Spontaneous abortion (© 2016 Elsevier Inc. All rights reserved. www.netterimages.com. Used with permission)
The spontaneous loss of an intrauterine pregnancy (IUP) prior to 20 weeks of gestation is diagnostic of abortion. This is accompanied by low or falling levels of Human Chorionic Gonadotropin (hCG), bleeding and/or midline cramping pain, open cervical os, and the complete or partial expulsion of the products of conception.
Nearly 20% of clinically diagnosed pregnancies terminate in spontaneous abortion.
Greater than 60% of spontaneous abortions result from chromosomal defects.
Another 15% of losses are associated with maternal trauma, infection, dietary deficiency, diabetes mellitus, hypothyroidism, the lupus anticoagulant-anticardiolipin-antiphospholipid antibody syndrome, and anatomic malformations.
Evidence suggests that psychic stimuli such as severe fright, grief, anger, or anxiety can induce pregnancy loss. However, there is no evidence that electromagnetic fields are associated with an increased risk of abortion.
Symptoms and Signs
Incompetent cervix typically presents as “silent” cervical dilation (without contractions) between weeks 16 and 28 of gestation. An antecedent history is valuable in such patients. A “threatened abortion” is any bleeding in the first half of pregnancy. There may or may not be cramping noted and evaluation with imaging, etc., demonstrates that the pregnancy is intact. There is no cervical dilation noted in cases of threatened abortion  (Fig. 6.2).
Inevitable abortion implies that the process has begun towards eventual pregnancy loss. The cervix in this case is dilated and the fetal membranes can have undergone rupture. There has been no passage of the products of conception but if visible at the cervical os, then abortion would be inevitable .
Complete abortion is defined as the passage of intact products of conception usually accompanied by the alleviation of cramping and pain, with or without persistent spotting and bleeding. The patient’s cervical os can already have closed upon visual inspection .
Incomplete abortion describes the passage of partial products of conception while a portion thus remains in the uterus. The patient can have mild cramps and can experience bleeding which is persistent and at times presents as hemorrhage.
Missed abortion is a term used to describe a pregnancy that has ceased to develop, but the products of conception have not been expelled. This diagnosis is usually made sonographically. The gravida can note brownish vaginal discharge but generally there is no active bleeding. Often, both the subjective and objective signs and symptoms of pregnancy disappear, often rather abruptly .
The pregnant patient who is experiencing abdominal and pelvic pain in the first half of pregnancy must be considered for the evaluation of a pregnancy loss.
Other diagnoses that should be closely considered include ectopic pregnancy, hydatidiform mole, anovulatory bleeding in a nonpregnant women, cervical neoplasm, and other uterine pathologies.
The diagnosis of spontaneous abortion is rarely challenging or confusing, especially when accurate laboratory studies and imaging are readily available.
Simple measurement of the serum hCG will demonstrate declining levels. If there is considerable blood loss, a complete blood count should be obtained immediately. It is critical to ascertain the Rh type and Rho (D) Ig should be administered if the maternal blood type is Rh negative. Failure to do so can result in Rh isoimmunization. Any passed tissue should be assessed by a pathologist, as this can provide clues to other processes such as choriocarcinoma or hydatidiform mole. Transvaginal sonography (TVS) can identify a gestational sac 5–6 weeks from the first day of the last menstrual period, a fetal pole by 6 weeks, and fetal cardiac activity at 6–7 weeks. A small, irregular sac without a fetal pole is usually diagnostic of an abnormal pregnancy [1, 2].
Antibiotics should not be routinely administered unless there is evidence of infection. The use of Misoprostol, 200–800 μg orally or vaginally once, combined with an antiprogesterone (i.e., mifepristone, 600 mg orally once) has afforded a nonsurgical option in the treatment of early pregnancy loss; however, if there is excessive bleeding, a surgical procedure can be required.
Incomplete or inevitable abortions are treated with prompt removal of any remaining products of conception to stop bleeding and prevent infection.
