tailieunhanh - LATE PREGNANCY COMPLICATIONS

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). Nonobstetric causes are much less common in pregnancy and generally are less hazardous. Of the obstetric causes, various forms of placental bleeding account for the vast majority. The most frequent are placenta previa or premature. | 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 placental 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 surgery occurs in up to 1 of patients previously delivered by cesarean 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 . 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 common 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 fetal 325 Copyright 2001 The McGraw-Hill Companies. Click Here for Terms ofUse. 326 BENSON PERNOLL S HANDBOOK OF OBSTETRICS AND GYNECOLOGY TABLE 11-1 ETIOLOGIC CLASSIFICATION OF THIRD TRIMESTER BLEEDING Risk Causes Obstetric Nonobstetric High Placenta previa Abruptio placentae Uterine rupture Vasa previa with fetal bleeding Coagulopathies Cervicouterine neoplasms Lower genital malignancies Moderate Circumvallate placenta Marginal sinus rupture Vaginal varices Vaginal lacerations Low Cervical mucous extrusion bloody show Cervicitis .