Differential Diagnosis for 16-Week Pregnant Woman with Abdominal, Hip, and Back Pain

• Single most likely diagnosis:
  • Urinary tract infection (UTI) or pyelonephritis: The symptoms of pain in the lower right abdomen, right hip, and mid right back, along with a high heart rate and nausea, could be indicative of a UTI or pyelonephritis, which are common during pregnancy due to physiological changes that predispose to urinary stasis and infection.
• Other Likely diagnoses:
  • Kidney stone: The acute onset of severe pain in the flank or lower abdomen, radiating to the groin, along with nausea and a high heart rate, is consistent with a kidney stone. Pregnancy increases the risk of kidney stones due to increased urine calcium excretion and urinary stasis.
  • Appendicitis: Although less common during the second trimester, appendicitis can occur and presents with abdominal pain, nausea, and sometimes a high heart rate. The pain typically starts near the navel and then moves to the lower right abdomen.
  • Round ligament pain: As the uterus expands, the round ligaments stretch, causing pain in the lower abdomen and groin. However, this typically does not cause a high heart rate or severe nausea.
• Do Not Miss diagnoses:
  • Ectopic pregnancy: Although less likely at 16 weeks of gestation, an ectopic pregnancy that has advanced can cause severe abdominal pain, nausea, and a high heart rate due to internal bleeding. This is a medical emergency.
  • Placental abruption: This condition, where the placenta separates from the uterus, can cause severe abdominal pain, nausea, and a high heart rate. It is a serious condition that can endanger both the mother and the fetus.
  • Ovarian torsion: This rare condition can cause severe, sudden pain in the lower abdomen and is more common during pregnancy due to the displacement of the ovaries by the expanding uterus.
• Rare diagnoses:
  • Pancreatitis: Inflammation of the pancreas can cause severe abdominal pain that radiates to the back, nausea, and a high heart rate. It is less common in pregnancy but can be associated with hypertriglyceridemia, which can occur in pregnancy.
  • Adrenal crisis: Although rare, an adrenal crisis can cause severe abdominal pain, nausea, and a high heart rate. This would be more likely in someone with a known history of adrenal insufficiency.