Threatened abortion is managed with conservative observation. Whether bed rest reduces the incidence of pregnancy loss has never been substantiated in any studies to date. The recommendation of abstinence from coitus and douching is also unsubstantiated but seems to make sense.
When the pregnancy loss is inevitable or in cases of missed abortion, medically induced first-trimester treatment with prostaglandins (i.e., misoprostol given vaginally or orally in a dose of 200–800 μg) combined with an antiprogesterone (i.e., mifepristone 600 mg orally) has been shown to be safe, effective, less invasive, and more private than surgical intervention. However, if this approach is unsuccessful or if bleeding is excessive, then a surgical procedure (dilation and curettage, suction curettage) can still be needed [1, 2].
Midtrimester fetal loss ranges from 12 weeks until the fetus weighs ≥500 g or gestational age reaches 20 weeks. A gestational age of 22–23 weeks is more accurate. The etiology of midtrimester pregnancy loss can be more readily explained if a careful evaluation is undertaken.
Incidence and Etiology
By the end of the first trimester, spontaneous abortion becomes much less common and continues to decline as the pregnancy progresses. Spontaneous loss in the second trimester is estimated at 1.5–3%. After 16 weeks , the incidence is about 1% [3, 4]. Bleeding in the first trimester increases the incidence of second-trimester loss by a factor of two [5, 6]. Unlike first-trimester abortions that commonly are caused by chromosomal aneuploidies, midtrimester fetal losses are the result of a multitude of causes. The accurate estimate of the incidences of these various causes has no supportive data.
Race, ethnicity, prior poor obstetrical outcomes, and extremes of maternal age are risk factors for second-trimester abortion. There is speculation that first-trimester bleeding has been cited as a potent risk factor . Edlow et al. found that 27% of women with such a loss in the index pregnancy had a recurrent second-trimester loss in their next pregnancy. Furthermore, one-third of these women had a subsequent preterm birth .
The clinical presentation of second-trimester abortion is much like first-trimester loss. The gravida can present with pain and cramping in the lower abdomen, in the midline. Multigravid women who have experienced labor may report that their symptoms are very similar to labor contractions. Membrane rupture and/or vaginal bleeding are significant, ominous signs. When evaluated for their symptoms, cervical dilatation can be advanced and delivery of a nonviable fetus can be inevitable.
Other diagnoses need consideration if the patient is having pain, but does not seem to be contracting or is not bleeding. The differential diagnosis should include torsion of an adnexa, degeneration of uterine leiomyomata, urinary tract infection or calculi, and any number of gastrointestinal disorders including bowel obstruction. Concealed placental abruption should also be considered.
Normally, the blastocyst implants in the endometrial lining of the uterine cavity following fertilization and fallopian tube transit. Implantation anywhere other than that is considered an ectopic location. Ectopic pregnancies comprise 1–2% of all first-trimester pregnancies in the United States. Nonetheless, this disproportionally accounts for 6% of all pregnancy-related deaths [8, 9]. Furthermore, subsequent successful pregnancy likelihood is reduced after an ectopic pregnancy.
Urine and serum human chorionic gonadotropin (hCG) assays and transvaginal sonography have facilitated early diagnosis and treatment . Consequently, maternal survival and conservation of reproductive capability has improved (Fig. 6.3).
Approximately 95% of ectopic pregnancies occur in the fallopian tube giving rise to fimbrial, ampullary, isthmic, or interstitial tubal pregnancies [10, 11]. The ampulla is the most frequent site, followed by the isthmus. Five percent of non-fallopian tube ectopic pregnancies implant in the ovary, peritoneal cavity, cervix, or prior cesarean scar. Rarely, a twin pregnancy occurs with one conceptus in the uterus and the other one implanted ectopically. This “heterotopic” pregnancy rate is approximately 1 per 30,000 pregnancies. Conversely, the development of assisted reproductive technologies (ARTs) has increased their incidence to 1 in 7000 overall, and following ovulation induction, it can be as high as 0.5–1% . Twin tubal pregnancy with both embryos in the same tube or with one in each tube has been reported [13, 14]. The admiration of immunoglobulin G (IgG) anti-D immunoglobulin should be given to D-negative (Rh negative) women with ectopic pregnancies (Fig. 6.4).
