From the Guidelines
The most appropriate next step to confirm the diagnosis in this case is transvaginal ultrasonography. This patient presents with concerning symptoms of a possible early pregnancy loss, including lower abdominal discomfort and vaginal spotting at 11 weeks gestation. The transabdominal ultrasound showing a gestational sac without an embryo or heartbeat is suggestive of a failed pregnancy, but transvaginal ultrasound provides superior resolution and visualization of early pregnancy structures, as noted in the study by 1. Transvaginal ultrasound can more accurately determine if this is truly an anembryonic pregnancy (empty sac) or if there is a small embryo with cardiac activity that was missed on the transabdominal scan.
The increased resolution of transvaginal ultrasound allows for detection of embryos as small as 2-3 mm and cardiac activity as early as 5.5-6 weeks. According to the study by 1, the absence of an embryo in a gestational sac with a mean sac diameter (MSD) of greater than 25 mm is diagnostic of a nonviable intrauterine pregnancy (IUP). However, for smaller gestational sacs, time-based criteria for follow-up US may be useful. None of the other options (amniocentesis, cervical cultures, maternal serum estrogen, or alpha-fetoprotein measurements) would be appropriate for confirming pregnancy viability at this stage, as they do not provide direct visualization of the embryo or gestational sac.
If the transvaginal ultrasound confirms absence of an embryo in a gestational sac of appropriate size, this would establish the diagnosis of an anembryonic pregnancy (previously called blighted ovum). The study by 1 also supports the use of transvaginal ultrasonography as the preferred modality for evaluating patients with abnormal vaginal bleeding in the first trimester of pregnancy. Key points to consider when performing the transvaginal ultrasound include:
- The presence or absence of an embryo
- The size of the gestational sac
- The presence or absence of cardiac activity
- The appearance of the yolk sac and amniotic cavity.
By using transvaginal ultrasonography, clinicians can make an accurate diagnosis and provide appropriate management for patients with suspected early pregnancy loss, ultimately improving outcomes and reducing morbidity and mortality.
From the Research
Diagnosis of Pregnancy Complications
The patient is a 30-year-old woman, G3 P2, at 11 weeks gestation, experiencing lower abdominal discomfort and vaginal spotting for three days. The cervix is closed, and there is no current bleeding on examination. Transabdominal ultrasound shows a gestational sac with no evidence of embryo or detectable heartbeat.
Appropriate Next Steps
To confirm the diagnosis, the following options are considered:
- Amniocentesis: not appropriate at this gestational age for diagnosis of pregnancy complications
- Cervical cultures: not relevant to the diagnosis of pregnancy complications
- Measurement of maternal serum estrogen level: not a standard test for diagnosis of pregnancy complications
- Serial measurements of maternal serum alpha-fetal protein level: not relevant to the diagnosis of pregnancy complications at this gestational age
- Transvaginal ultrasonography: the most appropriate next step to confirm the diagnosis, as it can provide more detailed information about the pregnancy and help identify any potential complications 2, 3
Rationale
Transvaginal ultrasonography is a valuable tool in the evaluation of early pregnancy complications, including miscarriage and ectopic pregnancy 2, 3. It can provide high-resolution images of the uterus and adnexal structures, allowing for accurate diagnosis and management of pregnancy complications. In this case, the patient's symptoms and transabdominal ultrasound findings suggest a potential pregnancy complication, and transvaginal ultrasonography is the most appropriate next step to confirm the diagnosis 4, 3.