|Classification and external resources|
The common clinical features are smaller symphysio fundal height, fetal malpresentation, undue prominence of fetal parts and reduced amount of amniotic fluid.
Diagnosis is made by ultrasound measurement when there is an amniotic fluid index (AFI) of less than 5 to 6 cm. Several different methods exist for calculating AFI, that produce different index numbers below which oligohydramnios is said to be present.
It is typically caused by fetal urinary tract abnormalities such as bilateral renal agenesis (Potter's syndrome), fetal polycystic kidneys, or congenital urinary tract obstruction. Uteroplacental insufficiency is another common cause. Most of these abnormalities can also be detected by obstetric ultrasound. It may also occur simply due to dehydration of the mother, maternal use of angiotensin converting enzyme inhibitors, or without a determinable cause (idiopathic).
Complications may include cord compression, musculoskeletal abnormalities such as facial distortion and clubfoot, pulmonary hypoplasia and intrauterine growth restriction. Amnion nodosum is frequently also present (nodules on the fetal surface of the amnion).
Potter syndrome is a condition caused by oligohydramnios. Affected fetuses develop pulmonary hypoplasia, limb deformities, and characteristic facies. Bilateral agenesis of the fetal kidneys is the most common cause due to the lack of fetal urine.
A Cochrane Review concluded that simple maternal hydration appears to increase amniotic fluid volume and may be beneficial in the management of oligohydramnios and prevention of oligohydramnios during labour or prior to external cephalic version.
In severe cases oligohydramnios may be treated with amnioinfusion during labor to prevent umbilical cord compression. There is uncertainty about the procedure's safety and efficacy, and it is recommended that it should only be performed in centres specialising in invasive fetal medicine and in the context of a multidisciplinary team.
- Carr, Phyllis L.; Ricciotti, Hope; Freund, Karen M.; Scott Kahan (2003). In a Page Ob/Gyn & Women's Health (In a Page). Cambridge, MA: Blackwell Publishers. pp. p105. ISBN 1-4051-0380-9.
- Adeniran AJ, Stanek J, (2007). "Amnion nodosum revisited: clinicopathologic and placental correlations". Arch Pathol Lab Med 131 (12): 1829–33. doi:10.1043/1543-2165(2007)131[1829:ANRCAP]2.0.CO;2. PMID 18081444.
- Johnson JM, Chauhan SP, Ennen CS, Niederhauser A, Magann EF (2007). "A comparison of 3 criteria of oligohydramnios in identifying peripartum complications: a secondary analysis". Am. J. Obstet. Gynecol. 197 (2): 207.e1–7; discussion 207.e7–8. doi:10.1016/j.ajog.2007.04.048. PMID 17689653.
- Elsandabesee D, Majumdar S, Sinha S (2007). "Obstetricians' attitudes towards 'isolated' oligohydramnios at term". Journal of obstetrics and gynaecology : the journal of the Institute of Obstetrics and Gynaecology 27 (6): 574–6. doi:10.1080/01443610701469669. PMID 17896253.
- Hofmeyr GJ, Gülmezoglu AM (2000). "Maternal hydration for increasing amniotic fluid volume in oligohydramnios and normal amniotic fluid volume". In Novikova, Natalia. Cochrane Database of Systematic Reviews (Online) (2): CD000134. doi:10.1002/14651858.CD000134. PMID 10796151.
- Oligohydramnios at the National Institute for Health and Clinical Excellence. Based on the overview Therapeutic amnioinfusion for oligohydramnios during pregnancy (excluding labour) in 2006
- Morris, R. K.; Malin, G. L.; Quinlan-Jones, E.; Middleton, L. J.; Hemming, K.; Burke, D.; Daniels, J. P.; Khan, K. S.; Deeks, J.; Kilby, M. D. (2013). "Percutaneous vesicoamniotic shunting versus conservative management for fetal lower urinary tract obstruction (PLUTO): A randomised trial". The Lancet 382 (9903): 1496. doi:10.1016/S0140-6736(13)60992-7.