Acute renal failure in pregnancy.

Acute renal failure is a most challenging clinical problem when it occurs in pregnancy. It requires an understanding of the normal physiology of the kidney in pregnancy and the natural history of different underlying renal diseases when pregnancy occurs. Because patients with chronic renal disease may present with worsening proteinuria, hypertension, and renal function, these disorders must be excluded from those conditions that cause acute deterioration of renal failure in otherwise normal women during pregnancy. As in all patients who develop acute renal failure, prerenal and obstructive causes must be excluded. Particularly important causes of prerenal azotemia in pregnancy include hyperemesis gravidarum and uterine hemorrhage, especially if it is unsuspected as in abruptio placentae. Infectious causes of acute renal failure in the pregnant woman include acute pyelonephritis and septic abortion. The clinical presentation of both these conditions should be apparent, and appropriate diagnosis and treatment can then be promptly instituted. Renal cortical necrosis is another cause of renal failure that occurs more frequently in pregnancy, and it must be differentiated from the many causes of acute tubular necrosis that may be associated with pregnancy. Those conditions that cause renal failure unique to pregnancy must always be considered when renal function deteriorates in the last trimester or the postpartum period. Severe preeclampsia, acute fatty liver of pregnancy, and idiopathic postpartum acute renal failure may all present similar complications, but the approach to each of these clinical disorders must be individualized. By understanding the causes of renal functional deterioration in pregnancy, a logical differential diagnosis can be established, allowing appropriate therapeutic decisions to preserve both maternal and fetal well-being.