The patient was a 24-year-old female who visited our hospital due to fever, dysuria, urinary frequency and left flank pain for two days. She had no systemic disease or a family history of systemic disease and seldom visited a hospital. The primary survey at our urology clinic included physical examinations, urinalysis, renal and bladder sonography, and abdominal X-ray according to her symptoms. Her abdomen was soft and flat, with no palpable mass. A throbbing pain was noted during the examination of the left costovertebral angle. The urinalysis showed pyuria and hematuria. Abdominal X-ray showed no urolithiasis. However, renal sonography showed dilatation of the left renal pelvis and an absent right kidney. The right kidney was found in the pelvic cavity near the bladder by bladder sonography. The primary diagnoses were left acute pyelonephritis, left hydronephrosis, and right ectopic kidney. The patient was admitted to our hospital for further treatment and evaluations due to acute illness. After admission, the initial vital signs indicated fever (38.2℃), tachycardia (heart rate 124/min), normal respiratory rate (16/min), and low blood pressure (101/57mmHg). Laboratory data showed a white blood cell count of 8390/µL, hemoglobin level of 11.9 g/dL, and BUN/CRE of 10.4/0.59. Broad-spectrum empirical antibiotics were given for infection control. Computed tomography (CT) was performed to identify the etiology of the left hydronephrosis. The CT showed right ectopic kidney in the pelvis, dilatation of left renal pelvis without definite ureteral lesion, and good bilateral renal contrast enhancement. In addition, compression of the celiac axis due to obstruction by the MAL was incidentally noted. We rechecked her history for abdominal symptoms due to the CT images. Some evidence was found during repeat history taking. She was underweight (158 cm, 42 kg, BMI = 16.82) and had experienced postprandial nausea, abdominal pain, and delayed gastric emptying for many years. The findings were explained to the patient and her family. After a full explanation and discussion, they refused further evaluations and treatments for the celiac artery obstruction due to worry about side effects. Because there was no obvious ureteral obstruction on imaging, drainage treatment was not initially recommended for the patient. Thereafter, no further surgical intervention was scheduled due to significant improvement in clinical symptoms after conservative treatment. After three days of antibiotic use (cefazolin, 1 g, intravenous drip, every 8 h), her symptoms improved. The only other symptomatic treatment is acetaminophen. The urine culture showed Escherichia coli without drug resistance. Therefore, she was discharged for follow-up at our outpatient clinic with oral antibiotics (cephalexin, 500 mg/cap, four times a day). At clinic visit after one week antibiotic treatment, urinalysis was normal. At the same time, the patient did not have any symptoms.