Congenital anomalies of the kidney

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					Congenital anomalies of the kidney
Objectives: 1-To identify the common renal anomalies. Classification of renal anomalies: 1. Anomalies of the number a. Renal agenesis b. supernumerary kidney 2. Anomalies of the size a. Renal hypoplasia 3. Anomalies of kidney structure a. polcystic kidney b. medullary sponge kidney 4. Anomalies of position a. ectopic pelvic kidney b. ectopic thoracic kidney c. crossed ectopic kidney with and without fusion 5. Anomalies of fusion a. Horseshoe kidney b. Crossed ectopic kidney with fusion 6. Anomalies of the renal collecting system a. Calcyeal diverticulum. b. Megacalicosis c. Ureterpelvic junction stenosis 7. Anomalies of the renal vasculature a. Arteriovenous malformations and fistulae b. Aberrant and accessory vessels. c. Renal artery stenosis Renal agenesis Failure of development of the ureteral bud results in absence of ipsilateral kidney with its hemitrigone. Renal hypoplasia This term implies congenitally small kidney but otherwise normal. Hypoplastic kidney may lead to reno-vascular hypertension, and hence treated by nephrectomy


Polycystic kidney Hereditary condition characterized by progressive distortion of the renal parenchyma by multiple cysts and peritubular fibrosis.

Types: 1-Infantile polycystic kidneys: autosomal recessive, rare disease in which life expectancy is short due rapid destruction of the renal parenchyma of both sides. 2-Adult polycystic kidneys: autosomal dominant slowly progressive disease causing slow destruction of the renal parenchyma of both sides. Cysts of the liver, spleen, and pancreas may be noted in both types. Etiology and pathogenesis Renal cysts occur due to failure of fusion of the collecting tubules with the convoluted tubules of the same nephron. As the cysts enlarge, they compress adjacent parenchyma, destroy it by ischemia, and occlude normal tubules. The result is progressive renal destruction. Pathology: Grossly, polycystic kidney disease is bilateral disease. Both kidneys are usually enlarged and very firm in consistency. Their surfaces are studied with multiple cysts of varying size. On section, the cysts found to be scattered through out the parenchyma. All the cysts are non communicating to each other and also non communicating to the pelvicalcyceal system. The fluid in the cyst id usually amber colored but may be hemorrhagic. Microscopically, the cysts are lined with flat epithelial lining, and are surrounded by reactionary diffuse peritubular fibrosis. Renal glomeruli are reduced in number, some of which may be hyalinized.


Gross appearance of poly cystic kidney

Cut section in polycystic kidney Clinical picture Patients with Adult type of polycystic kidney disease remains asymptomatic till the age fourties Symptoms: Adult type usually present at middle age with these symptoms -Renal pain: in one or both kidneys due to the drag on the vascular pedicle by the heavy weighted kidney. -Hematuria: due to rupture of a vessel in the cyst wall into calyx. -infection (fever and chills) commonly complicate polycystic kidneys -Symptoms of renal insufficiency (headache, nausea and vomiting). Signs -Hypertension in 60-75% of cases -Renal swelling: usually bilateral and tender


Laboratory findings: -Urine analysis: hematuria, pyuria , proteinuria and renal casts, and decrease in the specific gravity of the urine( indicating renal failure). -Anemia -Uremia Radiological findings: - Plain X-ray film : increased renal shadow on both sides - Intravenous urogram: compressed and stretched calyces with elongated narrowed calcyeal necks (spider leg appearance). - Ultrasonography: diffuse small echo lucent cysts on both kidneys Differential diagnosis -Bilateral hydronephrosis: -Bilateral renal tumor -simple renal cyst: usually unilateral with preserved renal function. Complications - Pyelonephritis - Infected cysts - Gross hematuria which may be life threatening. - End stage renal failure. Treatment 1General measure: low protein diet, ample fluids, limited exercise, control hypertension and hemodialysis if needed 2Surgery: only indicated in large cyst compressing the upper ureter. Also renal transplantation. 3Treatment of complications

Ectopic kidney In a 6 weeks embryo, normally both kidneys present in the pelvis, close to the midline, with each renal pelvis facing anteriorly. At full term, both kidneys become located at the level of the third lumbar vertebrae, further away from the midline, with each renal pelvis facing medially. I-Simple ectopy: due to failure of ascent of the kidney to its normal position. i)-pelvic kidney: the commonest type of ectopic kidney in which the kidney lies over the pelvic brim or over the pelvis and its renal pelvis is facing anteriorly. It


takes blood supply from adjacent vessels with short ureter. Such a kidney may be palpable. Also it has a short ureter.

It is palpable in the iliac fossa due to its superficial position. Intravenous urogram shows the pelvic position of the kidney with short ureter (DD. Nephroptosis have long tortuous ureter). Obstruction and infection may complicate Ectopic kidney and should be treated by appropriate means. ii)-Thoracic kidney: in which one kidney is carried up in the chest. It accounts 5% of Ectopic kidneys, due to delayed closure of the diaphragmatic aperture and renal ascent. II-Crossed ectopy without fusion: in which on kidney is crossing the midline, due to presumed migration of the ureteral bud to the other side during intrauterine life, or rotation of the caudal end of the foetus at the time of bud formation. III- Crossed ectopy with fusion: in which the two kidneys are fused together in one side Renal fusion Types 1- Horseshoe kidney The lower pole of both kidneys are fused with each other and connected by an isthmus.


Both kidneys are lower than the normal, as there ascent are blocked by the inferior mesenteric artery during fetal development The longitudinal axis of the kidneys is directed downward and medially. With malrotation in them, and much lower in position than normal kidneys.

Gross appearance of horseshoe kidney


Fig:IVU showing horseshoe kidney. 2- Crossed ectopy with fusion


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