Hydronephrosis Risk in Acute Kidney Injury Patients
The 58-year-old woman undergoing chemotherapy and radiation for advanced cervical cancer is most likely to have hydronephrosis on ultrasound evaluation.
Rationale for Advanced Cervical Cancer
Cervical cancer with chemoradiation therapy creates the highest risk for hydronephrosis through multiple mechanisms:
Malignant obstruction from tumor compression of the ureters is a well-established cause of hydronephrosis, particularly in advanced cervical cancer 1, 2.
Radiation-induced hydronephrosis (RIH) occurs in approximately 7.2% of kidneys at 5 years post-treatment, with an overall incidence of 15.8% for new hydronephrosis during follow-up after chemoradiation 3.
The combination of external beam radiation with concurrent cisplatin and brachytherapy specifically increases risk, with Point A dose, bladder D2.0cc, and high-risk clinical target volume all independently associated with hydronephrosis development 3.
Hydronephrosis occurs in 12-23% of cervical cancer patients overall, with higher rates in those receiving radiotherapy (43% versus 25% in non-radiated patients) 4, 5, 6.
Both direct tumor invasion and treatment-related ureteral stenosis contribute to obstruction, making this a dual-mechanism risk 3.
Why Other Options Are Less Likely
E. coli O157:H7 with TTP (19-year-old female)
- Thrombotic thrombocytopenic purpura causes intrarenal microvascular thrombosis, not obstructive uropathy 1.
- This represents intrinsic renal disease (acute tubular necrosis pattern), which does not produce hydronephrosis 1.
- Ultrasound would show normal-sized kidneys without collecting system dilation 1.
Gonococcal Sepsis with Purpura Fulminans (57-year-old male)
- Sepsis-induced AKI is prerenal or intrinsic (acute tubular necrosis), not obstructive 1.
- Obstructive uropathy is found in only about 1% of ICU patients with acute renal failure 1.
- Purpura fulminans indicates disseminated intravascular coagulation, causing intrarenal injury rather than obstruction 1.
Autosomal Dominant Polycystic Kidney Disease (75-year-old male)
- ADPKD causes multiple renal cysts, not hydronephrosis 1.
- While cysts can mimic hydronephrosis on ultrasound, they represent a distinct pathology without collecting system obstruction 1.
- Chronic kidney disease from ADPKD would show small echogenic kidneys if causing renal failure, not acute obstruction 1.
Pyelonephritis with Sepsis (elderly nursing home resident)
- Pyelonephritis alone does not typically cause hydronephrosis unless complicated by obstruction 1.
- While 33% of complicated urinary tract infections show sonographic abnormalities, these are usually parenchymal changes rather than hydronephrosis 1.
- Pyonephrosis (infected hydronephrosis) requires pre-existing obstruction as the primary pathology 2.
Clinical Implications
The cervical cancer patient requires urgent evaluation because:
- Bilateral hydronephrosis with elevated creatinine is a medical emergency requiring immediate decompression 7, 2.
- Progressive dilation leads to permanent nephron loss if not corrected 1, 8.
- Ultrasound has >90% sensitivity for detecting hydronephrosis and can guide intervention 1, 7.
Key Pitfalls to Avoid
- Do not delay imaging in cervical cancer patients with AKI, as both tumor progression and radiation effects can cause obstruction 3, 5.
- Hydronephrosis in cervical cancer is associated with significantly worse survival (hazard ratios 1.47-4.69), making early detection critical 6.
- Approximately 20% of cervical cancer patients have persistent hydronephrosis after definitive treatment, requiring ongoing surveillance 3.
- Silent (asymptomatic) hydronephrosis occurs, so imaging should not be withheld based on absence of flank pain alone 4, 9.