Differential Diagnosis for 27-year-old with IUD in situ and Waves of Pain

• Single most likely diagnosis:
  • IUD Perforation or Malposition: The patient's complaint of the IUD feeling like it has moved, combined with waves of pain, suggests that the IUD might not be in its correct position. This could be due to perforation of the uterus or malposition of the device, which are known complications of IUD insertion.
• Other Likely diagnoses:
  • IUD Expulsion: The sensation of the IUD moving could also indicate that it is being expelled from the uterus, which can cause pain.
  • Pelvic Inflammatory Disease (PID): Although less directly related to the sensation of the IUD moving, PID is a known complication of IUD use, especially in the first 20 days after insertion. It can cause significant pelvic pain.
  • Ovarian Cyst or Torsion: These conditions can cause severe, intermittent pain and might be considered, especially if the pain is localized and severe.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Ectopic Pregnancy: Although the patient has an IUD, the failure rate is not zero, and ectopic pregnancy is a life-threatening condition that must be ruled out in any woman of childbearing age presenting with abdominal pain.
  • Ruptured Ovarian Cyst: This condition can lead to severe hemorrhage and requires immediate surgical intervention.
  • Uterine Rupture: Although rare, especially in a non-pregnant woman, uterine rupture is a catastrophic event that could occur if the IUD has perforated the uterus.
• Rare diagnoses:
  • Endometriosis: While endometriosis can cause chronic pelvic pain, it's less likely to cause acute, severe pain related to the sensation of an IUD moving.
  • Adhesions or Bowel Obstruction: These are rare complications that could potentially cause pain but are less directly related to the IUD's perceived movement.