Congenital Malformations

Question 1

Congenital malformations of the kidney

Answer 1

Abnormalities in size/number

1. Renal Agenesis
2. Renal Hypoplasia

Abnormalities in position/shape

1. Ectopic Kidney
2. Horseshoe Kidney

Question 2

Features of renal agenesis

Answer 2

• due to lack of metanephric primordia
• failure of ureteral bud development
• failure of contact of ureteral bud & metanephros
• bilateral: rare, incompatible with life, stillborn, more common in M
• unilateral: more common in M, opposite kidney usually enlarged (compensatory hypertrophy)

Question 3

Features of renal hypoplasia

Answer 3

• small kidney, reduced number of lobules & calyces
• microscopic: primitive glomeruli & tubules in dense fibrous/fatty interstitium
• renal hypoplasia with oligomeganephronia - small kidney + hypertrophied glomeruli

Question 4

Features of ectopic kidney

Answer 4

• displacement of kidneys
• above pelvic brim or within the pelvis
• complications: kinking/tortuousity of ureters - obstruction w urinary inf

Question 5

Features of horseshoe kidney

Answer 5

• fusion of lower (90%) or upper poles

- complications: renal calculi predisposed by abnormalities in drainage causing urinary stasis