The underlying cause of many tubal ectopic pregnancies is abnormal fallopian tube anatomy. Previous surgeries for prior tubal pregnancy, fertility restoration, or for sterilization render the highest risk of tubal implantation. After one previous ectopic pregnancy, the chance of another approximates 10% [15, 16]. History of sexually transmitted disease or other tubal infection, which can alter normal tubal anatomy, is a common risk factor. One episode of salpingitis can result in a subsequent ectopic pregnancy in up to 9% of women . Peritubal adhesions consequent of salpingitis, appendicitis, or endometriosis can further increase the risk of tubal pregnancy. Salpingitis isthmica nodosa, a condition in which epithelium-lined diverticula protrude into a hypertrophied muscularis layer of the uterus, additionally poses an increased risk . Congenital fallopian tube anomalies, especially those secondary to in utero diethylstilbestrol exposure (extremely rare today), can result in anomalous tubes and higher ectopic rates .
In modern practice, ectopic pregnancies rarely rupture. This is due to earlier patient presentation and more precise diagnostic technology . Early on, symptoms and signs of ectopic pregnancy are typically subtle or even absent. The gravida has no suspicion of tubal pregnancy and assumes that she has a normal early pregnancy or is experiencing a miscarriage.
A “classic” presentation is typified by the triad of delayed menstruation, pain, and vaginal bleeding or spotting . When rupture ensues, there is usually severe lower abdominal and pelvic pain that is commonly described as sharp, stabbing, or tearing. Tenderness is elicited during abdominal palpation. Bimanual pelvic examination causes exquisite pain. Cervical motion tenderness is often present. The posterior vaginal fornix can bulge from blood in the rectouterine cul-de-sac, or a tender, boggy mass can be felt to one side of the uterus. The uterus can be displaced to one side by an ectopic mass. The uterus can also be somewhat enlarged due to hormonal stimulation. Shoulder or neck pain, a result of diaphragmatic irritation, is observed in about half of patients with significant hemoperitoneum.
Vaginal spotting or bleeding is reported by 60–80% of women with tubal pregnancy. Occasionally, there is profuse vaginal bleeding which is suggestive of an incomplete abortion. Furthermore, ectopic pregnancy can lead to profound intraabdominal hemorrhage. Moderate bleeding can induce no change in vital signs, a slight rise in blood pressure, or a vasovagal response with bradycardia and hypotension. Birkhahn and colleagues observed that in 25 gravidas with ruptured ectopic pregnancy, the majority at presentation had a heart rate <100 beats per minute and a systolic blood pressure >100 mm Hg . Blood pressure will fall and pulse will rise only if bleeding persists and hypovolemia becomes significant. Vertigo or syncope can develop.
Hemoglobin or hematocrit readings can at first show only a slight reduction even with significant hemoperitoneum. Therefore, following an acute hemorrhage, a decrease in hemoglobin or hematocrit level over several hours is a more valuable index of blood loss than is the initial level. In roughly half of women with a ruptured ectopic pregnancy, a leukocytosis of up to 30,000/μL can be found.
Endometrium that is hormonally prepared for pregnancy is called decidua , and the degree to which the endometrium is converted with ectopic pregnancy is variable. Consequently, along with bleeding, women with ectopic tubal pregnancy can pass a decidual cast. This is the sloughed endometrium that takes the form of the endometrial cavity (Fig. 6.6). Significantly, decidual sloughing can occur with uterine abortion. This tissue should be evaluated and then submitted to pathology for evidence of a conceptus. If there is no clear gestational sac or if no chorionic villi are identified histologically, then consideration of ectopic pregnancy must be entertained by the clinician.
