Kidney biopsy during pregnancy or wait postpartum: two decades experience from a single center

Kidney biopsy is the gold standard for diagnosing kidney disease, yet its use during pregnancy remains controversial due to concerns about procedure related complications and limited contemporary evidence. This study evaluates long term kidney outcomes with biopsy timing in pregnant and postpartum females.

We conducted a retrospective cohort study spanning over 22-years including females aged ≥ 18 years who underwent native kidney biopsy during pregnancy or within three months postpartum. Demographic, clinical, histopathological, maternal, fetal, and long-term kidney outcomes were abstracted from electronic health records. Kaplan-Meier analysis evaluated kidney survival, defined as time to dialysis initiation and statistical significance was set at p-value < 0.05.

In our cohort, 29 females met inclusion criteria: 13 biopsied during pregnancy and 16 postpartum. Long term kidney survival did not differ significantly between groups (log rank p = 0.3). Complication rates were comparable between groups; low, limited to small, and self-limiting hematomas. Lupus nephritis was the most frequent diagnosis in both groups.

Although long term dialysis rates were comparable between the two groups, the postpartum cohort had a shorter duration of follow up. Biopsies performed during pregnancy and postpartum were safe in this cohort and yielded clinically meaningful information that frequently altered acute management. Nephrotic range proteinuria and an eGFR below 60 mL/min/1.73 m² were key predictors of progression to ESKD.

In our study, no statistically significant difference in long-term kidney survival was observed by biopsy timing during pregnancy vs. postpartum, even though pregnancy group had much longer follow-up than the postpartum group.