Definitions of the levels of evidence (I, II-1, II-2, II-3, and III) and grades of recommendations (A-E and I) are provided at the end of the "Major Recommendations" field.
Diagnosis and Classification
Measurement of Blood Pressure (BP)
- BP should be measured with the woman in the sitting position with the arm at the level of the heart. (II-2A)
- An appropriately sized cuff (i.e., length of 1.5 times the circumference of the arm) should be used. (II-2A)
- Korotkoff phase V should be used to designate diastolic BP. (I-A)
- If BP is consistently higher in one arm, the arm with the higher values should be used for all BP measurements. (III-B)
- BP can be measured using a mercury sphygmomanometer, calibrated aneroid device, or an automated BP device that has been validated for use in preeclampsia. (II-2A)
- Automated BP machines may underestimate BP in women with preeclampsia, and comparison of readings using mercury sphygmomanometry or an aneroid device is recommended. (II-2A)
- Ambulatory BP monitoring (by 24-hour or home measurement) may be useful to detect isolated office (white coat) hypertension. (II-2B)
- Patients should be instructed on proper BP measurement technique if they are to perform home BP monitoring. (III-B)
Diagnosis of Hypertension
- The diagnosis of hypertension should be based on office or in-hospital BP measurements. (II-2B)
- Hypertension in pregnancy should be defined as a diastolic BP of > 90 mm Hg, based on the average of at least two measurements, taken using the same arm. (II-2B)
- Women with a systolic BP of > 140 mm Hg should be followed closely for development of diastolic hypertension. (II-2B)
- Severe hypertension should be defined as a systolic BP of ≥160 mm Hg or a diastolic BP of > 110 mm Hg. (II-2B)
- For non-severe hypertension, serial BP measurements should be recorded before a diagnosis of hypertension is made. (II-2B)
- For severe hypertension, a repeat measurement should be taken for confirmation in 15 minutes. (III-B)
- Isolated office (white coat) hypertension should be defined as office diastolic BP (dBP) of > 90 mm Hg, but home BP of < 135/85 mm Hg. (III-B)
Measurement of Proteinuria
- All pregnant women should be assessed for proteinuria. (II-2B)
- Urinary dipstick testing may be used for screening for proteinuria when the suspicion of preeclampsia is low. (II-2B)
- More definitive testing for proteinuria (by urinary protein: creatinine ratio or 24-hour urine collection) is encouraged when there is a suspicion of preeclampsia, including in hypertensive pregnant women with rising BP or in normotensive pregnant women with symptoms or signs suggestive of preeclampsia. (II-2A)
Diagnosis of Clinically Significant Proteinuria
- Proteinuria should be strongly suspected when urinary dipstick proteinuria is > 2+. (II-2A)
- Proteinuria should be defined as > 0.3 gram/day (g/d) in a 24-hour urine collection or > 30 mg/mmol) urinary creatinine in a spot (random) urine sample. (II-2B)
- There is insufficient information to make a recommendation about the accuracy of the urinary albumin: creatinine ratio. (II-2 I)
Classification of Hypertensive Disorders of Pregnancy (HDP)
- Hypertensive disorders of pregnancy should be classified as pre-existing or gestational hypertension on the basis of different diagnostic and therapeutic factors. (II-2B)
- The presence or absence of preeclampsia must be ascertained, given its clear association with more adverse maternal and perinatal outcomes. (II-2B)
- In women with pre-existing hypertension, preeclampsia should be defined as resistant hypertension, new or worsening proteinuria, or one or more of the other adverse conditions. (II-2B)
- In women with gestational hypertension, preeclampsia should be defined as new-onset proteinuria or one or more of the other adverse conditions. (II-2B)
- Severe preeclampsia should be defined as preeclampsia with onset before 34 weeks' gestation, with heavy proteinuria or with one or more adverse conditions. (II-2B)
- The term PIH (pregnancy-induced hypertension) should be abandoned, as its meaning in clinical practice is unclear. (III-D)
Table. Classification of the Hypertensive Disorders of Pregnancy*
| Primary Diagnosis |
Definition of Preeclampsia1 |
| Pre-existing Hypertension |
| With comorbid conditions2 |
|
With preeclampsia →
(after 20 weeks' gestation)
|
Resistant hypertension, or
New or worsening proteinuria, or
One/more adverse condition(s)3
|
| Gestational Hypertension |
| With comorbid conditions2 |
|
With preeclampsia →
(after 20 weeks' gestation)
|
New proteinuria, or
One/more adverse condition(s)3
|
* Women may be classified into more than one subgroup.