Decidual cast (© McGraw-Hill Inc. All rights reserved. Williams’ Textbook of Obstetrics, 24th ed. Used with permission)
Abdominal pain in the pregnant patient creates an extensive differential diagnosis. Uterine conditions such as miscarriage, infection, degenerating or enlarging leiomyomata, molar pregnancy, or round-ligament pain are all under consideration. Adnexal pathology includes ectopic pregnancy; hemorrhagic, ruptured, or torsioned ovarian masses; salpingitis; or tuboovarian abscess. Furthermore, appendicitis, cystitis, renal stone, or gastroenteritis are nongynecologic sources of lower abdominal pain in early pregnancy.
Several algorithms have been proposed to diagnose ectopic pregnancy. The majority includes these crucial components : physical findings, transvaginal sonography (TVS), and serum hCG level measurement (the initial and the consequent pattern of rise or decline) and diagnostic surgery. Surgical options include uterine curettage, laparoscopy, and, occasionally, laparotomy. Women with presumed or obvious rupture should undergo urgent surgical intervention. When evaluating a suspected unruptured ectopic pregnancy, care must be taken to avoid the interruption of a normal pregnancy. However, strategies that reduce the potential for normal pregnancy interruption can postpone the diagnosis of an ectopic pregnancy.
Beta Human Chorionic Gonadotropin
The diagnosis of ectopic gestation requires a rapid and accurate determination of pregnancy. Available serum and urine pregnancy tests utilizing enzyme-linked immunosorbent assays (ELISAs) for hCG are sensitive to levels of 10–20 mIU/mL and are positive in >99% of ectopic pregnancies . Ectopic pregnancies with negative hCG levels are rare.
Patients who present with bleeding or pain as well as a positive pregnancy test result should undergo initial transvaginal sonography (TVS) to identify the location of the gestation. Diagnosis is ascertained if a yolk sac, embryo, or fetus is identified within the uterus or the adnexa. However, often a TVS is nondiagnostic, and tubal pregnancy remains possible. When neither intrauterine nor extrauterine pregnancy is identified, the term “pregnancy of unknown location” (PUL) is applied until additional clinical findings allow determination of pregnancy location.
Levels Above the Discriminatory Zone
Several investigators have elucidated discriminatory hCG levels above which nonvisualization of an intrauterine pregnancy (IUP) indicates that the pregnancy is either nonviable or is ectopic. Barnhart et al. found that an empty uterus with a serum hCG concentration ≥1500 mIU/mL was 100% accurate in ruling out a live uterine pregnancy . There are several institutions that set their discriminatory threshold higher at ≥2000 mIU/mL. Moreover, Connolly and colleagues stated that there is evidence to suggest an even higher threshold. They posited that with a viable uterine pregnancy, a gestational sac was seen 99% of the time with a discriminatory level of 3510 mIU/mL .
When initial hCG level surpasses the set discriminatory level and there is no evidence for a uterine pregnancy observed with TVS, then the diagnosis is attributed to a failed uterine pregnancy, completed abortion, or an ectopic pregnancy. However, early multifetal gestation should be considered. If in a stable patient that a PUL that could still have a normal pregnancy, it is judicious to continue expectant management with serial hCG level assessment to prevent aborting an early normal pregnancy. The serial hCG levels will drop rapidly when the patient history or extruded tissue suggests a completed abortion. Curettage will differentiate an ectopic from a nonviable uterine pregnancy. Barnhart and colleagues do not recommend diagnostic curettage as it results in unnecessary surgical therapy . This can be countered by concern for methotrexate toxicity if it is administered inappropriately to patients with a presumed ectopic pregnancy.
