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Oligohydramnios and Maternal Hydration Therapy


Jignesh Kansaria*, Meghana Mathure**, SV Parulekar***


53 patients with oligohydramnios were advised maternal hydration therapy (at least 2 litres of oral fluids in a day) to assess its effects on amniotic fluid volume and pregnancy outcome. Maternal hydration therapy plays an important role to improve Amniotic fluid volume (AFV) in patients with oligohydramnios and also prevents occurrence of oligohydramnios in patients with IUGR and normal liquor volume.

Amniotic fluid volume is a very important determinant for in utero foetal well being. Abnormalities of amniotic fluid volume on either side of normal are associated with poor perinatal outcome and complications. Oligohydramnios is defined as liquor volume less than the 5th percentile of normal. Patients with oligohydramnios secondary to isolated placental dysfunction, pregnancy induced hypertension, or idiopathic intrauterine growth retardation can have a good perinatal outcome as compared to those with congenital anomalies and chromosomal abnormalities. Research is going on into the mechanics of oligohydramnios in these cases. Maternal plasma volume forms an important denominator which affects the liquor volume directly.1 Oral maternal hydration therapy has been tried to improve liquor volume with varying results.

Material and Methods
53 women detected clinically of IUGR were prospectively studied for presence of oligohydramnios.

Obstetric ultrasonography was done to evaluate foetal growth, placental maturity, amniotic fluid index, to rule out foetal congenital anomalies.

These 53 patients with late onset IUGR were advised aCL IgM and IgG, Lupus anticoagulant, BFP-VDRL tests for identification of aetiological factors in affording patients.

All these patients with IUGR were advised complete bed rest in left lateral position, high protein diet, foetal kick count (Cardiff’s count of ten), biweekly NST, repeat Obstetric USG 2 weekly for foetal growth, and weekly for amniotic fluid index in those with oligohydramnios. Patients with gestational age less than 34 weeks were started on low dose aspirin.

Plenty of oral fluids i.e. oral maternal hydration therapy was advised to all patients with oligohydramnios to improve liquor volume and even to those with normal liquor volume to prevent oligohydramnios. They were advised to take approximately 2 litres of fluid per day or more orally and AFI was assessed weekly in the oligohydramnios group.

Other causes of oligohydramnios like foetal congenital anomalies were excluded. Oligohydramnios was defined as amniotic fluid index of 5 cm or less.2 AFI of less than 2 cm was defined as severe oligohydramnios and may require delivery in correlation with antepartum foetal surveillance tests and gestational age of foetus.

Response to therapy was assessed by improvement in AFI done weekly.

All patients were treated on domiciliary basis. 2 litres of fluid per day at least, roughly 200-300 ml every 2 hours was advised orally.

Unless patient went into spontaneous labour, labour was induced at 37 completed weeks or before that if antepartum foetal surveillance tests showed abnormalities or there was maternal indication for early delivery e.g. worsening of PIH.

Oligohydramnios may be responsible for malpresentations, umbilical cord compression, concentration of meconium in the liquor and difficult or failed external cephalic version. Simple maternal hydration appears to increase amniotic fluid volume and may be beneficial to reduce some of these problems.3

Table 1 shows the incidence of oligohydramnios. In a total of 53 cases, 33 were complicated with oligohydramnios (AFI 5 cm) along with IUGR while 20 had normal amniotic fluid indices.

Thirty three patients with oligohydramnios were advised complete bed rest in left lateral position and plenty of oral fluids (upto 2 litres/day or 200 ml/2 hrs. in form of water, coconut water, drinks and fruit juices) and maintaining Cardiff’s count of ten. Of these 24 patients (70%) showed improvement in AFV.

The outcome of this fluid therapy was based on compliance regarding complete bed rest and fluid therapy. The AFI showed no change in 9 cases despite treatment (Table 2).

