Incomplete Abortion

Background:

The most common complication of pregnancy is spontaneous abortion, which occurs in an estimated 10-15% of pregnancies. Spontaneous abortions are categorized as threatened, inevitable, incomplete, complete, or missed. Spontaneous abortions can be classified further as sporadic or recurrent. By definition, an incomplete abortion is the partial expulsion of the products of conception before the 20th week of gestation.

Pathophysiology:
The timing of miscarriage suggests the pathophysiology of a spontaneous abortion. Genetic anomalies (eg, trisomies); hormonal abnormalities; and infectious, immunologic, and environmental factors usually result in first-trimester pregnancy loss. Anatomic factors usually are associated with second-trimester pregnancy loss.

Age:

  • Age and increased parity affect a woman's risk of miscarriage. In women younger than 20 years, miscarriage occurs in an estimated 12% of pregnancies. In women older than 20 years, miscarriage occurs in an estimated 26% of pregnancies.
  • Age primarily affects the oocyte. When oocytes from young women are used to create embryos for transfer to older recipients, implantation and pregnancy rates mimic those seen in younger women. The number of miscarriages and chromosomal anomalies decreases, suggesting that the uterus is not responsible for poor outcomes in women of advanced reproductive age.

CLINICAL PRESENTATION

History: Although classified as different entities, incomplete and inevitable miscarriages present in a similar clinical fashion and have similar treatment. An inevitable abortion involves continuous and progressive dilation of the cervix without expulsion of the products of conception before the 20th week of gestation.

  • The patient history should include the following:

    • Last menstrual period (LMP)
    • Estimated length of gestation
    • Ultrasound results, if previously performed
    • Bleeding (eg, degree, duration, presence/passage of tissue): Bleeding may be quantified roughly by the number of pads soaked per hour or day. An average pad absorbs approximately 20-30 mL of blood.
Physical Examination:
  • Vital signs should be within reference ranges unless infection is present or hemorrhage has caused hypovolemia.
  • The abdomen usually is soft and nontender.
  • On pelvic examination, products of conception may be partially present in the uterus, may protrude from the external os, or may be present in the vagina. Bleeding and cramping usually persist.
  • The cervix appears dilated and effaced.
  • Bimanual examination reveals an enlarged and soft uterus.

Causes:

  • Genetic factors Approximately 5% of spontaneous abortions occur because of genetic factors.

o        Trisomy chromosomes commonly are encountered, with trisomy 16 accounting for approximately a third of chromosomal abnormalities in early pregnancy.

  • Anatomic factors: Congenital or acquired anatomic factors are reported to occur in 10-15% of women who have recurrent spontaneous abortions.

o        Congenital anatomic lesions include müllerian duct anomalies (eg, septate uterus, diethylstilbestrol [DES]-related anomalies). Müllerian duct lesions usually are found in second-trimester pregnancy loss.

o        Anomalies of the uterine artery with compromised endometrial blood flow are congenital.

o        Acquired lesions include intrauterine adhesions (ie, synechiae), leiomyoma, and endometriosis.

  • Endocrine factors

    • Endocrine factors potentially contribute to recurrent abortion in 10-20% of cases.

    • Luteal phase insufficiency (ie, abnormal corpus luteum function with insufficient progesterone production) is implicated as the most common endocrine abnormality contributing to spontaneous abortion.

    • Hypothyroidism, hypoprolactinemia, poor diabetic control, and polycystic ovarian syndrome are contributive factors in pregnancy loss.

  • Infectious factors

    • Presumed infectious etiology may be found in 5% of cases.

    • Bacterial, viral, parasitic, fungal, and zoonotic infections are associated with recurrent spontaneous abortion.

  • Immunologic factors

    • Immunologic factors may contribute in up to 60% of recurrent spontaneous abortions.

    • Both the developing embryo and the trophoblast may be considered immunologically foreign to the maternal immune system.

    • Antiphospholipid antibody syndrome generally is responsible for more second-trimester pregnancy losses than first-trimester losses.

  • Miscellaneous factors

    • Miscellaneous factors may account for up to 3% of recurrent spontaneous abortions.

    • Other contributing factors implicated in sporadic and recurrent spontaneous abortions include environment, drugs, placental abnormalities, medical illnesses, and male-related causes.

