LATE PREGNANCY COMPLICATIONS ppsx

325

THIRD TRIMESTER HEMORRHAGE

DEFINITION AND ETIOLOGY

The only bleeding that normally occurs during late pregnancy is a

very small amount (15 mL), with loss of the mucous plug prior

to delivery. All other bleeding is abnormal and merits investigation.

A useful list of the causes of third trimester bleeding is contained

in Table 11-1.

The health care provider must distinguish between obstetric and

nonobstetric bleeding (the two major classifications). Nonobstet￾ric causes are much less common in pregnancy and generally are

less hazardous. Of the obstetric causes, various forms of placen￾tal bleeding account for the vast majority. The most frequent are

placenta previa or premature separation of a normally implanted

placenta. Rupture of the uterus, rare without previous uterine sur￾gery, occurs in up to 1% of patients previously delivered by ce￾sarean section. Uterine rupture may cause vaginal bleeding, but

most of the loss will be concealed. Nonplacental bleeding, rare

during pregnancy, may be due to blood dyscrasia or lower genital

tract disorders (e.g., cervical or vaginal infections, neoplasms, or

varices). Generally, the bleeding is slight, even with carcinoma of

the cervix.

INCIDENCE AND IMPORTANCE

Second trimester vaginal bleeding of obstetric origin is more com￾mon in multiparous women and those with a history of prior preterm

delivery. Second trimester bleeding is ominous, being associated

with an increased risk of preterm delivery (relative risk 1.9), fetal

11

LATE PREGNANCY

COMPLICATIONS

CHAPTER

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BENSON & PERNOLL’S

326 HANDBOOK OF OBSTETRICS AND GYNECOLOGY

death (relative risk 5.4), and perinatal death (5-fold increase). If

sonography reveals an intrauterine clot, membrane separation, or

placenta previa, there is further risk and in these patients, perinatal

mortality exceeds 250 per 1000. The etiologies of second trimester

bleeding include: circumvallate placenta, early abruptio placenta,

and placenta previa. Currently, expectant management is the most

common treatment option for pregnancies complicated by second

trimester bleeding.

Significant vaginal bleeding occurs in 5%–10% of third tri￾mester pregnancies and must be carefully evaluated because ob￾stetric hemorrhage is the largest cause of maternal morbidity and

mortality. Two of the major causes of late pregnancy hemorrhage

(placenta previa and placenta abruption) are associated with ciga￾rette smoking.

Additionally, it is a significant factor in perinatal morbidity and

mortality. Most patients have 500 mL bleeding, but serious hem￾orrhage .500 mL will occur in 2%–3% of pregnancies. Overall, mul￾tiparas are more commonly affected.

TABLE 11-1

ETIOLOGIC CLASSIFICATION OF THIRD

TRIMESTER BLEEDING

Causes

Risk Obstetric Nonobstetric

High Placenta previa Coagulopathies

Abruptio placentae Cervicouterine

Uterine rupture neoplasms

Vasa previa Lower genital

with fetal malignancies

bleeding

Moderate Circumvallate Vaginal varices

placenta

Marginal sinus Vaginal lacerations

rupture

Low Cervical mucous Cervicitis, eversion,

extrusion erosion, polyps

(bloody show)

DIAGNOSIS OF THE CAUSE OF BLEEDING

INITIAL EXAMINATION

There are three principles of investigation of third trimester hem￾orrhage.

● Because of the extreme hazard of uncontrollable bleeding

with placenta previa, vaginal or rectal examination must be

avoided until that diagnosis can be excluded. ● All third trimester vaginal bleeding must be investigated in

a hospital with the capability of dealing with maternal hem￾orrhage and perinatal compromise. ● Immediate assessment of blood loss and hemodynamic sta￾tus guides the earliest stage of therapy. Recall that the signs

and symptoms of hypovolemic shock include pallor with

clammy skin, orthostatic hypotension, syncope, thirst, dys￾pnea, restlessness, agitation, anxiety, confusion, declining

blood pressure, tachycardia, and oliguria.

