Due to impaired blood supply during the embryonic period or other reasons, the renal tissue fails to develop fully, forming a small organ with a lobulated surface, maintaining a primitive and immature kidney state. The nephrons are extremely few, the renal calyces are short and thick, the renal pelvis is narrow, and the ureter is often underdeveloped, leading to abnormal urinary function. The blood vessels, especially the stirred pulse, are often small and hardened. Most patients are accompanied by hypertension. Such kidneys may be found in the normal position and are often associated with ectopic kidneys (ectopic kidneys have a higher chance of dysplasia). The position, morphology, and function of the contralateral kidney are mostly normal and may exhibit compensatory hypertrophy. The incidence of renal hypoplasia is approximately 1 in 600 philtrums. According to autopsy data, 34 cases were found in 19,046 autopsies, approximately 1:560.

bubble_chart Clinical Manifestations

In cases of bilateral renal agenesis, patients often die shortly after birth. Unilateral agenesis, if uncomplicated, is frequently undetected. Among the complications, hypertension is the most prominent. Clinically, patients are often children or young adults presenting with hypertension. Upon further examination, one kidney is found to be significantly smaller. This type of hypertension is usually severe, responds poorly to antihypertensive medications, progresses rapidly, and can lead to visual impairment or even blindness within 1 to 2 years.

bubble_chart Diagnosis

During pyelography, a significantly reduced kidney shadow is observed, with thin renal parenchyma, hypoplastic and narrow renal pelvis, absence of renal calyces, and a rod-shaped renal pelvis, which can be correlated clinically. The external shape of the kidney may appear lobulated or exhibit other deformities, losing its normal contour. Diagnosis can be made in conjunction with clinical manifestations.

When the contralateral kidney functions well, the removal of the diseased kidney often results in blood pressure returning to normal immediately after surgery, typically within a short period. Vision also recovers shortly after the procedure. Clinical observations indicate that the younger the patient, the faster the postoperative recovery and the better the prognosis.

bubble_chart Complications

High blood pressure