Second Trimester Interstitial Ectopic Pregnancy

Abstract

Background and Clinical Significance: Interstitial ectopic pregnancy is a rare but potentially life-threatening type of ectopic gestation that carries high risk of rupture and hemorrhage due to its vascular location and predisposition for delayed presentation. Case Presentation: We present a 33-year-old female with acute abdominal pain and elevated β-hCG, with transvaginal ultrasound demonstrating a live left adnexa ectopic pregnancy dated at approximately 14 weeks. MRI confirmed the gestational sac as tubal ectopic, but poorly localized within the interstitial fallopian tube. Exploratory laparoscopy revealed the gestational sac mainly in the interstitial left fallopian tube without rupture or distal involvement. Conclusions: This case demonstrates absent classic imaging findings associated with tubal, interstitial, and ovarian ectopic gestations including tubal ring sign, interstitial line sign, endo-myometrial mantle measurement, or claw sign due to location and advanced gestational age. Familiarity with these challenges and recognition that interstitial ectopic pregnancy may present atypically are important for timely recognition and management.

Keywords: ectopic; fallopian tube; interstitial; pregnancy.

Figure 1

A 33-year-old female presented with diffuse abdominal pain. Transverse ultrasound of the pelvis through the level of the uterus demonstrating gestational sac outside of the uterus and free pelvic fluid. Estimated live extrauterine gestational age of 13 weeks 6 days +/− 1 week 2 days. It is unclear whether the ectopic pregnancy is located within the left fallopian tube or involves the left ovary.

Figure 2

MRI without contrast showed that the ectopic gestational sac exerted mass effect upon the uterus and bladder, and was associated with a moderate amount of pelvic fluid. (a) Axial T2 HASTE demonstrating ectopic pregnancy in the left adnexa with associated mass effect on the bladder and uterus which deviate to the right. The placenta is located anteriorly within the gestational sac. (b) Sagittal T2 HASTE demonstrating ectopic pregnancy located anterior to uterine fundus and superior to bladder. The anterior wall of the gestational sac is located approximately 1.3 cm deep to the overlying skin surface. There is a moderate amount of complex free pelvic fluid. (c) Coronal T2 HASTE demonstrating intact gestational sac superior to the bladder in the left adnexa. The left ovary is partially visualized superior to the gestational sac and contains an incidental 2.0 cm follicle.

Figure 2

MRI without contrast showed that the ectopic gestational sac exerted mass effect upon the uterus and bladder, and was associated with a moderate amount of pelvic fluid. (a) Axial T2 HASTE demonstrating ectopic pregnancy in the left adnexa with associated mass effect on the bladder and uterus which deviate to the right. The placenta is located anteriorly within the gestational sac. (b) Sagittal T2 HASTE demonstrating ectopic pregnancy located anterior to uterine fundus and superior to bladder. The anterior wall of the gestational sac is located approximately 1.3 cm deep to the overlying skin surface. There is a moderate amount of complex free pelvic fluid. (c) Coronal T2 HASTE demonstrating intact gestational sac superior to the bladder in the left adnexa. The left ovary is partially visualized superior to the gestational sac and contains an incidental 2.0 cm follicle.

Figure 3

Intraoperative photo taken during diagnostic laparoscopy demonstrating intact gestational sac within dilated portion of left fallopian tube. The gestational sac (arrow) is located primarily within the interstitial portion of the fallopian tube with no involvement of the distal end. There is increased musculature surrounding the fallopian tube which may represent extended myometrium from the uterine cornua.