DIFFERENTIAL DIAGNOSIS

Abortion, Complete
Abortion, Complications
Abortion, Inevitable
Abortion, Missed
Abortion, Septic
Abortion, Threatened
Pregnancy, Ectopic

Other Problems to be Considered:

Molar pregnancy

 

 

LABORATORY STUDIES

 

  • Complete blood count with differential

  • Blood type and Rh

  • Qualitative and quantitative human chorionic gonadotropin-beta

Imaging Studies:

  • Ultrasound is useful in evaluation of incomplete abortion.

  • An incomplete abortion may demonstrate a variety of sonographic findings as follows:

    • The gestational sac may be misshaped or collapsed, or it may be intact, containing a nonliving embryo. In addition, an irregular complex mass within the endometrial or endocervical canal may be present.

    • Echogenic material or debris within the endometrial canal may represent retained products of conception or clotted blood.

    • First-trimester molar pregnancies may simulate an incomplete abortion, with echogenic material within the endometrial cavity that has no characteristic vesicles or cysts.

    • Intrauterine fluid collections may represent pseudogestational sacs found in ectopic pregnancies.

Procedures:

  • Transabdominal ultrasound of the pelvis provides an overall view of the pelvic structures. A full bladder is required as a sonographic window.

  • Endovaginal ultrasound gives a detailed view of the endometrium of the uterus, ovaries, adnexa, and cul-de-sac. An empty bladder is required for optimal imaging.

TREATMENT

Prehospital Care:

  • Maintain routine universal precautions in view of potentially heavy vaginal bleeding.

  • Encourage the patient to bring any passed tissue to the hospital for evaluation.

Emergency Department Care:

  • Treat all patients with vaginal bleeding of any etiology as follows:

    • Determine hemodynamic stability and treat instability.

    • Determine pregnancy status (qualitative and quantitative).

    • Pelvic ultrasonography may be useful in clinically classifying spontaneous abortion. Determination of Rh status and hematocrit usually is indicated.

  • In most cases, vacuum or suction curettage can be performed in the outpatient setting.

  • The treatment goal is evacuation of the uterus to prevent complications such as further hemorrhage and/or infection.

MEDICATION

The goals of pharmacotherapy are to prevent complications and reduce morbidity.

Drug Category: Immune globulins -- These agents suppress immune response and antibody formation.

Rho(D) IMMUNOGLOBULIN:

>13 weeks GA: 300 mcg IM  

 

FOLLOW-UP

Further Inpatient Care:

  • If bleeding cannot be controlled , transfer the patient to the operating room (OR) for examination. Anesthetize the patient and perform uterine evacuation.

  • After curettage, observe the patient for 4-6 hours. If stable, the patient can be discharged.

  • Administer the standard dose of Rho(D) immune globulin (ie, 300 mcg) to women who are Rh-negative to prevent Rh immunization.

  • Send products of conception for pathologic evaluation.

Complications:

  • Potential complications include septic abortion and hypovolemic or septic shock.

  • Preexisting anemia may make patients more susceptible to hypovolemic shock.

Prognosis:

  • The prognosis for a successful pregnancy depends upon the etiology of previous spontaneous abortions.

    • Correction of an endocrine abnormality in women with recurrent abortion has the best prognosis for a successful pregnancy (>90%).

    • In women with an unknown etiology of prior pregnancy loss, the probability of achieving successful pregnancies is 40-80%.

    • The live-birth rate after documentation of fetal cardiac activity at 5-6 weeks of gestation in women with 2 or more unexplained spontaneous abortions is approximately 77%.

Patient Education:

  • Advise patients to return upon occurrence of symptoms such as the following:

    • Profuse vaginal bleeding

    • Severe pelvic pain

    • Temperature above 38°C (100.4°F)

  • Patients may experience intermittent menstrual-like flow and cramps during the following week. The next menstrual period usually occurs in 4-5 weeks.

  • Patients can resume regular activities when able but should refrain from intercourse and douching for approximately 2 weeks.

MISCELLANEOUS

Medical Pitfalls:

  • Ectopic pregnancy

    • Endometrial shedding, which clinically simulates miscarriage, may occur with an ectopic pregnancy. This misdiagnosis is the greatest potential pitfall.

    • An empty uterus on ultrasound may represent an ectopic pregnancy.