Missed Miscarriage: Symptoms, Causes & Treatment

A missed miscarriage occurs when an embryo or fetus stops developing in the uterus, but the pregnancy tissue is not expelled right away. In some cases, the tissue may remain in the uterus for weeks. This type of miscarriage most often happens between the 8th and 12th week of pregnancy.

Missed miscarriages are usually related to chromosomal abnormalities or problems with fetal development and are rarely caused by anything the pregnant person did or did not do. They often cause few or no symptoms and may only be suspected when pregnancy symptoms begin to lessen.

Treatment is managed by an OB‑GYN or midwife and typically involves safely emptying the uterus. Emotional support is also important, and many people find it helpful to talk with a mental health professional or counselor afterward.

Common symptoms

The main symptoms of a missed miscarriage are:

• Brown or reddish vaginal discharge

• No increase in belly size or uterine size

• A decrease or disappearance of pregnancy symptoms, such as breast tenderness or nausea

These signs differ from those of a spontaneous miscarriage, which can cause vaginal bleeding, severe abdominal pain, fever, or chills, among other symptoms.

Other typical pregnancy symptoms, like tiredness or needing to urinate more often, may also lessen or disappear. However, a missed miscarriage often causes no symptoms and is most commonly detected during routine prenatal visits.

Confirming a diagnosis

The diagnosis of a missed miscarriage is usually made by an OB-GYN using an ultrasound, often a transvaginal ultrasound during early pregnancy. It is confirmed when no fetal heartbeat is detected.

In very early pregnancy, serial beta-hCG blood tests may be used together with repeat ultrasounds for further evaluation.

Because a missed miscarriage often causes no symptoms, it is frequently found during a routine prenatal ultrasound.

Possible causes

According to the American College of Obstetricians and Gynecologists (ACOG), about half of early pregnancy losses are caused by fetal chromosomal abnormalities.

Other possible causes and risk factors for missed miscarriage include:

• Fetal malformations
• Advanced maternal age
• Previous miscarriage
• Smoking, alcohol, drug use, or use of some medications
• Untreated thyroid disease
• Obesity or uncontrolled diabetes
• Infections
• Problems with the cervix

In general, one missed miscarriage does not usually increase the risk of miscarriage in a future pregnancy, unless there are underlying risk factors.

Treatment options

Treatment for a missed miscarriage should be guided by an OB-GYN and usually involves removing the pregnancy tissue from the uterus.

The main treatments for a missed miscarriage are:

1. Expectant management

According to  ACOG, expectant management for a missed miscarriage in the first trimester involves allowing the body to naturally pass the pregnancy tissue. In many cases, this happens without medication or surgery.

During this time, the OB-GYN monitors the pregnancy with follow-up care, which may include an ultrasound or, in some cases, serial beta-hCG blood tests to confirm that the pregnancy tissue has passed completely.

If the pregnancy tissue does not pass naturally or complications develop, the doctor may recommend medication or a procedure to remove the remaining tissue from the uterus.

2. Medication

Medication may be recommended by an OB-GYN to help the uterus pass the pregnancy tissue. According to ACOG, mifepristone followed by misoprostol should be considered for the medical management of early pregnancy loss when available.

Mifepristone helps block progesterone, a hormone needed to maintain pregnancy, while misoprostol causes uterine contractions and helps soften the cervix. Misoprostol may be given vaginally as tablets and may also be used to prepare the cervix before a dilation and curettage (D&C) procedure.

3. Manual vacuum aspiration

Manual vacuum aspiration is a procedure performed by an OB-GYN for missed miscarriage up to the 12th week of pregnancy.

This procedure uses a syringe that creates suction and a soft, flexible plastic cannula with no sharp tip to aspirate the contents of the uterus.

4. Dilation and curettage

Dilation and curettage is a surgical procedure performed by an OB-GYN to scrape and empty the uterus in cases of missed miscarriage in pregnancies over 12 weeks.

Possible complications

If a missed miscarriage is not properly managed, retained pregnancy tissue can lead to bleeding or infection, which may become life-threatening.

In addition, when treatment involves curettage, complications such as perforation of the uterine cavity, organ injury, bleeding, and scarring in the uterus may occur.