Kidney Week

Abstract: TH-PO1095

Clinicopathological Spectrum of Kidney Biopsy Findings During Pregnancy: An Analysis of 49 Biopsies from a Single Institution

Session Information

• Pathology and Lab Medicine
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pathology and Lab Medicine

• 1700 Pathology and Lab Medicine

Authors

• Nakayama, Shingo, Cedars-Sinai, Los Angeles, California, United States

Shingo Nakayama, MD, PhD

• Kubota-Nakayama, Fumie, Cedars-Sinai, Los Angeles, California, United States

Fumie Kubota-Nakayama, MD, PhD

• Choung, Hae Yoon Grace, Cedars-Sinai, Los Angeles, California, United States

Hae Yoon Grace Choung, MD

• Lin, Mercury Y., Cedars-Sinai, Los Angeles, California, United States

Mercury Y. Lin, MD

• Haas, Mark, Cedars-Sinai, Los Angeles, California, United States

Mark Haas, MD, PhD

• Nast, Cynthia C., Cedars-Sinai, Los Angeles, California, United States

Cynthia C. Nast, MD, FASN

• Hou, Jean, Cedars-Sinai, Los Angeles, California, United States

Jean Hou, MD

• Yamashita, Michifumi, Cedars-Sinai, Los Angeles, California, United States

Michifumi Yamashita, MD, PhD, FASN

Background

Kidney biopsy during pregnancy is considered when worsening renal dysfunction and/or severe proteinuria may affect maternal and/or fetal outcomes, and when a pathological diagnosis is required to determine therapeutic strategies. However, pathological information on kidney biopsies performed during pregnancy remains scarce. Here, we report a series of kidney biopsies performed during pregnancy with detailed pathological characterization.

Methods

We retrospectively reviewed 52,868 native kidney biopsies evaluated at Cedars-Sinai Medical Center, Los Angeles, CA, USA, from January 1, 2006, to December 31, 2025.

Results

Forty-nine kidney biopsies performed during pregnancy were identified. The median age (interquartile range) and gestational age at biopsy were 27.0 years (22.0-30.0 years) and 18.0 weeks (14.0-24.0 weeks), respectively. Lupus nephritis (LN) was the most common diagnosis (28.6%), followed by IgA nephropathy (IgAN; 24.5%), secondary focal segmental glomerulosclerosis (2°FSGS; 10.2%), preeclampsia (8.2%), and diabetic glomerulosclerosis (6.1%). Cases were stratified by gestational age (<20 vs. ≥20 weeks): Of 43 patients with available data, 26 biopsies were performed before 20 weeks and 17 after 20 weeks of gestation. Although preeclampsia is considered the most common cause of acute kidney injury after 20 weeks of gestation, only 3 cases were diagnosed as preeclampsia in our cohort. The remaining cases in the ≥20-week group comprised LN, IgAN, 2°FSGS, infection-related glomerulonephritis, membranous nephropathy, and dense deposit disease.

Conclusion

In this biopsy-based cohort, LN was the most frequent pathological diagnosis during pregnancy, followed by IgAN, with a wide spectrum of kidney diseases. Although preeclampsia is commonly reported as a major cause of pregnancy-related acute kidney injury, it was infrequent among cases that underwent kidney biopsy, likely because biopsy tends to be avoided beyond 20 gestational weeks.