CRITICAL HEMORRHAGE

(HEMODYNAMICALLY

UNSTABLE PATIENTS)

Antishock therapy must be immediately instituted in all hemodynam￾ically unstable patients. The following is one method of initiating that

therapy. The patient is placed in the Trendelenburg position. Care is

taken that this is not so steep that respiration is compromised. An ad￾equate airway is guaranteed by a plastic oral airway, or endotracheal

tube. A large-bore (18 gauge) IV is inserted for crystalloid re￾placement (saline or lactated Ringer’s solution). Blood is obtained

from another vein for CBC, platelets, fibrinogen, PT and PTT, fibrin

split products, type and crossmatch for 4–6 units of whole blood or

packed red blood cells. In severe cases, it may also be necessary to

obtain fresh frozen plasma, platelet packs, electrolytes, and blood

gases. The necessity of hemodynamic monitoring is considered. The

use of vasoactive drugs is weighed. They are desirable for their phar￾macologic effects (e.g., increasing myocardial contractility) or if vol￾ume expansion is ineffective. One effective agent is dopamine, 200 mg

in 500 mL saline at 2–5 mg/kg/min increasing to 20–50 mg/kg/min.

Once the acute measures are taken, an indwelling Foley catheter

may be inserted to measure urinary output and obtain details of the

acute episode.

CHAPTER 11

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BENSON & PERNOLL’S

328 HANDBOOK OF OBSTETRICS AND GYNECOLOGY

Use the clot fragility observation test if serial determinations of

fibrinogen levels are not immediately available. This is performed

by drawing venous blood (2–3 mL) into a clean test tube q 1h. If

clot formation fails to occur within 5–10 min or if dissolution of a

formed clot follows gentle shaking, a clotting deficiency due pri￾marily to lack of fibrinogen and platelets is likely.

Examination of the abdomen is gently conducted and the fun￾dus measured or the uterine apex marked. The fetal heart rate is

frequently recorded and electronic fetal monitoring initiated. Uter￾ine tone, fetal presentation, and possible engagement of the pre￾senting part (engagement largely excludes total placenta previa) are

all observed. Next, it is decided whether the patient must be taken

to surgery immediately or if blood transfusions and stabilization

must be accomplished first.

The patient is readied for surgery (prepare abdomen, obtain in￾formed consent, notify the operating room, anesthesia department,

and neonatal–pediatrics). Frequent vital signs and FHR (every 2–15

min depending on status) are continued until definitive therapy is

accomplished. Delivery and control of hemorrhage are accom￾plished as soon as practical. In postpartum hemorrhage, it is evaluated

whether selective arterial embolization, prophylactic uterine, or hy￾pogastric artery ligation will be of assistance. In all cases of hem￾orrhage, erythropoietin use after the acute episode is considered.

LESS THAN CRITICAL

HEMORRHAGE

(HEMODYNAMICALLY STABLE

PATIENTS)

The patient is placed at bedrest and the history of the acute episode

obtained. Also, the obstetric history is obtained and the patient’s vi￾tal signs ascertained. A gentle abdominal examination is conducted

and the fundus measured or the uterine apex marked. Fetal heart

rate is ascertained and electronic fetal monitoring initiated. If elec￾tronic fetal monitoring is not available, the FHR is frequently

recorded. Uterine tone, uterine irritability, fetal presentation, and

the likely station of the presenting part are determined. A large-bore

(18 gauge) IV is started to initiate crystalloid maintenance re￾placement (saline or lactated Ringer’s solution). Venous blood is

obtained for CBC, platelets, fibrinogen, PT and PTT, fibrin split

products, type and crossmatch for 2–4 units of whole blood or

packed red blood cells from another vein. A gentle vaginal exami￾nation is considered. Vaginal examination is indicated before ultra￾sonic examination only if delivery may be imminent, the present￾ing part is unquestionably engaged, or the patient is in active labor.