Renal agenesis is a defect occurring early in embryonic development that prevents one or both kidneys from forming. Medical professionals are unsure of the exact causes of agenesis, though chromosomal abnormalities and maternal smoking, drinking, and drug use seem to play significant roles. Unilateral renal agenesis, a single kidney deformity, is often asymptomatic and does not lead to serious medical complications. When both kidneys are missing in a bilateral condition, survival past very early infancy is unlikely.
Doctors usually use the term renal agenesis to refer to the complete absence of a kidney, though it can also describe a partially formed or non-functional organ. The unilateral variety is fairly common and often goes undetected until a patient receives diagnostic imaging tests for another medical issue. When doctors do notice the absence of one kidney, they usually perform a series of tests to ensure the existing organ is capable of handling essential renal functions.
As long at the kidney is healthy, it can sufficiently filter waste, promote the absorption of nutrients, and control blood pressure without medical intervention. A patient who has blood pressure issues may be prescribed daily medication to help prevent heart complications. Children who have unilateral renal agenesis may be placed on low-protein diets to take excess strain off of their kidneys. With regular checkups, most patients are able to lead healthy, active lifestyles.
Most fetuses who suffer from bilateral renal agenesis fail to survive until childbirth, and infants who are born are not likely to live for more than one or two weeks. Bilateral renal agenesis is especially devastating if it is accompanied by other complications, such as low birth weight, congenital heart defects, and underdeveloped lungs. It is often difficult for doctors to pinpoint a specific cause, though genetic testing may reveal underlying problems. The condition has been associated with mutations that result in an extra copy of a particular chromosome, such as Down syndrome. In addition, the likelihood of having a child with unilateral or bilateral renal agenesis is increased when one or both parents have kidney problems, or when the mother abuses drugs or alcohol during pregnancy.
When a baby is born with bilateral renal agenesis, he or she is usually placed on a mechanical ventilator and given a feeding tube. The infant's circulatory system may be severely impacted, causing abnormally high or low blood pressure that needs to be controlled with medications and surgery. A baby usually remains on a ventilator and a dialysis machine for several days while specialists determine the likelihood of survival.