What is the appropriate evaluation and management of upper abdominal pain in a pregnant woman in late pregnancy?

Evaluation and Management of Upper Abdominal Pain in Late Pregnancy

Initial Approach: Ultrasound First

Begin with ultrasound as the primary imaging modality for upper abdominal pain in late pregnancy, as it provides essential diagnostic information without radiation exposure and can identify most life-threatening conditions. 1

Critical Differential Diagnoses to Consider

Upper abdominal pain in late pregnancy requires immediate consideration of both pregnancy-specific and general surgical/medical conditions:

Pregnancy-Related Causes

• Preeclampsia with severe features presenting as epigastric or right upper quadrant pain (HELLP syndrome) 2
• Placental abruption with referred upper abdominal pain 3
• Acute fatty liver of pregnancy 4

Surgical Emergencies

• Acute cholecystitis/cholelithiasis (most common surgical cause of upper abdominal pain in pregnancy) 1, 4
• Acute appendicitis (most common nonobstetric surgical emergency requiring surgery, though typically presents with right lower quadrant pain, location may be atypical in late pregnancy) 1, 5
• Pancreatitis 1, 4
• Internal hernia (especially in patients with prior bariatric surgery) 6
• Bowel obstruction 1, 4

Other Conditions

• Herpes zoster (shingles can present as severe abdominal pain before vesicles appear) 7
• Hepatic pathology 1
• Mesenteric ischemia (rare but catastrophic) 1

Diagnostic Algorithm

Step 1: Immediate Assessment

• Check vital signs immediately, including blood pressure to evaluate for preeclampsia 8
• Assess for hemodynamic instability requiring immediate intervention 2
• Obtain focused history including: timing of pain onset, radiation pattern, associated symptoms (headache, visual changes, vaginal bleeding, decreased fetal movement), prior abdominal surgeries (especially bariatric procedures) 6, 4

Step 2: Physical Examination

• Palpate for localized tenderness, peritoneal signs, and hepatomegaly 3, 4
• Examine for rash or vesicles that may indicate herpes zoster 7
• Assess fetal heart tones and uterine tenderness 4

Step 3: Laboratory Testing

• Complete blood count, comprehensive metabolic panel, liver function tests 4
• Urinalysis 4
• If significant bleeding or severe preeclampsia suspected: platelet count, PT/PTT, fibrinogen, LDH, uric acid 2

Step 4: Imaging Strategy

Ultrasound abdomen is the initial imaging modality of choice 1:

• Highly sensitive for cholecystitis, cholelithiasis, and hepatobiliary pathology 1
• Can assess for free fluid, liver abnormalities, and some pancreatic pathology 1
• No radiation exposure to fetus 1

MRI without contrast is the preferred next step if ultrasound is nondiagnostic or equivocal 1:

• Can be performed in 10 minutes or less with tailored protocols 1
• Accuracy of 99% for diagnosing acute abdominal conditions including bowel inflammation, obstruction, and pancreaticobiliary disease 1
• Avoids radiation exposure 1
• Particularly valuable for evaluating pancreaticobiliary inflammatory processes that may be missed on CT 1

CT should be reserved for emergent situations when MRI is not readily available and ultrasound is nondiagnostic 1:

• The negative predictive value of CT for upper abdominal pain is relatively low at 64%, with commonly missed diseases including pancreaticobiliary inflammatory processes, gastritis, and duodenitis 1
• However, CT may be necessary if mesenteric ischemia is suspected or if the clinical scenario is emergent 1

Management Principles

Immediate Interventions

• Consult obstetrics immediately for all pregnant patients with significant upper abdominal pain 8
• Consult general surgery if surgical pathology is suspected (cholecystitis, appendicitis, bowel obstruction) 5
• Do not delay surgical intervention when indicated, as maternal and fetal outcomes worsen with delayed diagnosis and treatment 3, 4, 5

Specific Conditions

• If preeclampsia with severe features is diagnosed: initiate magnesium sulfate, antihypertensive therapy, and prepare for delivery 2
• If cholecystitis is confirmed: surgical consultation for possible cholecystectomy (can be performed safely in pregnancy) 4
• If appendicitis is diagnosed: prompt surgical intervention is critical to prevent perforation and fetal loss 1, 5

Critical Pitfalls to Avoid

• Do not attribute all upper abdominal pain to normal pregnancy discomfort, as this leads to delayed diagnosis of serious conditions 3, 4
• Do not delay imaging due to radiation concerns when ultrasound and MRI are available as first-line options 1
• Anatomical and physiological changes of pregnancy alter typical presentations, requiring high index of suspicion 3, 5
• Do not dismiss pain that persists or worsens despite initial negative workup—shingles can present as severe abdominal pain before vesicles appear 7
• Delay in diagnosis and treatment leads to adverse maternal and fetal outcomes, particularly with appendicitis (increased perforation risk) and surgical emergencies 1, 4, 5
• Liberal use of surgical and obstetric consultants is warranted when diagnosis is uncertain 5