Abdominal pregnancy is a rare type of ectopic pregnancy, in which the embryo attaches to virtually any surface in the abdominal cavity. The diagnosis can often be missed until advanced fetal age is reached, while main symptoms include abdominal tenderness, an easy palpation of the limbs of the fetus and gastrointestinal complaints. Both maternal and fetal mortality rates are substantially higher in abdominal pregnancy, implicating that an early diagnosis is detrimental.
Abdominal pregnancy (AP), in which the fetus grows outside the female reproductive tract and within the peritoneum, is a very rare type of ectopic pregnancy (EP), accounting for 1% of all EPs [1]. The incidence rate ranges considerably from study to study (1 in 400-50,000 live births), but it must be noted that abdominal pregnancy is the only type of EP that can end as a successful delivery of a full-term newborn [1] [2] [3]. AP is further divided into primary, when the fertilized ovum directly implants at a site within the peritoneal cavity (bowels, the appendix, spleen, and virtually any other organ, as well as blood vessels, uterine structures, and the omentum, are reported sites), whereas secondary implies implantation of the ovum in the peritoneum after initial adhesion in the reproductive tract and its rupture from various reasons [3] [4]. Regardless of the type, the clinical presentation is comprised of the following symptoms - persistent pain, either in the abdomen or in the suprapubic area, nausea, vomiting, painful movements of the fetus, regular menstruation cycles, vaginal discharge (bloody), and malaise [1] [3] [5] [6]. Because the fetus grows adjacent to several vital organs and blood vessels, both the mother and the fetus are at a much higher risk for complications such as severe and uncontrollable bleeding, maternal bowel obstruction, infections, pulmonary embolism, fistula formation (between the amniotic sac and the intestines) and even disseminated intravascular coagulation [1] [2] [7]. Furthermore, perinatal mortality rates reach as high as 50%, and up to half of all children born after an abdominal pregnancy have some congenital abnormality - torticollis, facial or cranial asymmetry, limb defects or deficits of the central nervous system (CNS) are most common, with oligohydramnios being the presumably pathogenic mechanism [1] [4] [6]. Maternal mortality rates, on the other hand, are somewhat lower (around 12%), but these numbers suggest that an early diagnosis can be life-saving [6].
Unfortunately, the diagnosis of an abdominal pregnancy is often missed, especially in the first few months of gestation, and studies report that more than 50% of cases were not diagnosed on regular ultrasonographic exams [5] [6] [7]. For this reason, clinical judgment is necessary during diagnostic workup. A high index of suspicion must be present if patients report excessive abdominal pain in the first semester, bleeding, previous pelvic surgery, and a history of infertility, implying that a properly obtained patient history is vital in making a presumptive diagnosis [6]. A meticulous physical examination is equally important, as relatively easy palpation of fetal limbs and an abnormal lie, as well as abdominal or suprapubic tenderness, are important features of AP [1] [6]. Once clinical criteria have been solidified, imaging studies are used for confirmation. Standard fetal ultrasonography, however, may not reveal any pathological findings unless the physician patiently looks for the uterus and reveals an empty uterine cavity [1]. Insertion of a balloon catheter into the uterus is often recommended to confirm the absence of the fetus inside the uterus [1] [6]. A definite diagnosis can be made by performing more advanced imaging studies, either computed tomography (CT) or magnetic resonance imaging (MRI) [2] [3]. Laboratory studies are usually normal for a regular pregnancy, showing high levels of human chorionic gonadotropin (βhCG) and/or serum alpha-fetoprotein (AFP) [1].
