Sorry to hear that your wifes doc thinks she could be developing PE. I'm glad you've found us. You'll get some great responses from people with lots of experience with PE.
The time frame for the two BP readings does not necessarily have to be exactly 6 hours apart...just more than one reading of 140/90 or higher at "least" 6 hours apart, to make sure it wasn't a fluke, or an adrenaline response. It coud be taken 2 weeks apart and still count. The weight gain is concerning, and we normally tell our gals to be on the lookout for 2lbs or more a week, or 6lbs weight gain in a month as being potentially concerning, assuming she's been eating normally. The doppler scans seem to be a decent screening tool.
A 24 hour urine catch would be important to accurately determine protein in the urine, which measures kidney function, and if the disease is having an impact on the kidneys. It does not predict severity though. Preeclampsia is not known to cause permanent kidney damage, and function generally returns to normal within a few weeks to a few months after baby is born.
An official diagnosis of preeclampsia comes with at least 2 BP readings of 140/90 or higher..at least a few hours apart AND 300mg of protein, or more in a 24 hour urine catch.
Aspirin has been shown to have some effect on those with blood clotting issues, which could be the case with poor placental blood flow. Though I usually see docs say to take a baby aspirin or low dose aspirin which is 81mg. But I'm not a doc, so you should take it in the dose your doc has prescribed. :-) It won't prevent preeclampsia or make it go away, but it may help get more blood flow to the placenta and buy time for the baby.
While some people are sensitive to salt and it can make them retain water, cutting out salt will not prevent preeclampsia, either. If it helps your wife with swelling and makes her more comfortable than it's probably ok to try and cut out those obvious salt ridden foods. 'Chesley's Hypertension Disorders in Pregnancy' says,"Sodium restriction is likely to aggravate the preexisting plasma volume contraction and is not routinely recommended for women with preeclampsia."
Reducing salt, or anything else we try will unfortunately not prevent preeclampsia, as it is a disease process originating of the placenta, that is thought to start at implantation. We all want and expect a great and normal pregnancy, and when something goes wrong we assume that we have done something wrong, or that we can do something to prevent it, but we haven't and we can't. It's a disorder that has no one cause, or known cause, and currently no cure other than delivery of the baby and placenta. There are some management tools out there (bedrest, bp meds, aspirin, etc, but nothing can prevent it. And even then, only certain management strategies work for any individual.
I'm putting in a link to our signs and symptoms page, and to a thread on doing kick counts below, as reference for you and your wife. Please look over the signs and symptoms and have your wife notify the doctor if she experiences any additional symptoms, if symptoms get worse, or if she feels "ill", or "off", or "not right". Of great concern are visual disturbances such as blurry vision, sparkles or flashes of light in the eyes, headaches that won't go away with tylenol, pain in the upper right abdomen area - under the ribs or breastbone, right arm, or right shoulderblade, and flu like symptoms. Those are symptoms that would warrant a trip directly to Labor and delivery at the hospital for further evaluation.
Preeclampsia is very unpredictable, and can move slowly or quickly, so keeping a close eye on things is very important. It sounds like her doctor is being proactive and watching out for her, so that's good.
If I were in her shoes I would fidn out exactly what those BP numbers were, I'd want a 24 hour urine catch, and a PIH or Preeclampsia blood panel (which it sounds like you might be getting). You've just had the doppler it appears, but a biophysical profile of baby would be something I'd be asking about to...it helps determine how baby is doing.
I would also be doing daily kick counts to make sure baby's movement is consistent. You can also buy digital BP monitors for home use at any drugstore, if she wanted to keep track of her Bps between appointments. If she has any concerns, or worries, she should call her doctor, day or night.
Hopefully it won't progress for her into preeclampsia, but it's great to be educated and prepared, in case it does develop. Please post back with questions and to let us know how she's doing. WHen is her next appointment?
http://www.preeclampsia.org/forum/viewtopic.php?t=5216 (kick counts, Laura's response)
http://www.preeclampsia.org/symptoms.asp (signs and symptoms page, main website]