Differential Diagnosis
- Single most likely diagnosis
- Preterm labor: The patient is experiencing intermittent contractions that have progressed in frequency and duration, and she is found to be 3 cm dilated on speculum examination. The fact that the contractions began after intercourse and the patient has a history of a urinary tract infection caused by group B Streptococcus, which increases the risk of preterm labor, supports this diagnosis.
- Other Likely diagnoses
- False labor (Braxton Hicks contractions): Although the patient's contractions have increased in frequency and she is dilated, the possibility of false labor cannot be entirely ruled out, especially since the contractions may have been triggered by intercourse.
- Dehydration: The patient's attempt to alleviate the contractions by drinking water suggests that dehydration could be a contributing factor, although it is less likely given that the contractions persisted.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Placental abruption: Although the patient reports no vaginal bleeding, placental abruption can sometimes present without overt bleeding, and it is crucial to consider this diagnosis due to its potential severity and impact on both maternal and fetal health.
- Uterine rupture: Given the patient's history of a previous term vaginal delivery, the risk of uterine rupture is low but not negligible, especially if there were any complications or interventions during the previous delivery that could have weakened the uterine wall.
- Chorioamnionitis: The patient's history of a group B Streptococcus urinary tract infection increases her risk for chorioamnionitis, an infection of the fetal membranes, which can lead to severe consequences for both the mother and the fetus if not promptly diagnosed and treated.
- Rare diagnoses
- Cervical insufficiency: This condition, where the cervix begins to dilate prematurely due to weakness, could be a contributing factor to the patient's current state, especially if she has a history of cervical trauma or previous cervical surgery.
- Ureteral colic or kidney stone: Although less likely, the pain from ureteral colic or a kidney stone could potentially be mistaken for contractions, especially if the patient has a history of urinary tract issues, as suggested by her previous group B Streptococcus infection.