Levels Below the Discriminatory Zone
When the initial hCG level falls below the set discriminatory value, the location of the pregnancy may not be technically discernible with TVS. With cases of PUL, serial hCG level assays are repeated to identify patterns that specify either a growing or failing uterine pregnancy. Results that rise or fall outside these expected ranges increase the concern for ectopic pregnancy. Therefore, women with a suspected ectopic pregnancy, but whose initial hCG level is below the discriminatory threshold, are reevaluated at 2 days intervals. First, with early normally progressing uterine pregnancies, Kadar and Romero noted that the mean doubling time for serum hCG levels was approximately 48 h . The lowest normal value for this increase was 66%. Barnhart et al. reported a rise of 53% within 48-h with a 24-h minimum rise of 24% . Seeber and associates proposed a more conservative 35% 48-h rise . Silva and colleagues advise that one-third of women with an ectopic pregnancy experience a 53% rise at 48 h. Furthermore, they reported that no single pattern characterizes ectopic pregnancy and that approximately 50% of ectopic pregnancies are found to have decreasing hCG levels, whereas the other half will have increasing levels .
Failing intrauterine pregnancies also show patterns of hCG level decline as well. Decline rates ranging between 21% and 35% are typical.
In pregnancies without these expected rises or falls in hCG levels, distinction between a nonliving intrauterine and an ectopic pregnancy can be aided by repeat hCG level evaluation . Uterine curettage can be performed as well. Barnhart and coworkers concluded that endometrial biopsy was less sensitive than curettage . Prior to curettage, a repeat TVS examination can reveal new informative findings .
Serum progesterone determinations can clarify the diagnosis in a few patients [31, 32]. A value of 25 ng/mL or higher eliminates the likelihood of ectopic pregnancy with 92.5% sensitivity [33, 34]. Values <5 ng/mL are found in only 0.3% of normal pregnancies . Therefore, values <5 ng/mL indicate either a nonviable uterine pregnancy or an ectopic pregnancy. Ectopic pregnancies typically demonstrate progesterone levels ranging between 10 and 25 ng/mL; therefore, the clinical utility of progesterone is limited . One exception is that pregnancy conceived via ART can be associated with higher than usual progesterone levels .
Patients with an ectopic pregnancy require TVS to find evidence of a uterine pregnancy or an ectopic gestation. An intrauterine gestational sac is typically observable between 4½ and 5 weeks. The yolk sac appears between 5 and 6 weeks, and a fetal pole with cardiac activity is first detected at 5½ to 6 weeks. These structures are visualized slightly later with transabdominal sonography.
In patients with an ectopic pregnancy, a trilaminar endometrial pattern can be diagnostic (Fig. 6.7). However, its specificity is 94%, but with a sensitivity of only 38% . In addition, Moschos and Twickler found that in women with PUL at presentation, no normal pregnancies had a stripe thickness <8 mm .
Trilaminar sonographic pattern associated with ectopic gestation (© McGraw-Hill Inc. All rights reserved. Williams’ Textbook of Obstetrics, 24th ed. Used with permission)
Collections of anechoic fluid, often observed normally with an early intrauterine gestational sac, can possibly be seen with ectopic pregnancy. Two features observed include pseudogestational sac and decidual cyst. A pseudosac is a fluid collection between the endometrial layers and conforms to the cavity shape. Finding a pseudosac increases the risk of ectopic pregnancy [40, 41]. Secondly, a decidual cyst is an anechoic area within the endometrium but distant from the canal and often at the endometrial-myometrial border. Ackerman et al. proposed that this finding signifies early decidual breakdown and leads to decidual cast formation .
These findings are dissimilar to the intradecidual sign seen with intrauterine pregnancy, that being an early gestational sac and is eccentrically located within one of the endometrial stripe layers . The American College of Obstetricians and Gynecologists recommends restraint in diagnosing a uterine pregnancy when a definite yolk sac or embryo is absent .
The sonographic evidence of ectopic pregnancy depends on visualization of an adnexal mass separate from the ovary. An ectopic pregnancy is clearly confirmed if fallopian tubes and ovaries are seen and an extrauterine yolk sac, embryo, or fetus is identified. There are cases in which a hyperechoic halo or tubal ring surrounding an anechoic sac can be imaged. Alternatively, an inhomogeneous complex adnexal mass is usually the result of hemorrhage inside the ectopic sac or by an ectopic gestation that has ruptured into the tube. Generally, roughly 60% of ectopic pregnancies are seen as an inhomogeneous mass next to the ovary; 20% appear as a hyperechoic ring; and 13% have an obvious gestational sac with a fetal pole . It is important to note that not all adnexal masses are ectopic pregnancies, and correlation of sonographic findings with other clinical information is essential in making an accurate diagnosis.
