FUSED PELVIC KIDNEYS: CASE REPORT Cyril V. Chavis, MD, Harry C. Press, Jr, MD, and Roma V. Gumbs, MD Washington, DC
A case of fused pelvic kidneys is presented. We believe this to be the first report using ultrasound, computed tomography, and magnetic resonance imaging for presentation of a rare anatomic renal anomaly. (J Nati Med Assoc. 1 992;84:980-982.) Key words * fused pelvic kidneys * renal ectopia
Unilateral pelvic renal ectopia is not an uncommon finding and is usually discovered during routine urologic evaluation. However, bilateral pelvic kidneys with or without fusion is rare. Masih et al recorded a case of fused pelvic kidneys after the previously documented 11th case presented by Glen."2 Recently, we have encountered a case of bilateral pelvic fused kidneys. This report is the first reported case of fused pelvic kidneys with ultrasonographic, computed tomographic, and magnetic resonance imaging (MRI) findings.
CASE REPORT A 44-year-old, gravida 1, para 1, premenopausal African-American woman presented with a 5-month history of dull and continuous left lower abdominal pain. The pain increased at menses. The patient had a 2-month history of frequency and nocturia. Abdominal examination revealed mild tenderness to deep palpitation of the left lower quadrant. Pelvic examination revealed a pelvic mass and mild left adnexal tenderness. Physical examination was otherwise normal. Real-time sonography of the abdomen and pelvis was performed. The sonographic examination revealed bilateral pelvic kidneys with questionable mild left From the Department of Radiology, Howard University Hospital, Washington, DC. Requests for reprints should be addressed to Dr Harry C. Press, Jr, Dept of Radiology, Howard University Hospital, 2041 Georgia Ave, NW, Washington, DC 20060. 980
hydronephrosis (Figure 1). Bilateral retrograde pyelography did not demonstrate hydronephrosis nor did it show fusion. The patient was clinically assessed as having normal pelvic kidneys. Computed tomography (CT) of the lower abdomen and pelvis with axial and coronal images confirmed the pelvic location of the kidneys (Figure 2). In addition, there appeared to be continuity of the superior poles of the kidneys, thereby indicating superior pole fusion. Magnetic resonance imaging was performed with both T- 1 and T-2 weighted images. Fusion of the upper poles was most clearly demonstrated on the T- 1 weighted coronal images (Figure 3). There were no other anomalies of the genitourinary, gastrointestinal, or skeletal systems. Outside of the patient's pelvic renal ectopia and fusion anomaly, a definite cause of her lower abdominal pain has not been determined.
DISCUSSION Fused pelvic kidneys is an anomaly of position and fusion of the genitourinary tract. Anomalies of position and fusion include kidneys that have migrated to become fused with the contralateral mate and are subdivided clinically on the basis of whether both or only one kidney moves toward or crosses the midline.3 An endless number of position and fusion conformities may occur that defy conventional classification. Numerous embryologic theories have sought to provide explanation for anomalies of position and fusion, which occur very early in gestation. Faulty ureteral bud development, abnormalities of renal vasculature limiting ascent, and teratogenic factors have been offered as explanations.3'4 Cook and Stephens have posed a theory that relates the position and fusion anomalies to abnormal variation in growth or flexion of the hind end of the developing embryo.5 Another postulation is renal fusion resulting from the pressing together of the nephrogenic blastema by the umbilical JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 84, NO. 11
FUSED KIDNEYS
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Figure 1. Transverse ultrasound image of the pelvis. The right renal parenchyma (R) and pelvis (arrows) are clearly demonstrated as well as the left renal pelvis (arrowheads). Fusion is not obvious.
Figure 3 Coronal TI-weighted (783120) MR image more clearly shows fusion of the upper poles of the pelvic kidneys.
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Figure 2. Contrast-enhanced axial CT scan shows bilateral pelvic kidneys that appear fused posteriorly.
