Case Report

Pelvic ectopic kidney with acute pyelonephritis: wolf in sheep’s clothing

Abstract

The differential diagnosis of right lower quadrate pain at the emergency department is quite perplexing. We describe a 38-year-old woman presenting with characteristic clinical and Laboratory features of ruptured appendicitis with severe sepsis. However, contrast-enhanced computed tomography scan of the abdomen established the diagnosis of pelvic ectopic kidney with acute pyelonephritis. Antibiotic treat- ment eventually achieved satisfactory resolution without compromise of renal function. It is should be addressed that, even with the advent of modern imaging modalities, there can be a diagnostic pitfall in General practice when managing right lower quadrate pain in patients with typical presenta- tions of acute appendicitis without sonographic evidence, as illustrated in this case. In conclusion, early recognition using exquisite imaging studies with raised awareness in the clinical setting and prompt antibiotic treatment can avoid unnecessary intervention, preserve renal function, and prevent a life-threatening catastrophe.

A previously healthy 38-year-old woman presented to the emergency department with a 2-day history of worsening Right lower quadrant abdominal pain associated with nausea, vomiting, and fever. She reported no illicit drug use, sexual exposure, recent traveling, or trauma history. Review of systems provided no evidences of abnormal menstruation, dysmenorrhea, dysuria, urinary urgency or frequency, or weight loss. Her family history was noncontributory. Upon examination, she is drowsy, and her blood pressure was 90/60 mm Hg, heart rate 121 beat/min, respiratory rate

22 breath/min, and body temperature 40.1?C. She had striking pain over the right iliac fossa with rebound tenderness and involuntary guarding, along with positive Rovsing and psoas signs. The remainder of the physical examination was normal. Laboratory studies showed hemo- globin level of 10.1 g/dL, platelet count of 275 x 10⁹/L, and leukocyte count of 18 x 10⁹/L with neutrophils predomi- nance (90%). Serum biochemistry revealed markedly elevated C-reactive protein (12.4 mg/dL), metabolic acido- sis, and normal liver and renal functions. Urinalysis showed

about 18 to 20 leukocytes per high-power field without bacteriuria, hematuria, or case formation and negative pregnancy test. KUB only showed dilated bowel loops. Accordingly, acute appendicitis with severe sepsis was highly suspected. Ultrasonography is unaccessible because of severe ileus. Coronal reformatted contrast-enhanced computed tomography scan of the abdomen was shown in Fig. 1, characteristic of pelvic ectopic kidney with acute pyelonephritis. Searching for other congenital anomaly yielded bicornuate uterus. Urine and blood cultures grew Escherichia coil. Intravenous administration of ceftriaxone 2 g once daily for consecutive 2 weeks eventually achieved satisfactory resolution without compromise of renal function. Pelvic ectopic kidney, usually opposite the sacrum and below the aortic bifurcation, has been estimated to occur in 1 of 2100 to 3000 autopsies without difference in incidence between the sexes [1]. It is to be differentiated form renal ptosis, in which the kidney initially is located in its proper place and has normal vascularity but moves downward in relation to its primary site. Factors that may prevent the orderly movement of kidneys include ureteral bud mal- development, defective metanephric tissue that by itself fails

Fig. 1 Coronal reformatted contrast-enhanced computed tomogra- phy scan of the abdomen illustrating an enlarged, edematous ectopic pelvic kidney characterized by multifocal confluent low attenuation areas, obliteration of the corticomedullary differentiation, and surrounding fat stranding, consistent with acute pyelonephritis.

0735-6757/$ – see front matter (C) 2008

517.e4 Case Report

to induce ascent, genetic abnormalities, and maternal illnesses or teratogenic causes.

The ectopic kidney is usually smaller than normal, and it may not conform to the usual reniform shape because of the retained fetal lobulations. The axis of the kidney is slightly medial or vertical, but it may be tilted as much as 90? laterally, so that it lies in a true horizontal plane. The renal pelvis is usually anterior to the parenchyma because the kidney has incompletely rotated. As a result, 56% of ectopic kidneys have a hydronephrotic collecting system. Half of these cases result from obstruction: 25% from reflux and 25% from the malrotation alone [2].

Although the contralateral kidney is usually normal, it is associated with a number of congenital defects [3]. The most striking feature is the association of genital anomalies. In women, bicornuate or unicornuate uterus with atresia of one horn, rudimentary or absent uterus and proximal and/or distal vagina, and duplication of the vagina are characteristic. Among male patients, 10% to 20% have a recognizable associated genial defect, and undescended testes, duplication of the urethra, and hypospadias are the most common.

The ectopic kidney is more susceptible to the develop- ment of hydronephrosis or urinary calculus formation than the normally positioned kidney [2,4]. This is in part a result of the anteriorly placed pelvis or an anomalous vasculature that partially blocks one of the major calyces or the upper ureter. In addition, there may be an increased risk of injury from blunt abdominal trauma because the low-lying kidney is not protected by the rib cage.

Most patients with ectopic kidney are clinically asympto- matic. Vague Abdominal complaints of frank ureteral colic secondary to an obstructing stone are still the most frequent symptoms leading to discovery of the misplaced kidney. To our knowledge, pelvic ectopic kidney with acute pyelone- phritis masquerading as ruptured appendicitis has never been reported. Even with the advent of modern imaging modalities, this case illustrates a diagnostic pitfall in general practice when managing right lower quadrate pain in patients with typical presentations of acute appendicitis without sonographic evidence [5]. Contrast-enhanced computed tomography scan is a reliable tool for diagnosing and evaluating this disease [6]. Therefore, early recognition by exquisite imaging studies with raised awareness in the

clinical setting and prompt antibiotic treatment can avoid unnecessary intervention, preserve renal function, and prevent a life-threatening catastrophe.

Yu-Tzu Tsao MD Department of Emergency Medicine Tri-Service General Hospital National Defense Medical Center

Neihu 114, Taipei, Taiwan, Republic of China

Division of Nephrology Department of Medicine

Tri-Service General Hospital National Defense Medical Center

Neihu 114, Taipei, Taiwan, Republic of China

Shih-hua Lin MD Yuh-Feng Lin MD, PhD Pauling Chu MD, PhD Division of Nephrology Department of Medicine

Tri-Service General Hospital National Defense Medical Center

Neihu 114, Taipei, Taiwan, Republic of China E-mail address: [email protected]

doi:10.1016/j.ajem.2007.08.023

References

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3. Downs RA, Lane JW, Burns E. Solitary pelvic kidney. Its clinical implications. Urology 1973;1:151-6.
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