Today I review, link to, and exceerpt from The American College Of Gynecology‘s Early Pregnancy Loss, Practice Bulletin, PB Number 200, November 2018. [Full-Text HTML].
All that follows is from the above resource.
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Number 200 (Replaces Practice Bulletin Number 150, May 2015. Reaffirmed 2021)
INTERIM UPDATE: This Practice Bulletin is updated as highlighted to reflect recent evidence regarding the use of mifepristone combined with misoprostol for medical management of early pregnancy loss. This Practice Bulletin also includes limited, focused updates to align with Practice Bulletin No. 181, Prevention of Rh D Alloimmunization.
ABSTRACT: Early pregnancy loss, or loss of an intrauterine pregnancy within the first trimester, is encountered commonly in clinical practice. Obstetricians and gynecologists should understand the use of various diagnostic tools to differentiate between viable and nonviable pregnancies and offer the full range of therapeutic options to patients, including expectant, medical, and surgical management. The purpose of this Practice Bulletin is to review diagnostic approaches and describe options for the management of early pregnancy loss.
Background
Definition
Early pregnancy loss is defined as a nonviable, intrauterine pregnancy with either an empty gestational sac or a gestational sac containing an embryo or fetus without fetal heart activity within the first 12 6/7 weeks of gestation 1. In the first trimester, the terms miscarriage, spontaneous abortion, and early pregnancy loss are used interchangeably, and there is no consensus on terminology in the literature. However, early pregnancy loss is the term that will be used in this Practice Bulletin.
Incidence
Early pregnancy loss is common, occurring in 10% of all clinically recognized pregnancies 2 3 4. Approximately 80% of all cases of pregnancy loss occur within the first trimester 2 3.
Etiology and Risk Factors
Approximately 50% of all cases of early pregnancy loss are due to fetal chromosomal abnormalities 5 6. The most common risk factors identified among women who have experienced early pregnancy loss are advanced maternal age and a prior early pregnancy loss 7 8. The frequency of clinically recognized early pregnancy loss for women aged 20–30 years is 9–17%, and this rate increases sharply from 20% at age 35 years to 40% at age 40 years and 80% at age 45 years 7. Discussion of the many risk factors thought to be associated with early pregnancy loss is beyond the scope of this document and is covered in more detail in other publications 6 7.
Clinical Considerations and Recommendations
What findings can be used to confirm a diagnosis of early pregnancy loss?
Common symptoms of early pregnancy loss, such as vaginal bleeding and uterine cramping, also are common in normal gestation, ectopic pregnancy, and molar pregnancy. Before initiating treatment, it is important to distinguish early pregnancy loss from other early pregnancy complications. Treatment of an early pregnancy loss before confirmed diagnosis can have detrimental consequences, including interruption of a normal pregnancy, pregnancy complications, or birth defects 9. Therefore, a thorough evaluation is needed to make a definitive diagnosis. In combination with a thorough medical history and physical examination, ultrasonography and serum β-hCG testing can be helpful in making a highly certain diagnosis.
Ultrasonography, if available, is the preferred modality to verify the presence of a viable intrauterine gestation. In some instances, making a diagnosis of early pregnancy loss is fairly straightforward and requires limited testing or imaging. For example, early pregnancy loss can be diagnosed with certainty in a woman with an ultrasound-documented intrauterine pregnancy who subsequently presents with reported significant vaginal bleeding and an empty uterus on ultrasound examination. In other instances, the diagnosis of early pregnancy loss is not as clear. Depending on the specific clinical circumstances and how much diagnostic certainty the patient desires, a single serum β-hCG test or ultrasound examination may not be sufficient to confirm the diagnosis of early pregnancy loss.
