A 31 year old female was referred to our Magnetic Resonance Imaging (MRI) department with history of lower abdominal pain for three days. The patient had a history of irregular periods, with no definite period of amenorrhea. There was no history of bleeding per vagina. The ultrasound performed by the referring physician showed a complex right adnexal lesion abutting the uterus with no free fluid in the pelvis, prompting the physician to think of a broad ligament fibroid. Subsequently the patient tested mildly positive for urine gravindex. As the physician felt that ultrasound was not contributing to a proper diagnosis, MRI pelvis was requested to help solve the clinical problem. Blood sample was given for assessment of Serum human chorionic gonadotropin (beta hCG) level at this same time. MRI images are shown as Fig. 1, Fig. 2, Fig. 3 and Fig. 4.
1. Diagnosis: ruptured ectopic pregnancy
MRI of the pelvis revealed a tubular structure with T2 hypointense fluid level measuring ∼4.1 × 2.3 × 4.1 cm in the right adnexal region, medial to the right ovary (Fig. 1). There was an ovoid T2 and GRE hypointense signal lesion with T2 hyperintense center within the tubular lesion (Fig. 2). There was a T1 hyperintense signal around the right adnexal lesion (Fig. 3). Free fluid with T1 intermediate signal and T2 hypointense signal was also seen in the pelvis (Fig. 4). Uterine endometrial thickness measured ∼9.7 mm with no intrauterine gestational sac. Right hematosalpinx with ectopic tubal gestation along with rupture, peritubal hematoma and hemoperitoneum was considered and the referring clinician was alerted. The patient was taken for laparotomy without waiting for the serum beta hCG level. About 500 ml of intraperitoneal blood was noted. Tubectomy was performed for the ruptured right fallopian tube gestation. Serum beta hCG level turned out to be 7356 IU/ml. The patient recovered well following the surgery.
Ectopic pregnancy, an important cause of morbidity and mortality in the first trimester, does not always present classically with the triad of abdominal pain, bleeding per vagina and adnexal lesion. Prompt diagnosis helps in alleviating the morbidity and avoiding mortality. Though ultrasound is the primary modality for diagnosing ectopic pregnancy, MRI of the pelvis has a definite role as a problem solving tool.(1) Though more than 90% of ectopic pregnancies are visualized on transvaginal ultrasound, false positive diagnoses account for about 5–6%.(2) Corpus luteum, bowel, paratubal cyst, hydrosalpinx, endometrioma and fibroid account for the false positive diagnoses of ectopic pregnancy.(3)
The classic findings of ectopic pregnancy on MRI are lack of intrauterine pregnancy, hemoperitoneum, tubal mass, hematosalpinx and wall enhancement of the dilated fallopian tube.(4, 5) The presence of hematosalpinx in a woman with a positive pregnancy test and with no intrauterine gestational sac is highly concerning for ectopic pregnancy, even in the absence of a clearly identifiable extra-uterine gestational sac.(5) The inclusion of a T1-weighted pulse sequence is helpful in identifying blood products and is recommended as part of imaging protocol for pregnant patients.(5) Mimics of ectopic pregnancy include corpus luteal cyst and ovarian masses. Differentials for hemoperitoneum include placentation abnormalities like placenta accreta and percreta.(5)
It is imperative that the radiologists, obstetricians and emergency physicians be familiar with these features and always consider the possibility of ectopic pregnancy in the setting of hemoperitoneum or a pelvic mass in a woman of child-bearing age.(1)