Would you biopsy this woman?

Today a woman came to see me who was 6 months pregnant. She was seeing me for a second opinion. During her first prenatal visit her OB discovered 4+ proteinuria and the patient was referred to nephrology. A 24-hour urine subsequently documented 7 grams of proteinuria with excellent renal function. She had a serum creatinine of 0.4 mg/dL.

The serologic work-up was negative. No ANA, negative ANCA, no viral hepatitis, compliments were not decreased, HIV was negative. Antiphospholipids were not checked.

The nephrologist then sent her for an ultrasound-guided renal biopsy, which  showed membranous nephropathy.

Now she is six months pregnant and doing well. She has a lot of lower extremity edema but no other symptoms. I advised no specific therapy at this time and close, continuous follow-up.

The whole time I’m seeing her I’m thinking would I have biopsied her? What are the indications for a kidney biopsy in a pregnant patient?

I love it when Dr. Google has just what you wanted to know:

And it’s NDT, so hastle free PDFs. Yay!

From the introduction:

Indeed one group recommend no modification of the indication for renal biopsy in pregnancy and suggest that all pregnant women with abnormalities in urinalysis indicative of renal disease should undergo renal biopsy to guide treatment [4], but this is not standard practice. Although it has been established that there is no greater risk of complications of renal biopsy in pregnancy, the consequences to the mother and fetus of post-biopsy haemorrhage could be severe.

The article reviews 20 women who had kidney biopsies during pregnancy and 75 who had post-natal biopsies.

Biopsies during pregnancy (N=20)

  • median age 28
  • Gestation at biopsy: 20 weeks

Indications for the biopsy:

  • 4 with previous diagnosis of lupus and new loss of renal function
  • 4 with proteinuria and positive auto-immune serologies
  • 4 with new nephrotic syndrome
  • 3 in the first with proteinuria and decreased renal function
  • 5 in the second trimester with worsening hypertension and proteinuria

The pregnancies resulted in 17 children, 2 miscarriages and one still birth. The average gestation at delivery was 34 weeks. The biopsies all went well with only one complication, mild hematuria that resolved spontaneously. The biopsy changed therapy in 9 of the patients.

Biopsies after pregnancy (N=75)

  • median age 31

Indication for the biopsy:

  • 50 presented with proteinuria during pregnancy
    • 23 associated with pre-eclampsia
    • 27 without pre-eclampsia
  • 6 with nephrotic syndrome
  • 6 with new renal impairment
  • 4 with isolated hematuria
  • 3 with acute renal failure

By my count that is only 69 patients, not sure what happened to the other 6.

The authors presented follow-up data on 47 patients who followed up within their hospital system. The patients who received follow-up tended to be patients with more severe disease, as patents with mild disease were discharged to primary care.

Grey is bad. Black is better.

The authors conclude that the modern kidney biopsy is generally safe during pregnancy and should be performed in the following circumstances:

In the first trimester
Structurally normal kidneys and:

  • an active urinary sediment or
  • nephrotic syndrome or
  • unexplained CKD (with proteinuria and no evidence of scarring) or
  • those with renal impairment and proteinuria in the context of systemic disease or positive autoimmune serology

We feel a diagnosis at this stage of pregnancy is of benefit to guide treatment and allow an informed discussion of the risks:benefit ratio of continuation of pregnancy.

In the second trimester
Renal biopsy should be reserved for those with:

  • unexplained nephrotic range proteinuria
  • progressive CKD and renal disease in the presence of active systemic disease

Interesting, so by these authors recommendations the biopsy was indicated (she has nephrotic syndrome), despite the fact that it didn’t change her therapy. Good to know.