Final answer:
Renal anomalies are the most common fetal anomalies associated with oligohydramnios. ACE inhibitors can induce fetal renal failure, leading to oligohydramnios, resulting in serious complications such as pulmonary hypoplasia and limb contracture.
Step-by-step explanation:
Fetal anomalies most often associated with oligohydramnios are renal anomalies. Oligohydramnios can result from renal agenesis (absence of kidneys), obstructive uropathy (obstruction of normal urine pathways), or renal dysplasia (abnormal kidney development). Angiotensin converting enzyme (ACE) inhibitors are known to cause fetal renal failure and oligohydramnios, leading to severe complications such as pulmonary hypoplasia (underdeveloped lungs) and limb contracture. Additionally, fetal cranial bone abnormalities are also common in cases of oligohydramnios.
Some renal diseases such as congenital hydronephrosis, polycystic kidney disease, and other urinary tract obstructions can lead to oligohydramnios. The presence of insufficient amniotic fluid impacts fetal development, potentially resulting in limb contractures, club feet, and the life-threatening condition of hypoplastic lungs, which can be fatal shortly after birth due to inadequate lung development.