What is Incomplete Miscarriage?
There’s some confusion globally about how to define different types of pregnancy loss, based on how far along the pregnancy is. However, in the US, we generally use the term “miscarriage,” or sometimes “spontaneous abortion,” for a pregnancy that ends on its own within the first 20 weeks. We refer to a loss of a fetus after 20 weeks of pregnancy as a “stillbirth” or “intrauterine fetal demise”. A miscarriage that happens extremely early, before 10 to 13 weeks, is often referred to as an “early miscarriage” or “early pregnancy loss”. A situation where not all of what formed the pregnancy (called the “products of conception”) has left the uterus is generally defined as an “incomplete miscarriage”, “incomplete pregnancy loss” or an “incomplete spontaneous abortion”.
Sometimes, medical professionals would use the term “inevitable miscarriage” to describe a situation where a miscarriage seems likely due to symptoms such as the cervix opening, vaginal bleeding and cramping, but the products of conception have not yet been expelled. This term can be hard to differentiate from an incomplete miscarriage because they are quite similar, and for this reason, the term “inevitable miscarriage” is often avoided.
On the whole, about 10% to 15% of pregnancies that we know about result in miscarriage. The exact rate of incomplete pregnancy loss is less clear, but we know that such loss resulting from second-trimester abortions is rare. The causes for miscarriages are often not found, but as many as half of them might be due to issues with the fetus’s chromosomes.
Doctors usually diagnose incomplete miscarriages through medical history, physical exam, and ultrasound; in early stages of pregnancy, a hormone level test may also be necessary. Symptoms of an incomplete miscarriage often include vaginal bleeding, lower belly/pelvic pain or cramping, and an open cervix before 20 weeks of pregnancy. Doctors need to distinguish this condition from a threatened miscarriage, where there is vaginal bleeding but the cervix is closed and the pregnancy is still viable. This also needs to be differentiated from a complete miscarriage, where all the products of conception have left the uterus, and the cervix has closed again. Other conditions that may cause similar symptoms should also be ruled out such as an ectopic pregnancy, molar pregnancy, and non-pregnancy-related causes of bleeding.
Treatment options for an incomplete miscarriage range from watchful waiting, to medication, to surgery. More often than not, the body successfully resolves the situation on its own. Severe complications, like a severe infection from retained products of conception, severe bleeding, or shock caused by cervix damage, are not common but can be serious. However, the overall prognosis for patients with an incomplete miscarriage is generally good, given proper diagnosis, careful monitoring by an obstetrician, and patient education.
What Causes Incomplete Miscarriage?
The exact reason why some of the pregnancy tissue isn’t fully expelled from the body during a miscarriage is not known. This might happen during a spontaneous miscarriage (one that happens naturally) or an induced abortion (when medical treatment is used to end a pregnancy). In the past, all miscarriages were considered to be incomplete until a procedure called a uterine curettage confirmed that all pregnancy tissue had been expelled.
Several factors can lead to a miscarriage that may present with or without symptoms. In about half of the cases, an early miscarriage happens because of problems with the baby’s chromosomes (the structures in cells that contain genes). Other factors that increase the risk of miscarriage include the mother’s age, health conditions (like diabetes, high blood pressure, kidney disease, thyroid disorders, celiac disease, lupus, and antiphospholipid syndrome), being significantly underweight or overweight, problems with the structure of the uterus, exposure to harmful substances (like drugs, alcohol, or radiation), infections (like parvovirus B19, syphilis, or Listeria), and physical trauma. Birth defects and genetic syndromes can also lead to miscarriage.
Induced abortions can also occasionally result in not all the pregnancy tissue being expelled, similar to a spontaneous miscarriage. Abortions that are performed in unsafe conditions might raise the risk of this happening. The World Health Organization (WHO) defines an unsafe abortion as one performed by individuals who lack the necessary skills or in an environment that doesn’t meet basic medical standards, or both. Other definitions also include the use of dangerous methods, such as taking harmful substances, abdominal injuries, and the use of tools inside the uterus.
