| Abdominal pregnancy | |
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| A fetus being removed from the abdomen after childbirth in abdominal pregnancy | |
| Specialty | Obstetrics |
Anabdominal pregnancy is a rare type ofectopic pregnancy where theembryo orfetus is growing and developing outside theuterus, in theabdomen, and not in afallopian tube (usual location), anovary, or thebroad ligament.[1][2][3]
Because tubal, ovarian and broad ligament pregnancies are as difficult todiagnose andtreat as abdominal pregnancies, their exclusion from the most common definition of abdominal pregnancy has been debated.[4]
Others—in the minority—are of the view that abdominal pregnancy should be defined by aplacenta implanted into theperitoneum.[5]
Symptoms may include abdominal pain or vaginal bleeding during pregnancy.[1] As this is nonspecific in areas where ultrasound is not available the diagnosis was often only discovered duringsurgery to investigate the abnormal symptoms.[1] They are typically diagnosed later in the developing world than the developed.[6] In about half of cases from a center in the developing world the diagnosis was initially missed.[7]
It is a dangerous condition as there can be bleeding into the abdomen that results inlow blood pressure and can be fatal. Other causes of death in women with an abdominal pregnancy includeanemia,pulmonary embolus,coagulopathy, andinfection.[8]
Risk factors are similar totubal pregnancy withsexually transmitted disease playing a major role;[8] however about half of those with ectopic pregnancy have no known risk factors (which include damage to the fallopian tubes fromprevious surgery or from previous ectopic pregnancy, andtobacco smoking).[9]
Implantation sites can be anywhere in the abdomen but can include theperitoneum outside of the uterus, therectouterine pouch (culdesac of Douglas),omentum,bowel and itsmesentery,mesosalpinx, and the peritoneum of the pelvic wall and the abdominal wall.[10][11] The growing placenta may be attached to several organs including tube and ovary. Rare other sites have been theliver andspleen,[12] giving rise to a hepatic pregnancy[13] or splenic pregnancy, respectively.[14] Even an early diaphragmatic pregnancy has been described in a patient where an embryo began growing on the underside of thediaphragm.[15]
A primary abdominal pregnancy refers to a pregnancy that first implanted directly in theperitoneum, save for the tubes and ovaries; such pregnancies are very rare, only 24 cases having been reported by 2007.[16] Typically an abdominal pregnancy is a secondary implantation which means that it originated from a tubal (less common an ovarian) pregnancy and re-implanted.[11] Other mechanisms for secondary abdominal pregnancy includeuterine rupture, rupture of auterine rudimentary horn andfimbrial abortion.[17]
Suspicion of an abdominal pregnancy is raised when the fetal anatomy can be easily felt, or thelie is abnormal, thecervix is displaced, or there is failedinduction of labor.[1]X-rays can be used to aid diagnosis.[11] Sonography can demonstrate that the pregnancy is outside an empty uterus, there is reduced to noamniotic fluid between the placenta and the fetus, no uterine wall surrounding the fetus, fetal parts are close to the abdominal wall, the fetus has an abnormal lie, the placenta looks abnormal and there isfree fluid in the abdomen.[8][18]MRI has also been used with success to diagnose abdominal pregnancy and plan for surgery.[16][19] Elevatedalpha-fetoprotein levels are another clue of the presence of an abdominal pregnancy.[20]
Most cases can be diagnosed byultrasound.[21] The diagnosis however may be missed with ultrasound depending on the operator's skill.[7][22]
To diagnose the rare primary abdominal pregnancy, Studdiford's criteria need to be fulfilled: tubes and ovaries should be normal, there is no abnormal connection (fistula) between the uterus and the abdominal cavity, and the pregnancy is related solely to the peritoneal surface without signs that there was a tubal pregnancy first.[23][24] Studdiford's criteria were refined in 1968 by Friedrich and Rankin to includemicroscopic findings.[25]
Depending ongestational age thedifferential diagnoses for abdominal pregnancy includemiscarriage,intrauterine fetal death,placental abruption, anacute abdomen with an intrauterine pregnancy and afibroid uterus with an intrauterine pregnancy.[6]
Ideally the management of abdominal pregnancy should be done by ateam that has medical personnel frommultiple specialties.[26] Potential treatments consist of surgery with termination of the pregnancy (removal of the fetus) vialaparoscopy orlaparotomy, use ofmethotrexate,embolization, and combinations of these. Sapuri and Klufio indicate that conservative treatment is also possible if the following criteria are met: 1. there are no major congenital malformations; 2. the fetus is alive; 3. there is continuous hospitalization in a well-equipped and well-staffed maternity unit which has immediate blood transfusion facilities; 4. there is careful monitoring of maternal and fetal well-being; and 5. placental implantation is in the lower abdomen away from the liver and spleen.[27] The choice is largely dictated by the clinical situation. Generally, treatment is indicated when the diagnosis is made; however, the situation of the advanced abdominal pregnancy is more complicated.
