hypertensives Disorders Of Pregnancy (Preeclampsia/Eclampsia)

 

Pregnancy-specific hypertensive conditions, in particular preeclampsia/eclampsia, are among the leading causes of SAMM and maternal deaths. Four types of such conditions complicate pregnancy (Table 7).



As seen in Figure 3, 9–29% of maternal deaths are caused by hypertensive disorders in world regions. Hypertension complicates approximately 5% of all and 11% of first pregnancies, respectively. Preeclampsia constitutes half of these cases (2–3% of all pregnancies and 5–7% of first pregnancies). Between 0.8–2.3% of women with preeclampsia develop eclampsia (Magpie Trial Collaborative Group, 2002). Similar to hemorrhage, the likelihood of dying from preeclampsia or eclampsia is much higher in developing country settings than in more developed ones. Around 5% of women with eclampsia and 0.4% with preeclampsia die in developing country settings. These figures are as low as 0.7% and 0.03%, respectively, in more developed countries.

Preeclampsia is a multisystem disorder usually characterized by sudden onset of hypertension and proteinuria during the second half of pregnancy. The basic causes are changes in the endothelium, which is an intrinsic part of all blood vessels. Preeclampsia, therefore, has the potential of affecting any organ system. The nature of the signs and symptoms varies according to which organs are affected. In addition to hypertension, proteinuria, oliguria, cerebral or visual disturbance, pulmonary edema, cyanosis, thrombocytopenia, or signs of impaired liver function can be detected in a preeclamptic woman. It is, however, proteinuria and hypertension that are the defining features of preeclampsia.

A variety of definitions of preeclampsia with different specifications for both features is used, particularly for research purposes. Clinically:

 	
hypertension is defined as blood pressure of equal to or greater than 140 mmHg systolic or 90 mmHg diastolic in two consecutive measurements and occurring after the 20th week of pregnancy
 	
proteinuria is defined as a protein concentration of more than 500 mg/l in a random specimen of urine or a protein excretion of more than 300 mg per 24 h
 	
eclampsia is the occurrence of seizures in a woman with preeclampsia.

Women with first pregnancy, extremes of age, obesity, multiple pregnancy, preexisting hypertension or renal disease, who have had preeclampsia or eclampsia in a previous pregnancy, and with a family history of pregnancy are more at risk of developing preeclampsia.

Identification of reduced placental perfusion or vascular resistance dysfunction by Doppler ultrasonography or high levels of urinary kallikrein may be useful in diagnosing preeclampsia during early pregnancy, but widespread use of these techniques, particularly in resource-poor settings, is limited due to technological requirements. Regular screening of blood pressure, urinary protein, and fetal size during antenatal care visits is currently the only strategy for early diagnosis of preeclampsia. High-risk women should be screened more frequently between 24 and 30 weeks of pregnancy, when the onset of the disease is most common.

If the hypertension is severe (blood pressure≥ 170 mmHg systolic or ≥110 mmHg diastolic), treatment should include antihypertensive drugs. The effectiveness of antihypertensive treatment in mild to moderate hypertension has not been established. Magnesium sulfate is the drug of choice for preeclampsia to prevent eclampsia, as well as for eclampsia to reduce recurrence of convulsions and maternal death.

Studies on the effectiveness of a range of nutritional (vitamins, antioxidants) or non-nutritional (antiplatelet agents, calcium) strategies to prevent preeclampsia have provided no conclusive evidence. The only recommended strategy is the use of low-dose aspirin in high-risk nulliparous women and women with poor obstetric history.
Sepsis
Sepsis, in particular, postpartum sepsis, is an important cause of maternal death in developing countries, but is very rare in more developed countries where historically most of the deaths were due to sepsis. The invention and widespread use of antibiotics and recognition of the importance of clean delivery practices with skilled delivery attendants brought a sharp decline in the number of maternal deaths, in particular those caused by postpartum sepsis, during the first half of the 20th century. Currently, less than 1% of deliveries in developed country settings are complicated with sepsis, which usually results from rare hospital infections.

Sepsis is a systematic response to infectious agents or their byproducts. It develops most frequently from urinary tract infections, chorioamnionitis, postpartum fever (due to pelvic infection, surgical procedures, endometritis), or septic abortion. The infectious agents are either endogenous (i.e., they already exist as part of the normal flora of the woman’s genital tract or as an existing infectious agent) or exogenous (i.e., acquired from outside sources such as deliveries or abortions taking place under unhygienic conditions) and most frequently include Streptococcus, Gramnegative bacteria, gonococcus, chlamydia, herpes simplex, and the organisms causing bacterial vaginosis. The effects of malaria and HIV/AIDS in areas where these infections are frequent are also increasingly recognized, although the mechanisms by which these infections cause sepsis are not clearly identified.

The usual signs of infection, such as fever, tachycardia, and leukocytosis at the early stages, if not treated appropriately, convert to severe sepsis with signs of multiple organ effects, such as hypothermia, hypotension, encephalopathy, oliguria, and thrombocytopenia. This can further lead to septic shock, which is a highly lethal syndrome in both developing and developed countries.