Of these 9 women who showed persistent oligohydramnios, 5 were non-compliant and did not take adequate bed rest or oral fluids or both. These patients were admitted in the ANC ward for rest, observation and foetal surveillance. In 4 women, the AFI did not improve despite adequate bed rest and oral fluids, which on next follow up required admission and required immediate delivery because of poor result of antenatal foetal surveillance tests.

Failure or response to maternal therapy can be attributed to:

  1. Non compliant patient
  2. Severe Oligohydramnios refractory to treatment, i.e. Probably is this group with severe IUGR with severe oligohydramnios in irreversible phase.

The antenatal foetal surveillance tests showing abnormal results were higher in patients with oligohydramnios necessitating early preterm delivery. These were the patients which were given antenatal steroids.

Patients with oligohydramnios who responded to maternal hydration therapy had no significant decrease in operative intervention required for delivery for foetal distress. Gain was in terms of prolonging the intrauterine stay of foetus i.e. Alleviating the need for preterm delivery and subsequent neonatal complications of preterm IUGR foetus.

There was no perinatal mortality.

The results in both groups of oligohydramnios 1) responders and 2) non responders to maternal hydration therapy were good in terms of perinatal outcome and vaginal delivery. As the patients were under continuous close foetal surveillance antenatally and intrapartum; and immediate delivery was undertaken at the earliest sign of intrauterine foetal compromise, our perinatal mortality was zero. The risk of development of foetal distress and need for operative deliveries was almost the same in all the groups as shown in Table 3. The high incidence of operative delivery in the IUGR group without oligohydramnios suggests patients with borderline oligohydramnios i.e. AFI of 5-7 cm are at increased risk of intrapartum foetal distress, though these patients did not show any abnormality in antepartum foetal surveillance tests until intrapartum.

The basis of this oral hydration therapy is a study by Kilpatrick, et al4 in 1991. They studied and found for an oral maternal hydration with 2 litres of water was associated with an increase in the AFI by approximately 30% in women with decreased AFV, initial AFI < 6 cm.

Kilpatrick et al5 in 1993 also studied the effect of oral hydration on the AFI under conditions of normal amniotic fluid volume. Women were addressed in a controlled fashion by oral hydration by ingestion of 2 litres of water over 4-6 hrs compared to drinking only 100 ml during the same time period. Maternal oral hydration increased the AFI by approximately 10% whereas fluid restriction decreased the AFI by 8% in women with normal AFV. These findings support their previous data that maternal hydration increased the AFI by 31% in women with decreased AFV and suggest that maternal fluid volume or osmolality may have a role in maintaining the AFV.

In a similar study by Flack NJ6 et al in 1995, they confirmed that oral maternal hydration with water significantly increased AFI in women with oligohydramnios (AFI < 5 cm). The mean AFI increased from 4.3 to 7.5 cm 2 hrs after the patients completed drinking the water. In addition the authors noted a significant increase in umbilical artery mean velocity but no significant increase in hourly foetal urine production rate. Their data also suggested that maternal hydration may work to increase AFI by improving uteroplacental blood flow or by bulk transfer of water across the placenta. Both maternal serum and urinary osmolality significantly decreased after drinking 2 litres of water.

Goodlin et al7 1983, reported a correlation between measured maternal intravascular volume and AFV if patients with diabetes and foetal congenital anomalies were excluded. In cases of oligohydramnios, the maternal plasma volume was found to be decreased from normal but both conditions improved with maternal oral or IV hydration. Therefore uterine perfusion may contribute to amniotic fluid production and regulation.

Chandra PC8 et al investigated whether oral or intravenous hydration affects oligohydramnios in cases with normal biophysical profile scores. A total of 50 subjects with normal biophysical profile (8 of 10) whose labour was not induced at once fell into two nonrandom, convenience sample groups : (1) 20 who were advised to drink fluids, and (2) 30 given intravenous hydration. They concluded that oral and intravenous hydration may correct uncomplicated oligohydramnios, but neither appears to be particularly advantageous over the other.

