Management
After initial diagnosis of oligohydramnios has been made, the next step is to perform a thorough history and physical exam, followed by diagnostic testing if indicated. Retaking a maternal and family history and performing a physical exam can point to maternal conditions or medications that might be causing the oligohydramnios. Premature prelabor rupture of membranes or prelabor rupture of membranes is ruled out with a nitrizine test, evidence of ferning, or evidence pooling of liquid in the cervix. Sonographic evaluation of the fetus is done to identify fetal anomalies, aneuploidy, fetal growth restriction, or placental abnormalities. The National Institute of Health recommends detailed documentation of certain fetal organs that are most likely to be involved such as the kidneys, bladder, and the umbilical cord. If the lack of amniotic fluid prevents accurate visualization on ultraosund, MRI imaging can be considered. Genetic testing can be useful if fetal anomalies are documented on imaging. An elevated maternal serum alpha fetal protein (MSAFP) can indicate leaking amniotic fluid due to damage to fetal membranes or the placenta. This is associated with a poor prognosis. A maternal blood test or amniotic fluid test can be performed if suspicion of a TORCH infection is high. Increasing amniotic fluid
There is no way to permanently increase the volume of amniotic fluid, but it can be temporarily increased to allow for a complete anatomy scan of the fetus on ultrasound.One way to achieve this is through an amnioinfusion, which is the insertion of 200mL of saline into the amniotic sac.
These conditions decrease the blood flow to vital organs such as the placenta which supplies blood, oxygen, and nutrients to the developing fetus. Decreased blood flow to the fetus causes impaired urine production which leads to reduced amniotic fluid and oligohydramnios. Medications such as angiotensin converting enzyme inhibitors (lisinopril), prostaglandin synthetase inhibitors (NSAIDs, anti-inflammatory steroids), and trastuzumab decrease blood flow to the kidneys of the fetus. When the fetal kidneys are not able to produce adequate amounts of urine, this leads to reduced amniotic fluid or oligohydramnios. Maternal dehydration, especially in the hotter summer months
Infections such as the TORCH infections (toxoplasma gondii, rubella, cytomegalovirus, herpes simplex virus) and parvovirus B19

Fetal
Chromosomal abnormalities such as Down syndrome which are associated with gastrointestinal abnormalities
Congenital abnormalities such as renal agenesis and cystic renal disease are associated with impaired urine production, and posterior urethral valves or urethral atresia which are associated with obstruction of the lower urinary tract
Intrauterine demise
Post-term pregnancy
Rupture of membranes
Intrauterine growth restriction (IUGR) associated with placental insufficiency
Amnion nodosum; failure of secretion by the cells of the amnion covering the placenta

Placental
Placental abruption
Twin-twin transfusion
Placental thrombosis or infarction

Diagnosis
Clinical Manifestation
The volume of amniotic fluid typically increases until 36 weeks and starts decreasing after 40 weeks in post-term gestations. For this reason, discrepancies between fundal height measurements and gestational age can be a clinical indication of amniotic fluid abnormality and should be evaluated by ultrasound. Other common clinical presentations include fetal malpresentation, undue prominence of fetal parts, premature rupture of membranes, and reduced amount of amniotic fluid.