Infections in Pregnancy: Septic Shock

Shock is a clinical syndrome that affects the entire body and is caused by inadequate delivery of oxygen and nutrients to tissues. Septic shock is an infection, as well as a whole-body response to the infection, with both increased metabolic demands and insufficient support from the heart and blood vessels to deliver oxygen and nutrients to meet those demands. Urinary tract infections (UTIs) in pregnancy can sometimes progress from the original site of infection to the kidneys (acute pyelonephritis)-and kidney infection, in turn, can lead to septic shock. Fortunately, fewer than 4% of women with pyelonephritis develop septic shock.

The most common organisms responsible for septic shock are aerobic gram-negative bacilli (rod-shaped bacteria), principally Escherichia coli (E. Coli), Klebsiella pneumoniae, and Proteus species. Gram-negative bacteria, unlike other types of bacteria, have a double membrane, which makes them tougher to kill and more resistant to antibiotics. However, the most virulent and drug-resistant gram-negative bacilli, such as Pseudomonas, Enterobacter, and Serratia species, are usually not involved in septic shock-except for women with weakened immune systems.

What Are the Symptoms and Consequences of Septic Shock?

Aerobic gram-negative bacilli have a complex lipopolysaccharide (fat and carbohydrate compound) in their cell wall called an endotoxin. When the bacterial cell is destroyed, allowing endotoxin to circulate throughout the body, it can cause irregularities in the blood and blood circulation, immune system, central nervous system, and endocrine system, and it can ultimately lead to dysfunction in virtually every major organ in the body.

Septic shock causes a variety of systemic signs and symptoms, such as:

• restlessness and disorientation;
• rapid heart rate (tachycardia) and low blood pressure (hypotension);
• high fever (103 to 104? F)-though some experience low body temperature (hypothermia);
• skin that is warm and flushed due to dilation of the blood vessels (vasodilation);
• extensive narrowing of the blood vessels (vasoconstriction), causing cool and clammy skin;
• irregular heart rhythms;
• jaundice (yellowing of the skin);
• decrease in urinary output or acute renal (kidney) failure; and
• spontaneous bleeding from the genitourinary (genital or urinary) tract or punctured veins.

Adult respiratory distress syndrome (ARDS) is another common complication of severe sepsis. Marked by shortness of breath, rapid and labored respirations, coughing, and lung congestion, ARDS is a major cause of death in severe sepsis.

How Is Septic Shock Usually Diagnosed?

If you are pregnant and have symptoms such as those just described, your doctor will have to determine whether you have septic shock or shock due to another cause. Other possible causes of shock include hemorrhage, heart attack, diabetic ketoacidosis, anaphylactic reaction (severe allergic reaction), a reaction to anesthesia, or a massive blood clot in the lung. Your doctor will be able to distinguish between these disorders on the basis of a thorough history and physical examination and a limited number of laboratory studies.

A number of laboratory findings indicate septic shock. Your white blood cell count may be decreased initially but will likely elevate later. If blood loss has occurred, your red blood cell count may be decreased. Tests of how well your blood is clotting and your liver and kidney function may reveal further abnormalities.

A chest x-ray will be taken in order to determine whether you have ARDS or pneumonia. In addition, various imaging tests-including CT scan, MRI, and ultrasound-may help identify the primary infection site. You will also require electrocardiographic monitoring to detect irregular heart rhythms and signs of injury to your heart.

How Should Septic Shock Be Treated?

There are three major goals in the treatment of septic shock.

• The first objective is to correct the problems in blood circulation caused by endotoxin. Your doctor uses a large intravenous catheters to administer fluids intravenously. Your pulse, blood pressure, and urine output will be monitored in order to administer the proper amounts of these fluids. If the initial fluid infusion does not restore proper blood circulation, your doctor may insert a right heart catheter as a further monitoring device. You may also be prescribed dopamine. In appropriate doses, this drug improves the function of the heart and increases blood flow to major organs.

• The second objective of treatment is to administer antibiotics targeted against the most likely bacteria. For genital tract infections, the combination of penicillin or ampicillin plus clindamycin or metronidazole, plus gentamicin or aztreonam, is a highly effective treatment. Alternatively, imipenem-cilastatin or meropenem can be administered as single drugs.

  
  
  
  
  

  If the source of infection is unclear, your doctor may perform additional tests. This may include an amniocentesis to determine if there is an infection within the pregnant uterus. In cases of intramniotic infection, delivery may be indicated to avoid severe maternal illness. Sometimes delivery must occur at such an early gestational age that the fetus is not expected to survive.

  
  
  
  
  

  In addition, you may require surgery-perhaps to drain a pelvic abscess (collection of pus) or to remove badly infected pelvic organs. Even if your condition is unstable, surgery should not be delayed since the operation may reverse the circulatory problems caused by septic shock.

  Other measures may help treat a severe infection. An infusion of granulocytes (white blood cells) may be appropriate for women whose immune systems are suppressed. Another approach is to administer antisera (anti-toxin) directed against the usual bacteria that cause septic shock. This therapy has appeared promising in some investigations, but remains experimental.

• The third major objective of treatment is to provide comprehensive supportive care. Your temperature should be maintained as close to normal as possible through antipyretics (medications that reduce fever) and a cooling blanket. Coagulation (clotting) abnormalities should be identified promptly and treated by an infusion of blood platelets and coagulation factors.

  
  
  
  
  

  Blood glucose levels should be kept reasonably well controlled. Your doctor may periodically check your blood glucose and administer insulin if needed. Good blood glucose control can minimize the risk of additional infections.

  
  
  
  
  

  Finally, you will be given supplemental oxygen and observed closely for evidence of ARDS. Your oxygen status should be closely monitored with one of two devices: a pulse oximeter or a radial artery catheter. If respiratory failure becomes evident, you will be put on an oxygen support system.

What Is the Prognosis for Those with Septic Shock?

The prognosis for patients with septic shock clearly depends upon the severity of a woman's underlying illness. In women who have other life-threatening illnesses such as cancer, mortality may approach 80%. But in otherwise healthy patients, mortality rarely exceeds 15%. Fortunately, most obstetric patients are in the latter category. Therefore, provided that you receive timely, competent treatment, your prognosis for complete recovery is excellent.