Table 2.

Preeclampsia: focus on classifications and definitions.

Term	Definition	Main Problems and Limits
Preeclampsia (PE)	Hypertension and proteinuria or end-organ damage in a previously healthy woman; involvement is reversible 1–3 months after delivery	Usually defined as new onset of proteinuria above 300 mg/day and hypertension after the 20th gestational week (GW) in a patient who was previously normotensive and without proteinuria or kidney disease. The syndrome resolves within three months from delivery. New definitions include hypertension in the absence of proteinuria but in the presence of end-organ damage, including creatinine increase. Does not apply to patients with chronic kidney disease or on dialysis, due to baseline hypertension, proteinuria, or to no urine output.
Eclampsia	Same as above, with neurological damage and convulsions	This definition is no longer universally accepted. Some authors consider it synonymous with untreated (or inadequately treated) PE.
Mild PE	PA ≥140/90 <160/110 proteinuria ≥0.3 <5.0 g/day in the absence of the criteria set forth above	The definition of mild and severe PE is somewhat static; mild PE can abruptly evolve into severe PE. Therefore, this definition should be used to: identify ALL cases of severe PE, that should be followed accordingly; identify cases in which the disease is not severe, allowing pregnancy to continue under careful surveillance, keeping in mind that mild PE can abruptly progress to severe PE.
Severe PE	Central nervous system involvement Liver damage Poorly controlled hypertension Proteinuria ≥5 g/24 h Platelets <100.000 Oliguria <500 mL/24 h Pulmonary oedema Intrauterine growth restriction (IUGR)
Early PE	Before 34 completed GW	This pragmatic definition has the advantage of simplicity, and makes the early identification of cases possible; however a late diagnosis of early PE may in fact be identified as “late” PE.
Late PE	After 34 completed GW
Maternal PE	With maternal predisposing disease	This pragmatic definition is clinically relevant (maternal PE is usually, but not uniformly milder); the definition of maternal disease is elusive, and the equation early = placental = severe; late = maternal = mild is imperfect and may be misleading.
Placental PE	Severe placental involvement in the absence of the above
Angiogenic PE	Altered angiogenic/non-angiogenic balance	This is a promising approach, with the advantage of simplicity and of employing numeric values, and is possibly more objective; however, there is no agreement on how best to test for the condition: cut-points are not univocal, the levels and the ratio between factors may change over time and the availability of the tests is limited.
Non angiogenic PE	Absence of the above
Superimposed PE	PE with underlying CKD	Some but not all CKD are proteinuric or hypertensive before pregnancy; this definition tries to correct for the baseline values. However, there is no agreed level of “worsening” of proteinuria or hypertension, in part because of the adaptation of anti-hypertensive treatments in pregnancy. Albeit of potential interest, this definition is ambiguous and less frequently encountered.
Postpartum PE	A clinical syndrome with the clinical features of PE, occurring postpartum	A rare occurrence, probably accounting for less than 5% of PE. The clinical picture is often severe and onset is abrupt; diagnosis may be difficult and delayed, since it may occur after hospital discharge.
Other related definitions (other hypertensive disorders of pregnancy)
Pregnancy induced hypertension (PIH)	“Isolated” hypertension in pregnancy	Hypertension occurring after the 20th week of pregnancy in a previously normotensive woman; the definition is the same as for PE; the absence of proteinuria is however no longer sufficient to exclude PE (see above).
Pregnancy induced proteinuria	“Isolated” proteinuria in pregnancy.	Proteinuria above 300 mg/day occurring after the 20th week of pregnancy in a previously non-proteinuric woman. Often a sign of underlying CKD.
HELLP syndrome	A virulent syndrome of endothelial damage	The acronym stands for hypertension, elevated liver enzymes, low platelets (HELLP); it is a severe syndrome, often abrupt, potentially occurring in the immediate postpartum period. Some authors consider it as the end of the spectrum of PE (severest disease); others consider it a separate disease, due to the frequent lack of prodromal PE.
IUGR	Intrauterine growth restriction	Some authors relate IUGR to the hypertensive disorders of pregnancy, due to its pathogenesis, which is related to insufficient placental vascularization. See Table 3 for details.