Perinatologist Corner - C.E.U/C.M.E. Modules
Preterm Labor and Preterm Premature Rupture of Membranes
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5. Speculum exam versus digital exam
The reason you want to defer the digital exam is so that you can do a sterile speculum exam . Be sure to avoid lubricant as it will confound the tests you want to collect. Most patients will have sufficient vaginal secretions so that a gentle exam will hopefully not be too uncomfortable without lubricant. You will usually need a large speculum with a long blade because of the redundancy of the vaginal folds in the third trimester. You need to check for ferning to be sure PPROM isn't part of the diagnosis. Remember, in the case of PPROM, “the examining finger winds the clock of infection”, so defer digital exam if your suspect ruptured membranes.
Management of PPROM
The latency period before birth after PPROM is usually inversely related to the gestational age. With the most immature fetuses you want to prolong that as much as possible, so “keep fingers out”! Visual inspection of the cervix may also help you. If you see a small circle of membranes or hair surrounded by cervix, you can be sure that the cervix is at least 4 cm dilated. (It could be 8 cm dilated too, so this would be the patient you would definitely want to check before transport!) If the cervix looks closed, it may be 0-3 cm dilated, but delivery will not be imminent. At this time you also should collect a vaginal and rectal specimen for group B strep culture, as well as another very helpful laboratory investigation, a fetal fibronectin . Other PPROM management tips are here.