1Severe preeclampsia corresponds to preeclampsia: with onset before 34 weeks' gestation, with heavy proteinuria (3 to 5 g/d according to other international guidelines), or with one or more adverse conditions.
2Comorbid conditions, such as type I or II diabetes mellitus, renal disease, or an indication for antihypertensive therapy outside pregnancy.
3Other adverse conditions consist of maternal symptoms (persistent or new/unusual headache, visual disturbances, persistent abdominal or right upper quadrant pain, severe nausea or vomiting, chest pain or dyspnea), maternal signs of end-organ dysfunction (eclampsia, severe hypertension, pulmonary edema, or suspected placental abruption), abnormal maternal laboratory testing (elevated serum creatinine [according to local laboratory criteria]; elevated aspartate aminotransferase [AST], alanine aminotransferase [ALT] or lactate dehydrogenase [LDH] [according to local laboratory criteria] with symptoms; platelet count <100x109/L; or serum albumin < 20 g/L), or fetal morbidity (oligohydramnios, intrauterine growth restriction, absent or reversed end-diastolic flow in the umbilical artery by Doppler velocimetry, or intrauterine fetal death).
Investigations to Classify HDP
- For women with pre-existing hypertension, serum creatinine, serum potassium, and urinalysis should be performed in early pregnancy if not previously documented. (II-2B)
- Among women with pre-existing hypertension, additional baseline laboratory testing may be based on other considerations deemed important by health care providers. (III-C)
- Women with suspected preeclampsia should undergo the maternal laboratory (II-2B) and fetal (II-1B) testing described in Table 3 of the original guideline document.
- If initial testing is reassuring, maternal and fetal testing should be repeated if there is ongoing concern about preeclampsia (e.g., change in maternal and/or fetal condition). (III-C)
- Uterine artery Doppler velocimetry may be useful among hypertensive pregnant women to support a placental origin for hypertension, proteinuria, and/or adverse conditions. (II-2B)
- Umbilical artery Doppler velocimetry may be useful to support a placental origin for intrauterine fetal growth restriction. (II-2B)
Definitions:
Quality of Evidence Assessment*
I: Evidence obtained from at least one properly randomized controlled trial
II-1: Evidence from well-designed controlled trials without randomization
II-2: Evidence from well-designed cohort (prospective or retrospective) or case-control studies, preferably from more than one centre or research group
II-3: Evidence obtained from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments (such as the results of treatment with penicillin in the 1940s) could also be included in this category
III: Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees
Classification of Recommendations**
A. There is good evidence to recommend the clinical preventive action
B. There is fair evidence to recommend the clinical preventive action
C. The existing evidence is conflicting and does not allow to make a recommendation for or against use of the clinical preventive action; however, other factors may influence decision-making
D. There is fair evidence to recommend against the clinical preventive action
E. There is good evidence to recommend against the clinical preventive action
I. There is insufficient evidence (in quantity or quality) to make a recommendation; however, other factors may influence decision-making
*The quality of evidence reported in these guidelines has been adapted from the Evaluation of Evidence criteria described in the Canadian Task Force on the Preventive Health Care.
**Recommendations included in these guidelines have been adapted from the Classification of Recommendations criteria described in the Canadian Task Force on the Preventive Health Care.
