RENAL BIOPSIES IN PREGNANCY AND POST-PARTUM: HISTOPATHOLOGICAL EVALUATION

Introduction:

Pregnancy is the physiologic condition that causes immunologic and hemodynamic changes throughout its course. Kidney injury can occur due to pregnancy related complications like hyperemesis, preeclampsia etc or due to glomerular diseases. Pregnancy related kidney injury poses potential threat to maternal and fetal health. The renal tissue diagnosis in pregnancy and postpartum reveals the etiology and degree of renal injury and guides treatment. Our study is aimed at evaluating the renal biopsy findings in pregnancy and post-partum over 11-year period.

Methods:

We conducted observational study of all the renal biopsies performed during pregnancy and within six weeks postpartum. The biopsies were reported at a single pathology centre from August 2013 to August 2024. The clinicopathologic features were analysed between the pregnancy and postpartum groups. The statistical analysis was performed using SPSS software version 21. p value of <0.05 is statistically significant.

Results:

207 cases were enrolled in the study. 26 biopsies were performed during pregnancy and 181 during postpartum. The mean age of the study population at the time of biopsy was 25.8±4.51. The clinical presentations were acute kidney injury (72.9%), proteinuria (25.1%) and rapidly progressive renal failure (1.9%).  The mean serum creatinine was 3.77±2.29 mg/dl. The pregnancy related complications present in the study cohort include eclampsia (2.4%), preeclampsia (8.2%), pregnancy induced hypertension (11.5%), postpartum hemorrhage (3.3%), postpartum sepsis (2.8%), postpartum cardiomyopathy (0.9%), Takayasu arteritis (0.4%). There was intrauterine death of fetus in 1.9% of the cases. The pathologic diagnosis was divided into four categories as in Figure 1 namely glomerular disease (40.1%), tubulointerstitial disease (13.5%), Thrombotic microangiopathy or TMA (37.2%) and renal cortical necrosis (9.2%).

Proteinuria was significantly found in pregnancy group, while acute kidney injury was common in postpartum (p-0.001). The biopsies during pregnancy showed predominantly glomerular diseases (p-0.001). Thrombotic microangiopathy was found in postpartum biopsies exclusively (p-0.001). The spectrum of pathologic diagnosis in each trimester of pregnancy is enlisted in Table 1.

Thrombotic microangiopathy features in biopsy was localised in glomerulus (34/77), vascular compartment (33/77) or both (10/77). TMA was associated with patchy cortical necrosis (<50% of biopsied tissue) in 3 cases and diffuse cortical necrosis in 35 cases. Cortical necrosis found exclusively without TMA in the biopsy (19/207) are categorized separately.

Conclusions:

Renal biopsy is done during pregnancy when therapeutic decisions depend on precise histopathological diagnosis. The spectrum of glomerular diseases observed in pregnancy is diverse. Lupus nephritis and membranous nephropathy are the most common glomerular diseases in pregnancy in our population. Thrombotic microangiopathy with or without cortical necrosis is the significant pathology in post-partum kidney injury.

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.