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A prospective clinical study of foetomaternal outcome in relation to oligohydramnios in pregnancies beyond 36 weeks of gestation

The amniotic fluid is contributed by both mother and foetus. Its volume is controlled by the interactions among foetal, placental and maternal compartments. It is composed of both organic and inorganic compounds which help in the growth of the foetus. It is alkaline in nature having a specific gravity of 1.010. Initially, dye dilution method was used which is a standard method to measure amniotic fluid volume. Currently, it is not practiced as it is being found an invasive one. So, other methods including single deepest vertical pocket (SVP) method by Chamberlain and amniotic fluid index (AFI) by Phelan are being used. Oligohydramnios is defined as AFI<5 or SVP<2. Its incidence is 1 to 5% of total pregnancies. It is caused by maternal conditions like hypertension, post-term pregnancy which affect blood supply towards foetus and cause a decrease in amniotic fluid production. Drugs like ACE inhibitors, NSAIDS affect foetal urine production. Foetal malformations like hydronephrosis, renal agenesis, polycystic kidney, chromosomal abnormalities can also cause oligohydramnios. There is an increased blood flow towards brain rather than kidneys in growth restricted babies, ultimately, leading to decrease urine production. Oligohydramnios increases maternal morbidity by ABSTRACT


INTRODUCTION
The amniotic fluid is contributed by both mother and foetus. 1 Its volume is controlled by the interactions among foetal, placental and maternal compartments. 2 It is composed of both organic and inorganic compounds which help in the growth of the foetus. It is alkaline in nature having a specific gravity of 1.010. 3 Initially, dye dilution method was used which is a standard method to measure amniotic fluid volume. Currently, it is not practiced as it is being found an invasive one. So, other methods including single deepest vertical pocket (SVP) method by Chamberlain and amniotic fluid index (AFI) by Phelan are being used. 4,5 Oligohydramnios is defined as AFI<5 or SVP<2. Its incidence is 1 to 5% of total pregnancies. 6 It is caused by maternal conditions like hypertension, post-term pregnancy which affect blood supply towards foetus and cause a decrease in amniotic fluid production. Drugs like ACE inhibitors, NSAIDS affect foetal urine production. Foetal malformations like hydronephrosis, renal agenesis, polycystic kidney, chromosomal abnormalities can also cause oligohydramnios. There is an increased blood flow towards brain rather than kidneys in growth restricted babies, ultimately, leading to decrease urine production. 7 Oligohydramnios increases maternal morbidity by increasing the rate of caesarean section and thus increases blood loss and infection and perinatal morbidity by causing limb deformities, cord compression leading to passage of meconium and meconium aspiration syndrome, lower Apgar scores, intensive care unit admission and neonatal mortality. [8][9] Management depends on the period of gestation. When diagnosed before 36 weeks of gestation in the presence of normal anatomy and growth, then it can be managed expectantly by increasing maternal hydration and also with drugs like L-arginine which releases nitric oxide and thus causes vasodilation. Amnioinfusion is done to decrease the cord compression during pregnancy. After 36 weeks, delivery is conducted according to maternal and foetal indications.

METHODS
This study was being conducted in pregnant females beyond 36 weeks of gestation with decreased liquor clinically and confirmed sonographically. It was conducted for a period of one year from May 2018 to May 2019. 230 pregnant females participated in the study.

Inclusion criteria
• Pregnant females beyond 36 weeks of gestation • Decreased liquor clinically and confirmed with ultrasonography • Membranes should be intact.

Exclusion criteria
• Females with leaking per vaginum • Patients who did not give consent • Intrauterine foetal death.
After applying both the inclusion and exclusion criteria, 230 pregnant females beyond 36 weeks of gestation with decreased liquor clinically and confirmed sonographically, were selected. Informed and written consents were taken. These patients with oligohydramnios were admitted and delivered according to maternal and foetal condition. Complete labour record was made. Complete physical examination of both mother by obstetrician, and baby by paediatrician was done.
Assessment of maternal outcome in terms of mode of delivery and foetal outcome in terms of birth weight, Apgar score at one and five-minute, respiratory distress, meconium aspiration, seizures in the first 24 hours of life, congenital malformations, neonatal intensive care unit admission and death of baby was done in this study.

Statistical analysis
Linear variables were summarized as mean and standard deviation, whereas, nominal/categorical variables were presented as proportions (%). Unpaired t test was used for analysis of linear variables and chi-square test and Fischer exact test were used for nominal/categorical variables. p value <0.05 was taken as significant. Medcale 16.4 version software was used for statistical calculations.

RESULTS
In a one year of study, there were 230 pregnant females who fulfilled the criteria. As per Table 1, it was found that most of the females 189 (82%) were in between 21 to 30 years of age group and 121 (53%) were primigravida. 129 (56%) females were booked and belonged to middle socioeconomic status. Mostly females 202 (88%) were Hindu and from urban areas 137 (57%). Hypertension 62 (27%) was the most common maternal condition associated with oligohydramnios followed by hypothyroidism, asthma, heart disease and diabetes. No cause was detected in 142 (62%) of the pregnancies as shown in Table 2.  Maternal outcome was assessed in terms of mode of delivery. There were 119 (52%) females who underwent for caesarean section whereas 111 (48%) delivered vaginally as seen in Table 3. Most common indication of LSCS was foetal distress followed by failed induction. As shown in Table 4, 59 (26%) babies were growth restricted. Malpresentation was found in 18 (8%) patients and 6 (3%) were having malformations like hydronephrosis and polycystic kidney. As shown in Table 5, there was poor foetal outcome in patients with oligohydramnios. Out of the 230 babies, 97 (42%) babies had Apgar score <7 at 1 minute, 93 (40%) had Apgar score <7 after 5 minutes. 52 (23%) aspirated meconium and 92 (40%) had respiratory distress and seizure occurred in 2 (1%) babies. There were 93 (40%) babies who were admitted in NICU and 11 (4.78%) babies died after birth.

DISCUSSION
Pregnancies with oligohydramnios are high risk pregnancies. It can be diagnosed clinically and confirmed by ultrasonography. In this study, it was found that 53% of the pregnant females were primigravida and 47% were multigravida. In a study done by Ghimire et al, 58% were primigravida and 42% were multigravida. 10 10,13,14 There were 26% growth restricted babies in this study. There were 12.7% growth restricted babies in a study by Tajinder K et al, in study by Ahmer R et al. 14,15 No significant difference in birth weight was observed in Ghimire et al study. 10

CONCLUSION
Oligohydramnios increases the incidence of maternal morbidity and perinatal morbidity and mortality.