Introduction
Pelvic kidney is an uncommon congenital renal positional anomaly resulting from failure of normal renal ascent during embryologic development. Although most pelvic kidneys remain asymptomatic, their abnormal position, vascular anatomy, and ureteral course may predispose patients to urinary obstruction and other urological complications. Ureteropelvic junction (UPJ) obstruction in an ectopic pelvic kidney is particularly challenging because of the altered anatomy and may present with nonspecific symptoms.
We present a rare case of a postpartum woman with a pelvic kidney who developed severe hydronephrosis, acute kidney injury, fever, and pelvic pain due to clinically significant UPJ obstruction. The case also highlights the potential limitations of functional imaging in anatomically abnormal kidneys and the importance of correlating imaging findings with the clinical course.
Case Presentation
A 34-year-old woman, approximately three months after an uncomplicated vaginal delivery, presented to the emergency department with progressively worsening pelvic (hypogastric) pain accompanied by fever. Initial laboratory investigations revealed significant leukocytosis and acute kidney injury, with a serum creatinine level of 3.5 mg/dL. The patient also developed oliguria.
Abdominal and pelvic ultrasonography initially suggested a pelvic cystic lesion. Because of the elevated serum creatinine and oliguria, the patient was evaluated by the internal medicine and urology teams. Further imaging, including computed tomography of the abdomen and pelvis, demonstrated a severely hydronephrotic ectopic pelvic kidney, raising concern for significant urinary tract obstruction.
Given the acute deterioration in renal function and the severe hydronephrosis, ultrasound-guided percutaneous nephrostomy was performed to decompress the affected kidney. Following nephrostomy placement, the patient's fever and pelvic pain improved substantially, and serum creatinine progressively decreased to 1.2 mg/dL. She was subsequently discharged with the nephrostomy tube in place and continued outpatient urological evaluation.she underwent nephrostography.
Because UPJ obstruction was suspected, antegrade nephrostography and diuretic renal scintigraphy with DTPA were performed. Surprisingly, the DTPA scan did not demonstrate definite evidence of significant UPJ obstruction, although the affected kidney showed reduced functional contribution compared with the contralateral kidney.
The patient experienced significant discomfort related to the nephrostomy tube. A trial of nephrostomy clamping was therefore performed. Within several hours, however, she developed recurrent and increasing pelvic pain, requiring immediate declamping and restoration of nephrostomy drainage. Given the discrepancy between the functional imaging findings and the patient's clinical response to urinary drainage, as well as the persistent suspicion of mechanical obstruction, surgical exploration was planned with the possibility of pyeloplasty.
At surgical exploration, a stenotic segment at the ureteropelvic junction was identified, confirming the presence of anatomical UPJ obstruction. Pyeloplasty was subsequently performed. The postoperative course was uneventful. During two months of follow-up, the patient's serum creatinine remained within the normal range, and her pelvic pain and other presenting symptoms completely resolved.