Abdominal Pregnancy Abdominal pregnancies are classified as primary and secondary. Listed in Table 20.7 are criteria for classifying a primary abdominal pregnancy. Secondary abdominal pregnancies are the most common and result from tubal abortion or rupture or, less often, from subsequent implantation within the abdomen after uterine rupture. The incidence of abdominal pregnancy varies from 1 in 372 to 1 in 9,714 live births and accounts for 1.4% of ectopic pregnancies (1,256). Risk factors for abdominal pregnancy include PID, multiparity, endometriosis, assisted reproductive techniques, and tubal damage (257,258). Abdominal pregnancy is associated with high morbidity and mortality, with the risk for death seven to eight times greater than from tubal ectopic pregnancy and 50 times greater than from intrauterine pregnancy (256). There are scattered reports of term abdominal pregnancies. When this occurs, perinatal morbidity and mortality are high, usually as a result of growth restriction and congenital anomalies such as fetal pulmonary hypoplasia, pressure deformities, and facial and limb asymmetry. The incidence of congenital anomalies ranges from 20% to 40% (259,260).
The presentation of patients with an abdominal pregnancy varies and depends on the gestational age. In the first and early second trimesters, the symptoms may be the same as with tubal ectopic gestation; in advanced abdominal pregnancy, the clinical presentation is more variable. The patient may report painful fetal movement, fetal movements high in the abdomen, or sudden cessation of movements. Physical examination may disclose persistent abnormal fetal positioning, abdominal tenderness, a displaced uterine cervix, easy palpation of fetal parts, and palpation of the uterus separate from the gestation. The diagnosis may be suspected when there are no uterine contractions after oxytocin infusion. Other diagnostic aids include abdominal radiography, abdominal ultrasonography, CT, and MRI (261–263).
Because the pregnancy can continue to term, the potential maternal morbidity and mortality are very high. As a result, surgical intervention is recommended when an abdominal pregnancy is diagnosed. At surgery, the placenta can be removed if its vascular supply can be identified and ligated, but hemorrhage can occur, requiring abdominal packing that is left in place and removed after 24 to 48 hours. Angiographic arterial embolization was described (264). If the vascular supply cannot be identified, the cord is ligated near the placental base, and the placenta is left in place. Placental involution can be monitored using serial ultrasonography and assessment of β-hCG levels. Potential complications of leaving the placenta in place include bowel obstruction, fistula formation, and sepsis as the tissue degenerates. There are concerns regarding the use of methotrexate treatment in abdominal pregnancies. Specifically, there is
Table 20.7 Studdiford’s Criteria for Diagnosis of Primary Abdominal Pregnancy 1.
Presence of normal tubes and ovaries with no evidence of recent or past pregnancy.
2.
No evidence of uteroplacental fistula.
3.
The presence of a pregnancy related exclusively to the peritoneal surface and early enough to eliminate the possibility of secondary implantation after primary tubal nidation.