Risk Factors and Frequency for Incomplete Miscarriage
Incomplete pregnancy loss, by definition, happens in women who are less than 20 weeks into their pregnancy. When all types of miscarriages are looked at together, around 10 to 15% of pregnancies that have been confirmed by medical professionals end in miscarriage. However, it’s not clear exactly how often incomplete miscarriages occur. In one study, it was found that after one month, about 34% of pregnancies with no developing embryo hadn’t fully passed all pregnancy tissue. Also, in 26% of pregnancies where the embryo had stopped developing, all pregnancy tissue hadn’t been completely passed after one month.
Signs and Symptoms of Incomplete Miscarriage
When it comes to medical history, it’s important for doctors to understand your personal conditions, as well as your reproductive history, such as if you’ve had miscarriages, any uterine abnormalities, and when your last menstrual period occurred. This helps them identify risk factors and other factors that might affect treatment. Doctors may also review any previous ultrasound results to confirm details such as your predicted due date.
Doctors also need to know about any symptoms you might be experiencing, like cramping, pelvic pain, or vaginal bleeding. Information about the onset of these symptoms, the amount of bleeding, the size of any clots, and whether or not you’ve passed any tissue is also important. For example, if you’ve been passing clots or tissue, this could suggest an incomplete pregnancy loss, especially if the bleeding is heavier or lasts longer than a normal period. Severe menstrual-like cramping that doesn’t go away is another potential sign of incomplete pregnancy loss. Even your level of anxiety can affect the amount of pain you experience.
During a physical examination, your doctor will first check your vital signs and look for signs of lower blood volume, such as a rapid heart rate or low blood pressure, which might suggest heavy bleeding. A fever could indicate an infection and the possibility of a septic miscarriage, which would require urgent professional care.
A pelvic examination may reveal an incomplete pregnancy loss if the cervix is open and there are products of conception (POC) in the vagina or protruding from the cervix. If the doctor observes pus-like discharge and uterine tenderness, this could indicate an infection. The doctor will also check the vagina and vulva area to rule out any other causes of bleeding, such as injury or bleeding polyps.
Normally, an abdominal exam doesn’t reveal much. But if the examination shows signs of irritation in the abdominal lining, such as rebound tenderness, guarding, or rigidity, then an urgent consultation with obstetric or general surgery specialists may be necessary.
Testing for Incomplete Miscarriage
If you’re suspecting a pregnancy loss, the best way to confirm it is through a specific type of ultrasound known as a transvaginal ultrasound. This tool can show if the pregnancy contents have been partly expelled or if there are unusual or dense materials in the womb or cervix. If the ultrasound finds evidence of a mass or thickening within the womb, or if blood flow can be detected in this area, it could mean that some pregnancy contents are still present. Additionally, if the hormone related to pregnancy (β-hCG) continues to show up in tests, but the pregnancy is not viable according to imaging, this also suggests a partial pregnancy loss.
If no prior ultrasound shows a viable pregnancy, a nonviable pregnancy can be confirmed with 100% certainty if either a fetus larger than 7 mm is found without a heartbeat, or if no embryo is found within a sac larger than 25 mm. However, experts don’t agree on the features from a transvaginal ultrasound that definitely indicate a completed miscarriage. In most cases, the absence of a pregnancy sac and a womb thickness less than 30 mm is generally used to identify a miscarriage.
When it comes to assisting in your care, laboratory tests play a critical role. One of these, the β-human chorionic gonadotropin (β-hCG) test, can provide important information when used alongside an ultrasound, especially if you’re unsure of your last menstrual period or if the location of the pregnancy is unknown.
Typically, a pregnancy should be visible on an ultrasound around the 5th or 6th week. But if the age of the pregnancy isn’t known, the β-hCG test can help interpret the ultrasound results. Previously, if the β-hCG level was between 1,000 to 2,000 mIU/mL and a pregnancy wasn’t visible on an ultrasound, it generally meant a pregnancy outside the uterus (ectopic pregnancy) or a pregnancy loss. But some recent studies suggest that the β-hCG level should be over 3,500 mIU/mL for these conditions to be more accurately determined.
For a pregnancy of unknown location, where an ultrasound doesn’t clearly show a pregnancy in the uterus or outside, you should monitor the β-hCG levels over several days. A slow rise or fall in β-hCG levels before they level off around the 10th week of pregnancy could indicate a pregnancy that’s failing or abnormal. It’s important to remember that pregnancies outside the uterus might have β-hCG levels that first decrease, then increase, and can even rupture while the β-hCG levels are decreasing.
