. Certain forms of nephritis (e.g. focal glomerulosclerosis and mesangiocapillary glomerulonephritis) recur in transplants, and it is helpful to know

rapidly progressive glomerulonephritis, such as polyarteritis or antiglomerular basement disease. 7. Chronic and end-stage renal failure - provided kidneys are not small and shrunken, biopsy is useful in determining the cause and prognosis. Certain forms of nephritis (e.g. focal glomerulosclerosis and mesangiocapillary glomerulonephritis) recur in transplants, and it is helpful to know this for future management. 8. Special situations - (a) Uncontrolled hypertension may lead to renal impairment, hematuria and proteinuria, and this may occasionally result in nephrotic syndrome. Once hypertension is controlled, renal biopsy may be the sole criterion for determining whether the problem is due to pure hypertension or underlying nephritis. (b) In 10-20% of patients with diabetes mellitus, proteinuria and impaired renal function may be due to causes other than diabetic nephrosclerosis, particularly in those with no other evidence of microvascular disease e g diabetic retinopathy. 9. Renal allograft dysfunction -(a) It provides only reliable method of distinguishing rejection from cyclosporin nephrotoxicity. (b) It helps in deciding the scale of antirejection therapy and differentiating allograft nephropathy form recurrent or de novo nephritis. Contraindications - 1. Single kidney or severe malfunction of one kidney. 2 Uncontrollable bleeding diathesis. 3. Small, shrunken kidneys (difficult to locate and information obtained usually nonspecific). 4 Presence of cystic disease, nephrolithiasis, reflux nephropathy or obstruction or hemangioma. Technique - Localization of the kidney- Lateral border of lower pole of kidney is the safest part to biopsy. Ultrasound is the preferred imaging technique to mark the position of the kidney. It is particularly preferred in patients with impaired function as it avoids use of contrast media (as in IVU) Attachments are available for ultrasound probes which can precisely direct the needle to the kidney Biopsy needle - (a) Franklin-modified Vim Silverman needle (b) Tru-Cut needles are disposable needles and not composed of different parts. (c) Biopsy gun is a spring-loaded device which 'shoots' a variant of tru-cut needle into the organ. (d) Biopsy needles with tips which are easily seen by ultrasound They are smaller but adequate tissue can usually be obtained Biopsy of the native kidney - (a) Pre-medication to allay anxiety and pain. (b) 'Fixing1 the kidney - so that it does not move significantly with patient's respirations. Patient's upper abdomen and lower chest should be supported by pillows so adjusted that patient's diaphragm is well splinted.(c) Sedation - with IV diazepam to produce deep sleep. (d) Position of lower pole of the kidney as determined by ultrasound is marked on the skin and depth of the kidney measured. (e) Biopsy is then performed. Enough tissue must be taken for light microscopy, electron microscopy, immuno-fluorescence or immunoperoxidase techniques and, if appropriate for culture Biopsy of transplanted kidney - The allograft may be easily palpable in the iliac fossa but it should be localised by ultrasound aiming for the lateral border of upper pole. Since transplanted kidney often becomes encased in fibrous tissue, this must be penetrated before biopsy is taken. If it is not, cutting prongs of a modified Vim Silverman needle or cutting tip of a Tru-Cut disposable needle may 'bounce' off the kidney and lacerate it, causing hemorrhage. Fine-needle aspiration biopsy (FNAB) - is used in