How to Diagnose Acute Pancreatitis During Pregnancy

Acute pancreatitis during pregnancy, which can occur at any stage of gestation or during the postpartum period, has an incidence rate ranging from 1 in 1,000 to 1 in 4,000. It is a serious condition characterized by rapid onset, quick progression, and a high risk of complications. Due to its atypical presentation, it can be easily misdiagnosed and poses a significant threat to both maternal and fetal health. Research indicates that it most commonly occurs in the third trimester, and its incidence has been rising in recent years, likely due to changes in lifestyle and dietary habits.

Causes of Acute Pancreatitis During Pregnancy

The causes of acute pancreatitis during pregnancy are similar to those in the general population. The most common include biliary etiology and hypertriglyceridemia. Other less frequent causes include hypercalcemia due to hyperparathyroidism, and ischemic damage to the pancreas caused by vasospasm associated with preeclampsia. Identifying the underlying cause is crucial for determining the appropriate treatment plan.

Biliary pancreatitis in pregnancy is often linked to metabolic changes during gestation. In the second and third trimesters, the liver produces bile with higher cholesterol content and lower bile acids and phospholipids, leading to cholesterol supersaturation. High estrogen levels reduce gallbladder motility, causing bile stasis. Additionally, the enlarging uterus increases intra-abdominal pressure, potentially compressing the duodenum and biliary system, impairing bile drainage. These factors contribute to gallstone formation, which can obstruct the common channel of the pancreatic and bile ducts at the ampulla of Vater, causing bile reflux, enzyme activation, and subsequent pancreatic inflammation.

In normal pregnancy, lipid metabolism changes to support fetal development. Hormones like prolactin, estrogen, progesterone, and glucocorticoids increase insulin resistance, especially in the third trimester, leading to elevated lipid levels. However, in women with obesity, rapid weight gain, advanced maternal age, pre-existing diabetes, preeclampsia, or lipid metabolism disorders, triglycerides, cholesterol, and free fatty acids can reach dangerously high levels. This increases blood viscosity, promotes microthrombosis, and impairs pancreatic microcirculation, potentially triggering pancreatitis. When combined with necrotizing pancreatitis, these factors significantly increase the severity and risk of complications.

Clinical Presentation of Acute Pancreatitis During Pregnancy

The classic triad of symptoms includes nausea, vomiting, and upper abdominal pain. The pain is often described as persistent epigastric or left upper quadrant discomfort radiating to the back, and does not subside after vomiting. Some patients report a history of high-fat meals before the onset.

Any upper abdominal pain during pregnancy should raise suspicion for acute pancreatitis, especially since symptoms can be mild or atypical. In early pregnancy, severe and frequent vomiting can mimic pancreatitis, while in late gestation, epigastric pain may be mistaken for labor contractions.

Physical findings may also be atypical due to anatomical changes in pregnancy. Abdominal tenderness, rebound tenderness, or palpable masses may not be prominent. Instead, patients may only exhibit deep epigastric tenderness or back discomfort. Fever, decreased bowel sounds, and abdominal distension may also be present. In biliary pancreatitis, jaundice of the skin and sclera can occur.

Diagnostic Approach to Acute Pancreatitis During Pregnancy

Diagnosing acute pancreatitis during pregnancy involves four key considerations: (1) confirming the presence of acute pancreatitis, (2) assessing severity, (3) identifying the underlying cause, and (4) determining the stage of pregnancy.

The diagnosis relies on a combination of clinical history, physical examination, laboratory tests, and imaging studies. Women with a history of biliary disease, previous pancreatitis, diabetes, or familial hypertriglyceridemia should be closely monitored if they experience acute abdominal pain during pregnancy.

When a pregnant woman presents with nausea, vomiting, and upper abdominal pain, acute pancreatitis should be strongly considered. However, differential diagnoses include acute pneumonia, perforated peptic ulcer, splenic rupture, appendicitis, ectopic pregnancy, hyperemesis gravidarum, and preeclampsia.

Laboratory tests typically include serum and urine amylase levels. Serum amylase usually rises within 24 hours and peaks within 48 hours, while urine amylase elevation may lag. Simultaneous testing and trend monitoring are essential for accurate diagnosis. Serum lipase rises later, peaks between 24–72 hours, and remains elevated for up to 10 days, making it more reliable and less affected by pregnancy.

Elevated liver enzymes and bilirubin suggest a biliary origin. In hypertriglyceridemia-induced cases, plasma may appear chylous. Triglyceride levels above 11.3 mmol/L are associated with increased risk, and should be reduced below 5.6 mmol/L. Hypercalcemia may point to hyperparathyroidism, while persistent hyperglycemia and hypocalcemia indicate a more severe disease course.

Imaging Modalities for Diagnosis

Ultrasound is the first-line imaging modality during pregnancy. It can detect pancreatic swelling, peripancreatic fluid collections, gallstones, and biliary dilation. However, bowel gas and maternal body habitus can limit visualization. Ultrasound also allows for fetal assessment, including gestational age and signs of distress.

Enhanced CT is the most accurate imaging method for evaluating pancreatitis severity, but radiation exposure is a concern. According to the International Commission on Radiological Protection, radiation doses below 0.05 Gy pose negligible teratogenic risk. Upper abdominal CT delivers less than 0.01 Gy to the fetus, while lower abdominal scans deliver less than 0.03 Gy. In cases of severe late-term symptoms, CT may be justified to guide decisions on delivery and surgical intervention.

Severity Assessment and Management Implications

Severity classification is essential. Acute severe pancreatitis is defined by organ failure, local complications such as necrosis, abscess, or pseudocyst, or a combination. An APACHE II score of 8 or higher also indicates severe disease. Fulminant pancreatitis is diagnosed when organ failure persists despite aggressive fluid resuscitation within 72 hours. Prompt diagnosis allows for timely surgical or intensive care interventions, which are critical in managing these high-risk pregnancies.