Oligohydramnios is a condition in which the amount of amniotic fluid is reduced to < 200 ml at term. ACOG (2016) defines oligohydramnios as an AFI of <5cm or single deepest pocket of < 2 cm⁸. Anhydramnios is the absence of any measurable pocket of amniotic fluid. Borderline oligohydramnios is when the AFI is between 5 cm and 8cm. Incidence of oligohydramnios is about 4% of all pregnancies. In conditions causing uteroplacental insufficiency the incidence is much higher. Amniotic fluid protects the fetus from trauma, prevents umbilical cord compression, supplies nutrients, has antibacterial properties, provides space for the growth and development of musculoskeletal system, gastrointestinal system and fetal lungs. The volume of amniotic fluid varies according to gestational maturity. It measures about 20 ml at 10 weeks, 400 ml at 20 weeks, 750 ml at 28 weeks, and peaks to about 800ml-1.0L at 36 weeks. It reduces to about 700ml at term. Beyond 41 weeks, AFV decreases rapidly. Fetal complications include intrauterine growth restriction, pulmonary hypoplasia, respiratory distress syndrome, postmaturity syndrome, fetal malpresentation, umbilical cord compression, skeletal deformities, contracture bands, meconium aspiration, increased perinatal mortality, low APGAR scores, hypoxic ischemic encephalopathy and increased operative deliveries. Maternal complications include chorioamnionitis, higher risk of labor induction, instrumental delivery and caesarean section.

In the first trimester etiology of oligohydramnios is unknown. Reduced fluid prior to 10 weeks is generally associated with poor outcome. In the second trimester, the common causes are chromosomal and congenital anomalies Eg:renal agenesis or outflow obstruction in the fetal urinary tract, polycystic kidneys), rupture of membranes, and fetal growth restriction. Oligohydramnios can also be idiopathic. An elevated maternal serum alpha-fetoprotein in association with oligohydramnios carries a poor prognosis. In the third trimester decreased renal blood flow due to fetal growth restriction and placental insufficiency results in decreased urine output and oligohydramnios. Post term pregnancy and rupture of membranes are common causes. Maternal dehydration also results in reduced AFV in hot summer months. Maternal ingestion of prostaglandin synthetase inhibitors (Ibuprofen, indomethacin) can result in oligohydramnios. In the third trimester, oligohydramnios is an important parameter for the monitoring of placental insufficiency and fetal growth restriction.

By the second and third trimester, amniotic fluid is produced primarily by fetal urine, and is reabsorbed through fetal swallowing, fetal lung and directly by placenta. Amniotic fluid is affected by the status of maternal hydration and status of maternal osmolality. Acute oligohydramnios results from ruptured membranes. Chronic oligohydramnios arises from chronic fluid leakage, prerenal, renal and post renal causes in the fetus. Since maternal dehydration increases chances of oligohydramnios, simple oral hydration of pregnant women is supposed to increase amniotic fluid volume thereby decreasing the rates of perinatal mortality and morbidity. Maternal hydration increases amniotic fluid volume by causing fetal diuresis and by improving placental perfusion. In labor to avoid cord compression Amnioinfusion can be done which also decreases variable deceleration.

AIMS AND OBJECTIVES

To evaluate the effectiveness of oral hydration therapy in third trimester pregnancies with isolated oligohydramnios on Amniotic fluid index and maternal and perinatal outcome.

