PMC3692029_01
(a) Sagittal and (b) transverse images from a pelvic ultrasound show a gravid retroflexed uterus measuring 12.4 x 6.5 x 7.1 cm corresponding to a volume of 299.3 cc. (c, d) Additional transabdominal images show a single intrauterine gestation with positive fetal cardiac activity measuring 159 beats per minute and a crown-rump length measuring 2.1 cm corresponding to an estimated gestational age of 8 weeks and 5 days
JCIS-3-16-g002.jpg
PMC3692029_01_JCIS-3-16-g002.jpg
F1
A subsequent pelvic ultrasound showed a retroflexed gravid uterus with a single viable pregnancy in the lower uterine segment abutting the urinary bladder [Figure 1a-d]. Given the position of the gestation in the lower uterine segment and the history of two prior cesarean sections, the findings on initial ultrasound examination raised the suspicion of a cesarean scar ectopic pregnancy with possible isthmic-cervical involvement [Figure 1a-d].
(a) Sagittal T1-weighted fat-saturated contrast-enhanced image of the uterus just off midline demonstrates an intrauterine gestational sac distending the endometrial cavity. The sac produces an outward bulge in the lower uterine segment at the site of cesarean section scar (white arrowheads) and is intimately related to the urinary bladder roof. Enhancing trophoblastic tissue/placenta (red arrow) is present at the bulging site. (b) Sagittal T2-weighted image of the uterus again shows the outward bulging gestational sac through the cesarean scar. Marked thinning of the myometrium is seen at the base/periphery of the bulging gestational sac. The central portion of the bulging gestation sac appears to be covered only by thin hypointense serosa (yellow arrowheads). Of note on this image is the preserved urinary bladder wall with a separating hyperintense fat plane (white arrows). (c) Coronal T2-weighted and (d) coronal T2-weighted fat-saturated images demonstrate the preserved hypointense urinary bladder wall at the level where the gestational sac bulging through the scar sits atop the urinary bladder. Note also the marked thinning of the overlying myometrium (black and white arrowheads)
JCIS-3-16-g003.jpg
PMC3692029_01_JCIS-3-16-g003.jpg
F2
MRI confirmed an intrauterine pregnancy bulging through the myometrium of the lower uterine segment with resultant mass effect on the superior right parasagittal aspect of the urinary bladder [Figure 2a-d] without direct invasion of the urinary bladder wall.
(a, b) Photographs of the gross specimen post-hysterectomy show a gestational sac with a single embryo (dashed yellow arrow) measuring 2.4 cm in length attached by a 2.6 cm long umbilical cord (not shown). Four limb buds (red arrows) are present with ambiguous genitalia. (c) Microscopic evaluation of the sample from the scarred portion of the lower uterine segment in the implantation site shows myometrium ranging from 0.1 cm to 1.8 cm in thickness (black arrowheads) and chorionic villi with trophoblasts (black arrows) invading into 1 mm of fibroadipose tissue, suggesting impending rupture. (Hematoxylin and eosin stain, x20)
JCIS-3-16-g004.jpg
PMC3692029_01_JCIS-3-16-g004.jpg
F3
An embryo with four limb buds and ambiguous genitalia was present within the gestational sac [Figure 3a-c].