Omental pregnancy: case report and review of literature

Pregnancy, the implantation of a fertilized ovum outside the endometrial cavity, occurs in 1.5%-2% of pregnancies. It is one of the major causes (about 6%) of maternal death during the first trimester of pregnancy. The remaining 5% implant in the ovary, peritoneal cavity, within the cervix, and the omental pregnancy is the least common form of abdominal pregnancies. A review of the literature on Medline for the period 1958-2012 reported only 16 cases of omental pregnancy. Here we report a case of primary omental pregnancy in a nulliparous woman. A 24 year-old woman gravid 1, para 0, with lower abdominal pain. Her last menstrual period occurred 8 weeks before the visit. The physical examination revealed abdominal tenderness in the lower quadrants, she was not bleeding. Transvaginal ultrasound showed: a free anechoic/hypoechoic area of 30 x 57 mm in the pouch of Douglas and the endometrium was homogeneus with a thickness of 12 mm and no evidence of gestational sac in the uterine cavity. Laboratory data revealed a normal cell blood count and beta hcg levels of 8047 IU / L. Because of continuing abdominal pain and a diagnosis of ectopic pregnancy a diagnostic laparoscopy was performed, which showed hemoperitoneum. Further inspection of abdominal cavity revealed a bloody lesion that was tenaciously adherent to the omentum, using non traumatic laparoscopic forceps and bipolar scissors we carefully removed a friable mass of about 30 mm from the omental attachments. Histological examination showed the presence of blood clot material mixed with trophoblastic tissue. Ultrasound evaluation and and hCG assessment are important to determine the extrauterine location of the ectopic pregnancy but the early diagnosis of abdominal pregnancy requires also a laparoscopic evaluation and, as our case has highlighted, thorough abdominal exploration especially in the absence of adnexal findings when ectopic pregnancy is highly suspected. Early diagnosis of omental pregnancy is difficult but essential to reduce the high mortality risk for the mother.