Kidney Biopsy During Pregnancy: Risks Exist but Not Without Benefit

Pregnancy has been described as a “great occasion” for the diagnosis of kidney disease. Kidney diseases are estimated to affect 3% of women of childbearing age (1). When kidney disease is newly diagnosed or flares during pregnancy, there are many issues concerning whether and in what circumstances kidney biopsy should be performed. This decision should be based on several factors, including the stage of pregnancy, severity of the kidney disease, and suspected underlying diagnoses.

The early diagnosis of glomerular diseases can have a profound therapeutic impact on the mother and the fetus. If kidney biopsy results offer a chance at a significant alteration in patient management, then a biopsy should be considered. A diagnosis that allows for immediate initiation of targeted treatment may allow progression of pregnancy to fetal viability with maternal protection. It also can be the grounds for discussion about the risk of continuing a pregnancy if the severity of the glomerular disease is high, and due to the side effects of medications, only a course of suboptimal therapy can be offered.

Kidney biopsies are typically performed in the prone position. As the pregnancy progresses, a gravid uterus can make the standard position untenable. In pregnant patients, biopsies have been successfully and safely performed with the patient sitting upright or in the lateral decubitus position. Kidney biopsies during pregnancy should be performed under ultrasound guidance and not computed tomography guidance to limit radiation exposure to the developing fetus. Otherwise, the logistics of performing a kidney biopsy during pregnancy are unchanged from the nonpregnancy technique.

The major risk of kidney biopsy is bleeding, which can range from minor to major. Major bleeds result in the need for blood transfusion, selective angiography and embolization, or death (2). In pregnancy, there is additional risk to the fetus with severe bleeding; not only would blood flow to the placenta be compromised, but shielding the fetus from radiation exposure during angiography is challenging.

The rates of complications from kidney biopsy during pregnancy range from 4% to 7% (3–6). Complications increase with gestational age of pregnancy and collectively are higher during pregnancy than in the postpartum period (7% vs 1%, respectively) (3). A meta-analysis of kidney biopsy performed in pregnancy found that kidney biopsy in early pregnancy (0–21 weeks, before fetal viability at 22 weeks) was not associated with increased risk of complications. At 23–28 weeks, more major bleeding episodes occurred that were associated with severe obstetric complications, including early preterm delivery and presumed fetal death. Late pregnancy biopsies (after 28 weeks) were rare (3).

Consensus is to biopsy before the 28th week (beginning of the third trimester), although clinical practice guidelines in the United Kingdom suggest limiting kidney biopsies to the first and early-second trimesters. The potential risks to the fetus are likely too great after 28 weeks. Management options in the third trimester include empiric treatments that are considered safe in pregnancy (e.g., steroids and azathioprine), early induction of labor followed by kidney biopsy, or delayed treatment and biopsy until after delivery.

Kidney biopsies can and should be performed in selected women during pregnancy. Extensive counseling about the risks and benefits of the procedure is important. In women with presumed rapidly progressive glomerulonephritis, in which the results of the biopsy would lead to immediate changes in therapy, kidney biopsy should be considered to allow for the best possible outcomes.