Incomplete Miscarriage

Excerpt

The gestational ages and classifications professional organizations use to categorize miscarriages differ in terminology. Currently, the gestational age divisions for various pregnancy loss terms, particularly internationally, are not well defined. Traditionally in the US, however, a "miscarriage," sometimes termed a "spontaneous abortion," is defined as a spontaneous loss of a nonviable intrauterine pregnancy within the first 20 weeks of gestation; a fetal demise after 20 weeks of gestation is generally termed a "stillbirth" or "intrauterine fetal demise." An "early miscarriage" or "early pregnancy loss" commonly refers to a loss occurring before 10 to 13 weeks of gestation. The term "incomplete miscarriage," also known as an "incomplete pregnancy loss" or "incomplete spontaneous abortion," is generally defined as a specific subtype of miscarriage in which the products of conception (POC) have not been completely expelled from the uterus.

The term "inevitable miscarriage" was sometimes used by clinicians to characterize a miscarriage in which the cervical os is open, and symptoms of vaginal bleeding and pelvic cramping are present; however, no POC have been expelled. In an incomplete pregnancy loss, though the cervical os is also open and vaginal bleeding and cramping are also present, there is partial, but not yet complete, expulsion of the POC. Differentiating these two traditional subtypes can be difficult, and they have no significant prognostic or management differences. For this reason, many clinicians prefer not to use the term "inevitable miscarriage."

The overall incidence of spontaneous pregnancy loss is 10% to 15% in clinically recognized pregnancies. The incidence of incomplete pregnancy loss has not been well studied; however, the incidence of incomplete second-trimester abortions following surgical and medical modalities is 1% and 8%, respectively. The etiology of any spontaneous pregnancy loss is often unknown, but up to 50% of cases are thought to be due to fetal chromosomal abnormalities.

An incomplete miscarriage is typically diagnosed with a history, physical exam, and pelvic ultrasound; at early gestational ages, a β-human chorionic gonadotropin (β-hCG) level may also be indicated to make a proper diagnosis. Patients with an incomplete miscarriage typically present with vaginal bleeding, lower abdominopelvic pain or cramping, and an open cervical os before 20 weeks of gestation. Incomplete miscarriage should be differentiated from a threatened miscarriage, which refers to a pregnancy complicated by vaginal bleeding with a closed cervical os that is found to be viable on ultrasound, and a complete miscarriage in which all the POC have been expelled from the uterus, and the cervix has closed again. Other differential diagnoses should also be excluded (eg, ectopic pregnancy, molar pregnancy, and nonobstetric causes of bleeding).

Management options include expectant, medical, and surgical treatments, although expectant management alone is often highly successful. Complications, such as sepsis from retained POC, hemorrhagic shock, or cervical shock, are rare but can be severe. The prognosis for these patients is generally good, with proper diagnosis, close obstetric follow-up, and patient education.