing enterocolitis.[6] Its use in polyhydramnios should be restricted to severe cases of symptomatic polyhydramnios with preterm labor and the society of Maternal-Fetal Medicine recommends against the use of indomethacin solely to decrease amniotic fluid.[6]  

The timing of delivery is dependent on the severity of polyhydramnios, underlying congenital malformations, and presentation of preterm labor or premature rupture of membranes. Mild and idiopathic polyhydramnios are not indications for induction of labor and the mode of delivery should be based on the usual labor characteristics determined by maternal and fetal factors. In laboring patients with polyhydramnios, an ultrasound should be performed to determine fetal presentation. An external cephalic version may be performed for breech presentation in the absence of contraindications. Continuous fetal monitoring is recommended during labor. There is an associated risk for delayed 1st stage of labor due to over uterine distension and an increased rate of amniotomy. Cord prolapse risk is increased due to the lack of fetal head engagement, which warrants cesarean delivery. Cesarean delivery risk increases with delayed labor progression and other factors including fetal macrosomia.[1][6]

Shoulder dystocia risk is increased due to fetal macrosomia risk with reported increased incidence of fetal weight > 4000g.[26] Pediatric support should be available in neonates affected by polyhydramnios as there is an increased incidence of transient tachypnea of the newborn, which results in increase NICU admissions. Postpartum hemorrhage risk is increased due to uterine atony from uterine overdistension. Preparation should be made to respond to postpartum hemorrhage.[1][6]

There is no consistent evidence to support bed rest to prevent complications associated with polyhydramnios and bed rest is associated with increased risk for venous thromboembolic disease in pregnancy.[27][28]

The differential diagnosis is broad and includes disease processes leading to rapid abdominal enlargement such as volume overload states (cirrhosis, ascites, congestive heart failure, end-stage renal disease, pre-eclampsia), chorioangioma, hematoma in placental abruption, or multiple gestations. An enlarging uterus may also result in symptoms of dyspnea. Dyspnea is a common symptom complaint in pregnancy and can be secondary to a venous thrombotic event such as pulmonary embolism, reactive airway disease or exacerbation of a chronic pulmonary condition, cardiac arrhythmia or pregnancy induce cardiomyopathy, musculoskeletal disorder, or infection. Edema of the extremities can also be seen in normal pregnancies, pre-eclampsia or pregnancy-induced hypertensive disorders, varicose veins or venous insufficiency, or deep vein thromboses.

The prognosis for mild idiopathic polyhydramnios is excellent. Maternal and fetal prognosis decreases with the severity of polyhydramnios. The majority of cases of idiopathic polyhydramnios resolve on their own.

The risk of complications increases with overdistension of the uterus. These include maternal dyspnea, preterm labor, premature rupture of membranes, breech presentation, umbilical cord prolapse, postpartum hemorrhage, fetal macrosomia associated maternal diabetes, hypertensive disorders, as well as urinary tract infections. 

Data on the intrauterine fetal demise in polyhydramnios is inconsistent. Severe and rapidly progressing polyhydramnios is an independent risk factor for perinatal mortality. In addition small for gestational age fetuses that are found to have polyhydramnios have the worst prognosis. The prognosis is directly correlated to the underlying cause of polyhydrmanios.[1][6]

Polyhydramnios is associated with underlying conditions which increase the risk for poor maternal and neonatal outcomes. Polyhydramnios is complicated by a higher incidence of intrauterine fetal demise, preterm labor, premature rupture of membranes, cord prolapse, fetal macrosomia, breech presentation, cesarean delivery, and postpartum hemorrhage. The complications of polyhydramnios are dependent on the excessive amniotic fluid volume which contribute to uterine distension, which is a significant risk factor for postpartum hemorrhage due to uterine atony.

Additionally, polyhydramnios is associated with the increased risk for cesarean delivery due to several factors including the increased risk for breech presentation, umbilical cord prolapse, and labor dystocia. Other complications of polyhydramnios may be correlated directly with the disease processes which altered the normal amniotic fluid equilibrium resulting in increased amniotic fluid. Fetal macrosomia, which is commonly seen in gestational diabetes is an increased risk factor for neonatal hypoglycemia, shoulder dystocia, and cephalopelvic disproportion requiring cesarean delivery.

In severe polyhydramnios, maternal-fetal medicine should be consulted for antenatal testing to include ultrasound evaluation for anatomic abnormalities, serial growth scans for macrosomia or intrauterine growth trestriction, non-reactive stress testing for fetal assessment, assessment of middle cerebral artery peak systolic velocity measurement to assess for fetal anemia, management of twin-twin transfusion syndrome, the potential need for indomethacin and reductive amniocentesis for symptomatic polyhydramnios, and recommendations for timing of delivery. Fetal surgery consultation is indicated for laser therapy to treat severe twin-twin transfusion syndrome. The pediatric team including neonatologist, pediatric pulmonologists, and cardiologists, as well as surgeons.

