Imagine drawing two lines on your abdomen through your belly button, one top to bottom and one left to right. You divide your abdomen into four areas, or quadrants: upper right, upper left, lower right, and lower left. So upper right quadrant pain is on your right side above the belly button. Sometimes it feels closer to center, sometimes it refers upward along the nerves to the right shoulder or bra band area, and sometimes it goes through to the back. But it does not go to the left side unless you happen to have mirror image organs (organs on the opposite side of your body), which is pretty rare. (There are reasons for upper left quadrant pain as well, but they are not associated with preeclampsia or HELLP.)
There are a lot of possible reasons for upper right side pain ranging from harmless but annoying to life threatening. The most dangerous is liver inflammation from HELLP syndrome. HELLP is a fast moving condition that develops over the course of hours to at most a couple days and requires delivery soon after appearing. Most women describe this pain as severe, or if it starts mild it gets severe quickly. Some describe it like really bad heartburn, only it is not heartburn. HELLP pain does not improve with treatment like pain meds, heartburn meds, hot packs, stretching, changing position, etc. If your pain is severe and not improving, or if you are worried and just want to be sure, call your doctor or go to the hospital for evaluation.
If your pain is mild, improves with treatment, or if your blood work comes back good, you can move on to other possible causes, and there are a lot of them. Gall bladder pain is very similar to the pain of HELLP, and also often flares up in pregnancy. Heartburn is very common in pregnancy and can be pretty uncomfortable. Round ligament pain, baby pushing up against the ribs, or pulled muscle can also be possible causes.
New onset of vomiting in later pregnancy can also be a symptom of HELLP. You could have the vomiting without/before the pain, or the pain without the vomiting. But if you have both together, it is even more important to get checked. (If you have hyperemesis and have been vomiting all the way through, it can be harder to know if it is just your usual hyperemesis or something more.)
Like other symptoms, vomiting can have other causes. You could have a stomach virus or food poisoning. Sometimes you may just have a single episode of vomiting due to hormone shifts or baby pushing against your stomach. But new vomiting should still be reported even if it is not related to HELLP. It can lead to dehydration, which in turn can lead to preterm labor.
If you are experiencing URQ pain, you can try a pain medication like Tylenol as approved by your doctor. If you notice a pattern to the pain, like if it is worse after eating or eating certain foods but then improves later, you may want to talk to your doctor about gall bladder or heartburn. Pregnancy changes the way we carry ourselves and puts extra strain on our muscles. If you think your pain could be a pulled muscle or round ligament pain from the growing uterus, try a hot or cold pack and some stretching. If you can feel baby pushing up against your ribs, changing positions could encourage baby to move as well.
If you have tried everything and your pain is only getting worse, or if you are just worried and want the reassurance, you can always call your doctor or go in. A simple blood test can confirm or rule out HELLP. If it is HELLP, you will be delivering soon. If it comes back normal, you can discuss other causes like gall bladder as well as possibly stronger pain or heartburn medication, depending on what they suspect the cause is.