Williams Manual of Pregnancy Complications, 23 ed.

CHAPTER 21. Postpartum and Postoperative Infections

Puerperal infection is a general term used to describe any bacterial infection of the genital tract after delivery. Pelvic infections are the most common serious complications of the puerperium, and along with preeclampsia and obstetrical hemorrhage, for many decades formed the lethal triad of causes of maternal deaths. Infection is the fifth leading cause of maternal death in the United States.

Puerperal fever is technically defined as temperature 38°C (100.4°F) or higher, the temperature to occur on any 2 of the first 10 days postpartum, exclusive of the first 24 hours, and to be taken by mouth by a standard technique at least four times daily. In practice, however, any maternal fever (38°C or higher) usually prompts a search for its causes and corresponding treatment. Though most persistent fevers associated with childbirth are caused by genital tract infections, extragenital causes must be excluded. These include breast engorgement, respiratory infection, pyelonephritis, and thrombophlebitis.

EXTRAGENITAL CAUSES OF POSTPARTUM FEVER

Breast Engorgement

This condition commonly causes a brief temperature elevation. About 15 percent of postpartum women develop fever from breast engorgement, usually 2 to 3 days following delivery. The fever rarely exceeds 39°C, and characteristically lasts no longer than 24 hours. By contrast, the fever of bacterial mastitis develops later, and is usually sustained. It is associated with other signs and symptoms of breast infection that become overt within 24 hours.

Respiratory Complications

These complications are most often seen within the first 24 hours following delivery and almost invariably are in women delivered by cesarean section. They are much less common if epidural or spinal anesthesia was used. Complications include atelectasis, aspiration pneumonia, or occasionally, bacterial pneumonia. Atelectasis is best prevented by encouraging coughing and deep breathing, usually every 4 hours for at least 24 hours following operative delivery.

Pyelonephritis

Acute renal infection may be difficult to distinguish from postpartum pelvic infection. In the typical case, bacteriuria, pyuria, costovertebral angle (CVA) tenderness, and spiking temperature clearly indicate renal infection. In the puerperal woman the first sign of renal infection may be a temperature elevation, with costovertebral angle tenderness, nausea, and vomiting developing later. See Chapter 65 for management of pyelonephritis during pregnancy.

Thrombophlebitis

Superficial or deep venous thrombosis (DVT) of the legs may cause minor temperature elevations in the puerperal woman. The diagnosis is made by observation of a painful, swollen leg, usually accompanied by calf tenderness, or occasionally femoral triangle area tenderness. See Chapter 70 for management of thrombophlebitis.

GENITAL TRACT CAUSES OF POSTPARTUM FEVER

Endomyometritis (Endometritis or “Metritis”)

Uterine infections are a major problem in women delivered by cesarean section. Whereas endomyometritis following vaginal delivery occurs in about 1 to 2 percent of women, rates as high as 40 to 50 percent have been reported following cesarean delivery. Other risk factors for endomyometritis include prolonged membrane rupture, labor, multiple cervical examinations, anemia, internal fetal monitoring, and chorioamnionitis (see Chapter 15). Such risk factors have resulted in routine administration of prophylactic antibiotics to women undergoing cesarean delivery. For example, at Parkland Hospital, all afebrile women delivered by cesarean (except those scheduled electively) receive cefazolin, 2 g intravenously.

Pathogenesis

Bacteria commonly responsible for postpartum genital tract infections are listed in Table 21-1. These organisms normally colonize the cervix, vagina, perineum, and gastrointestinal tract. Though usually of low virulence, they become pathogenic in the setting of devitalized tissue and hematomas that are inevitable with delivery. Postpartum infections are polymicrobial (usually two to three species) and occur at the surgical site or area of placental implantation.

TABLE 21-1. Bacteria Commonly Responsible for Female Genital Infections

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Clinical Manifestation

Uterine infection should be a prime consideration in a postpartum woman with fever. There is often a foul, profuse bloody vaginal discharge (lochia). Abdominal and parametrial uterine tenderness is often present during bimanual examination. Discernment of uterine tenderness due to metritis may be obscured by the expected tenderness associated with a cesarean incision. Postpartum (postoperative) maternal fever, in the absence of another identified cause, should be presumed to be due to endomyometritis.

