ABORTION, SPONTANEOUS

ABORTION, SPONTANEOUS - Paul Lyons, MD
BASICS
DESCRIPTION
Abortion is the separation of products of conception from the uterus prior to the potential for fetal survival outside the uterus. Gestationally, the point at which potential fetal viability exists has been the subject of much legal and scientific debate, and definitions vary from state to state; however, a "potentially viable" fetus generally weighs at least 500 g and/or has a gestational age of >20 weeks.
• Spontaneous abortion
- Expulsion of all (complete abortion) or part (incomplete abortion) of the products of conception from the uterus prior to the 20th completed week of gestation. The placenta, either in whole or in part, can be retained and leads to continuing vaginal bleeding (sometimes profuse). Abortion is considered "threatened" when vaginal bleeding occurs early in pregnancy, with or without uterine contractions, but without dilatation of the cervix, rupture of the membranes, or expulsion of products of conception. Cervical dilatation, rupture of membranes, or expulsion of products in the presence of vaginal bleeding portends "inevitable abortion." Differentiation between threatened and inevitable abortion is desirable because management differs.
• Missed abortion
- Failed 1st-trimester pregnancy but without the usual signs and symptoms, such as bleeding or cramping
- Term blighted ovum replaced by anembryonic gestation; ultrasound findings of "empty sac"
• Induced abortion
- Evacuation of uterine contents or products of conception by either medical or surgical methodology
• Infected abortion
- Infection involving the products of conception and the maternal reproductive organs
• Septic abortion
- Dissemination of bacteria (and/or their toxins) into the maternal circulatory and organ system
• Habitual spontaneous abortion
- 3 or more consecutive spontaneous abortions
- Risk of another spontaneous abortion is ~25-30%, with 70% rate of successful pregnancy in subsequent pregnancy
• System(s) Affected: Endocrine/Metabolic; Reproductive
• Synonym(s): Miscarriage; Habitual abortion; Recurrent abortion
GENERAL PREVENTION
• Any vaginal bleeding in intrauterine pregnancy is abnormal and should be considered a "threatened" abortion. In reality, vaginal bleeding in early pregnancy is common (occurring in up to one-third of pregnancies), and often the bleeding source eludes diagnosis.
• All pregnant patients with first-trimester bleeding require evaluation for both threatened abortion and ectopic pregnancy
• In habitual abortion, the abortus should be sent for karyotyping. Explore other causes of habitual abortion with the couple to determine the best therapy.
• Special care and attention for the patient who has a subsequent pregnancy
EPIDEMIOLOGY
• Predominant age
- Increases with advancing age, especially after 35 years of age
- At age 40, the loss rate is twice that of age 20.
• Predominant sex: Female only
Prevalence
• ~10-15% of all clinically recognized pregnancies end in spontaneous abortion.
• Biochemical pregnancy manifests by the presence of -human chorionic gonadotropin (HCG) in the blood 7-10 days after conception. When both clinical and biochemical pregnancies are considered, >50% of conceptions are spontaneously aborted.
RISK FACTORS
Most cases of spontaneous abortion occur in patients without identifiable risk factors.
• Chromosomal abnormalities
• Luteal phase defect
• Leiomyomas
• Incompetent cervix
• Infections
• Antifetal antibodies
• Autoimmune disease
- Phospholipid syndrome
• Alloimmune disease (shared paternal antigens)
• Drugs, chemicals, noxious agents (alcohol, smoking, caffeine)
• X-irradiation
• Contraceptive intrauterine device
Genetics
~2/3 of 1st-trimester spontaneous abortions have significant chromosomal anomalies, with 1/2 of these being autosomal trisomies and the remainder being triploidy, tetraploidy, or 45X monosomies.
ETIOLOGY
See "Risk Factors".


DIAGNOSIS
SIGNS AND SYMPTOMS
• Consider a diagnosis of spontaneous abortion in a woman of childbearing age presenting with abnormal vaginal bleeding.
• In a previously diagnosed intrauterine pregnancy
- Vaginal bleeding
- Uterine cramping
- Cervical dilation
- Ruptured membranes
- Passage of nonviable products of conception
History
• In relation to the bleeding: Characteristics (amount, color, consistency, associated symptoms), onset (abrupt or gradual), duration, intensity/quantity, and exacerbating/precipitating factors
• In relation to prenatal course: Toxic or infectious exposures, family or personal history of genetic abnormalities, past history of ectopic pregnancy or spontaneous abortion
Physical Exam
• Fetal heart rate, uterine contractions
• Maternal heart rate, pulse, BP (including orthostatic changes), abdominal tenderness, pelvic examination for cervical dilation, blood, products of conception in os or vaginal vault, and uterine size and/or tenderness
TESTS
Lab
• Cultures: Gonorrhea and chlamydia
• CBC
• Rh type
• Urine HCG
• Serial serum -HCG measurements can assess viability of the pregnancy. Normal gestations have an approximate 67% increase over 2-day interval. Abnormal gestations do not rise appropriately, plateau, or decrease in level before the 8th week of gestation.
• Serum progesterone level
- >25 ng/mL: Consistent with normal intrauterine pregnancy; rarely seen in ectopic and/or nonviable pregnancy
- 5 ng/mL: Indicator of nonviable intrauterine gestation or ectopic pregnancy
Imaging
• Ultrasound examination to evaluate fetal viability and to rule out ectopic pregnancy (1C)
- Can be sensitive enough to confirm an intrauterine pregnancy in the 4th or 5th gestational week from last menstrual period
• Viable intrauterine pregnancy with fetal cardiac activity detected between 5 and 8 weeks from last menstrual period on transvaginal ultrasound
• Transvaginal ultrasound criteria for nonviable intrauterine gestation include 5-mm fetal pole without cardiac activity or 16-mm gestational sac without a fetal pole
Diagnostic Procedures/Surgery
Fetal heart tones can be auscultated with Doppler starting between 10 and 12 weeks' gestation from last menstrual period for a viable pregnancy.
