Large amount of fluid in the pelvis.
Diagnosis and treatment
Early IUP/threatened abortion
A patient presenting to the office for evaluation of early pregnancy symptoms may have the diagnosis of definite intrauterine pregnancy made when a yolk sac or an embryo is identified within an intrauterine gestational sac. Clarification regarding whether an intrauterine pregnancy is normal or abnormal depends upon an accurate history, careful evaluation with ultrasound, and occasionally use of serial β-hCG measurements. Skilled ultrasonographers may identify an early gestational sac by the fact that an ovoid lucency is present, implanted eccentric from the midline endometrial echo, and surrounded by a decidual reaction that is brighter than the endometrium itself. However, care should be taken not to mistake an intrauterine fluid collection for a gestational sac. A fluid collection will often have a “beak sign,” which is a visible tapering point to the fluid at its distal end. Additionally fluid within the endometrial cavity appears midline and lacks a decidual halo. Figure 11-3 demonstrates a fluid collection or pseudo sac. Figure 11-4 shows an early intrauterine pregnancy with gestational sac located off the midline at the fundus of the uterus. In a patient with a desired pregnancy, identification of an early gestational sac should be followed up in an appropriate time to confirm the development of a yolk sac and eventually a fetal pole. If the pregnancy is aborted, confirmation of products of conception should be confirmed by gross inspection or pathologic exam to confirm the diagnosis and avoid missing an ectopic pregnancy.
Gestational sac in the endometrial cavity at the fundus.
Blighted ovum/missed abortion
An anembryonic pregnancy or blighted ovum is diagnosed by the presence of an empty gestational sac on ultrasound. An abnormal pregnancy may be suspected based on a sure last menstrual period with lagging ultrasound findings, but a definitive diagnosis should be confirmed by meeting a minimum sac size without embryonic tissue or by failure of development on serial ultrasound.
The criteria most often used to diagnose pregnancy failure are the absence of cardiac activity by the time the embryo has reached a specified crown rump length, the absence of a visible embryo by the time the gestational sac has grown to a certain size, or the absence of a visible embryo by a certain point in time.[14] A single ultrasound showing a gestational sac diameter of 25 mm with no visible embryo yields a specificity and positive predictive value of 100% for an anembryonic gestation. Additionally recent studies have shown that a cutoff of 7 mm for crown rump length with no fetal cardiac activity is diagnostic of a failed pregnancy with specificity and positive predictive value of 100%.[15] The findings on ultrasound must be evaluated in the clinical context of the certainty of historical dating factors. Additionally, the patient’s desire to continue her pregnancy should be considered in situations where a definitive diagnosis of a failed pregnancy cannot be made on initial evaluation. A repeat ultrasound in 7–10 days will clarify the diagnosis in almost all situations. Table 11-4 includes guidelines for the diagnosis of pregnancy failure in the first trimester.[14]
| Findings diagnostic of pregnancy failure | Findings suspicious for pregnancy failure |
|---|---|
| CRL ≥7 mm and no heartbeat | CRL <7 mm and no heartbeat |
| MSD ≥25 mm and no embryo | MSD 16 mm–24 mm and no embryo |
| Absence of embryo with heartbeat ≥2 weeks after a scan that showed a gestational sac without a yolk sac | Absence of embryo with heartbeat 7–13 days after a scan that showed a gestational sac without a yolk sac |
| Absence of embryo with heartbeat ≥11 days after a scan that showed a gestational sac with a yolk sac. | Absence of embryo with heartbeat 7–10 days after a scan that showed a gestational sac with a yolk sac |
| Absence of embryo ≥6 weeks after LMP | |
| Empty amnion (amnion seen adjacent to yolk sac, with no visible embryo) | |
| Enlarged yolk sac (>7 mm) | |
| Small gestational sac in relation to the size of the embryo (<5 mm difference between MSD and CRL) |
Once a diagnosis of a failed intrauterine pregnancy is made three options should be considered: expectant observation, medication administration, and surgical treatment. Observation without intervention may appeal as a more “natural” approach to some women, while others will not want a delay in treatment or the uncertainty of knowing when the miscarriage will occur. A Cochrane review evaluated seven trials of expectant management. It found that expectant management was associated with higher rates of incomplete abortion at two weeks, blood transfusion, and unplanned surgical intervention. Rates of infection, levels of pain, and measures of psychological impact were similar. Costs incurred were lower with expectant care. The rate of surgical intervention for those who were managed expectantly was 28%.[16] Medical management of first trimester miscarriage has also been summarized in a Cochrane review. Of the studies evaluated, three compared misoprostol to expectant management and found no difference in rates of complete abortion or need for surgery. Twelve studies compared medical to surgical management. There was a lower incidence of complete miscarriage and more unplanned procedures with misoprostol.[17] Surgical evacuation of the uterus can be performed in the office setting with electric vacuum aspiration or manual vacuum aspiration, with a paracervical block and oral analgesia, with or without sedation. Complication rates associated with surgical intervention are low. The majority of studies evaluating the risk of dilatation and curettage in early pregnancy come from the literature reviewing elective abortion. The complications most commonly encountered are: infection (~1%), hematometra (<1%); incomplete abortion (1%–2%).[18]
Follow-up of patients with failed early intrauterine pregnancies depends upon the management chosen. Patients who elect expectant management should be seen for a return appointment in one to two weeks. Additionally, the clinician should provide information regarding the amount of pain and bleeding to expect as well as reasons to seek emergent care. A narcotic prescription can be provided for women in advance. For women using misoprostol for medical management, an antiemetic may be needed as well. Patients treated medically are generally followed up within the week after medication use. It is expected that the gestational sac would be expelled at that time, but the endometrial stripe may still be thick. Women undergoing surgical management may be followed up within two to four weeks. Pelvic exam is not indicated unless ongoing bleeding or signs of infection are present. However, future pregnancy planning and need for contraception should be addressed at that time.
