Acute Kidney Injury in Pregnancies Complicated With Preeclampsia or HELLP Syndrome

Abstract

Acute kidney injury that occurs during pregnancy or in the post-partum period (PR-AKI) is a serious obstetric complication with risk of significant associated maternal and fetal morbidity and mortality. Recent data indicates that the incidence of PR-AKI is increasing, although accurate calculation is limited by the lack of a uniform diagnostic criteria that is validated in pregnancy. Hypertensive and thrombotic microangiopathic disorders of pregnancy have been identified as major contributors to the burden of PR-AKI. As is now accepted regarding preeclampsia, HELLP syndrome and atypical hemolytic uremic syndrome, it is believed that PR-AKI may have long-term renal, cardiovascular and neurocognitive consequences that persist beyond the post-partum period. Further research regarding PR-AKI could be advanced by the development of a pregnancy-specific validated definition and classification system; and the establishment of refined animal models that would allow researchers to further elucidate the mechanisms and sequelae of the disorder.

Keywords: acute kidney injury (AKI); chronic kidney disease (CKD); hemolysis elevated liver enzymes low platelet count (HELLP); preeclampsia; renal injury.

Figure 1

PR-AKI can have prerenal, intrinsic, and post-renal etiologies. Prerenal causes may be secondary to hemorrhage, hypovolemia (¹from hyperemesis gravidarum), sepsis, or congestive heart failure. Intrinsic renal causes include acute tubular necrosis, renal cortical necrosis, thrombotic microangiopathy, preeclampsia spectrum disorders, acute fatty liver of pregnancy, glomerulonephritis, or acute interstitial nephritis (²from medication exposure). Postrenal etiologies include mechanical obstruction (³postsurgical), neoplasm, or uteropelvic (⁴obstruction from pregnancy).

Figure 2

Common primary causes of PR-AKI. The most common primary causes of pregnancy related—acute kidney injury (PR-AKI) worldwide are listed along with their reported incidence.

Figure 3

Hypothesis establishing the link between PR-AKI and neurocognitive impairment. Based on published studies and our own preliminary work we believe that in the setting of pregnancy related-acute kidney injury (PR-AKI), (1) there's an increase in circulating inflammatory mediators and oxidative stress which (2) damages the blood brain barrier^a which allows for (3) neuroinflammation to take place eventually contributing to neurocognitive impairment. ^aReview Varatharaj and Galea (111).