Polyhydramnios is an abnormal excess of amniotic fluid in pregnancy.

Polyhydramnios should be evaluated for an underlying cause with anatomy ultrasound and labs. Screening should also be performed for diabetes as this is a common condition associated with polyhydramnios.

The treatment for polyhydramnios depends on the degree of amniotic fluid and whether a patient has significant symptoms including difficulty breathing, significant abdominal discomfort due to a tense abdomen, or significant extremity swelling.

Amniotic fluid can be reduced through direct removal using a needle by a specialized doctor or using medicine to cause a decrease in the volume. Both of these procedures have risks including early labor, premature rupture of membranes or harm to the growing baby. The need for these treatments will be determined by your doctor.

Bed rest is not found to be helpful to treat this condition and can increase the risk of a blood clot, which can be life-threatening.

A growth scan should be performed as polyhydramnios is associated with babies with high birthweights > 4000g. Antenatal testing can be performed to monitoring the baby's well being in the third trimester. This would be determined by your doctor. This testing can help determine the timing of delivery. 

The birth of your baby should occur at a higher level care center with the capability for fetal monitoring, operative delivery, a neonatal intensive care unit and available specialists including obstetricians, a neonatologist (specialized newborn doctor), and other providers who can respond to maternal and neonatal emergencies.

• It is recommended that the infants affected by severe polyhydramnios be delivered at a tertiary care center.
• Patients with polyhydramnios should be screened for gestational diabetes.
• Reductive amniocentesis should be reserved for severe symptoms of polyhydramnios including maternal respiratory symptoms or severe discomfort.
• Indomethacin should not be used solely for the diagnosis of polyhydramnios.
• There is an increased risk for postpartum hemorrhage due to uterine atony from uterine overdistension.

Polyhydramnios is a pathologic excess of amniotic fluid in pregnancy that warrants workup for any underlying cause as the etiology, severity, and patient's symptoms dictate further evaluation and treatment. Most patients with mild cases of polyhydramnios should be evaluated for gestational diabetes, which along with fetal anomalies that affect swallowing are two of the most common causes of polyhydramnios. A fetal anatomy ultrasound should be performed to assess for congenital anomalies. Idiopathic polyhydramnios is a diagnosis of exclusion. However severe polyhydramnios may be secondary to significant fetal or maternal underlying disease processes.

As there are numerous potential etiologies the initial workup can be quite extensive. Additionally, these patients may exhibit no specific signs and symptoms or may demonstrate significant dyspnea and discomfort in pregnancy as well as signs of peripheral edema. Polyhydramnios is often an incidental finding in the third trimester during the sonographic evaluation of another pregnancy-associated concern. The evaluation and management of a patient with polyhydramnios may be a challenging endeavor.

The finding of polyhydramnios is often an incidental finding in the third trimester and the severity is dependent on the extent of amniotic fluid volume. The initial evaluation may be performed in various settings including the obstetric clinic, family practice clinic, or obstetric triage. Obstetricians, midwives, family medicine physicians, and residents may be involved in the care of patients affected by polyhydramnios. In severe polyhydramnios, it is important to consult with an interprofessional team including specialists in the field of maternal-fetal medicine, neonatology, and fetal surgery. The nurses are also vital members of the multidisciplinary team as they will monitor the patient's vital signs and provide education to the patient and family. The radiologist also plays a vital role in determining the cause through the interpretation of the anatomy ultrasound performed. The laboratory also provides diagnostic support for the evaluation of diagnostic laboratory screening for maternal diabetes, congenital abnormalities, and trisomies. Effective communication is important in assuring safe, current, and evidence-based practice to ensure the best outcomes for the patients.

The outcomes of polyhydramnios depend on the underlying cause. To improve outcomes in severe and symptomatic polyhydramnios, prompt consultation with a maternal-fetal medicine consult. The Society of Maternal-FetalMedicine has provided specific recommendations regarding the evaluation and care of patients with polyhydramnios. [6] 

It is suggested that polyhydramnios in singleton pregnancies be defined as either a DVP> 8cm or an AFI >24 cm (Grade 2C).

Recommendations are that amnioreduction is considered only for the indication of severe maternal discomfort, dyspnea, or both in the setting of severe polyhydramnios (Grade 1C).

It is recommended that indomethacin should not be used for the sole purpose of decreasing amniotic fluid in the setting of polyhydramnios (Grade 1B).

It is suggested that antenatal fetal surveillance is not required for the sole indication of mild idiopathic polyhydramnios (Grade 2C).

Recommendations are that labor should be allowed to occur spontaneously at term for women with mild idiopathic polyhydramnios; gestation in the absence of other indications; and that mode of delivery should be determined based on usual obstetric indications (Grade 1C).

It is recommended that women with severe polyhydramnios deliver at a tertiary center due to the significant possibility that fetal anomalies may be present (Grade 1C).