Differential Diagnosis for Vaginal Bleeding and Lower Abdominal Pain
The patient presents with vaginal bleeding, lower abdominal pain, and a positive pregnancy test without an intrauterine pregnancy visualized on ultrasound. The following differential diagnoses are considered:
Single Most Likely Diagnosis
- Ectopic Pregnancy: This is the most likely diagnosis given the patient's symptoms, positive β-hCG level, and the absence of an intrauterine pregnancy on transvaginal ultrasound. The patient's history of irregular menstrual periods and the presence of vaginal bleeding and abdominal pain further support this diagnosis.
Other Likely Diagnoses
- Spontaneous Abortion: Although the cervical os is closed, and there's no active bleeding, a spontaneous abortion (miscarriage) could still be considered, especially if the pregnancy was non-viable. However, the lack of visualization of an intrauterine pregnancy makes this less likely.
- Ovarian Cyst Rupture or Torsion: These conditions can cause acute abdominal pain and could potentially lead to vaginal bleeding, although they are less directly linked to the positive pregnancy test.
Do Not Miss Diagnoses
- Ruptured Ectopic Pregnancy: This is a medical emergency that requires immediate surgical intervention. Even though the patient is currently stable, the risk of rupture, especially with a rising β-hCG level and abdominal pain, necessitates close monitoring and possibly urgent intervention.
- Hemorrhagic Ovarian Cyst: While less common, a hemorrhagic ovarian cyst could cause significant bleeding and pain, and its diagnosis is crucial for appropriate management.
Rare Diagnoses
- Molar Pregnancy: Although rare, a molar pregnancy could present with vaginal bleeding and a positive β-hCG level. However, the absence of an intrauterine mass on ultrasound makes this less likely.
- Pregnancy in a Rudimentary Horn: This is an extremely rare condition where a pregnancy develops in a rudimentary horn of a unicornuate uterus. It can present similarly to an ectopic pregnancy and is a life-threatening condition if ruptured.