Management

The polymicrobial nature of these infections mandates broad-spectrum antimicrobial regimens in the treatment of endomyometritis following either vaginal delivery or cesarean section (Table 21-2). Several different regimens can be used. The regimen in use at Parkland Hospital includes clindamycin plus gentamicin and is sufficient for 95 percent of women. Enterococcus is associated with some clinical failures, and ampicillin is empirically added if there is no clinical response after 72 hours of clindamycin plus gentamicin. If fever persists, complications of endomyometritis (see next section) need to be excluded by pelvic examination and imaging studies. In the absence of such complications, women with endomyometritis receive intravenous antibiotics until they have been afebrile for 24 hours; at which time, the patient is discharged without oral therapy. This usually requires 2 to 3 days and seldom results in rehospitalization for uterine infection.

TABLE 21-2. Antimicrobial Regimens for Pelvic Infection Following Cesarean Delivery

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Complications of Endomyometritis

Wound Infections

The incidence of abdominal incisional infections following cesarean delivery ranges from 3 to 15 percent with an average of 6 percent. Prophylactic antibiotics decrease this incidence to less than 2 percent. Wound infections usually present about the fourth postoperative day as persistent fever despite adequate antimicrobial therapy. Incisional erythema, induration, and drainage are common. Treatment includes continuing broad-spectrum antimicrobials and opening the wound to allow drainage. Assurance of an intact underlying fascia is important. This can be accomplished by gently palpating the fascia through the open wound.

Peritonitis

Postcesarean peritonitis resembles surgical peritonitis, except that abdominal rigidity usually is less prominent because of the abdominal wall laxity associated with pregnancy. Pain may be severe. Bowel distention is a consequence of adynamic ileus. It is important to identify the cause of generalized peritonitis. If the infection began in the uterus and extended only into the adjacent peritoneum (“pelvic peritonitis”), the treatment is usually medical. Conversely, general abdominal peritonitis as the consequence of a bowel injury or uterine incisional necrosis (see later discussion) is best treated surgically.

Parametrial Phlegmon

In some women in whom metritis develops following cesarean delivery, parame-trial cellulitis is intensive and forms an area of induration, termed a phlegmon, within the leaves of the broad ligaments (parametria) or under the bladder flap overlying the uterine incision (Figure 21-1). The parametrial cellulitis is often unilateral and may extend laterally to the pelvic sidewall. These infections should be considered when fever persists after 72 hours despite treatment of endomyometritis following cesarean delivery.

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FIGURE 21-1 Parametrial phlegmon. Cellulitis causes induration in the right parametrium adjacent to the uterine cesarean incision. Induration extends to the pelvic sidewall. On bimanual pelvic examination, the phlegmon is palpable as a firm, three-dimensional mass. (Reproduced, with permission, from Cunningham FG, Leveno KJ, Bloom SL, et al (eds). Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010.)

Clinical response usually follows continued treatment with one of the intravenous antimicrobial regimens previously discussed. These women may remain febrile for 5 to 7 days, and, in some cases, even longer. Absorption of the induration follows, but it may take several days to weeks to dissipate completely. Surgery is reserved for women in whom uterine incisional necrosis is suspected (see later discussion).

Pelvic Abscess

Rarely a parametrial phlegmon will suppurate, forming a fluctuant broad ligament abscess. Should this abscess rupture, life-threatening peritonitis may develop. Drainage of the abscess may be performed using computed tomography guidance, colpotomy, or abdominally, depending on the abscess location. Bladder flap hematomas may also become infected and require drainage.

Subfascial Abscess and Uterine Scar Dehiscence

A serious complication of endomyometritis in women delivered by cesarean is dehiscence of the uterine incision due to infection and necrosis with extension into the adjacent subfascial space and, ultimately, separation of the fascial incision. This presents as subfascial drainage of pus in a woman with extended fever. Surgical exploration and removal of the infected uterus is necessary.

Septic Pelvic Thrombophlebitis

This complication is discussed in detail in Chapter 22.

Episiotomy Complications

Less than 1 percent of episiotomies or lacerations become infected. Fourth-degree lacerations are associated with the highest risk of serious infection. For this reason, prophylactic antibiotics are routinely administered to women with rectal lacerations at Parkland Hospital.

Clinical Manifestations

The apposing wound edges become red, brawny, and swollen. The sutures often tear through the edematous tissues, allowing the necrotic wound edges to gape, with the result that there is serous, serosanguineous, or frankly purulent drainage. Episiotomy breakdown (dehiscence) is most commonly associated with infection.

