Early Pregnancy Loss in Emergency Medicine Workup

Updated: Nov 05, 2018
  • Author: Slava V Gaufberg, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Laboratory Studies

Laboratory studies may include the following:

  • Qualitative urine pregnancy test, to confirm pregnancy

  • Complete blood count with differential

  • Blood type and Rh factor: Blood type must be documented for every pregnant patient with vaginal bleeding. If Rh-negative, administer RhoGAM to prevent hemolytic disease of the newborn in this pregnancy and subsequent pregnancies.

  • Hemoglobin and hematocrit: These studies establish baseline and detect hemorrhagic anemia.

  • Factor XIII and fibrinogen, if indicated per history

Quantitative human chorionic gonadotropin-beta

The discriminatory level of beta-hCG is approximately 1500 mIU/mL above which there should be sonographic evidence of early intrauterine pregnancy, if present. Beta-hCG level rises at rate of doubling approximately every 48 hours for 85% of intrauterine pregnancies. The remaining 15% may rise with a different slope or be plateaued.

A higher likelihood of ectopic pregnancy or subsequent miscarriage exists if hCG blood level is lower than predicted by estimated gestational age (GA) based on the last menstrual period (LMP).

The possibility of molar pregnancy exists if beta-hCG is very high and out of proportion to predicted gestational age. This pregnancy occurs with or without evidence of early normal trophoblast growth and function, as indicated by adequately rising beta-hCG levels.


Imaging Studies

Ultrasonography is used widely and is the imaging study of choice. Advantages of ultrasonography include bedside use, availability, low cost, and noninvasiveness. Disadvantages include operator dependency.

Ultrasonography aids identification of retained products of conception, fetal demise, incomplete miscarriage, ectopic pregnancy, or empty uterus; therefore, it provides a clinically relevant classification of early pregnancy loss. Following spontaneous first-trimester complete miscarriage, endovaginal ultrasonography has been found to be 81% sensitive and 94% specific in detection of retained products of conception. [14] Ultrasonography is the most accurate diagnostic modality in the confirmation of a viable pregnancy during the first trimester. [14]

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

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

Indications for ultrasonography in the ED include abdominal or pelvic pain, vaginal bleeding, persistently open cervical os, adnexal mass or fullness, cervical motion tenderness, discrepancy between uterine size and last menstrual period (LMP), and discrepancy between expected and measured beta-hCG levels.

Seymour et al sought to determine whether a physical examination was necessary in pregnant patients presenting with pregnancy-related complaints and a viable pregnancy as shown on bedside ultrasonography. Fifty patients were enrolled in the study; each patient received a pelvic examination before ultrasonography. In all patients, findings on physical examination were the same as those found by ultrasonography. Bedside ultrasonography provided all the information needed to determine immediate management of these patients. Few findings on pelvic examination are likely to alter this management. [15]

The findings of the study by Seymour et al also complement the findings of Close et al, who found there was very little inter-examiner reliability of the bimanual pelvic examination for identifying masses or uterine size, [16] which are principally the physical findings being evaluated in the early pregnant patient in the ED setting. Taken together, these studies highlight the impact that advances in technology has on the practice of medicine, but, at this time, the findings are unlikely to change current practice.

A high-resolution vaginal ultrasound probe can detect pregnancy at 3-4 weeks' gestation and fetal heart activity at 5 and a half weeks. The presence of fetal cardiac activity in women with bleeding in early pregnancy has been noted to have a sensitivity of 97% and a specificity of 98% for fetal survival to the 20th week of pregnancy. [14]

Fetal studies are limited in the first trimester due to small fetal size. Ultrasonography usually provides information in 3 major areas: location of pregnancy, pregnancy size, and absence or presence of fetal cardiac activity.

An apparently empty uterus revealed by ultrasonography in a pregnant woman (ie, positive beta-hCG findings, LMP within last 20 wk) suggests a very early pregnancy (ie, < 3 wk GA), a completed miscarriage, or an ectopic pregnancy. (See Bedside Ultrasonography, First-Trimester Pregnancy.)

Sonographic signs suggestive of a nonviable pregnancy include the following:

  • Irregular gestational sac (ie, gestational sac >25-mm mean sac diameter [MSD] on transabdominal sonogram; >16-mm MSD on endovaginal sonogram without a detectable embryo)

  • Nonliving embryo (embryo without a heartbeat)

  • Presence of abnormal hyperechoic material within the uterine cavity, as depicted in the sonogram below

    This endovaginal longitudinal view demonstrates fl This endovaginal longitudinal view demonstrates fluid within the uterus (Ut). Echogenic debris also is present within the endometrial cavity. This image shows a large pseudogestational sac of an ectopic pregnancy.