Kilpatrick JS1 says whether maternal hydration is an effective and safe way to manage oligohydramnios is at this time unknown and may be related to the cause of the oligohydramnios. One might propose in a severely growth retarded foetus with chronic oligohydramnios and compromise that maternal hydration would be insufficient to alter amniotic fluid volume. Additional studies are needed to understand the role of maternal hydration state and amniotic fluid volume in both the normal pregnancy and in pregnancies complicated by abnormal fluid volumes.

Speculations are that oligohydramnios associated with foetal hypoxia is caused by placental dysfunction in addition to the hypoxia.9

Severe oligohydramnios refractory to treatment was seen in 4 patients all of whom had severe IUGR. The placental grade in all these 4 patients was Grade III at 1st visit. The possible explanation for refractoriness to hydration therapy could be; due to chronic placental insufficiency causing severe IUGR there is long standing placental vascular changes with increase in countervails pressure, decrease perfusion across the placental barrier (premature aging of placenta) which is refractory to changes in maternal fluid volume. The studies by Flack NJ et al6 and Goodwin et al7 suggest an important role of improved placental blood flow and increase maternal intra vascular volume, in improving amniotic fluid induces.

Fait G et al10 evaluated the effect of long-term (1 week) oral hydration on amniotic fluid volume in women with an amniotic fluid index (AFI) < 10th percentile. This prospective, non randomized, interventional study was conducted on 30 women with AFI < 10th percentile. The women were instructed to drink at least 2L of water daily; their AFI was evaluated before and 1 week after the initiation of oral hydration. The study group was compared to a control group of 30 women matched for age and gestational age, with AFI > 10th and < 90th percentile. AFI increased from 8.1 ± 0.73 (mean ± SD) to 11.8 ± 2.4 1 week later (P < .01) in 25 (83%) of the study subjects. The AFI was similar before and 1 week after oral hydration in all the controls. They concluded that long-term maternal oral hydration seems to significantly increase the AFI in selected women with reduced fluid and possibly prevents oligohydramnios.

Doi S et al11 determined the effect of maternal hydration with intravenous (iv) isotonic fluid, iv hypotonic fluid, and oral water on amniotic fluid index (AFI) in women with oligohydramnios. Patients with low AFI and gestational age over 35 weeks without maternal complications were randomized into four groups (2L/2 h iv isotonic fluid, 2 L/2 h iv hypotonic fluid, 2 L/2 h oral water, control). Maternal plasma osmolality, AFI, haematocrit, and haemoglobin concentration were measured before and after hydration. Eighty-four patients (n=21/group) completed the study without any maternal adverse effects. The mean increase in AFI after hydration was significantly greater in the iv hypotonic and oral water groups (2.8 ± 1.9, P < .001; 3.8 ± 1.9, P < .001, respectively), but not in the iv isotonic group (0.5 ± 1.1), compared with the control group (0.5 ± 1.1). Significant decreases in maternal haematocrit and haemoglobin concentration were found only after iv isotonic hydration (32.0 ± 2.9 to 29.5 ± 2.3, P < .001; 11.0 ± 1.6 to 10.1 ± 1.4, P < .001, respectively). Changes in maternal osmolality correlated with the changes in AFI in both the iv hypotonic group (r=.58, P < .001) and oral water group (r =.63, P < .001). They concluded that maternal hydration with either iv hypotonic fluid or oral water increases AFI in oligohydramnios. Maternal osmotic change rather than maternal volume expansion had a more direct impact on increasing amniotic fluid volume with short-term acute hydration.

In our study we have used oral maternal hydration therapy in contrast to some studies using Intravenous hydration therapy. Intravenous hydration therapy is not preferred as there is need for prolonged intravenous therapy which is not acceptable to many patients; there is high risk of complications like thrombophlebitis, patient is bed-ridden, and a potential risk of fluid overload. Maternal hydration definitely plays an important role to improve AFV in patients with oligohydramnios and also prevents occurrence of oligohydramnios in patients with IUGR and normal liquor volume.


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*Lecturer; **Third Year Resident; ***Professor and Head, Department of Obstet and Gynaec, Seth GS Medical College, KEM Hospital, Parel, Mumbai.