Tc-99m Renal Scintigraphy in Complex Congenital Systemic Syndromes Associated with Congenital Anomalies of the Kidney and Urinary Tract: A Retrospective Single-Center Study

Abstract Congenital anomalies of the kidney and urinary tract (CAKUT) result from embryonic developmental defects and are usually not isolated. We evaluate the functional status of the kidney with Tc-99m renal scintigraphy in CAKUT patients associated with a rare complex systemic syndrome/sequence. We retrospectively screened 788 Tc-99m EC (ethylenedicysteine) and 187 Tc-99m DMSA (dimercaptosuccinic acid) renal scintigraphies performed between January 2022 and November 2024. Patients were selected based on the presence of congenital systemic syndrome and CAKUT. The Kruskal–Wallis test was used to compare grading of functional impairment of kidneys across different systemic syndromes. The Mann–Whitney U-test was used to compare the functional impairment of the kidney for continuous variables. A total of 38 patients (23 males, 15 females, mean age: 6.7 ± 6.7, range 0.03–33 years) of congenital systemic syndrome with associated CAKUT were identified. The most common systemic syndrome was anorectal malformation in 15 patients (39.5%). A few patients had features of more than one syndrome. The most common CAKUT was an orthotopic or ectopic nonfunctioning kidney in 15 patients (39.5%). The Tc-99m renal scintigraphies showed abnormal findings in 31 patients and normal findings in 7 patients. The proportion of abnormal findings was 81.6% (95% confidence interval: 65.7–92.3%). The difference in proportion of abnormal findings of renal scintigraphy across different syndromes was not statistically significant (Fisher's exact test, p = 0.128). The Kruskal–Wallis H-test revealed significant differences in the grading of functional impairment of kidneys across different systemic syndromes, H(16) = 27.24, p = 0.039. The Mann–Whitney U-test revealed significant difference (p = 0.007) in serum creatinine of normal Tc-99m scintigraphy (mean = 0.49, n = 7) and abnormal Tc-99m scintigraphy (mean =1.25, n = 31), U = 36.5, z = 2.71, r = 1.65. However, there was no significant difference (p = 0.097) in the age of patients who showed normal and abnormal Tc-99m scintigraphies. A complex systemic syndrome may have occult CAKUT that remains silent initially but presents as a complicated case later. Thus, these patients need functional evaluation with Tc-99m EC and Tc-99m DMSA scintigraphies for early diagnosis of renal anomaly and timely management and follow-up, especially after surgical intervention, to avoid future complications.