Back pain, Nausea, and Diarrhea in Third Trimester

Q & A: I'm 34 weeks, and I'm having back pain, nausea, and diarrhea. Please comment. Yours is a very general question, but I chose to answer it to touch on the thinking we obstetricians run through our minds with these types of complaints.

From the "Terminal Miseries of Pregnancy" archives, back pain can be nothing more than ligament pain--uterosacral ligaments stretching as the uterus gets bigger. This is usually low down and central--and quite harmless. If the pain is down low but just to the right or left of the midline, this can be sacroiliac pain, which is where joints of the back of the pelvic ring are pressing together--also quite harmless. Remember, you're trying to cram two people into the space of one.

But there are more serious considerations, too.

Middle back pain on either side of the spine could possibly indicate a kidney infection, which pregnant women are VERY prone to. A simple urinalysis and urine culture can give that answer. Undiagnosed, this "pyelonephritis" can lead to sepsis.

If the pain is central but to the right, I will generally want to get liver function tests and a blood count to rule out liver complications of pregnancy, like HELLP syndrome, a complication of Pregnancy Induced Hypertension (PIH), which can be life threatening. This is important to rule out, because it's considered an obstetrical emergency.

The nausea adds a bit of confusion, because this could represent more liver worries, or it could just be a flu--especially with the associated diarrhea. But plain ol' pain can cause nausea as well.

Then there's always an unusual presentation of preterm labor. The transition between false labor and the real thing can often be accompanied by nausea, and at 34 weeks would of course be considered undesirable .

In this simple answer I've covered about 5 chapters of obstetrics, which is kind of ridiculous, but these symptoms are problematic enough to warrant a call or visit to your doctor, because harmless things can feel very bad, but very bad things can present as the harmless things. And that's what prenatal care is all about--to get you to the end of your pregnancy without the sneaky disasters.