In nonpregnant patients, acute pancreatitis is almost equally associated with gallstones and alcohol abuse. During pregnancy, however, cholelithiasis is almost always the predisposing condition. Other causes are hyperlipidemias, usually hypertriglyceridemia; hyperparathyroidism; congenital ductal anomalies; ERCP; some drugs; and rarely autoimmune pancreatitis (Cain, 2015; Ducarme, 2014). N onbiliary pancreatitis occasionally develops postoperatively, or it is associated with trauma, drugs, or some viral infections. Certain metabolic conditions, including acute fatty liver of pregnancy and familial hypertriglyceridemia, also predispose to pancreatitis (Nelson, 2013). Cases of acute and chronic pancreatitis have been linked to numerous mutations of the cystic fibrosis transmembrane conductance regulator gene (Chang, 2015).
The incidence of pancreatitis varies with the population studied. At Parland Hospital, with a predominant Mexican American population, acute pancreatitis complicated approximately 1 in 3300 pregnancies (Ramin, 1995). At Brigham and Women's Hospital, with a more diversely ethnic population, Hernandez and colleagues (2007) reported an incidence of 1 in 4450. In a multiple-institution :Midwestern three-state review, the incidence of acute pancreatitis was 1 in 3450 (Eddy, 2008). In contrast, from California birth certificate data, the incidence approximated only 1 case in 6000 pregnancies (Hacker, 2015).
Acute pancreatitis is characterized by mild to incapacitating epigastric pain, nausea and vomiting, and abdominal distention. Patients are usually distressed and have low-grade fever, tachycardia, hypotension, and abdominal tenderness. As many as 10 percent have systemic inlammatory response syndrome (SIRS), which causes endothelial activation and can lead to acute respiratory distress syndrome (Chap. 47, p. 921).
Of laboratory tests, serum amylase levels usually measure three times values considered the upper limit of normal. In 173 pregnant women with pancreatitis, the mean amylase value approximated 2000 lUlL, and the mean lipase value approached 3000 lUlL (Table 55-5). Importanty, the degree of enzyme elevation and disease severiy do not reliaby correlate. Indeed, by 48 to 72 hours, amylase levels may return to normal despite other evidence for continuing pancreatitis. Serum lipase activity is also increased and usually remains elevated with continued inlammation. Leukocytosis is usually found, and 25 percent of patients have hypocalcemia. Elevated serum bilirubin and aspartate transaminase levels may signiY gallstone disease.
Several prognostic scoring systems have been used to classiY pancreatitis severity, but not all of these are useful in pregnancy. For instance, two of the ive Ranson criteria determined
TABLE 55-5. Laboratory Values in 173 Pregnant Women with Acute Pancreatitis
Hepatic, Biliary, and Pancreatic Disorders 1071 at admission include variables speciic to nonpregnant patients. Similarly, certain criteria for the Apache II scoring system do not account for the changes in pregnancy physiology. In contrast, the Atlanta Classiication incorporates the degree of organ failure as a measure of severity and may be more applicable in pregnancy (Banks, 2013; Cain, 2015).