There is a color Doppler image referred to as “the ring of fire” which represents placental blood flow within the periphery of the complex adnexal mass. Though this can assist in the diagnosis, this finding also appears with a corpus luteum of pregnancy; therefore, differentiation can be challenging.
Evaluation for hemoperitoneum can add valuable clinical information in women suspected of having an ectopic pregnancy. Usually, this is detected with sonography. However, this can also be diagnosed by culdocentesis, a valuable diagnostic test that is utilized less and less today.
The sonographic fluid noted in cases of hemoperitoneum is anechoic or hypoechoic. Blood accumulates initially in the dependent retrouterine cul-de-sac, and then surrounds the uterus as it fills the pelvis (Fig. 6.8). Fifty milliliters can be imaged in the cul-de-sac using TVS, and transabdominal imaging improves the assessment of the extent of hemoperitoneum. Significant intraabdominal hemorrhage results in blood tracking up the pericolic gutters to fill Morison’s pouch near the liver. Free fluid in this pouch is usually not apparent until accumulated blood reaches 400–700 mL [46–48]. Peritoneal fluid in conjunction with an adnexal mass is highly predictive of ectopic pregnancy . A small amount of peritoneal fluid is physiologically normal.
(a) Sonographic evidence of hemoperitoneum. (b) Culdocentesis (© McGraw-Hill Inc. All rights reserved. Williams’ Textbook of Obstetrics, 24th ed. Used with permission)
Culdocentesis is a simple technique. It was used frequently in the past to diagnose hemoperitoneum. The cervix is grasped with a tenaculum and pulled outward and upward toward the symphysis. A syringe with a long 18-gauge needle is used to penetrate the posterior vaginal fornix into the retrouterine cul-de-sac. If fluid such as blood or pus is present, it can be aspirated. Failure to obtain fluid, however, is interpreted as an unsatisfactory entry into the cul-de-sac and does not rule out ectopic pregnancy. When fluid is obtained and contains fragments of old clots or frank nonclotting blood, this finding is compatible with the diagnosis of hemoperitoneum. Conversely, if the blood sample clots, it might have been drawn directly from an adjacent blood vessel or from a briskly bleeding ectopic pregnancy. A number of studies have challenged its usefulness, and culdocentesis has been largely replaced by TVS [50, 51]. This author appreciates the advances in imaging in the diagnosis of ectopic gestation, however, continues to train residents in the technique of culdocentesis so that if one encounters a patient with a suspected ectopic pregnancy and reliable imaging is unavailable, a simple diagnostic test can help to establish the diagnosis .
Minimally invasive, endoscopic procedures afford direct visualization of the fallopian tubes and pelvis. Pelviscopy affords a reliable diagnosis in the vast majority of cases of suspected ectopic pregnancy. Furthermore, pelviscopy is therapeutic in many instances, since the ectopic pregnancy can be managed with this technique.
Interstitial pregnancies are lodged in the proximal tubal segment that lies within the muscular uterine wall. Sometimes, they are inaccurately called cornual pregnancies ; however, cornual pregnancies describe a conception that develops in the rudimentary horn of a uterus with a müllerian anomaly. Risk factors are similar to others mentioned for tubal ectopic pregnancy; however, previous ipsilateral salpingectomy is a specific risk factor for interstitial pregnancy . Interstitial pregnancies tend to rupture later than more distal tubal ectopic pregnancies, between 8 and 16 weeks of amenorrhea. This is consequent to greater distensibility of the myometrium covering the interstitial fallopian tube segment. Ruptures of interstitial gestations are associated with an increased risk of mortality; as high as 2.5% because of the proximity of these pregnancies to the uterine and ovarian arteries, thus producing severe hemorrhage .
