Differential Diagnosis
- Single most likely diagnosis
- Placenta previa: This condition is characterized by the placenta covering or lying close to the internal cervical os, which can cause painless vaginal bleeding in the late third trimester. The patient's presentation of painless, moderate vaginal bleeding after the rupture of membranes, in the absence of uterine contractions, and with a history of previous uterine surgery (cesarean delivery), makes placenta previa a likely diagnosis. The fetal heart rate is also non-reassuring, which could be related to the bleeding.
- Other Likely diagnoses
- Abruptio placentae: Although this condition typically presents with painful vaginal bleeding and uterine tenderness due to placental abruption, a partial abruption could potentially present with less severe symptoms. However, the absence of abdominal pain and uterine tenderness makes this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Ruptured uterus: Given the patient's history of a previous cesarean delivery, there is a risk of uterine rupture, especially if she goes into labor. Although the patient is not currently in labor, this diagnosis should be considered due to the potential for catastrophic consequences.
- Ruptured vasa previa: This condition involves the rupture of fetal blood vessels that are exposed in the lower uterine segment or cervix, often associated with vaginal bleeding and fetal distress. The presence of moderate bleeding and a non-reassuring fetal heart rate makes this a critical diagnosis not to miss.
- Rare diagnoses
- Placenta accreta: This condition involves the abnormal adherence of the placenta to the uterine wall and can cause severe bleeding during delivery. While it is a possible diagnosis, especially given the patient's history of previous uterine surgery, it is less likely to present with bleeding before labor.
- Uterine dehiscence: Similar to uterine rupture, dehiscence (a partial tear) could occur, especially in a patient with a history of cesarean delivery. However, this would more likely be associated with labor or significant uterine contractions, which are not present in this case.