Giant hydronephrosis mimicking subacute intestinal obstruction: A 4-case series

Giant hydronephrosis (GHDN) is an uncommon sequela of chronic urinary obstruction, defined by accumulation of more than 1 L of urine within the renal collecting system. Although pelvi-ureteric junction (PUJ) obstruction is the most common cause, obstructive urolithiasis and congenital or acquired anomalies may also contribute. Clinical manifestations are often nonspecific and may mimic gastrointestinal pathologies, including subacute intestinal obstruction (SAIO), due to progressive abdominal distention and mass effect on bowel loops. Ultrasonography frequently demonstrates a large intra-abdominal anechoic lesion but may not reliably identify its renal origin. Contrast-enhanced computed tomography (CECT) provides definitive diagnosis by characterizing the extent of renal dilation, cortical thickness, and obstructing lesions. We present 4 patients with progressive abdominal distention initially interpreted as subacute intestinal obstruction. Ultrasonography was inconclusive in each case, whereas CT imaging confirmed GHDN. Three patients had unilateral GHDN secondary to obstructive ureteric calculi, and one had bilateral hydronephrosis due to pelvi-ureteric junction obstruction. All patients underwent appropriate urological intervention, including percutaneous drainage, ureteroscopic stone extraction, or nephrectomy, and recovered well. This case series highlights the diagnostic pitfalls associated with ultrasound evaluation of large abdominal fluid collections and underscores the essential role of CT in distinguishing GHDN from abdominal mimickers. Early recognition facilitates timely intervention and prevents complications such as infection, rupture, and irreversible renal damage.