Ectopic pregnancy refers to implantation of the fertilized ovum at sites other than the uterine endometrial cavity. The ectopic implantation usually occurs within the pelvis, i.e., fallopian tubes, uterine cornua, ovary, cervix, uterine caesarean scar; or less commonly in the abdominal cavity like in the peritoneum, omentum, liver, spleen or bowel.
Abdominal pregnancy can be primary or secondary. Secondary abdominal pregnancies are more common and occur secondary to tubal rupture or tubal abortion with migration of the gestational sac into the abdominal cavity.
The Studdiford criteria for diagnosing primary abdominal pregnancy include (1) normal tubes and ovaries with no evidence of recent or remote injury; (2) absence of any evidence of uteroplacental fistula; (3) presence of pregnancy related exclusively to peritoneal surface; and (4) pregnancy recent enough to eliminate the possibility of secondary implantation following nidation in tubes. Primary abdominal pregnancy accounts for almost 1% of all ectopic pregnancies . In primary hepatic pregnancy, the implantation occurs in liver and is associated with high mortality rate owing to the risk of catastrophic intra- or post-operative hemorrhage. The youngest patient reported with hepatic ectopic pregnancy was aged 25 and the oldest was of 46 years .
The etiology of primary abdominal pregnancy remains inconclusive with multiple theories proposed including fallopian tube damage secondary to pelvic inflammatory disease, use of oral contraceptives and intrauterine contraceptive devices, conceiving using assisted reproductive techniques in infertility.
Liver is the biggest solid organ of abdominal cavity capsula fibrosa and is a favorable site of profuse blood supply suitable for the growth of an embryo. Fertilized ovum attaches to capsula fibrosa, and as the gestational sac develops, the chorion infiltrates into the hepatic surface to meet constantly increasing blood supply of the embryo. Thus, the placenta mostly attaches to the inferior surface of the right lobe of the liver .
The clinical diagnosis may be delayed owing to non-specific symptoms and delayed presentation. Patients usually present with epigastric or right hypochondriac pain and gastrointestinal symptoms, sometimes with bleeding per vaginum as well and are misdiagnosed clinically to be hepatitis, cholecystitis, gastroduodenitis or acute gastroenteritis. Detailed menstrual history in reproductive age females is useful. In case of ruptured ectopic pregnancy, the patients are brought in to emergency department with low blood pressure and hypovolemic shock.
Early diagnosis can be established with the use of USG. USG has high temporal resolution, is faster and non-invasive and thus the modality of choice in emergency. Trans-abdominal USG confirms the site of pregnancy and is most useful in dating the pregnancy. In early pregnancy, gestational sac is visualized as cystic lesion with embryonic pole-yolk sac complex within. Cardiac activity may or may not be visualized. Surrounding peri-gestational hematoma is an early indicator of impending rupture. Color Doppler is useful to locate the blood supply. In advanced pregnancy, the fetus and placenta can be seen freely within the abdominal cavity separate from the uterus. Transvaginal USG is useful to confirm that there is no intrauterine pregnancy and to confirm that both fallopian tubes are normal.
Owing to its high spatial resolution, MRI is useful for surgical planning to outline the regional anatomy of the implantation site and its relation with the surrounding structures. The location of the placenta is useful in deciding whether to remove the placenta during laparotomy or not due to the risk of hemorrhage in the former .
The surgical management of hepatic pregnancy may be either by laparotomy or laparoscopy, carefully considering the high risk of intraoperative catastrophic hemorrhage. To reduce the risk of bleeding, procedures like hepatic artery ligation, omental transplantation, wedge resection or lobectomy and liver packing may be performed. Some authors recommend administering methotrexate injection during diagnostic laparotomy . A combination of preoperative catheter embolization of the arterial feeders followed by laparoscopic extraction of the fetus, and methotrexate injection post-operatively for the placenta left in situ are favored by few others . Methotrexate assists in faster degeneration of the trophoblastic tissue in residual placenta. The least invasive technique includes ultrasound-guided percutaneous injection of potassium chloride into the fetal heart for immediate fetal cardiac arrest, followed by intramuscular injection of 1 mg/kg of methotrexate as mentioned by Shippey et al. .