The Society of Radiologists in Ultrasound indicate the following findings are diagnostic of early pregnancy loss [1] :

  • A fetal crown–rump length of 7 mm or greater and absent heartbeat
  • A mean sac diameter of 25 mm or greater without an embryo
  • Absence of an embryo with a heartbeat 2 weeks or longer after a scan that showed a gestational sac without a yolk sac
  • Absence of an embryo with a heartbeat 11 days or longer after a scan that showed a gestational sac with a yolk sac

Consider the sonographic diagnosis of early pregnancy failure in relationship to developmental stage. Note the following:

  • Subclinical or preclinical loss: This occurs within the first 2 weeks after conception. Sonographic evidence of pregnancy does not exist at this stage.

  • Loss at 5-6 weeks: Loss at this stage is based upon gestational sac characteristics. Abnormal gestational sac size is the most reliable indicator of abnormal outcome. Gestational sacs should be 5-mm mean sac diameter (MSD) by the fifth gestational week. An abnormally large gestational sac, as determined by high-frequency endovaginal sonography (HFEVS), is observed when the MSD is more than 8 mm without a demonstrable yolk sac or is more than 16 mm without a demonstrable embryo.

  • Loss at 7-8 weeks: Sonographic evidence is based upon demonstration of an abnormal embryo or gestational sac.

  • Loss at 9-12 weeks: Sonographic diagnosis of embryonic demise is usually made on demonstration of an abnormal fetus. Sonographic evidence of a fetus lacking cardiac activity is the most specific indicator of embryonic demise. This is depicted in the sonogram below.

    This endovaginal ultrasonogram reveals an irregula This endovaginal ultrasonogram reveals an irregular gestational sac with an amorphic fetal pole. No fetal cardiac activity was noted. This image represents a missed miscarriage or fetal demise.

Caution is advised in the diagnosis of embryonic demise. Determination of whether the viewed structure is the embryo is critical, as no other morphologically recognizable structures, other than a heartbeat, exist at this stage of development. The embryo must be scanned thoroughly for evidence of a heartbeat. Note the following:

  • Most recommendations call for 2 independent examiners to view the embryo, either concurrent with the ED visit or at follow-up.

  • Most sonographers recommend repeating the scan within 3-7 days to determine if normal development is occurring.

  • On follow-up, a falling beta-human chorionic gonadotropin (hCG) level, as well as abnormal fetal development, confirms embryonic demise.

Sonography can identify presence of a subchorionic hematoma or hemorrhage (ie, bleeding between the endometrium and the gestational sac) and may include the following features:

  • A subchorionic hemorrhage is the most commonly identified source of first-trimester bleeding, appearing on sonography as a crescent-shaped hypoechoic area next to the gestational sac.

  • Subchorionic hemorrhage encompasses a spectrum of sonographic findings. Subchorionic fluid can be classified in relation to gestational sac size and length of gestation. Subchorionic bleeding is present when pulsation of the subchorionic fluid is noted.

  • Size of the subchorionic hemorrhage should be taken into consideration, as greater size relates to an increased risk of spontaneous miscarriage. A large subchorionic hematoma (ie, surrounding greater than 50% of the gestational sac) is a poor prognostic indicator for the pregnancy outcome. A subchorionic hemorrhage is depicted below.

    This endovaginal ultrasonographic image demonstrat This endovaginal ultrasonographic image demonstrates a subchorionic hemorrhage (SH) less than half the gestational sac size.
  • Subchorionic bleeding can be demonstrated using color Doppler imaging.

  • Endovaginal ultrasonography should be applied whenever possible to limit image distortion due to patient habitus or an overdistended bladder.

An incomplete miscarriage 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. Sonogram of an incomplete miscarriage is shown below.

    This image shows an endovaginal longitudinal view This image shows an endovaginal longitudinal view of a low-lying gestational sac (GS) within the uterus (Ut), representing an incomplete miscarriage.
  • 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 miscarriage, 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.

  • Studies suggest no statistically significant relationship between the initial presence of a gestational sac or endometrial thickness and the success rate of expectant management.

A complete miscarriage may demonstrate the following sonographic findings:

  • An empty uterus noted on endovaginal sonogram suggests a complete miscarriage; however, sonographic diagnosis includes ectopic pregnancy and early intrauterine pregnancy.

  • Careful scanning for adnexal masses and/or free fluid is advised.

No single ultrasonographic measurement of the different anatomical features in the first trimester has demonstrated a high predictive value for determining early pregnancy outcome. Relatively recent research suggests the finding of blood flow in the intervillous space in cases of first-trimester miscarriage using color Doppler ultrasonography as useful in the prediction of successful expectant management. Miscarriages with intervillous space blood flow were 4 times more likely to complete with expectant management.