Prevalence of Congenital Anomalies in Polyhydramnios : A Hospital based study from Western Nepal

Introduction: Polyhydramnios is excessive amount of amniotic fluid in relation to gestational age. It is frequently associated with congenital anomalies of the fetus. The aim of this study was to see the prevalence of congenital anomalies in polyhydramnios. Methods: Singleton pregnant irrespective of gestational age with amniotic fluid index more than 25 were included in the study. Degree of polyhydramnios was graded as mild, moderate and severe. Detail study of fetus was done for possible congenital anomalies. Congenital anomalies were confirmed with post-natal findings. Results: There were 39 pregnant women with amniotic fluid index (AFI) > 25 cm. Prevalence of polyhydramnios was 0.3%. Congenital anomalies were present in 31.6 % of pregnant women with polyhydramnios. In pregnant women with severe polyhydramnios; 66.6 % had congenital anomalies. Central nervous system, gastrointestinal and skeletal anomalies were the frequent anomalies associated with polyhydramnios. Conclusion: Polyhydramnios is associated with increased risk of congenital anomalies hence a detail survey of fetus should be done for possible congenital anomalies.


INTRODUCTION
The amniotic fluid is required for the proper growth and development of the fetus.The fetus is prevented from trauma by its cushion effect.It also acts as a barrier against infection and helps in fetal lung maturity.It varies with gestational age.Fetal urine; secretion from fetal lung, oral and nasal cavities; movement of water and metabolites Licensed under CC BY 4.0 International License which permits use, distribution and reproduction in any medium, provided the original work is properly cited between the placenta and the fetal blood and transudation of water and electrolytes across the amnion and chorion; movement of water across fetal skin and fetal swallowing are the sources influencing amniotic fluid volume. 1 Polyhydramnios is the excess of the amniotic fluid relative to the gestational age.It occurs in 1% of pregnancies. 2It may be associated with adverse fetal and maternal outcome.The aim of this study was to find the association between polyhydramnios and congenital malformations in pregnant women of western Nepal.To the best of our knowledge, no such study has been done in our part.

METHODS
This prospective study was conducted in the department of Radiology between January 2014 and June 2016.All the singleton pregnant ladies irrespective of gestational age with amniotic fluid index more than 25 were included in the study.Ultrasonography was done in supine position in GE Logiq P3 machine.Ultrasound transducer was held along the maternal longitudinal axis and was held perpendicular to the floor during measurement of amniotic fluid index.External pressure over maternal abdomen with transducer was avoided.Uterus was divided into four imaginary quadrants.Measurement was done in the pocket free of fetal limbs and umbilical cord.Amniotic fluid index was calculated by summation of deepest pocket in each quadrant.The degree of polyhydramnios was categorized as mild (AFI: 25.1-30cm), moderate (AFI: 30.1-35 cm) and severe (AFI>35 cm). 3,4,5Ladies with chronic illness, cardiac disease and multifetal pregnancy were excluded.
Detailed anomaly scan was done to look for congenital malformations.All the pregnant ladies were followed till delivery.Detailed physical examinations of new born babies were done and evaluated for congenital malformation.
Prior approval from the institutional review was done before the study.

RESULTS
There were 39 pregnant ladies with amniotic fluid index (AFI) of >25 cm during the study period.One of the pregnant lady with history of cardiac disease was excluded from the study.A total of 38 pregnant ladies with polyhydramnios were included for statistical analysis.Total deliveries during that period were 10,342.So the prevalence of polyhydramnios was 0.3%.
Mean age of the pregnant ladies was 28.8±6.3years.Most of the ladies were in the age group of 26-30 years (Table 1).Half of the ladies were more than 37 weeks of gestation at the time of examination (Table 2).1).

Figure 1: Diagram showing distribution of congenital anomalies
Among the various congenital malformations diagnosed by ultrasonography; central nervous system (CNS), Gastrointestinal (GI) and Skeletal malformations were the commonest (Table 4).
Congenital anomalies increased with severity of polyhydramnios (Table 5).The most common form of polyhydramnios in our study was an idiopathic one, found in approximately 68% of patients.It is consistent with the observation of other authors. 9,12,13ere is an association of polyhydramnios with congenital malformation. 9Six out of 27 patients with mild polyhydramnios (22%) had congenital malformations.Similarly, out of five patients with moderate polyhydramnios, congenital malformation was seen in 2 (40%) patients.Severe polyhydramnios was seen in 6 patients, out of which 4 (66.6%) had congenital malformations.
There is also increased association between severity of polyhydramnios and congenital malformations in studies by other authors. 9n a study by Pri-Paz et al; high incidence of anomalies (79.1 %) was seen in fetuses of mother with severe polyhydramnios (≥ 35 cm). 14 There were no cardiac anomalies in the present study.In contrast to this, cardiac anomalies were most frequently associated with polyhydramnios as described by Pri-Paz et al

Table 5 : Correlation of congenital anomalies with severity of polyhydramnios
14and Boito et al 15 .Central nervous system, Gastrointestinal and skeletal anomalies are among the highest in the present study.In a study by Kornacki et al 9 gastrointestinal tract anomalies were the most frequent congenital anomalies in polyhydramnios, especially in severe polyhydramnios.