‘Incarcerated uterus’ is one of those pregnancy-related terms that lands squarely in the iykyk (if you know, you know) category. For the rest of the world, our first reaction to the foreign phrase goes something like ‘a uterus might be what?’ There’s a big reason you’ve likely never heard of the term (unless you’ve been told it applies specifically to you): incarcerated uterus impacts only about 1 in 3,000-10,000 pregnancies. Contrast that with a term you probably do know, preeclampsia, which affects about 1 in 15-20 pregnancies.
But here’s the kicker: an incarcerated uterus can be a medical emergency just like preeclampsia (though in a very different way). The good news? Incarcerated uterus is very treatable and pregnancy tends to progress normally after it’s resolved. Here’s what to know.
What is an incarcerated uterus?
According to Up to Date, a reference website for physicians, “The uterus is retroverted (and/or retroflexed) in up to 20 percent of pregnancies [2]. As the uterus enlarges during pregnancy, the retroverted/retroflexed fundus normally rises from the hollow of the sacrum to an anterior ventral position, spontaneously correcting any retroposition. In rare cases, however, the fundus becomes wedged below the sacral promontory, where it continues to enlarge normally for a period of time [3]. The cervix becomes displaced cephalad against or above the symphysis pubis and pushes against the urethra and bladder, which can interfere with normal voiding.”
Did your eyes glaze over reading that? What does any of that mean? Let’s break it down. In up to 20% of pregnancies, the uterus tips backward as it grows (in a previous article for us, author Stacey Sumereau described it as “my uterus could beat everyone else’s at the limbo.”) At this point, the uterus is retroverted (tilted back, as if leaning) or retroflexed (more pronounced flexing backward, as if it’s doing the limbo). There’s a great graphic in this short video to help you picture this.
Having a retroverted or retroflexed uterus during pregnancy is fairly common…
About 15-20% of pregnancies (depending on your source) will have some degree of retroversion or retroflexion in the first trimester, but the vast majority will resolve on their own [1]. That’s why you could have 15 in 100 pregnant women with a retroverted or retroflexed uterus early on in pregnancy, but only 1 in 3,000-10,000 women will have an incarcerated uterus.
About 15-20% of pregnancies (depending on your source) will have some degree of retroversion or retroflexion in the first trimester, but the vast majority will resolve on their own
…The problem happens when the retroversion or retroflexion doesn’t resolve on its own
But sometimes the uterus doesn’t return to a normal, forward-facing position on its own. In those cases, the top of the uterus becomes wedged below, trapped in your pelvis. A trapped uterus cannot move up out of the pelvis and into the abdomen to expand normally as the baby grows. It pushes the cervix forward and upward. (Remember that the cervix is where the uterus opens, similar to a turtleneck being pulled over a head, so that the baby can come out.) When this occurs, if a doctor tried to check you for cervical dilation (as happens later during a pregnancy and during labor), they might not be able to feel the cervix at all.
The displaced cervix then causes pressure on your bladder and/or urethra (the tube that drains your urine from the bladder to the outside of your body) such that you have great difficulty urinating and/or pooping, or are unable to do one or the other at all. If by week 14 of pregnancy your uterus hasn’t moved up and out of the pelvis, it’s considered trapped or incarcerated. The likelihood of your uterus moving into a normal position on its own is very low, and medical intervention will likely be required.
If by week 14 of pregnancy your uterus hasn’t moved up and out of the pelvis, it’s considered trapped or incarcerated. The likelihood of your uterus moving into a normal position on its own is very low, and medical intervention will likely be required
What causes an incarcerated uterus?
When it comes to rare conditions, medical research tends to be more limited, and this is the case with an incarcerated uterus, too. Research into IC mostly consists of case reports, meaning a medical report about one or a few people. Additionally, much of the research is quite old (the first case report in this source is from 1909!) [2].
