Anembryonic Pregnancy

The signs and symptoms of an anembryonic pregnancy can potentially mirror those of an ectopic pregnancy. Anembryonic pregnancy is often incidentally noted on an initial first-trimester pregnancy sonogram. If an anembryonic pregnancy progresses to an early pregnancy loss, the patient can present with abdominal cramping and vaginal bleeding. Early pregnancy loss in the setting of an anembryonic pregnancy can be clinically silent.

Clinical signs and symptoms, a pregnancy test, and an ultrasound exam confirm the diagnosis. 

A pregnancy test can be obtained using urine or serum hCG levels.

Ultrasound exam (transabdominal or transvaginal) classically demonstrates an empty gestational sac without an embryo.

An anembryonic pregnancy is established on endovaginal ultrasound technique when there is no discernable embryo seen in a gestational sac with a mean sac diameter of ≥25 mm.

Alternatively, an anembryonic pregnancy can be established when there is no embryo on a follow-up endovaginal scan:

• ≥11 days after a scan demonstrating a gestational sac with a yolk sac, but an absent embryo
• ≥ 2 weeks (14 days) after a scan demonstrating a gestational sac without an embryo or a yolk sac

The three treatment options for early pregnancy loss include expectant management, medical management, and surgical treatment. Medical management with misoprostol and surgical treatment is considered more effective in the management of anembryonic pregnancy. Ultimately the decision on considering one of these options is based on an informed conversation between a patient and the provider.

• Expectant management
  • This constitutes the "watchful waiting" approach
  • The patient is closely followed without intervention for spontaneous and complete passage of tissue
  • Repeat sonograms and trending hCG levels are employed to confirm complete passage of tissue
  • A reasonable determination of a downtrending hCG is sufficient

• Medical management 
  • This employs misoprostol(an analog of prostaglandin), 800 mcg, administered vaginally
  • Optimal dosage is an ongoing area of research
  • This management option allows for a more predictable treatment course

• Surgical Treatment 
  • Surgical management employs uterine evacuation with a manual vacuum
  • Frequently employed in patients with hemodynamic instability
  • Uterine aspiration/evacuation is quicker to complete, especially when performed on an outpatient basis

The chief obstetric differential diagnosis for an anembryonic pregnancy includes:

• Pseudogestational sac which represents a small amount of intrauterine fluid
• Early intrauterine pregnancy
• An ectopic pregnancy
• Implantation bleeding from an otherwise viable pregnancy
• Gestational trophoblastic disease
• Complications relating to a viable pregnancy

Prognosis and successful management of early pregnancy loss depends on a variety of factors including gestation age. Prognosis is generally considered good with all three management options.

• Expectant management: in a meta-analysis of 20 studies, expectant management and medical management were both determined to be acceptable treatment options for incomplete abortion. [17]
• Medical management: medical management is more successful with multiple-dose regimens of misoprostol. Patients with incomplete abortion are treated more successfully with medical management than with expectant management.
• Surgical Treatment: at least one large randomized control trial determined a higher success rate in surgical treatment than with medical management, with a general conclusion of the general safety of both treatment options.  [18]

Serious complications of treatment are uncommon. Complications can include:

• Heavy bleeding/hemorrhage
• Uterine perforation(from surgical management)
• Infection to include fatal sepsis
• Complications from a missed ectopic pregnancy

• OB/GYN
• Primary care provider
• Psychologist/psychiatrist
• Emergency department physician
• Radiologist/sonographer(especially when there is a concern for an ectopic pregnancy)

The following represent key points in patient education:

• Patients should be advised to present to their emergency department if they experience heavy vaginal bleeding(two pads per hour for approximately two consecutive hours).
• Signs and symptoms of infection should be discussed with patients especially following surgical management.
• Treatment with misoprostol can cause a febrile reaction which can be misinterpreted as a sign of infection.
• Prophylactic antibiotics are not routinely administered but can be considered in select patients.
• Patients should adhere to follow-up sonogram and outpatient appointments especially when additional doses of misoprostol are considered to be clinically necessary.
• A miscarriage can be a traumatic experience for a patient. Reassurance and empathy play a key role in helping patients through the grieving process.

• Pregnancy loss is a common complication in the first trimester of pregnancy
• Most losses occur in the first trimester
• Early pregnancy loss without embryo development is likely due to chromosomal and genetic abnormalities
• There are specific sonographic criteria for determining an anembryonic pregnancy
• A pseudogestational sac, an ectopic pregnancy, and an early pregnancy are important differential diagnoses to consider when evaluating an anembryonic pregnancy
• Expectant management, medical treatment with misoprostol, and surgical treatment are the three primary options for management

Establishing an anembryonic pregnancy can sometimes b difficult on an ultrasound. Communication with the radiologist relaying hCG lab values and patient presentation can be helpful in avoiding a missed diagnosis of an ectopic pregnancy. The sonographer also plays an important role in accurately evaluating a patient to appropriately exclude an ectopic pregnancy. Patients presenting with complications of either initial presentation or from treatment often present to the emergency department. Interprofessional communication between an emergency department provider and an OB/GYN specialist includes communicating a detailed and thorough history and physical exam. This especially includes signs of sepsis or hemodynamic instability. The role of a mental health professional in following up with patients is also critical in ensuring the appropriate mental health management of a possibly traumatic experience for a patient.