Hypertension in Pregnancy

HYPERTENSION IN PREGNANCY

Resident’s Report

August 18, 1999

Lee Kiser

Categories: Chronic HTN, Preeclampsia-Ecclampsia, Gestational HTN, & Superimposed Preeclampsia

Incidence: 10-15% of all pregnancies will have some type of hypertensive disturbance

CHRONIC HYPERTENSION

Definition: 1. HTN diagnosed before pregnancy

2. HTN before 20 weeks with BP > 140/90 on 2 occasions

may be difficult to diagnose if no prior hx

additional aides to dx include end-organ dysfxn and HTN persistent after 6 weeks postpartum

Subdivided into mild and severe

Mild HTN if BP < 160/110 and no end organ dysfxn

Risks: Subsequent preeclampsia: mild – 4.7%, severe – 25-50%

Abruption: mild - <2%, severe – 2-10%

Poor perinatal outcome – more influenced by presence of proteinuria, especially if from preeclampsia

Fourfold increase in mortality, sixfold increase SGA in preeclampsia with proteinuria

Workup: UA & cx, lytes, 24 hour urine for protein & creatinine, uric acid, & glucose

Treatment: Mild: lowering of BP has not been shown to reduce preeclampsia , abruption, or perinatal outcome

Some recommend stopping all antihypertensive Rx & observing

ACE inhibitors MUST be stopped (D)– increased fetal deaths & abortions, fetal

Growth retardation, oligohydramnios, fetal anuria, and renal failure Diuretics (B/C) are controversial, but most experts recommend continuing, and Monitoring closely for volume depletion Must stop if develops subsequent preeclampsia – decreased perfusion

Methyldopa is drug of choice if needed, proven safe in pregnancy (B)

SE: Incr’d LFT’s, hemolytic anemia, lethargy

Severe HTN: treatment has been shown to be beneficial; goal is to keep DBP <105

Methyldopa also DOC

Labetalol: (C) no studies re: risks, but frequently used without problems

SE: similar to other B-blockers

Nifedipine: ( C) also no studies, but being used more frequently w/o problems

SE: same for CCB, edema may be problematic

Hypertensive Crisis

Nitroprusside ( C): still DOC by most experts, but careful monitoring to prevent fetal &

Maternal CN toxicity ( acidosis, SOB, mydriasis)

Hydralazine ( C): used frequently in preeclampsia

SE: N/V, HA, lupus-like rxn, GN

Labetalol: see above

GESTATIONAL HYPERTENSION

Definition: HTN ( >140/90) after the 20^th week with no other symptoms of preeclampsia

Most will do very well without complications; some will develop preeclampsia

Treatment: None needed if BP remains less 160/110; if markedly elevated, treat as above

PREECLAMPSIA

Seen in 10-15% of primiparas, 5-7% of multiparas, & 25% of multiparas with new paternity

Definition: 1. HTN: increase in SBP by 30 of DBP by 15 or > 140/90 after 20 weeks

2. Proteinuria: > 300 mg/24 hours or > .1 g/dL on spot urine

3. Peripheral Edema

Also divided into mild & severe

Severe: BP >160/110, proteinuria >5 g,oliguria, CNS changes, signs of HELLP,

Epigastric pain, pulmonary edema

Risks: Onset less than 37 weeks: perinatal mortality 10.5%, IUGR 18.2%, abruption 4.5%

Greater than 37 weeks: 0.6%, 5.6%, 1.0%

Etiology: Multiple theories; most recognized one is that there is failure of trophoblastic invasion

& subsequent failure of spiral arterioles of uterine wall to relax from muscular arteriole to sac-like, low resistance vessel Other theories include disregulation of TxA2/ PGI2 ratio, vascular endothelial injury, immune

mediated, lipid peroxide/free radical injury, & nitric oxide/endothelin disregulation

Prevention: trials of ASA and more recently calcium supplementation show no benefit; previous

Studies with Zn & Mg supplementation, and with salt restriction also disappointing

Mid trimester preeclampsia

If onset is less than 24 weeks, perinatal survival is 2 - 6%

Onset of preeclampsia in the 2^nd trimester warrants search for alternate diagnosis

Fetal Anomalies: triploidy, molar pregnancy, and idiopathic fetal hydrops

Diagnose with ultrasound and amniocentesis with karyotype

Hypercoagulabilty: Protein S deficiency, AT III deficiency, Factor V Leiden, Anti-cardiolipin

Antibody, and Hyperhomocysteinemia

Diagnose with appropriate tests postpartum ( may be decreased with preeclampsia)

See table below

TEST No. Tested No. Positive Percent Positive Positive Control

Chronic HTN	101	39	38.6 %	------
Protein S Deficiency	85	21	24.7%	.2-2%
APC Resistance	50	8	16.0%	3-7%
Protein C Deficiency	85	1	1.2%	.1-.3%
AT III Deficiency	85	1	1.2%	.1%
Lupus anticoagulant	85	0	0.0	0-3%
Hyperhomocysteinemia	79	14	17.7%	2-3%
ACA	95	27	28.4%	1-3%

Dekker et al. Underlying Disorders Associated with Severe Early Onset Preeclampsia. Am J. of Obstet. Gyn, 1995,Oct:173 (4):1042-8

Renal Disease: one article stated that 67% of primiparas & 63% of multiparas with early onset

Preeclampsia had underlying renal disease;

Most common was IgA nephropathy; others included MPGN, FSGS, and diabetic

changes Etiology is increased GFR due to pregnancy with subsequent increased proteinuria

Diagnose with renal U/S, 24 urine, & intraparum or postpartum renal biopsy

Classic Preeclampsia biopsy lesion is Endotheliosis

In patients with known preexisting renal disease, 60% probability SGA, 60% premature,

40%will have decrease in renal fx, & 10% will progress to severe renal insufficiency

These results were especially true if baseline Cr > 2.0

One study quoted fetal survival at 93% compared to previous studies at 50-80 %

Treatment:

DELIVERY, IF POSSIBLE

Mild disease, remote from delivery: watchful waiting; bed rest is controversial if any benefit

Severe: maternal & fetal evaluation – deliver if . 34 weeks, maternal or fetal distress, severe

IUGR, labor, progression to eclampsia MgSO4: seizure prophylaxis (not for hypertension)

Steroids if <32 weeks (for fetal lung maturity)

AntiHTN Rx: goal is to keep MAP <126, but >105; DBP <105, but >90

Hydralazine is DOC: 5-10 mg IV q 20-30 minutes prn (max’m 20 mg q 20 min)

Labetalol: 20-40 mg IV q 10 minutes (maxm 300 mg / d)

Nifedipine 10 mg po TID

Clonidine (C) .1mg po TID SE: sed’n, HA, constipation, confusion

References:

Obstetrics 1996.3^rd edition; p 935-987

Sibai BM. Treatment of Hypertension in Pregnant Women. NEJM 1996;335(4):257-265

Broekhuizen FF, et al. Early Onset Preeclampsia, Triploidy, and Fetal Hydrops. J Reprod Med 1983;28 (3):223-6

Dekker GA, et al. Underlying Disorders associated with Severe Early Onset Preeclampsia. Am J Ob Gyn 1995;173(4):1042-8

Ihle BU, et al. Early Onset Preeclampsia. BMJ 1987; 294 (6564): 79-81

Ferrazzani S, et al. Proteinuria & Outcome of 444 pregnancies complicated by HTN. Am J Ob Gyn 1990; 162: 366-71

Jones DC, Hayslett JP. Outcome of Pregnancy in Women with…Renal Insufficiency. NEJM 1996; 335:226-32