What do we know? There’s no known specific cause of an incarcerated uterus. According to this 2022 case report, certain women may be predisposed to having an incarcerated uterus [1]. These include women who have a retroverted uterus when they are not pregnant, as well as those with a history of “endometriosis, pelvic adhesion, pelvic inflammatory disease, previous abdominal or pelvic surgery, leiomyomas [fibroids], uterine anomalies, uterine prolapse, deep sacral concavity with an overlying sacral promontory, [or] uterine incarceration in previous pregnancy.”
What are the signs of an incarcerated uterus?
The majority of women with an incarcerated uterus have urinary symptoms, and they tend to be worst in the morning, after the woman has not peed for multiple, perhaps many, hours. Symptoms could include feeling the need to pee often (but not being able to get much out), peeing only small amounts at a time, taking a long time to pee (it may take several hours to pee after waking up) and/or pain with urination. The most severe urinary symptom, and the one that tends to send women to the emergency room, is a complete inability to urinate.
Constipation, up to a complete inability to poop, is another symptom. Pelvic, back, and vaginal pain are also possible [1].
How do you diagnose an incarcerated uterus?
While it may sound oddly specific, multiple sources report that an incarcerated uterus is likely to be diagnosed around week 17 of pregnancy, because at this point the uterus has grown to the point where it’s causing problems that can’t be ignored [1][2].
A doctor may suspect an incarcerated uterus based on symptoms plus known pregnancy. If they try to perform a pelvic exam, as mentioned above, they may have difficulty feeling for your cervix because it’s been displaced up and forward. Formal diagnosis requires abdominal ultrasound and/or MRI. Of note, incarcerated uterus “when not suspected, [incarcerated uterus] can be misinterpreted for ectopic pregnancy, abdominal pregnancy, placenta previa, or fetal malpresentation” [1]. Incarcerated uterus may also be misdiagnosed as early labor, twisted ovaries, a kidney issue, worsening fibroids, or a urinary tract infection [2].
How do you fix it?
In a best case, least painful scenario, when a urinary catheter is inserted and the bladder is decompressed, the uterus may return to its proper place on its own. If this is not the case, the doctor (and it may require multiple doctors to try) will attempt to manually reposition your uterus. If this sounds painful, that’s because it is. You should receive IV and oral medication to “take the edge off,” but you will likely be awake for the procedure.
Know that it may take multiple attempts, and in between each one you’ll likely be asked to pull your knees towards your chest. After a manual manipulation that appears to be successful, you’ll have an ultrasound to confirm, and may stay in the hospital overnight with a urinary catheter. Sometimes women are sent home with a catheter in place. You may also have a pessary placed to help keep your uterus in the proper position. It may take several tries to get the right size pessary, and unfortunately, pessary placement can be uncomfortable, too [3].
You might wonder whether the uterus can slip out of the proper position in the future, and you’d be right. It can. How often this occurs isn’t known, but if it does happen, manual manipulation may be required again. In some cases, more invasive measures to manipulate the uterus may be necessary, and those are referenced here and here.
What happens if you don’t fix it?
In an unknown percentage of cases, a woman will experience miscarriage due to her incarcerated uterus. Life-threatening complications include kidney failure, bladder rupture, uterine necrosis and sepsis.
If you suspect you have an incarcerated uterus, what should you do?
Because an incarcerated uterus is so rare, doctors–be they OB/GYNs or Emergency Department physicians– may not be thinking of it, or may not take it seriously, as occurred to this woman, whose OB/GYN first suggested an outpatient urology or neurology referral for her urinary symptoms. This was unfortunately author Stacey Sumereau’s initial experience as well. However (to give you hope!), a personal friend of mine was fortunate that the doctor in the Emergency Department where she presented for inability to urinate recognized right away what was likely happening.
Since an incarcerated uterus can become a medical emergency, it’s important to know (and receive prompt treatment) if you have it. Hopefully, your OB/GYN or whatever doctor you see will take your symptoms seriously and investigate quickly. If that’s not your experience, specifics on how to advocate for yourself if you think you might have an incarcerated uterus but your doctor is unfamiliar with (or unconcerned about) it are here.
