Differential Diagnosis for Severe Abdominal Pain in a 5-Month Pregnant Woman

Single Most Likely Diagnosis

• Preterm Labor: This is a common cause of severe abdominal pain in pregnant women, especially at 5 months. The pain is often accompanied by regular uterine contractions that lead to cervical dilation before 37 weeks of gestation.

Other Likely Diagnoses

• Placental Abruption: This condition involves the premature separation of the placenta from the uterus, which can cause severe abdominal pain, vaginal bleeding, and fetal distress.
• Urinary Tract Infection (UTI) or Pyelonephritis: Pregnant women are at higher risk for UTIs due to physiological changes. Severe abdominal pain, especially if accompanied by fever, dysuria, or flank pain, could indicate pyelonephritis.
• Gallbladder Disease: Pregnancy increases the risk of gallstones due to bile stasis and increased cholesterol secretion. Severe abdominal pain, especially after eating fatty foods, could indicate cholecystitis or a gallstone obstructing the bile duct.
• Appendicitis: Although less common in the second trimester, appendicitis can occur and presents with severe abdominal pain, initially diffuse or around the navel, then localizing to the right lower quadrant.

Do Not Miss Diagnoses

• Ectopic Pregnancy: Although less likely at 5 months, a heterotopic pregnancy (where one embryo implants in the uterus and another outside) can occur, especially in women undergoing fertility treatments. Severe abdominal pain with a missed period or irregular bleeding is a red flag.
• Uterine Rupture: This is a rare but life-threatening condition, more common in women with a previous uterine scar (e.g., from a cesarean section). Severe abdominal pain with vaginal bleeding and fetal distress necessitates immediate medical attention.
• Ovarian Torsion: This condition involves the twisting of an ovary, cutting off its blood supply. It can cause severe, sudden onset abdominal pain and is a surgical emergency.

Rare Diagnoses

• Hepatic Hemangioma or Adenoma Rupture: These are benign liver tumors that can rupture during pregnancy due to hormonal changes, leading to severe abdominal pain and potentially life-threatening bleeding.
• Splenic Artery Aneurysm Rupture: This is a rare condition where an aneurysm of the splenic artery ruptures, causing severe abdominal pain and potentially severe bleeding.
• Pancreatitis: Inflammation of the pancreas can cause severe abdominal pain radiating to the back, nausea, and vomiting. It is less common in pregnancy but can be associated with gallstones or hypertriglyceridemia.