Differential Diagnosis

• Single most likely diagnosis:
  • Incomplete Abortion or Miscarriage: The patient had confirmed ovulation, took progesterone, and then experienced a light and unusual period, which could indicate a failed pregnancy. The severe cramps and passing of a huge clot further support this possibility.
• Other Likely diagnoses:
  • Anovulatory Bleeding: Although ovulation was confirmed, the unusual bleeding pattern and the fact that the patient was taking progesterone could suggest that the hormonal balance was disrupted, leading to irregular bleeding.
  • Progesterone Withdrawal Bleeding: The patient stopped taking progesterone on Oct 16, and the bleeding started on Oct 21, which could be a withdrawal bleed caused by the sudden drop in progesterone levels.
  • Irregular Uterine Bleeding: The patient's symptoms, including light and watery bleeding, could be indicative of irregular uterine bleeding, possibly related to hormonal changes or other uterine factors.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Ectopic Pregnancy: Although the ultrasound showed mild thickness in the left fallopian tube, it is essential to rule out an ectopic pregnancy, especially given the patient's symptoms of severe cramps and unusual bleeding.
  • Molar Pregnancy: Although rare, a molar pregnancy could cause irregular bleeding and should be considered, especially if the patient's symptoms persist or worsen.
• Rare diagnoses:
  • Threatened Abortion with a Viable Pregnancy: The patient's symptoms could indicate a threatened abortion, but the negative UPT and the ultrasound findings make this less likely.
  • Uterine Pathology (e.g., Polyps, Fibroids): The patient's unusual bleeding pattern and the ultrasound finding of a 14mm endometrial thickness could suggest underlying uterine pathology, although this is less likely given the patient's age and symptoms.