Puerperal infection is a general term used to describe any bacterial infection of the genital tract after delivery. The earliest reference to puerperal infection is found in the works of Hippocrates from the 5th century bc, De Mulierum Morbis. He attributed the condition to retention of bowel contents. The history of puerperal infection is discussed in greater detail in previous editions of Williams Obstetrics.
Along with preeclampsia and obstetrical hemorrhage, puerperal infection formed the lethal triad of causes of maternal deaths for many decades of the 20th century. Fortunately, because of effective antimicrobials, maternal deaths from infection have become uncommon. Berg and associates (2003) reported results from the Pregnancy Mortality Surveillance System, which contained 3201 maternal deaths in the United States from 1991 through 1997. Infection caused 13 percent of pregnancy-related deaths and was the fifth leading cause of death. In a similar analysis of the North Carolina population from 1991 through 1999, Berg and colleagues (2005) reported that 40 percent of infection-related maternal deaths were preventable.
A number of factors can cause fever—a temperature of 38.0°C (100.4°F) or higher—in the puerperium. Most persistent fevers after childbirth are caused by genital tract infection. Filker and Monif (1979) reported that only about 20 percent of women febrile within the first 24 hours after giving birth vaginally were subsequently diagnosed with pelvic infection. This was in contrast to 70 percent of those undergoing cesarean delivery. It must be emphasized that spiking fevers of 39°C or higher that develop within the first 24 hours postpartum may be associated with virulent pelvic infection caused by group A streptococcus. Other common causes of puerperal fever are breast engorgement and pyelonephritis or occasionally respiratory complications after cesarean delivery (Maharaj, 2007).
About 15 percent of women who do not breast feed develop postpartum fever from breast engorgement. This figure is lower in breast-feeding women (see Chap. 30, Breast Engorgement). Attributable fever rarely exceeds 39°C in the first few postpartum days and usually lasts less than 24 hours. Acute pyelonephritis has a variable clinical picture, and postpartum, the first sign of renal infection may be fever, followed later by costovertebral angle tenderness, nausea, and vomiting. Atelectasis is caused by hypoventilation and is best prevented by coughing and deep breathing on a fixed schedule following surgery. Fever associated with atelectasis is thought to follow infection by normal flora that proliferate distal to obstructing mucous plugs. Minor temperature elevations in the puerperium may also occasionally be caused by superficial or deep-venous thrombosis of the legs.
Postpartum uterine infection has been called variously endometritis, endomyometritis, and endoparametritis. Because infection involves not only the decidua but also the myometrium and parametrial tissues, we prefer the inclusive term metritis with pelvic cellulitis.
The route of delivery is the single most significant risk factor for the development of uterine infection (Burrows and associates, 2004; Koroukian, 2004). In the French Confidential Enquiry on Maternal Deaths, Deneux-Tharaux and colleagues (2006) cited a nearly 25-fold increased infection-related mortality rate with cesarean versus vaginal delivery. Rehospitalization rates for wound complications and endometritis were increased significantly in women undergoing a planned primary cesarean delivery compared with those having a planned vaginal birth (Declercq, 2007).
Compared with cesarean delivery, metritis following vaginal delivery is relatively uncommon. Women delivered vaginally at Parkland Hospital have a 1- to 2-percent incidence of metritis. Women at high risk for infection because of membrane rupture, prolonged labor, and multiple cervical examinations have a 5- to 6-percent incidence of metritis after vaginal delivery. If there is intrapartum chorioamnionitis, the risk of persistent uterine infection increases to 13 percent (Maberry and colleagues, 1991). Finally, manual removal of the placenta, discussed in Chapter 35, Technique of Manual Placental Removal, increased the puerperal metritis rate threefold in the study by Baksu and associates (2005).
Single-dose perioperative antimicrobial prophylaxis is given almost universally at cesarean delivery. The American College of Obstetricians and Gynecologists (2003) recommends such prophylaxis for women at high risk for postpartum infection (see Chap. 25, Prevention of Postoperative Infection). Such single-dose antimicrobial prophylaxis has done more to decrease the incidence and severity of postcesarean delivery infections than any other practice in the past 30 years.
The magnitude of the risk is exemplified from reports that predate antimicrobial prophylaxis. In 1973, Sweet and Ledger reported an overall incidence of uterine infection of 13 percent among affluent women who underwent cesarean delivery compared with 27 percent of indigent women. Cunningham and associates (1978) described an overall incidence of 50 percent in women who had cesarean delivery at Parkland Hospital. Important risk factors for infection following surgery included prolonged labor, membrane rupture, multiple cervical examinations, and internal fetal monitoring. Women with all of these factors who were not given perioperative prophylaxis had a 90-percent serious pelvic infection rate (DePalma and colleagues, 1982).
It is generally accepted that pelvic infection is more common in women of lower socioeconomic status compared with those more advantaged (Maharaj, 2007). Except in extreme cases usually not seen in this country, it is unlikely that anemia or poor nutrition predispose to infection. Bacterial colonization of the lower genital tract with certain microorganisms—for example, group B streptococcus, Chlamydia trachomatis, Mycoplasma hominis,Ureaplasmaurealyticum, and Gardnerella vaginalis—has been associated with an increased risk of postpartum infection (Andrews, 1995; Jacobsson, 2002; Watts, 1990, and all their colleagues). Other factors associated with an increased risk of infection include cesarean delivery for multifetal gestation, young maternal age and nulliparity, prolonged labor induction, obesity, and meconium-stained amnionic fluid (Jazayeri, 2002; ...