List nine causes of unilateral nonvisualization (i.e., no contrast in or out; no urine out) on IVP.

1. Ureteral obstruction
2. Renal artery obstruction
3. Renal vein thrombosis
4. Fractured kidney
5. Neoplasm
6. Ectopic kidney
7. Absent kidney (i.e., renal agenesis, possibly associated with Mullerian anomalies)
8. Severe infection (tuberculosis or xanthogranulomatous pyelonephritis)
9. Multicystic dysplastic kidney