Pathological Findings
Products of conception, Placental villi
DIFFERENTIAL DIAGNOSIS
• Ectopic pregnancy
- A potentially life-threatening complication, difficult to distinguish from threatened abortion. Transvaginal ultrasonography can identify intrauterine gestational sacs at 32 days' gestation (at serum HCG levels of 1,500-2,000 IU/L). The absence of transvaginal ultrasound evidence of an intrauterine gestation with serum HCG >2,000 IU/L should be considered an ectopic pregnancy until proven otherwise.
• Cervical polyps, neoplasias, and/or inflammatory conditions can cause vaginal bleeding.
- This bleeding is not usually associated with pain/cramping and is apparent on speculum exam.
• Hydatidiform mole pregnancy
- Usually ends in abortion prior to the 20th week of pregnancy
- Bloody discharge prior to abortion is common
- An intrauterine grapelike-appearing mass on ultrasound is diagnostic ("snow storm" appearance)
- Serum HCG is often high.
• Membranous dysmenorrhea
- Characterized by bleeding, cramps, and passage of endometrial casts; can mimic spontaneous abortion
- HCG is negative.
• HCG-secreting ovarian tumor
TREATMENT
GENERAL MEASURES
• Explore any 1st-trimester vaginal bleeding.
• Serial quantitative -HCG determination and progesterone assay
• Transvaginal ultrasonography
Diet
No special diet
Activity
• If appropriate, bed rest
• Probably no effect on eventual outcome
IV Fluids
Hemodynamically unstable patients may require IV fluids and/or blood products to maintain BP.
MEDICATION (DRUGS)
• Bleeding following uncomplicated dilatation and curettage (DC) or spontaneous abortion usually controlled by the following
- Carboprost (Hemabate): 250 ug IM
- Oxytocin (Pitocin): 10 U IM or IV
- Methylergonovine (Methergine): 0.2 mg IM
• Analgesics if needed
• RhoD immune globulin if mother is Rh negative
• Progesterone, if deficiency confirmed prior to pregnancy
• Precautions
- Do not give methylergonovine IV
- Refer to manufacturer's literature
Second Line
Rh-negative patients should be given Rh immune globulin following spontaneous abortion (1)[C]
SURGERY
• Inevitable or incomplete abortion: DC (usually suction)
• When completeness of an abortion is uncertain, a DC for retained products should be performed.
• Surgical management of incomplete abortion has been shown to improve outcomes compared to medical or expectant management (2)[A] (NNT = 3)
FOLLOW-UP
DISPOSITION
Outpatient or inpatient, depending on severity of symptoms (bleeding or pain)
Issues for Referral
Patients should be monitored for development of anxiety and/or depression for up to 1 year following spontaneous abortion. (1)[C]
PROGNOSIS
• If bleeding ceases, prognosis is excellent.
• Habitual abortion
- Prognosis is dependent on etiology.
- After 2 consecutive abortions, most couples want some investigation of the problem.
- After 3 spontaneous abortions, evaluation is usually indicated.
- Prognosis is still excellent, with up to 70% rate of success with subsequent pregnancy.
COMPLICATIONS
• Complications of DC include uterine perforation, infection, and bleeding.
• Retained products of conception
• Depression and feelings of guilt (patient may need education and reassurance that she did not cause the miscarriage)
PATIENT MONITORING
• Identification of products of conception within material expelled from the uterus or DC specimen
• If abortion is complete, observe the patient for further bleeding.
• Complete abortion usually indicated by decreased bleeding, closed cervix, intact or complete products of conception passed, and ultrasound findings of empty uterus and endometrial stripe. Follow HCG level weekly to zero to confirm complete evacuation of products of conception: May take 2 weeks. If levels plateau, suspect retained products of conception or ectopic pregnancy. Up to 6% of clinically diagnosed complete abortions are subsequently found to be ectopic pregnancies (3)[A].
REFERENCES
1. Greibel CP, Halvorsen J, Golemon TB, Day AA. Management of spontaneous abortion. Am Fam Physician 2005;72:1243-1250.
2. Sotiriadis A, Makrydimas G, Papatheodorou S, Ionnidis J. Expectant, medical or surgical management of first trimester miscarriage: a meta-analysis. Obstetrics and Gynecology. 2005;105:1104-1113.
3. Condous G, Khalid A, Bourne T. Do we need to follow up complete miscarriages with serum human chorionic gonadotropin levels? Br J Obstet Gynaecol. 2005;112(6):827-829.
4. Daily CA, Laurent SL, Nunley WC Jr. The prognostic value of serum progesterone and quantitative -human chorionic gonadotropin in early human pregnancy. Am J Obstet Gynecol. 1994;171:380-384.
5. Ohno M, Maeda T, Matsunobu A. A cytogenic study of spontaneous abortion with direct analysis of chorionic villi. Obstet Gynecol. 1991;77:394-398.
6. Palmieri A, Moore G, et al. Ectopic pregnancy. In: Hacker and Moore, eds. Essentials of Obstetrics and Gynecology, 3rd ed. Philadelphia, PA: Saunders, 1998.
7. Rempen A. Diagnosis and viability of early pregnancy with vaginal sonography. J Ultrasound Med. 1990;9:711-716.
8. Simpson JL. Fetal wastage. In: Gabbe S, Niebyl J, et al., eds. Obstetrics: Normal and Problem Pregnancies, 3rd ed. New York, NY: Churchill Livingstone, 1996.