Advanced abdominal pregnancy refers to situations where the pregnancy continues past 20 weeks ofgestation (versus early abdominal pregnancy < 20 weeks).[2][28] In those situations, live births have been reported in thelay press where the babies are not uncommonly referred to as 'miracle babies'.[29][30] A patient may carry a dead fetus but will not go into labor. Over time, the fetus calcifies and becomes alithopedion.[31]
It is generally recommended to perform a laparotomy when the diagnosis of an abdominal pregnancy is made.[11] However, if the baby is alive and medical support systems are in place, careful watching could be considered to bring the baby toviability.[11] Women with an abdominal pregnancy will not go into labor. Delivery in a case of an advanced abdominal pregnancy will have to be vialaparotomy. The survival of the baby is reduced and highperinatal mortality rates between 40% and 95% have been reported.[32]
Babies of abdominal pregnancies are prone tobirth defects due to compression in the absence of theuterine wall and the often reduced amount ofamniotic fluid surrounding the unborn baby.[33] The rate ofmalformations and deformations is estimated to be about 21%; typical deformations are facial and cranial asymmetries and joint abnormalities and the most common malformations are limb defects and central nervous malformations.[33]
Once the baby has been deliveredplacental management becomes an issue. In normal deliveries the contraction of uterus provides a powerful mechanism to control blood loss, however, in an abdominal pregnancy the placenta is located over tissue that cannot contract and attempts of its removal may lead to life-threatening blood loss. Thusblood transfusion is frequent in the management of patients with this kind of pregnancy, with others even usingtranexamic acid andrecombinant factor VIIa, which both minimize blood loss.[1][34]
Generally, unless the placenta can be easily tied off or removed, it may be preferable to leave it in place and allow for a natural regression.[8][11] This process may take several months and can be monitored byclinical examination, checkinghuman chorionic gonadotropin levels and byultrasound scanning (in particular usingdoppler ultrasonography.[22] Use ofmethotrexate to accelerate placental regression is controversial as the large amount of necrotic tissue is a potential site for infection,[8]mifepristone has also been used to promote placental regression.[35] Placental vessels have also been blocked by angiographicembolization.[36] Complications of leaving the placenta can include residualbleeding,infection,bowel obstruction,pre-eclampsia (which may all necessitate further surgery)[21][35] and failure tobreast feed due toplacental hormones.[37]
Outcome with abdominal pregnancy can be good for the baby and mother; Lampe described an abdominal pregnancy baby and her mother who were well more than 22 years after surgery.[38]
About 1.4% of ectopic pregnancies are abdominal, or about 1 out of every 8,000 pregnancies.[21] A report fromNigeria places the frequency in that country at 34 per 100,000 deliveries and a report fromZimbabwe, 11 per 100,000 deliveries.[7][28] Thematernal mortality rate is estimated to be about 5 per 1,000 cases, about seven times the rate for ectopics in general, and about 90 times the rate for a "normal" delivery (1987 US data).[10]
Al-Zahrawi (936–1013) is credited with first recognizing abdominal pregnancy which was apparently unknown toGreek andRoman physicians and was not mentioned in the writings ofHippocrates;Jacopo Berengario da Carpi (1460–1530) the Italian physician is credited with the first detailed anatomical description of abdominal pregnancy.[39]
Because pregnancy is outside the uterus, abdominal pregnancy serves as amodel ofhuman male pregnancy or for females who lack a uterus, although such pregnancy would be dangerous.[40][41] Abdominal pregnancy has served to further clarify the diseasepre-eclampsia which was previously thought (1980s) to require a uterus for it to occur, however pre-eclampsia's occurrence in abdominal pregnancy (with theconceptus outside the uterus) helped throw light on pre-eclampsia'setiology.[42] Cases of combined simultaneous abdominal and intrauterine pregnancy have been reported.[35][43]
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