Objective: To assess the influence of maternal isosorbide mononitrate (IMN) vaginal supplementation in improving liquor volume in women with isolated oligohydramnios.

Study Design: Prospective randomized interventional study. Materials and Methods: 100 women with singleton pregnancy about 28-36 weeks, with isolated oligohydramnios [amniotic fluid index (AFI) < 5] were enrolled in the study. Before the proposed intervention, the antenatal risk factors were studied. Patients received 20 mg isosorbide mononitrate (IMN) vaginally. Patient were followed after 24 hours then weekly. The treatment was continued till the liquor improved significantly or until delivery. Outcome measures; mean increase in liquor, intervention delivery interval, and neonatal outcome were studied.

This prospective randomized interventional study was done in Obstetrics and Gynecology Department , Benha University Hospital, Alkalubia, Egypt from August 2013 to August 2015.

The study protocol was approved by the Local Ethics Committee and written informed consents were taken from patients entering the study. The study included 100 women aged 18-35 years with singleton pregnancy about 28-36 weeks gestation, with diagnosed isolated oligohydramnios (AFI less than 5 cm).

Initially, all the participants were subjected to through routine antenatal history taking and examination and by routine ultrasound scan using (Voluson, 730 Pro V, GE Medical System), AFI was assessed. All participants were instructed to take regularly the daily water requirement, especially in the two days before starting the study and throughout the study. Participants were randomly scheduled into two equal groups by computer-generated blocks into a control group received placebo vaginal tablets and a study group received 20 mg isosorbide mononitrate (IMN) vaginally once daily until delivery (Effox, Mina Pharma Co, Egypt; under license of Schwartz Pharma, Germany). Treatment allocation was concealed by using sequentially numbered opaque sealed envelopes, opened sequentially by a third person (study nurse). Amniotic fluid index was rechecked after two days and followed up weekly till delivery by one person to avoid interobserver variability. Drug treatment continues until the volume of the fluid reach the normal value or until delivery. Antenatal vitamins were continued.

Primary outcome measure was the change in AFI.

Secondary outcome measures were the side effect of isosorbide mononitrate if any, indications and mode of delivery, and neonatal outcomes as regard birth weight, still birth or neonatal death, Apgar score and the need for neonatal admission.

Inclusion Criteria:

• Singleton pregnancy
• 28-36 weeks gestation,
• Diagnosed isolated oligohydramnios (AFI less than 5 cm).

Exclusion Criteria:

• Multiple pregnancy;
• Fetal chromosomal or congenital abnormalities;
• Signs of fetal distress;
• Preterm rupture of membranes;
• Intrauterine infection;
• Receiving treatment for oligohydramnios ;
• History of maternal heart disease;
• Vasodilator use; sensitivity to NO donors ;
• Pre-existing chronic medical problems.