arteries as the developing kidneys ascend out of the pelvis.6 However, mechanical factors alone do not provide a comprehensive explanation when one considers that cardiovascular and skeletal anomalies are known to be associated with renal ectopia and fusion. Both the conditions of bilateral pelvic kidneys and fused pelvic kidneys appear to be very rare. Before the advent of cross-sectional imaging modalities, recorded cases of pelvic kidneys were usually diagnosed with intravenous pyelography (IVP) and therefore fusion could have been missed. Crossed renal ectopia has an autopsy incidence of about one in 2000 and a slight male predominance.3 Solitary pelvic kidney has an JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 84, NO. 11
autopsy incidence of 0.14% and a clinical expression incidence of 0.008%. Although fused pelvic kidneys are more or less related to the above entities, they occur much less frequently. The fact that the incidence of such renal anomalies is much higher in postmortem studies than in clinical situations suggests that many remain unrecognized during life. Most cases of pelvic ectopia are diagnosed between the fourth and seventh decades of life. In one series of 32 cases of pelvic kidneys, 44% presented with symptoms pertaining to the urogenital system and 34% presented with recurrent lower abdominal pain.8 Many patients with pelvic renal ectopia remain entirely asymptomatic. When symptoms are present, they typically relate to calculi, hydronephrosis, infection, or hematuria. Fusion anomalies and pelvic ectopia are prone to cause stasis of urine, pyelectasis, calicectasis, infection, and stone formation. The anomalous position of the kidneys, pelvis, and ureter predisposes to poor drainage and may result in extensive hydronephrosis. A variety of associated abnormalities, including sacral agenesis, scoliosis, cardiovascular, and gastrointestinal anomalies have been reported. Although the above anomalies can be associated with pelvic renal ectopia and fusion, their incidence is low.4 981
FUSED KIDNEYS
This case is of radiologic and urologic significance in that it is the first known report using ultrasound, CT, and MRI for presentation of a rare anatomic renal anomaly. Literature Cited 1. Masih S, Bakda R, Collins J. Pelvic fused kidneys: magnetic resonance imaging and intravenous pyelogram correlation. J Natl Med Assoc. 1988;80:925-927. 2. Glen JF Fused pelvic kidney. J Urol. 1958;80:7-9. 3. McDonald HJ, McClellan DS. Crossed renal ectopia. Am J Surg. 1957;93:995-998. 4. Kelalis PP, Malek RS, Segura FW. Observation on renal ectopia and fusion in children. J Urol. 1973;1 10:588-592. 5. Cook WA, Stephens FD. Fused kidneys: morphologic study and theory of embryogenesis. Birth Defects. 1977;1 3:327-340. 6. Witten DM, Myers GH, Utz DC, eds. Emmett's Clinical Urography. 4th ed. Philadelphia, Pa: WB Saunders Co; 1977. 7. Gillenwater JY. Adult and Pediatric Urology. Chicago, IlIl: Yearbook Medical Publishers; 1987. 8. Ward JN, Nathanson B, Draper JW. The pelvic kidney. J Urol. 1965;94:36-40.
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A small contribution from you can make a big difference to a young person: the difference between going to college, and not going. Few other investments are as immediately rewarding as this, and offer such potential to the student, society, and your company. Please support the United Negro College Fund. A mind is a terrible thing to waste.
United Negro College Fund. 982
A Mind Is A Temdble Thing To Waste. @
A case of fused pelvic kidneys is presented. We believe this to be the first report using ultrasound, computed tomography, and magnetic resonance imaging for presentation of a rare anatomic renal anomaly. (J Nati Med Assoc. 1 992;84:980-982.) Key words * fused pelvic kidneys * renal ectopia
Unilateral pelvic renal ectopia is not an uncommon finding and is usually discovered during routine urologic evaluation. However, bilateral pelvic kidneys with or without fusion is rare. Masih et al recorded a case of fused pelvic kidneys after the previously documented 11th case presented by Glen."2 Recently, we have encountered a case of bilateral pelvic fused kidneys. This report is the first reported case of fused pelvic kidneys with ultrasonographic, computed tomographic, and magnetic resonance imaging (MRI) findings.
CASE REPORT A 44-year-old, gravida 1, para 1, premenopausal African-American woman presented with a 5-month history of dull and continuous left lower abdominal pain. The pain increased at menses. The patient had a 2-month history of frequency and nocturia. Abdominal examination revealed mild tenderness to deep palpitation of the left lower quadrant. Pelvic examination revealed a pelvic mass and mild left adnexal tenderness. Physical examination was otherwise normal. Real-time sonography of the abdomen and pelvis was performed. The sonographic examination revealed bilateral pelvic kidneys with questionable mild left From the Department of Radiology, Howard University Hospital, Washington, DC. Requests for reprints should be addressed to Dr Harry C. Press, Jr, Dept of Radiology, Howard University Hospital, 2041 Georgia Ave, NW, Washington, DC 20060. 980
hydronephrosis (Figure 1). Bilateral retrograde pyelography did not demonstrate hydronephrosis nor did it show fusion. The patient was clinically assessed as having normal pelvic kidneys. Computed tomography (CT) of the lower abdomen and pelvis with axial and coronal images confirmed the pelvic location of the kidneys (Figure 2). In addition, there appeared to be continuity of the superior poles of the kidneys, thereby indicating superior pole fusion. Magnetic resonance imaging was performed with both T- 1 and T-2 weighted images. Fusion of the upper poles was most clearly demonstrated on the T- 1 weighted coronal images (Figure 3). There were no other anomalies of the genitourinary, gastrointestinal, or skeletal systems. Outside of the patient's pelvic renal ectopia and fusion anomaly, a definite cause of her lower abdominal pain has not been determined.