Management

In some women with obvious cellulitis but no purulence, broad-spectrum antimicrobial therapy with close observation is appropriate. In all others, the sutures are removed and the infected wound opened. Early repair of episiotomy breakdown is now advocated (Table 21-3). The surgical wound should be properly cleaned and free of infection. Once the wound is covered by pink granulation tissue (this usually takes 5 to 7 days), secondary repair may be performed in layers. Postoperative care includes local care, low-residue diet, stool softeners, and nothing per vagina or rectum until healed.

TABLE 21-3. Preoperative Protocol for Early Repair of Episiotomy Dehiscence

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Necrotizing Fasciitis

A rare but potentially fatal complication of perineal or vaginal wound infections is deep soft tissue infection involving muscle and fascia. These infections may follow either cesarean or vaginal delivery. Necrotizing fasciitis of the episiotomy site may involve any of the superficial or deep perineal fascial layers, and may extend to the thighs, buttocks, and abdominal wall. Although these infections may develop within a day of delivery, they more commonly do not cause symptoms until 3 to 5 days following delivery. Clinical symptoms vary, and it is frequently difficult to differentiate superficial from deep fascial infections. Early diagnosis, surgical debridement, antibiotics, and intensive care are of paramount importance in the successful treatment of necrotizing soft tissue infections.

Sepsis Syndrome

Sepsis (and septic shock) is caused by a systemic inflammatory response to bacteria. Gram-negative bacteria release endotoxin, which is commonly associated with septic shock and disseminated intravascular coagulation. Bacterial exotoxins may also be the instigating factor.

Clinical Manifestations

The spectrum of clinical disease is depicted in Figure 21-2, and the multiple organ effects are listed in Table 21-4.

TABLE 21-4. Multiple Organ Effects with Sepsis and Shock

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FIGURE 21-2 The sepsis syndrome begins with a systemic inflammatory response syndrome (SIRS) in response to infection that may progress to septic shock. (Reproduced, with permission, from Cunningham FG, Leveno KJ, Bloom SL, et al (eds). Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010. Redrawn with permission from Dr. Robert S. Munford.)

Management

Whenever serious bacterial infection is suspected, blood pressure and urine flow should be monitored closely. Septic shock, as well as hemorrhagic shock, should be considered whenever there is hypotension or oliguria. Most previously healthy women with sepsis complicating obstetrical infections respond well to fluid resuscitation, given along with intensive antimicrobial therapy and, if indicated, removal of infected tissue. If hypotension is not corrected following vigorous fluid infusion, then the prognosis is guarded. Oliguria and continued peripheral vasoconstriction characterize a secondary, cold phase of septic shock, from which survival may not be possible. Another poor prognostic sign with sepsis is continued end-organ dysfunction, to include renal (acute tubular necrosis), pulmonary (adult respiratory distress syndrome), and cerebral failure after hypotension has been corrected.

Shown in Figure 21-3 is a scheme for treatment of sepsis syndromes. Rapid infusion with 2 L and sometimes as much as 4 to 6 L of crystalloid fluids may be required to restore renal perfusion in severely affected women. Because there is a vascular leak, these women usually are hemoconcentrated; if the hematocrit is 30 volume percent or less, then blood is given along with crystalloid to maintain the hematocrit at about 30 volume percent. If aggressive volume replacement is not promptly followed by urinary output of at least 30 and preferably 50 mL/h, as well as other indicators of improved perfusion, then consideration is given for insertion of a pulmonary artery catheter (see Chapter 46). In women who are seriously ill, pulmonary capillary endothelium is also likely damaged, with alveolar leakage and pulmonary edema occurring even with low or normal pulmonary capillary wedge pressures—the adult respiratory distress syndrome (ARDS; see Chapter 45). This must be differentiated from circulatory overload from overly vigorous fluid therapy, with which wedge pressures will be abnormally high.

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FIGURE 21-3 Algorithm for evaluation and management of sepsis syndrome. Rapid and aggressive implementation is paramount for success. The three steps—evaluate, assess, and immediate management—are done as simultaneously as possible. (Reproduced, with permission, from Cunningham FG, Leveno KJ, Bloom SL, et al (eds). Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010.)

Broad-spectrum antimicrobials are administered in maximal doses after appropriate cultures are obtained. Generally, empirical coverage with regimens such as ampicillin plus gentamicin plus clindamycin suffices. Surgical removal of the infected uterus or debridement of necrotic tissue, or both, may be necessary.


For further reading in Williams Obstetrics, 23rd ed.,

see Chapters 31, “Puerperal Infection,” and 42, “Critical Care and Trauma.”