Before we get to the biopsy, let’s make sure we minimize the risk of bleeding in this patient.
Which of the following would be a relative contraindication to performing a kidney biopsy in this patient?
Elevated blood pressure (BP 162/92 on physical exam)
Correct, uncontrolled hypertension is a relative contraindication to percutaneous kidney biopsy. We should try to bring this patient’s blood pressure down to a goal of <140/90 before proceeding!
Prolonged partial thromboplastin time (PTT 42.2 seconds)
Though abnormal coagulation studies should be investigated, a mildly prolonged PTT is not a contraindication to biopsy. This patient’s prolonged PTT can likely be explained by her underlying condition and should be studied further.
Thrombocytopenia (platelet count 110 x 10^3/uL)
Though the platelet count is not normal, this level of thrombocytopenia is not prohibitive. However, an uncontrolled bleeding diathesis or use of anti-platelet agents or anticoagulants such as aspirin, clopidogrel, or warfarin might be a relative contraindication. Many nephrologists would consider a platelet count of less than 100 x 10^3/uL a relative contradication for kidney biopsy.
Fever
It’s a good thought, but fever is not a contraindication to biopsy in this patient. If we suspected a urinary tract infection or pyelonephritis, we may delay the biopsy until after treatment of the infection.
Excellent work, you’ve now prepared the patient for biopsy, her vital signs are stable, and she tolerates the procedure well. It’s the day afterwards and your pathologist shows you the H&E and the Periodic-Acid Schiff or PAS stain. Click here for some quick pathology tips.
Which of the following do you see below (more than one answer may be correct)?
Endocapillary proliferation
Correct! We do see endocapillary proliferation with obliteration of the capillary loops.
Crescent formation
Correct! There does appear to be a crescent visualized on the PAS stain below. Crescents are not specific to one disease, but rather a finding on histology consistent with glomerular damage. Note that Bowman’s space is obliterated and we see at least two layers of cells filling the space. Normally, Bowman’s space should be comprised of one layer of parietal epithelial cells.
Thickened capillary loops
Correct! The capillary loops are markedly thickened and have a “wire loop” appearance.
Podocyte effacement
The podocyte structure is best visualized under electron microscopy, not light microscopy.
Subepithelial deposits
Subepithelial deposits are best seen under electron microscopy, not light microscopy.
H&E
PAS
In this case, our pathologist informs us that greater than 50% of the glomeruli are affected.
Click here once you’re ready to look at more stains that might help you narrow down your differential diagnosis!
Case 7 Index
Case 7 Introduction
Case 7 Physical Exam
Case 7 Diagnostic Testing