Differential Diagnosis
- Single most likely diagnosis
- Ectopic pregnancy: This diagnosis is the most likely due to the patient's presentation of vaginal spotting, increasing lower abdominal pain, a positive home pregnancy test, and significant abdominal tenderness, particularly with the cervical os being open (fingertip size). The patient's symptoms of dizziness upon standing and diaphoresis also suggest hemodynamic instability, which can occur with a ruptured ectopic pregnancy.
- Other Likely diagnoses
- Inevitable abortion: Given the patient's history of vaginal spotting, abdominal pain, and an open cervical os, an inevitable abortion is a possible diagnosis. However, the severity of abdominal pain and the patient's hemodynamic instability make ectopic pregnancy more likely.
- Acute appendicitis: Although the patient presents with abdominal tenderness most severe in the right lower quadrant, which is suggestive of appendicitis, the combination of a positive pregnancy test, vaginal spotting, and an open cervical os makes this diagnosis less likely but still possible.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Ectopic pregnancy (already discussed): It's crucial to reiterate the importance of not missing this diagnosis due to its high mortality rate if left untreated.
- Ruptured ovarian cyst: Although not initially considered, a ruptured ovarian cyst could present with similar symptoms, including acute abdominal pain and hemodynamic instability. It's a diagnosis that requires immediate attention.
- Rare diagnoses
- Urinary tract infection: While a urinary tract infection could cause abdominal pain and discomfort, it does not typically cause the combination of severe abdominal tenderness, vaginal spotting, and hemodynamic instability seen in this patient.
- Pelvic inflammatory disease: PID could present with lower abdominal pain, but the acute onset, severity of pain, and presence of a positive pregnancy test make it less likely in this scenario.