Management of sepsis involves treatment of the causative agent with appropriate antibiotics and interventions targeted to deal with presenting signs, such as hypovolemia, encephalopathy, or clotting problems.

Sepsis is preventable by:

 	
treatment of existing infection with appropriate antibiotics;
 	
prophylactic use of antibiotics for cesarean section, for women with preterm pre-labor rupture of membranes, and for high-risk women (women with previous spontaneous preterm delivery, history of low birthweight, prepregnancy weight less than 50 kg, or bacterial vaginosis in the current pregnancy); and
 	
clean delivery/pregnancy termination practices (infection control), including hand hygiene of providers and use of sterile, preferably disposable, supplies and equipment.

Obstructed Labor
Obstructed labor is the failure of labor to progress due to mechanical obstruction. The source of the problem may be the mother (such as a contracted pelvis or tumor causing obstruction), the baby (such as a large or abnormal baby or abnormal position, presentation, or lie), or both. Most frequently, the problem is related to a relative size discrepancy between a normal baby and the pelvis of a healthy mother. In women experiencing their first pregnancy, obstructed labor usually leads to decreasing uterine activity and prolonged labor with the possibility of infection, postpartum hemorrhage, and vesicovaginal fistula formation, whereas in multiparous women uterine activity may continue to the point of uterine rupture.

Poor progress of labor may be due to obstruction, cervical dystocia, inefficient uterine activity, or a combination of these. The clinical diagnosis is usually based on poor progress of labor despite adequate uterine activity, together with visible signs of obstruction such as molding of the fetal skull. The definition of obstructed labor generally involves the length of labor (such as >12 or >18 h, or second stage >2 h), although other definitions involving clinical signs (such as uterine ring, pre-rupture, second stage transverse lie) are also used. According to the unpublished data from the WHO database of maternal mortality and morbidity, prevalence (with the definition of labor lasting >18 h) is in general less than 1% in developed country settings and may be up to 5% in less developed countries.

Black race, short maternal height, and maternal obesity were suggested as potential risk factors, although there are no agreed criteria for their use to predict obstructed labor. In settings where common, scarring due to female genital mutilation may cause obstructed labor. Women with previous obstructed labor are at risk of experiencing future obstruction.

In settings with ready access to safe cesarean section, the management of obstructed labor is straightforward and related maternal mortality is extremely rare, although perinatal and maternal morbidity may occur. However, when cesarean section is not readily accessible, obstructed labor is a major cause of maternal mortality and severe morbidity by leading to uterine rupture, postpartum hemorrhage, sepsis, and obstetric fistula. Uterine rupture is a serious complication of obstructed labor, particularly in less developed settings. In developed countries, uterine rupture is typically seen in women with scarred uterus due to previous cesarean section.

The widely accepted interventions for preventing obstructed labor are the correction of breech presentation by external cephalic version at term and cesarean section. When cesarean section is not available or unsafe, symphysiotomy is a life-saving intervention for both the mother and the baby, although it has long been regarded as an unacceptable operation due to the perceptions of complications.
Venous Thromboembolism
Venous thromboembolism refers to two related conditions – venous thrombosis and pulmonary embolism – that affect pregnant women. Pulmonary embolism arises from venous thrombosis, which is the process of clotting within the veins. It represents the leading cause of maternal deaths in developed country settings, despite being a rare event with a prevalence of less than 1%. Major risk factors for venous thromboembolism in pregnant women are shown in Table 8.



Venous thrombosis predominantly occurs in the legs and presents with clinical signs of pain, discomfort, swelling, and tenderness in the affected leg. Because problems such as swelling of the legs and discomfort are common in normal pregnancies, the clinical diagnosis of deep venous thrombosis is difficult. Only 10% of pregnant women who have such symptoms are diagnosed with deep venous thrombosis. It is, however, important to objectively diagnose the condition, because approximately one-fourth of women with untreated deep venous thrombosis develop pulmonary embolism.

In the majority of the cases where the thrombus is in the legs, the abovementioned clinical signs precede pulmonary embolism, but in others, where the thrombus is in the pelvic veins, the woman is usually asymptomatic until pulmonary embolus occurs. The most common clinical signs of pulmonary embolism are breathlessness, chest pain, cough, collapse, and hemoptysis. Advanced techniques such as compression ultrasonography and sophisticated computerized tomography scanners are used to diagnose deep venous thrombosis and pulmonary embolism, respectively.

The exact strategy to manage venous thromboembolism during pregnancy is still debated, but treatment generally includes the use of appropriate anticoagulants, mostly heparin. In deep venous thrombosis, the use of anticoagulants decreases the risk of developing embolism to less than 5%. Limitation of activity and use of elastic stockings are the recommended supportive measures. Anticoagulant use should be continued following delivery, but the evidence on the optimum length of use is limited. Current practice is to continue for at least 6 weeks. Thromboembolism can recur; thus, pregnant women with a previous event should be given prophylactic anticoagulants.
Other Major Morbidities
A summary of other contributors of severe maternal morbidity and mortality not examined above is shown in Table 9. A final category that requires special attention is the effect of non-pregnancy-related infections – namely those of AIDS and malaria. These are classified among the indirect causes of maternal deaths as a subcategory of non-pregnancy-related infections.