Recognizing an Incarcerated Gravid Uterus When the Cervical Canal Is Absent on Transvaginal Ultrasound

Incarcerated gravid uterus (IGU) is an uncommon but consequential condition in which a retroverted gravid uterus remains trapped within the sacral hollow and may mimic placental location abnormalities, risking iatrogenic injury if unrecognized. We report a 39-year-old primigravida referred at 31 weeks of gestation with a diagnosis of complete placenta previa and uterine myomas. Transvaginal ultrasonography showed placental tissue interposed between the probe and fetus with nonvisualization of the endocervical canal; pelvic examination and transabdominal ultrasonography demonstrated marked rightward, cephalad cervical deviation and an apparent posterior low-lying placenta. Magnetic resonance imaging (MRI) supported uterine incarceration, likely exacerbated by a myoma. At 38+1 weeks, elective cesarean delivery was initiated via a 7-cm infraumbilical vertical skin incision to assess the feasibility of manual reduction; because reduction was difficult, the incision was extended transversely at the umbilical level to optimize exposure. Intraoperative ultrasonography identified the internal os and confirmed rightward, superior displacement of the lower uterine segment, guiding a transverse uterine incision. A healthy male infant weighing 2.892 g was delivered; the placenta was expelled easily, the uterus was repositioned without adhesiolysis, estimated blood loss was 1,113 mL, and no transfusion was required. This case underscores the value of coordinated transvaginal/transabdominal ultrasonography with MRI. It highlights nonvisualization of the endocervical canal between the transvaginal probe and presenting part as a practical red-flag sign of IGU that may aid differentiation from true placenta previa, prompt targeted anatomic assessment, and support safer operative planning.