What are the causes and management of abdominal pain during a 5-month pregnancy?

Abdominal Pain at 5 Months Pregnancy

Abdominal pain at 5 months (mid-second trimester) pregnancy requires systematic evaluation prioritizing ultrasound imaging, with MRI as the next step if ultrasound is inconclusive, while avoiding CT unless life-threatening conditions are suspected. 1

Most Common Causes at This Gestational Age

Obstetric Causes

• Round ligament pain and uterine stretching are the most common benign causes of abdominal discomfort in mid-pregnancy, presenting as sharp, brief pains in the lower abdomen or groin 1
• Placental abnormalities including early abruption can present with abdominal pain, though more common in later pregnancy 1
• Preterm labor should be considered if pain is rhythmic or associated with contractions 2

Non-Obstetric Surgical Emergencies

• Appendicitis is the most common cause of abdominal pain requiring emergency surgery in pregnant patients and must be excluded first 3, 1, 4
  • At 5 months, the appendix is displaced superiorly and laterally by the gravid uterus, causing atypical pain location (often right upper quadrant or flank rather than right lower quadrant) 2, 5
  • MRI has 97% sensitivity and 95% specificity for diagnosing appendicitis in pregnancy 6
• Ovarian torsion presents with acute, severe unilateral pain and requires urgent diagnosis via ultrasound showing enlarged ovary with decreased or absent Doppler flow 6, 1
• Cholecystitis is more common in pregnancy due to increased gallstone formation, diagnosed by ultrasound showing gallbladder wall thickening >3mm, pericholecystic fluid, and sonographic Murphy sign 6

Gastrointestinal and Genitourinary Causes

• Urolithiasis and pyelonephritis are common causes of abdominal/flank pain during pregnancy 6, 1
• Constipation from hormonal changes can cause significant abdominal discomfort 1
• Inflammatory bowel disease flares can occur during pregnancy and require evaluation 3

Diagnostic Approach Algorithm

Step 1: Clinical Assessment

• Check vital signs immediately: fever, tachycardia (>100 bpm), and tachypnea together suggest serious infection or sepsis requiring urgent intervention 1, 7
• Assess pain characteristics: location (noting that normal anatomical landmarks are displaced), severity, timing, radiation, and associated symptoms 3, 8
• Look for peritoneal signs: guarding, rebound tenderness, and rigidity indicate surgical emergency 3, 8
• Check for vaginal bleeding or discharge: suggests obstetric complications 1
• Assess fetal heart rate: abnormalities may indicate maternal compromise affecting fetal perfusion 6

Step 2: Laboratory Studies

• Complete blood count to assess for infection or anemia 6, 7
• Urinalysis to evaluate for urinary tract infection or urolithiasis 6, 7
• Liver function tests and amylase/lipase if upper abdominal pain suggests hepatobiliary or pancreatic pathology 4

Step 3: Imaging Strategy

• Start with ultrasound as the primary imaging modality for all pregnant patients with abdominal pain 3, 1, 4

  • Obstetric ultrasound to assess fetal well-being and placental position 6
  • Targeted ultrasound of the painful area (right upper quadrant for cholecystitis, right lower quadrant/flank for appendicitis, kidneys for urolithiasis) 6, 4

• Proceed to MRI without contrast if ultrasound is inconclusive 3, 1, 4

  • MRI is safe in the second trimester and provides excellent soft tissue detail without radiation 3, 4
  • Gadolinium should be avoided unless absolutely necessary based on risk-benefit analysis 3

• Reserve CT with IV contrast for life-threatening situations only when diagnosis cannot be made by ultrasound or MRI and immediate intervention is needed 3, 1

  • Single-acquisition CT of abdomen/pelvis delivers <25 mGy, which poses minimal fetal risk 3
  • Do not withhold CT if maternal life is at risk 3, 7

Critical Red Flags Requiring Immediate Surgical Consultation

• Fever with peritoneal signs suggests intra-abdominal infection or abscess 3, 1
• Hemodynamic instability (hypotension, tachycardia >120 bpm, altered mental status) indicates potential sepsis or hemorrhage 3, 1
• Severe, unrelenting pain that is worsening despite conservative measures 8, 5
• Absent bowel sounds with distension suggests bowel obstruction 3

Management Principles

For Benign Causes

• Reassurance and conservative management for round ligament pain and constipation 1
• Dietary modifications: small, frequent meals, avoiding spicy/fatty foods for gastrointestinal symptoms 7
• Hydration and stool softeners for constipation-related pain 1

For Surgical Emergencies

• Do not delay surgical intervention when appendicitis, ovarian torsion, or cholecystitis is diagnosed, as maternal and fetal outcomes worsen with delayed treatment 2, 8, 5
• Laparoscopic surgery is safe in the second trimester and preferred over open surgery when feasible 3, 8
• Position patient in left lateral tilt during procedures to avoid aortic/IVC compression by the gravid uterus 3

Common Pitfalls to Avoid

• Do not attribute all abdominal pain to normal pregnancy changes without excluding serious pathology first 7, 2, 8
• Do not rely solely on laboratory values: leukocytosis is normal in pregnancy (up to 15,000-16,000/μL), and inflammatory markers may be elevated physiologically 2, 9
• Do not delay imaging due to radiation concerns when serious pathology is suspected—maternal death also results in fetal death 3, 7, 5
• Do not assume typical pain locations: anatomical displacement by the gravid uterus changes the presentation of appendicitis, cholecystitis, and other conditions 2, 4, 5
• Do not perform procedures with patient supine: always use left lateral tilt to prevent vascular compression 3