Diagnosing ectopic pregnancy in the emergency setting

Abstract

Ectopic pregnancy is the implantation of a fertilized egg outside the uterine endometrial cavity. For women presenting to the emergency department with abdominal pain and/or vaginal bleeding, ectopic pregnancy is an important diagnostic consideration. The diagnosis is made based on laboratory values and ultrasound imaging findings. The ultrasound appearance of both normal early pregnancy and ectopic pregnancy are variable and often subtle, presenting diagnostic challenges for radiologists. This pictorial essay describes and illustrates the sonographic findings of ectopic pregnancy and reviews the differential diagnoses that can mimic ectopic pregnancy on ultrasound. With the possibility of medical management, the value of early detection and prompt initiation of treatment has increased in improving clinical outcomes and preventing the complications of ectopic pregnancy.

Keywords: Diagnosis, differential; Methotrexate; Pregnancy, ectopic; Ultrasonography.

Fig. 1.. Transabdominal views of the pelvis.

A, B. Transabdominal sagittal and transverse views of the pelvis demonstrate a normal uterus and urinary bladder.

Fig. 2.. Transvaginal views of the pelvis.

A, B. Transvaginal sagittal and transverse views allow better visualization of the endometrium. An intrauterine gestational sac is seen with a yolk sac. No embryo is yet visualized in this patient with an early pregnancy, at approximately 5-6 weeks.

Fig. 3.. Diagnostic algorithm for ectopic pregnancy.

IUP, intrauterine pregnancy; US, ultrasonography; β-hCG, β-human chorionic gonadotropin.

Fig. 4.. Ectopic pregnancy seen as a hematoma.

In this 21-year-old woman with positive serum pregnancy test and vaginal bleeding, a complex echogenic mass (arrow) is seen in the right adnexa, which separates from the right ovary (open arrow) with applied pressure during transvaginal ultrasound. The echogenic adnexal mass is representative of a hematoma at the site of ectopic implantation. The patient was treated surgically.

Fig. 5.. Tubal ring sign.

A. In this 20-year-old woman with a positive pregnancy test presenting to the emergency department with pelvic pain and vaginal spotting, there is an adnexal mass with echogenic ring (arrow). B. A color Doppler image of the right adnexa shows increased vascularity in the echogenic ring. The patient was diagnosed with ectopic pregnancy based on a clinical and sonographic assessment and was treated successfully with methotrexate.

Fig. 6.. Live tubal ectopic pregnancy.

A. In this 25-year-old woman with a positive pregnancy test and vaginal bleeding, there was a gestational sac containing an embryo in the left adnexa, outside the left ovary. B. The M-mode ultrasound of the embryo in the left adnexa shows a fetal heart rate of 170 beats per minute. These findings are confirmatory of a live tubal ectopic pregnancy.

Fig. 7.. Simple free fluid.

In a 21-year-old woman presenting to the emergency department with pelvic pain and a positive pregnancy test, simple free fluid was found in the pelvic cul-de-sac. The patient also had an echogenic left adnexal mass (not included in this figure), which was confirmed to be an ectopic pregnancy intraoperatively.

Fig. 8.. Complex free fluid or hemoperitoneum.

In this 22-year-old woman with a prior history of ectopic pregnancy presenting to the emergency department with pelvic pain and a positive pregnancy test, a large volume of complex free fluid with internal echogenicity was found in the pelvic cul-de-sac, most likely representing hemoperitoneum. A ruptured tubal ectopic pregnancy was confirmed intraoperatively.

Fig. 9.. Pseudogestational sac in an ectopic pregnancy.

A 28-year-old woman with a positive pregnancy test presented to the emergency department with right lower quadrant pain. A. A small amount of free fluid is seen within the endometrial cavity, without evidence of a yolk sac or embryo (arrow). It is irregularly-shaped and centrally located, rather than in the eccentric location often seen with a normal gestational sac. However, it should be noted that in a woman with a positive β-human chorionic gonadotropin (β-hCG) test, any intrauterine sac-like fluid collection seen on ultrasound is highly likely to be a gestational sac. B. There is a right adnexal mass with an echogenic ring (open arrow), suspicious for ectopic pregnancy. This patient was followed clinically with serial β-hCG testing, and she was later diagnosed with ectopic pregnancy and treated medically.

Fig. 10.. Sonographic findings after methotrexate treatment.

This is a 31-year-old woman who has positive but declining serial β-human chorionic gonadotropin levels. A. There is a heterogeneous echogenic mass (arrow) in the left adnexa adjacent to the left ovary (open arrow). The patient was diagnosed with left tubal ectopic pregnancy and was started on medical treatment with methotrexate. B. On a follow-up pelvic ultrasound 10 days after initiation of methotrexate treatment, there is interval enlargement of the left tubal ectopic pregnancy (arrow) due to surrounding hemorrhage and edema.

Fig. 11.. Corpus luteum.

This figure represents a 32-year-old woman who presented to the emergency department with lower abdominal pain. A. There is an intraovarian cystic structure with echogenic ring and internal debris (indicated with cross-hair markings). This ovarian structure most likely represents a corpus luteum. B. A color Doppler ultrasonography of the same structure shows significant peripheral vascularity, which is often seen in a corpus luteum.

Fig. 12.. Paraovarian cyst.

In a 47-year-old woman, there is an anechoic cyst with a thin wall and posterior acoustic enhancement inferior to the right ovary, which is compatible with a paraovarian cyst (arrow).

Fig. 13.. Dermoid cyst.

This is a 17-year-old girl presenting to the emergency department with pelvic pain. A. There is a complex echogenic mass with posterior acoustic shadowing (arrow). B. Multiple thin echogenic bands, also known as a dot-dash pattern (open arrow), are seen in parts of the mass, representing hair follicles. These findings are compatible with a dermoid cyst.

Fig. 14.. Ectopic pregnancy misinterpreted as a bowel loop.

This figure represents a 28-year-old woman who presented to the emergency department with right lower quadrant pain and a positive pregnancy test. A. The sagittal view of the right adnexa shows a hemorrhagic cyst in the right ovary; otherwise, no definite adnexal mass can be seen. B. A transverse view of the right adnexa did not demonstrate a definitive mass in the right adnexa. At the time of the study, nonspecific echogenicity in the right adnexa was interpreted as bowel loops. C, D. The patient came back 3 days later with recurrent right lower quadrant pain. There is a mass with a thick, echogenic ring in the right adnexa, which is highly suspicious for ectopic pregnancy. The diagnosis of tubal ectopic pregnancy was confirmed intraoperatively.