Remember, a β-hCG level alone doesn’t provide a definitive diagnosis and should be interpreted within the bigger picture of your overall clinical situation to prevent a misdiagnosis. If the diagnosis remains unclear for patients who are stable, it’s often recommended to perform repeat ultrasound imaging and serial β-hCG tests, typically every 48 hours.
Due to the significant bleeding often seen in patients, it’s also important to check for sudden blood loss anemia. In addition, your blood type and Rh(D) status should be checked as part of the initial tests, as you may need a transfusion or treatment to prevent immune response against Rh(D)-positive red blood cells.
Any pregnancy tissue that’s removed or expelled should be sent for a detailed tissue examination to confirm the pregnancy loss and check for conditions like a molar pregnancy, where abnormal tissue grows in the uterus. If it’s suspected that the patient has a severe body response (sepsis) to an incomplete miscarriage, additional laboratory evaluation is indicated, including a complete blood count, a comprehensive look at how the body’s chemistry is doing, checking for high levels of lactic acid in the blood, along with testing for bacteria in the blood, urine, and cervix.
Treatment Options for Incomplete Miscarriage
When a woman experiences an early pregnancy loss, she has three management options available: expectant (waiting for the body to naturally miscarry), medical (using medication to lead to miscarriage), or surgical (removing the pregnancy tissue surgically). Each of these options has its pros and cons, and the choice depends on the individual’s situation and preference.
Expectant management involves carefully tracking the patient’s condition to allow for a natural miscarriage to occur if no harmful symptoms appear. This approach has a high success rate, with roughly half of women experiencing complete natural miscarriage within a week. However, it might take longer for the pregnancy tissue (POC) to be naturally expelled.
With medical management, a medication called misoprostol is used to cause the body to expel the pregnancy tissue. This medication is either injected vaginally, taken sublingually (under the tongue), or consumed orally, depending on the advice of medical professionals. Patients should expect heavy bleeding and cramping, symptoms that typically improve after the POC is expelled. It’s important to note that some minor bleeding can continue for several weeks. If bleeding becomes heavy (soiling two pads per hour) or symptoms such as dizziness or fever appear, medical care should be sought.
Surgical management is needed when other options have failed or when the patient is not stable or at high risk for bleeding. This approach involves the removal of pregnancy tissue via procedures like uterine aspiration or suction curettage, which can be done in an operating room or an outpatient setting.
Patients of all management types need follow-up care to ensure the miscarriage process has safely and completely occurred. In some cases, Rh(D)-immune globulin is administered to Rh-negative patients, to prevent harmful immune reactions; however, this practice varies across countries and institutions.
In short, when managing early pregnancy loss, your healthcare provider will work with you to understand all options and their pros and cons, and help you choose the best approach based on your personal situation and preferences.
What else can Incomplete Miscarriage be?
When a pregnant woman experiences vaginal bleeding, doctors consider several possible causes. These include:
- Incomplete miscarriage
- Ectopic pregnancy (when a fertilized egg implants outside the uterus)
- Complete miscarriage
- Threatened miscarriage (a potential sign of an upcoming miscarriage)
- Subchorionic hemorrhage or hematoma (bleeding and blood clots beneath the placenta or fetal membranes)
- Molar pregnancy (an abnormal form of pregnancy)
- Nonobstetric bleeding, which could be due to injury to the vagina or cervix, cancer, or polyps
- Infection of the vagina or cervix, such as yeast infection, bacterial vaginosis, or a specific type of sexually transmitted disease called Chlamydia trachomatis
- Septic abortion (a severe infection of the uterus following a miscarriage or abortion)
- Hemorrhagic shock (a life-threatening condition caused by massive blood loss)
- Cervical shock (a rare complication of severe cervical injury)
- Uterine rupture (a tear in the wall of the uterus, which is a serious emergency)
What to expect with Incomplete Miscarriage
Patients who experience an incomplete miscarriage generally have a good chance of recovery with patient or “expectant” management. This approach allows the body to naturally expel the remaining pregnancy tissue, with about 90% of patients accomplishing this within 4 weeks. Medical management, which involves using medications to help the process, also yields similar good results.
