Oligohydramnious Diagnosis :
– Clinical diagnosis is based on the finding of decreased amniotic fluid on U/S examination.
– There are both objective & subjective U/S criteria for diagnosing oligohydramnios:
1. Objective criterion is generally preferable (AFI ≤5 or single deepest pocket (SDP) <2 cm).
2. Subjective suspicion of AF volume by experienced examiners has similar sensitivity for diagnosing Oligohydramnious.
– Borderline/low normal AF means AFI >5.0 & ≤8.0 cm.
– Anhydramnios is the lack of a measurable AFI or SDP, although a thin echolucent rim may be imaged on the inner aspect of the uterus.
– Multiple gestation: measurement of AFI for each sac of a multiple gestation is difficult so single deepest vertical pocket is used for diagnosis as before.
Oligohydramnious Evaluation :
– Exclude maternal diseases as pre-eclampsia, ch. HTN, SLE & thrombophilia.
– Exclude use of drugs as anti-PG & ACE inhibitors.
– If twins, exclude TTTT ( oneoligo& other poly).
– Exclude IUFD, IUGR, kidney anomalies.
– Exclude ROM & postdate.
– Do a comprehensive U/S evaluation with fetal biometry & search for fetal anomalies (especially renal), markers suggestive of aneuploidy (eg, increased nuchal translucency), IUGR or placental abnormalities.
– If PROM is suspected, do speculum examination for vaginal pooling, Nitrazine& fern tests or Amnisure, whatever available.
– If there are fetal anomalies, amniocentesis (if available) may reveal an abnormal karyotype mostly triploidy.
Methods of increasing AFV
– Oral hydration with 1-2 liters of water or hypotonic solutions can transiently increase AF volume particularly in patients with dehydration. This approach is easier & safer than IV fluid administration or amnioinfusion. Hydration with water appears to reduce maternal plasma osmolality & Na concentration, resulting in osmotically driven maternal to fetal water flux; it also improves uteroplacental perfusion.
– Amnioinfusion: still investigational especially for 2nd trimester oligohydramnios.
– Fetal membrane sealants: 7ashish
– Sildenafil: attached a recent study down for its effect with the fluids on oligohydramnious.
Oligohydramnious Management :
First Trimester
* Oligohydramnious at this time is an ominous finding; the pregnancy usually aborts.
* We counsel these patients regarding the poor prognosis & inform them of the signs of miscarriage.
* Serial U/S is helpful for follow up (eg, worsening oligohydramnios, embryonic/fetal demise, or rarely resolution).
Second Trimester
* Borderline/low normal AF volume: generally have a good prognosis. Serial U/S is helpful for follow up, which may remain stable, resolve or progress to development of oligohydramnios&/or IUGR.
* Oligohydramnious often ends in fetal or neonatal death.
* Infants may have abnormalities, such as skeletal deformations, contractures & pulmonary hypoplasia.
* Do a fetal anatomic survey to look for CFMF.
* Administer oral maternal hydration.
* Serial U/S to monitor AF volume, fetal growth & fetal well-being.
Third Trimester
* There is an inverse relationship between AF volume in the third trimester & the incidence of adverse pregnancy outcomes.
* Adverse outcomes are related to meconium aspiration, umbilical cord compression &uteroplacental insufficiency which will lead to abnormalities in fetal heart then CS with low Apgar scores.
* Idiopathic isolated oligohydramnios at term appears to have a better prognosis.
* The duration of oligohydramnios is also a prognostic factor. Patients who present with idiopathic oligohydramnios at an earlier GA are at risk for adverse perinatal outcomes compared with those presenting at later GA.
* Patients with oligohydramnios early in the third trimester may be hospitalized to undergo evaluation of possible causes, daily CTG & maternal hydration.
Timing of Delivery
* Manage acc. to the ass. problem as preeclampsia, PPROM, IUGR, CFMF &postterm pregnancy.
* For idiopathic oligohydramnios indications for delivery include, but are not limited to, nonreassuring CTG or reaching 37-38 wk.
Alternatively, the patient can be followed with serial CTG & BPP until term gestation is reached; the risks & benefits of various management plans should be discussed with the patient.
* Obtaining a short CTG recording upon admission of patients in labor to help determine whether the FHR should be monitored continuously or whether intermittent monitoring is likely to be sufficient.
Best Regards