A prospective observational study was conducted in 100 pregnant women with isolated oligohydramnios in Siddhartha medical college, Vijayawada from Jan 2024 to Dec 2024.The inclusion criteria are primigravidas, singleton pregnancy with vertex presentation, Gestational age from 30 weeks to 40 weeks term pregnancies, maternal age from 18-35 years, non-anomalous fetus, initial AFI between 6-8 and with intact membranes. Multiple pregnancies, Congenital fetal anomalies, PROM and PPROM, IUD, postdated pregnancies, medical disorders unrelated to pregnancy GDM, preeclampsia, cardiac disease, thyroid disorders, all high-risk pregnancies and obstetric indication for immediate termination were excluded from study. The selected cases were subjected to detailed history, general, systemic and obstetrical examination. Antenatal investigations were done especially to rule out systemic medical disorders. Informed consent was obtained from each participant after thoroughly explaining about oral hydration therapy. Pre-treatment ultrasonography was done to note the AFI. Pregnant women were advised to take 3L of oral fluids/day (in the form of water, butter milk, coconut water, fruit juices), L-Arginine sachets TID, oral glucose, Cap. Astymine forte, Natural vitamin-E, High protein diet and rest in left lateral position. Then AFI was re-evaluated after 24hrs, 48hrs, 72hrs and then weekly after oral hydration therapy.. Amniotic fluid index was obtained sonographically by dividing the maternal abdomen into four quadrants, the linea nigra was used to divide abdomen into right and left halves and umbilicus was used to separate upper and lower halves. The largest amniotic fluid pocket was identified in each quadrant free of fetal limbs and cord loops and its vertical diameter was taken. All four vertical diameters were added to obtain AFI in centimeters. Monitoring is done by Daily fetal movement count, NST twice weekly and by doing Doppler studies weekly. All the cases were followed-up till delivery to obtain maternal and perinatal outcomes. Mode of delivery and neonatal outcome in the form of Apgar score were recorded

Table1: Improvement of amniotic Fluid Index with Oral Hydration Therapy In Different Age Groups in Study Population

Improvement in AFI is more evident in the younger age group than in the older age group. Similar results were observed in Annapurna S Hadalageri et al⁵.

Table 2: Improvement Of AFI In Different Gestational Age Groups After Oral Hydration Therapy

Improvement of AFI varies in the different age groups such that the improvement is better when Oral hydration therapy is started at an earlier age group.80% cases between 32-34weeks gestational age had AFI>8 cm while 70% cases between 34-36weeks had AFI >8cm and only 40% cases had AFI>8cm post oral hydration therapy.

Table 3: Umbilical Artery Study Changes In Study Group After Oral Hydration Therapy

Cases with improved AFI had Normal doppler than compared with cases without much improvement in AFI

Table 4: NST Changes in Study Group after Oral Hydration Therapy

                    All the participants of the study group had Reassuring NST

Table 5: Mode of Delivery after Oral Hydration Therapy in Study Group

80%of the cases had Normal Vaginal delivery and only 20% of the cases had underwent  LSCS out of which 15% were due to other indications.Similar results were observed in Meenakshi Chauhan et al (86% women had Normal vaginal delivery and 14% had LSCS ².

Table 6: Apgar Scores of Newborns in Study Group after Oral Hydration Therapy at 1 And 5 Minutes

Cases with improved AFI delivered babies with  better APGAR scores.100% cases with AFI 8cm delivered babies with APGAR of 8/10,99%cases with AFI 7cm delivered babies with APGAR 6/8 .98%cases with AFI 6cm  delivered babies with APGAR of 8/10 and 2% of babies born to mothers with AFI 6cm had APGAR scores of 6/8.

Improvement in AFI in isolated oligohydramnios depends on the gestational age at the time of oral hydration and the time available till delivery.Table1 demonstrates that there is improvement of AFI in younger age groups than elderly age groups. Increase in AFI is more in early gestational age than term pregnancies. Umbilical artery changes are normal in 89% of cases. There is increased flow in 10% of cases. Absent flow in 1% of cases. Nonstress test shows reassuring status in all cases. The outcome is Normal vaginal delivery in 80% of cases. LSCS was the outcome in 5% of cases. There is significant increase in APGAR scores at birth. There were no intrapartum deaths in our study.

Multiple therapeutic options are suggested for oligohydramnios as serial trans abdominal or trans- cervical amnio-infusion, intravenous hydration, Desmopressin (Ddavp) and amniotic sealing techniques in rupture of membranes cases but all are invasive, costly and have their own disadvantages. Maternal oral hydration therapy is simple, safe noninvasive and non expensive method to improve amniotic fluid volume and decrease in operative interferences in oligohydramnios but requires continuous therapy for long term to improve the perinatal outcome.

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