Surgery, viewed as a “definitive treatment”, is another management option and again, probabilities are positive. Having an incomplete miscarriage, no matter the treatment approach, does not impact future fertility. In fact, it’s safe to try to get pregnant again right after experiencing a miscarriage.
Research studies suggest that trying to conceive in the first 3 months following a miscarriage actually results in higher live birth rates, compared to those who wait longer to try to get pregnant again.
Possible Complications When Diagnosed with Incomplete Miscarriage
The risks of experiencing complications are roughly the same across treatment approaches for incomplete pregnancy loss during the initial trimester. These complications may include retaining parts of the pregnancy conception, heavy bleeding that might need a blood transfusion, a blood clotting disorder, inflammation of the uterus lining and a body-wide illness. The likelihood of an infection is higher in low-income countries compared to high-income ones; this could be a mixed infection caused by leftover pregnancy tissue and genital bacteria. Even though death is a possible outcome, it is extremely rare, especially for uncomplicated miscarriages before the 12th week.
After a medical treatment, patients may feel nauseous, vomit or have diarrhea. Meanwhile, surgical treatment could cause puncture in the uterus and reactions to anesthesia. Some evidence also indicates that surgical treatment could enhance the risk of developing uterine adhesions, particularly after sharp curettage surgery or multiple procedures.
When dealing with losses during the second trimester, the risks of complications increase. This could include heavy bleeding, infections, a cut in the cervix and a serious lung clot. Uterine rupture, while extremely rare, has been reported with medical management of second trimester losses.
One unique but rare complication specific to incomplete miscarriages is cervical shock. This occurs when parts of the pregnancy conception in the cervix can cause excessive vagus nerve stimulation, resulting in slow heart rate and low blood pressure. This does not improve with intravenous fluids. In this case, the remainder of the conception should be removed immediately from the cervix, which can typically be done using ring forceps or similar tools during a pelvic exam. In many cases, it’s not necessary to move the patient to an operating room or sedate them, as this could delay treatment.
Common Complications:
- Retaining parts of the pregnancy conception
- Heavy bleeding requiring a blood transfusion
- Blood clotting disorder
- Inflammation of the uterus lining
- Body-wide illness
- Increased risk of infections in low-income countries
- Possible mixed infection due to leftover pregnancy tissue and genital bacteria
- Nausea, vomiting and diarrhea after medical treatment
- Puncture in the uterus and anesthesia reactions after surgery
Preventing Incomplete Miscarriage
If you notice any bleeding during your pregnancy, don’t ignore it. It’s important you get medical attention quickly, as bleeding during pregnancy can lead to serious health risks, or in worst cases, death. If a healthcare professional diagnoses you with what’s known as an ‘incomplete pregnancy loss,’ they will explain the different ways in which this condition can be managed. Balancing the pros and cons of these options with your health professional will aid you in picking the best course of treatment.
After you’ve received the relevant treatment, you should be prepared to continue experiencing bleeding for about 1 to 2 weeks, or maybe even longer. Particularly, if you and your healthcare team decided to adopt the ‘expectant management’ approach. This approach basically means waiting for things to optimize naturally without medical intervention.
Your healthcare provider will also teach you what signs to look out for that would warrant an immediate return to the hospital. For instance, if you start bleeding heavily stocking up 1 to 2 pads in an hour for two straight hours, or if over-the-counter pain relievers cannot contain the pain, or if you develop a fever.
For follow-ups, they will schedule check-ups to ensure that all pregnancy-related tissues (referred to as ‘POC’) have been expelled from the uterus. This is generally done through a pelvic ultrasound. But if that’s not possible, a drop in your β-hCG levels (a hormone your body produces during pregnancy) by 50% after 2 days or by 87% after 7 days could serve as indication.
You should also be comforted to know that a straightforward pregnancy loss doesn’t interfere with your ability to get pregnant in the future. Moreover, you’re likely to start ovulating (release of egg) again within the first cycle after the pregnancy tissue has been expelled. Therefore, if you don’t want to get pregnant again straight away, you should consider using contraception.