Interstitial pregnancy can be detected early in many cases utilizing TVS and serum hCG assays, but diagnosis can still be challenging. At times, these pregnancies appear sonographically comparable to an eccentrically implanted intrauterine pregnancy, more so in a uterus with a müllerian anomaly. Differentiation includes an empty uterus, a gestational sac seen separate from the endometrium and >1 cm away from the most lateral edge of the uterine cavity, and a thin, <5-mm myometrial mantle surrounding the sac . Furthermore, an echogenic line, referred to as the “interstitial line sign,” extending from the gestational sac to the endometrial cavity most likely represents the interstitial portion of the fallopian tube and is highly sensitive and specific . Occasionally, three-dimensional sonography, magnetic resonance imaging (MRI), or diagnostic pelviscopy can also provide clarification [55, 56]. Pelviscopically, an enlarged protuberance lying outside the round ligament coexistent with normal distal fallopian tubes and ovaries is observed (Fig. 6.9).
(a) Sonographic evidence of interstitial pregnancy . (b) Operative view of interstitial pregnancy (© McGraw-Hill Inc. All rights reserved. Williams’ Textbook of Obstetrics, 24th ed. Used with permission)
Surgical management with cornual resection or cornuostomy can be undertaken via laparotomy or pelviscopy, depending on patient hemodynamic stability and surgeon expertise [57, 58]. Whatever approach is chosen, intraoperative intramyometrial vasopressin injection can decrease surgical blood loss. Postoperative hCG levels should be obtained to exclude remnant trophoblast. Cornual resection excises the gestational sac and surrounding cornual myometrium by means of a wedge resection, whereas cornuostomy involves incision of the cornua and suction or instrument extraction of the pregnancy. The availability of computer-assisted pelviscopy in the hands of this author has considerably improved this operation.
Conservative medical management can be considered if the diagnosis is made early on . Consensus regarding methotrexate route or regimen is lacking because of the low incidence of this ectopic gestation. Jermy and associates reported a 94% success with systemic methotrexate using a dose of 50 mg/m2 BSA . This, however, was a small series. Others have described direct methotrexate injection into the gestational sac . Importantly, because these patients usually have higher initial serum hCG levels at diagnosis, a longer period of surveillance is usually needed.
It is not clear what risk of uterine rupture with subsequent pregnancies is following either medical or conservative surgical management. Therefore, close observation of these patients during subsequent pregnancy, as well as the strong consideration of elective cesarean delivery, is reasonable.
Different than interstitial pregnancy, the term angular pregnancy describes intrauterine implantation in one of the lateral angles of the uterus and medial to the uterotubal junction and round ligament. This is relevant since angular pregnancies sometimes can be carried to term attendant with an increased risk of abnormal placentation and its consequences .
Abdominal Pregnancy (Fig. 6.5)
Abdominal pregnancy , technically, is an implantation in the peritoneal cavity exclusive of tubal, ovarian, or intraligamentous implantations. These pregnancies are rare with an incidence of 1 in 10,000 to 25,000 live births [63, 64]. A zygote can traverse the tube and implant primarily in the peritoneal cavity; however, the majority of abdominal pregnancies are assumed to follow early tubal rupture or abortion with reimplantation. In the rare instance of advanced extrauterine pregnancy, it is common that the placenta is still at least partially attached to the uterus or adnexa.
Diagnosis is challenging. There can be no or minimal symptoms. Laboratory tests are usually normal; however, maternal serum α-fetoprotein (MSAFP) levels can be elevated. Clinically, palpation can indicate an abnormal fetal position or the cervix can be displaced . Imaging of an abdominal pregnancy might not be recognized, and the diagnosis is often overlooked . Oligohydramnios is common but may or may not have significance. Other observations include a fetus seen separate from the uterus or eccentrically positioned within the pelvis; lack of myometrium between the fetus and the maternal anterior abdominal wall or bladder; and extrauterine placental tissue . MR imaging can provide additional anatomical information and can be used to confirm the diagnosis and provide maximal details regarding placental implantation [68, 69].