Molar pregnancy
The classic presentation of a molar pregnancy includes vaginal bleeding, passage of vesicles per vagina, uterine enlargement greater than expected for gestational age, and abnormally high levels of β-hCG. However, in one study 40% of molar pregnancies were asymptomatic, 60% presented with vaginal bleeding and 2% with hyperemesis symptoms.[19] Due to availability of present day ultrasound technology, many molar pregnancies are identified early in gestation as abnormal intrauterine pregnancies, and the diagnosis is confirmed later by pathology. On ultrasound, the typical “snowstorm” appearance is less likely to be seen in the first trimester. More commonly, an anembryonic pregnancy is detected. Only 40% of women with confirmed hydatidiform mole had a preevacuation ultrasound diagnosis suggesting molar pregnancy. The sensitivity, specificity, and positive and negative predictive values for routine pre-evacuation ultrasound examination for hydatidiform mole are 44%, 74%, 88%, and 23%, respectively.[20, 21] Molar pregnancy is often diagnosed after treatment of a failed pregnancy. However, if it is suspected preoperatively, suction dilatation and curettage is the preferred route of uterine evacuation to ensure complete removal and to allow pathologic evaluation of the tissue.[22] A quantitative β-hCG level, complete blood count, and chest x-ray should be obtained preoperatively. Additional laboratory tests may be indicated if there are signs of hyperthyroidism or preeclampsia.
Surgical evacuation in the operating room is recommend for uterine size greater than 16 weeks, due to the increased risk of hemorrhage. Hysterectomy can be considered for women who have completed childbearing.[23] Following uterine evacuation, the quantitative β-hCG level should be followed every one to two weeks until negative and then monthly for an additional six months. A plateau or rise in the β-hCG should trigger evaluation for a new conception, and if excluded, prompt referral for treatment of gestational trophoblastic disease. Women diagnosed with molar pregnancy should use an effective method of contraception during the six-month follow-up period.
Ectopic pregnancy
The classic, clinical presentation of ectopic pregnancy includes vaginal bleeding, abdominal pain, and a positive pregnancy test. In such a patient, if an ultrasound examination reveals a gestational sac with yolk sac or fetus visible in the adnexal area, the diagnosis of ectopic pregnancy is simple. Figure 11-5 demonstrates a gestational sac visible within the adnexal area. Likewise, an implantation in a cesarean section scar or in the cervix can be made by imaging alone; although it needs to be distinguished from a spontaneous abortion in progress. More commonly, ectopic pregnancies are originally diagnosed as pregnancies of undetermined location (PUL) and a final diagnosis made with additional follow-up over time. The diagnosis of ectopic pregnancy is often clinically challenging and may involve serial β-hCG follow-up or diagnostic surgery including dilation and curettage or laparoscopy. It is incumbent upon the clinician to avoid potentially harmful intervention with methotrexate in an early normal pregnancy and to establish a correct diagnosis for the individual patient.[24]
The concept of a discriminatory level of β-hCG has been utilized for ectopic evaluation. This refers to the value above which an ultrasound should be diagnostic of an intrauterine pregnancy. The discriminatory value is both user and equipment dependent. It should be considered a relative concept.[25] Uterine malposition or malformation, the presence of fibroids, and patient obesity can all affect the quality of imaging. Most algorithms in use suggest that, if a normal intrauterine pregnancy is present, it would be detected on ultrasound when the β-hCG level is 2,000 or more.[26] This assumes a singleton IUP. In multiple gestations the β-hCG will be higher at any particular point in gestation. Additionally, a recently published analysis of one center’s experience described a patient with β-hCG of 2317 with no IUP visualized, who went on to develop a normal, singleton pregnancy. The authors modeled the association of β-hCG and visualization of the gestational sac. They found that the probability of detecting a sac would be 99% at a level of 3,510, suggesting that the discriminatory value in their institution may be higher, and the concept should be used cautiously.[27] An accurate assessment of gestational age based on dates is better predictive of ultrasound landmarks than is a single measurement of β-hCG. In the stable patient, with a level below the discriminatory value, serial β-hCG follow-up may be useful in evaluation PUL.
Initial work by Kadar suggested that a rise of 66% should be expected over a 48 hour period of time.[28] Subsequent studies have identified a somewhat lower rate of rise, 53%, as being compatible with normal pregnancy.[29] If such a rise does not occur, then the pregnancy is abnormal, but not necessarily extrauterine. Uterine evacuation with pathology evaluation can be diagnostic of a failed IUP if chorionic villi are found. Alternatively, it may be suggestive of an ectopic pregnancy if no villi are identified and the β-hCG fails to drop appropriately postoperatively. If an appropriate rise occurs it could still be ectopic. The patient should be followed closely and undergo repeat ultrasound examination when the β-hCG reaches the discriminatory zone. Published algorithms are useful in assisting the clinician to come to a timely diagnosis.[26] Figure 11-6 shows that currently in use at our institution.