DISCUSSION Fused pelvic kidneys is an anomaly of position and fusion of the genitourinary tract. Anomalies of position and fusion include kidneys that have migrated to become fused with the contralateral mate and are subdivided clinically on the basis of whether both or only one kidney moves toward or crosses the midline.3 An endless number of position and fusion conformities may occur that defy conventional classification. Numerous embryologic theories have sought to provide explanation for anomalies of position and fusion, which occur very early in gestation. Faulty ureteral bud development, abnormalities of renal vasculature limiting ascent, and teratogenic factors have been offered as explanations.3'4 Cook and Stephens have posed a theory that relates the position and fusion anomalies to abnormal variation in growth or flexion of the hind end of the developing embryo.5 Another postulation is renal fusion resulting from the pressing together of the nephrogenic blastema by the umbilical JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 84, NO. 11
FUSED KIDNEYS
~ ~ ~ ~ ~ ~ ~ IN i
~
~
~
~
4
Figure 1. Transverse ultrasound image of the pelvis. The right renal parenchyma (R) and pelvis (arrows) are clearly demonstrated as well as the left renal pelvis (arrowheads). Fusion is not obvious.
Figure 3 Coronal TI-weighted (783120) MR image more clearly shows fusion of the upper poles of the pelvic kidneys.
*|
E
l!
Figure 2. Contrast-enhanced axial CT scan shows bilateral pelvic kidneys that appear fused posteriorly.
arteries as the developing kidneys ascend out of the pelvis.6 However, mechanical factors alone do not provide a comprehensive explanation when one considers that cardiovascular and skeletal anomalies are known to be associated with renal ectopia and fusion. Both the conditions of bilateral pelvic kidneys and fused pelvic kidneys appear to be very rare. Before the advent of cross-sectional imaging modalities, recorded cases of pelvic kidneys were usually diagnosed with intravenous pyelography (IVP) and therefore fusion could have been missed. Crossed renal ectopia has an autopsy incidence of about one in 2000 and a slight male predominance.3 Solitary pelvic kidney has an JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION, VOL. 84, NO. 11
autopsy incidence of 0.14% and a clinical expression incidence of 0.008%. Although fused pelvic kidneys are more or less related to the above entities, they occur much less frequently. The fact that the incidence of such renal anomalies is much higher in postmortem studies than in clinical situations suggests that many remain unrecognized during life. Most cases of pelvic ectopia are diagnosed between the fourth and seventh decades of life. In one series of 32 cases of pelvic kidneys, 44% presented with symptoms pertaining to the urogenital system and 34% presented with recurrent lower abdominal pain.8 Many patients with pelvic renal ectopia remain entirely asymptomatic. When symptoms are present, they typically relate to calculi, hydronephrosis, infection, or hematuria. Fusion anomalies and pelvic ectopia are prone to cause stasis of urine, pyelectasis, calicectasis, infection, and stone formation. The anomalous position of the kidneys, pelvis, and ureter predisposes to poor drainage and may result in extensive hydronephrosis. A variety of associated abnormalities, including sacral agenesis, scoliosis, cardiovascular, and gastrointestinal anomalies have been reported. Although the above anomalies can be associated with pelvic renal ectopia and fusion, their incidence is low.4 981
FUSED KIDNEYS
This case is of radiologic and urologic significance in that it is the first known report using ultrasound, CT, and MRI for presentation of a rare anatomic renal anomaly. Literature Cited 1. Masih S, Bakda R, Collins J. Pelvic fused kidneys: magnetic resonance imaging and intravenous pyelogram correlation. J Natl Med Assoc. 1988;80:925-927. 2. Glen JF Fused pelvic kidney. J Urol. 1958;80:7-9. 3. McDonald HJ, McClellan DS. Crossed renal ectopia. Am J Surg. 1957;93:995-998. 4. Kelalis PP, Malek RS, Segura FW. Observation on renal ectopia and fusion in children. J Urol. 1973;1 10:588-592. 5. Cook WA, Stephens FD. Fused kidneys: morphologic study and theory of embryogenesis. Birth Defects. 1977;1 3:327-340. 6. Witten DM, Myers GH, Utz DC, eds. Emmett's Clinical Urography. 4th ed. Philadelphia, Pa: WB Saunders Co; 1977. 7. Gillenwater JY. Adult and Pediatric Urology. Chicago, IlIl: Yearbook Medical Publishers; 1987. 8. Ward JN, Nathanson B, Draper JW. The pelvic kidney. J Urol. 1965;94:36-40.
Looking fora small investment that.pays big dividends? 0w
A small contribution from you can make a big difference to a young person: the difference between going to college, and not going. Few other investments are as immediately rewarding as this, and offer such potential to the student, society, and your company. Please support the United Negro College Fund. A mind is a terrible thing to waste.
United Negro College Fund. 982
A Mind Is A Temdble Thing To Waste. @
