ASSOCIATION OF SONOGRAPHIC POLYHYDRAMNIOS WITH PRETERM BIRTH

Ayesha Tariq, Mishal Javaid, Muhammad Zubair, Sarah Maryam, Yousef Gilani and Syed Amir Gilani. University Institute of Radiological Sciences and Medical Imaging Technologies, Faculty of Allied Health Sciences, University of Lahore, Lahore, Pakistan. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 11 February 2019 Final Accepted: 13 March 2019 Published: April 2019


Introduction:-
Polyhydramnios is a medical condition describing an excess of amniotic fluid in the amniotic sac 1 . Polyhydramnios is generally detected either by physical examination if the uterus appears larger or measures larger than expected by the pregnancy dating, by sonography at the time of the fetal anatomic survey, or when the development of other conditions warrants assessment of the amniotic fluid or fetal growth during a pregnancy 2 . Amniotic fluid provides an optimal environment for normal fetal growth and development. The AFV is the result of a series of complex and dynamic pathways influencing the movement of fluid into and out of the amniotic space. This balance is regulated by mechanisms that are not yet completely understood 3 . The main sources determining the AFV include fetal urine production, fetal swallowing, secretion of fetal lung fluid, movement of water and solutes between fetal blood and the placenta (intramembranous pathway), movement of water and solutes across the surface of the amnion and chorion (trans membranous pathway), secretions by the fetal oral and nasal cavities, and movement of fluid across fetal skin during early gestation 4 . A disturbance in any of these processes can result in an abnormally low or high AFV, referred to as oligohydramnios or polyhydramnios, respectively. The main routes of amniotic fluid removal are fetal swallowing and absorption via the intramembranous pathway 3 . Polyhydramnios can result from an imbalance in any of these pathways. Decreased elimination of amniotic fluid, either from anomalies (e.g., choanal atresia, esophageal atresia, tracheoesophageal fistula, and duodenal or intestinal atresia) or as a result of reduced swallowing ability or function, which can be due to neurologic impairment (e.g., anencephaly) or neuromuscular disorders (eg, myotonic dystrophy), drug-induced, or potentially a result of fetal hypoxia as evidenced in the ovine model, can all result in hydramnios 5 . Polyhydramnios has three terms the terms mild, moderate, and severe have been used to describe degrees of polyhydramnios. Mild hydramnios has been defined as an AFI of 25 to 30 cm or an SDP of 8 cm or greater, moderate hydramnios as an AFI of 30.1 to 35 cm or an SDP of 12 cm or greater, and severe hydramnios as an AFI of 35.1 cm or greater or SDP of 16 cm or greater 6 . Increasing severity of polyhydramnios appears to correlate with an increased risk of perinatal mortality and congenital abnormalities 7 . Polyhydramnios is associated with fetal and maternal complications such as respiratory distress, thromboembolism, preterm labour, atonic uterus, anaemia, caesarean section, premature fetus, umbilical cord prolapse caused by the rupture of the membranes and fetal distress 8 . A fetus close to term will produce between 500-1200 ml urine and swallow between 210-760 ml of amniotic fluid per day. Even small changes in this equilibrium can result in significant changes in amniotic fluid volumes 9 . A disturbed equilibrium can be the result of compromised swallowing function or increased urination and can lead to polyhydramnios 9 . Increased urine production, as occurs with increased cardiac output associated with fetal anaemia, can also result in increased production of amniotic fluid 10 .
The risk of the preterm birth, umbilical cord prolapse is increased when polyhydramnios is present due to overexpansion of the uterus 11 . The rate of preterm delivery at < 34 weeks increases as the maximal AFI increases, and reaches 19.4% with an AFI ≥ 35 cm 12 . Preterm labour and subsequent preterm delivery are often thought to be directly related to polyhydramnios, as a result of the increasing volume of amniotic fluid. This correlation is reasonable to make considering that the increasing distention of the uterus can result in uterine contractions. Thus, one would expect there to be a higher rate of preterm labour and preterm delivery in those women with increasingly higher AFVs correlating with increasing severity of polyhydramnios 2 . Preterm birth, defined as delivery prior to 37 completed weeks, is a public health priority Because preterm birth can result in significant morbidities and mortalities 13,14 . Premature birth is a birth that takes place more than three weeks before the baby's estimated due date. In other words, premature birth is one that occurs before the start of the 37th week of pregnancy. Very preterm, born at less than 32 weeks of pregnancy. Extremely preterm, born at or before 25 weeks of pregnancy 15 . Ultrasound is still a useful diagnostic and follow-up modality in polyhydramnios patients 16 . Clinically, polyhydramnios is identified using either the clinician's subjective impression of an increased amount of amniotic fluid during a sonographic assessment or using a sonographic measurement to estimate the amniotic fluid volume (AFV). Two commonly used sonographic measurements that suggest a high volume of amniotic fluid include an amniotic fluid index (AFI) of 25 cm or greater or a single deepest pocket (SDP) of 8 cm or greater 17 . In mild cases, simple control and follow-ups, continuous ultrasound and conservative treatment methods are recommended 18 . It is also the method of choice in multiple gestations. In cases with multiple gestations, a range of 3-8 cm is defined as normal. With this method, polyhydramnios is classified as mild, moderate or severe 19 For the 4-quadrant method (AFI -Amniotic Fluid Index) the deepest amniotic pocket in each of the four quadrants is measured vertically and the values added together 20

Results:-
Out of 64 patients, the Mean ±S.D age was 26.92 ± 3.55. The Minimum age of patient were 21 and Maximum age 38 in table 1, figure 1.

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According to table 1.3, in the age group 21-29, out of 42 of polyhydramnios patients, 16 had full term and 26 had preterm labour. And without polyhydramnios, 7 had full term and 2 had preterm out of 9. In age group 30-38, out of 10 of polyhydramnios patients, 2 had full term and 8 had preterm. And without polyhydramnios, 2 had full term and 1 had preterm out of 3. Delivery  Total  Full term  preterm  21---29  Other reason  with polyhydramnios  16  26  42  without polyhydramnios  7  2  9  Total  23  28  51  30----38 Other

Delivery * other reason Cross tabulation
Other reason  Total  with polyhydramnios  without  polyhydramnios  Delivery  Full term  18  9  27  preterm  34  3  37  742   Total  52  12  64  Table 4:-Delivery * other reason Cross tabulation   was selected. A result shows that significantly higher preterm labours were noted in the polyhydramnios group compared with the control group. In the end, he concluded that although perinatal outcomes are conflicting in literature, idiopathic polyhydramnios warrants close surveillance, especially near term. The result of my study shows that there was an association of polyhydramnios with preterm birth but preterm birth also occurs due to many other reasons. Ultrasonography is almost always a decent beginning decision and is uncomplicated circumstances, might be all that is required. So my study agrees with the others study that apart from the affectability and specificity of ultrasound, it is non-invasive, readily available, portable and inexpensive.

Conclusion:-
The significant value of the current study is .021, so it's justified to state that there is an association of polyhy dramnios with preterm birth.