The use of ultrasound criteria to confirm the diagnosis of early pregnancy loss was initially reported in the early 1990s, shortly after vaginal ultrasonography became widely available. Based on these early studies, a crown–rump length (CRL) of 5 mm without cardiac activity or an empty gestational sac measuring 16 mm in mean gestational sac diameter have been used as diagnostic criteria to confirm early pregnancy loss 10 11. Recently, two large prospective studies have been used to challenge these cutoffs. In the first study, 1,060 women with intrauterine pregnancies of uncertain viability were followed up to weeks 11–14 of gestation 12. In this group of women, 55.4% received a diagnosis of nonviable gestation during the observation period. A CRL cutoff of 5 mm was associated with an 8.3% false-positive rate for early pregnancy loss. A CRL cutoff of 5.3 mm was required to achieve a false-positive rate of 0% in this study 12. Similarly, the authors reported a 4.4% false-positive rate for early pregnancy loss when using a mean gestational sac diameter cutoff of 16 mm. A mean gestational sac diameter cutoff of 21 mm (without an embryo and with or without a yolk sac) on the first ultrasound examination was required to achieve 100% specificity for early pregnancy loss. In a second study of 359 women from the first study group, the authors concluded that growth rates for the gestational sac (mean gestational sac diameter) and the embryo (CRL) could not predict viability accurately 13. However, the authors concluded that if a gestational sac was empty on initial scan, the absence of a visible yolk sac or embryo on a second scan performed 7 days or more after the first scan was always associated with pregnancy loss 13.
Based on these studies, the Society of Radiologists in Ultrasound Multispecialty Panel on Early First Trimester Diagnosis of Miscarriage and Exclusion of a Viable Intrauterine Pregnancy created guidelines that are considerably more conservative than past recommendations and also have stricter cutoffs than the studies on which they are based 14 Table 1. The authors of the guidelines report that the stricter cutoffs are needed to account for interobserver variability; however, this already was accounted for in the original study through its use of multiple ultrasonographers 12 15. Other important limitations in the development of these guidelines should be recognized. For example, there were few cases at or near the measurements ultimately identified as decision boundaries. Similarly, the time between observing a gestational sac and expecting to see a yolk sac or embryo was increased from 7 days or more in the clinical study 13 to 14 days in the guidelines 14. The basis of this recommendation is unclear.
Obstetrician–gynecologists caring for women experiencing possible early pregnancy loss should consider other clinical factors when interpreting the Society of Radiologists in Ultrasound guidelines, including the woman’s desire to continue the pregnancy; her willingness to postpone intervention to achieve 100% certainty of pregnancy loss; and the potential consequences of waiting for intervention, including unwanted spontaneous passage of pregnancy tissue, the need for an unscheduled visit or procedure, and patient anxiety. It is important to include the patient in the diagnostic process and to individualize these guidelines to patient circumstances.
Criteria that are considered suggestive, but not diagnostic, of early pregnancy loss are listed in Table 1 14. Slow fetal heart rate (less than 100 beats per minute at 5–7 weeks of gestation) 16 and subchorionic hemorrhage also have been shown to be associated with early pregnancy loss but should not be used to make a definitive diagnosis 17. These findings warrant further evaluation in 7–10 days 14.
In cases in which an intrauterine gestation cannot be identified with reasonable certainty, serial serum β-hCG measurements and ultrasound examinations may be required before treatment to rule out the possibility of an ectopic pregnancy. A detailed description of the recommended approach to ectopic pregnancy diagnosis and management is available in Practice Bulletin Number 193, Tubal Ectopic Pregnancy 18.
What are the management options for early pregnancy loss?
Accepted treatment options for early pregnancy loss include expectant management, medical treatment, or surgical evacuation. Although these options differ significantly in process, all have been shown to be reasonably effective and accepted by patients. In women without medical complications or symptoms requiring urgent surgical evacuation, treatment plans can safely accommodate patient treatment preferences. There is no evidence that any approach results in different long-term outcomes. Patients should be counseled about the risks and benefits of each option. The following discussion applies to symptomatic and asymptomatic patients.
For details on each of these management options, please see the Practice Bulletin.
