Infection after cesarean delivery: diagnosis, pathophysiology, management, and prevention

Infection is one of the 2 most common complications associated with cesarean delivery. The principal infections, in descending order of frequency, are endometritis (organ space infection), wound infection (surgical site infection and incisional infection), and urinary tract infection. The major microorganisms that cause endometritis are anaerobic Gram-negative bacilli, anaerobic Gram-positive cocci, aerobic Gram-negative bacilli, aerobic Gram-positive cocci, and Ureaplasma urealyticum. The principal pathogens that cause wound infections are the organisms listed above plus the staphylococcal and streptococcal organisms that colonize the skin of the patient's abdomen, including methicillin-resistant Staphylococcus aureus. The dominant uropathogens are the aerobic Gram-negative bacilli Escherichia coli, Klebsiella pneumoniae, and Proteus species. Group B streptococci, enterococci, and Staphylococcus saprophyticus are less common, but still important, uropathogens. The principal risk factors for endometritis and wound infection are obesity, extended duration of labor and ruptured membranes, multiple vaginal examinations after membrane rupture, internal fetal monitoring, smoking, insulin-dependent diabetes, immunosuppressive disorders, use of immunosuppressive medications, extended duration of surgery, and excessive intraoperative blood loss. The key risk factors for urinary tract infection are the technique for insertion of the urinary catheter and the duration of bladder catheterization. The initial differential diagnosis of postoperative fever includes endometritis, lower respiratory tract infection, and acute pyelonephritis. When postoperative fever persists, the differential must be broadened to include resistant microorganism(s), wound infection, pelvic abscess, septic pelvic vein thrombophlebitis, retained products of conception, drug fever, and reactivation of connective tissue disease. The appropriate antibiotic therapy for endometritis is either a combination regimen, such as clindamycin plus gentamicin or metronidazole plus ampicillin plus gentamicin, or single agents such as extended-spectrum penicillins, cephalosporins, or carbapenems that provide coverage against the broad range of pelvic pathogens. For wound infection, the addition of a specific antistaphylococcal antibiotic such as vancomycin or linezolid, and, in some instances, surgical drainage are indicated. For a lower urinary tract infection, the oral antibiotics, nitrofurantoin monohydrate macrocrystals or trimethoprim-sulfamethoxazole, are preferred. For pyelonephritis, ceftriaxone is an excellent choice for therapy. Several measures are of great value in reducing the frequency of endometritis and wound infection: preoperative antibiotics, clipping (rather than shaving) the hair at the incision site, preparation of the skin with chlorhexidine (rather than povidone-iodine), removal of the placenta by traction on the cord (rather than by manual extraction), closure of the deep subcutaneous layer if it exceeds 2 cm in thickness, and closure of the skin with a thin monofilament suture (rather than with staples or with a multifilament suture). The key preventive measures for reducing the frequency of urinary tract infection are strict aseptic technique in inserting the catheter and removal of the catheter within 12 to 24 hours of surgery. This review focuses primarily on the pathophysiology, clinical manifestations, diagnosis, and treatment of endometritis, wound infection, and urinary tract infection. It also provides a brief overview of the diagnosis and management of the potentially very serious complications that may arise from the original infection at the operative site, namely pelvic abscess, septic pelvic vein thrombophlebitis, and septic shock. The review concludes with a summary of key measures to prevent postoperative infections.