Rare Ectopic Pregnancies – A Literature Review for the Period 2007 – 2019 on Locations Outside the Uterus and Fallopian Tubes

Key words

ectopic pregnancy - rare locations - abdominal pregnancy

Introduction

The frequency of ectopic pregnancies (EP) is estimated as 11 ectopic per 1000 (eutopic) pregnancies [1]. Despite improvements in diagnosis and treatment options, EP is still associated with a high risk of mortality and accounts for around 6 – 13% of all pregnancy-related deaths in the first trimester of pregnancy [2]. Tubal pregnancies are the most common form of EP with an incidence of 95%, followed by implantation sites in the cervix, the ovary and the abdominal cavity [3]. Non-tubal EP are reported to have a 7 – 8 times higher risk of maternal mortality compared to tubal pregnancies [4], [5].

Known risk factors for non-tubal ectopic pregnancies include a previous history of EP, minor pelvic infections, pregnancy by assisted reproductive technology, and smoking [3]. Typical leading clinical symptoms of a ruptured EP are progressive pain in the lower abdomen, often accompanied by pronounced peritonism, shoulder area pain if hemoperitoneum is present, and acyclic vaginal bleeding, as well as dizziness, faintness and nausea [6]. As abdominal bleeding may be quite heavy, ectopic pregnancy is a real gynecological emergency because of the rapid onset of hemorrhagic shock. Vaginal ultrasound scan is usually carried out in patients with a positive pregnancy test to obtain the correct diagnosis as quickly as possible. In cases with EP, imaging will show a thickened endometrium but no intrauterine gestational sac or only a pseudo-gestational sac with no yolk sac [1]. In some cases, the implantation site in the adnexal area and fluid in the pouch of Douglas can be identified on imaging. The implantation site and the extent of symptoms determine the type of treatment and urgency of treatment. Particularly in cases with advanced abdominal EP, the question is often whether the ectopic placenta can be resected with limited bleeding or whether it can be left in situ. There are currently no guidelines by the AWMF (the Association of the Scientific Medical Societies in Germany) or the DGGG (the German Society for Gynecology and Obstetrics) on the appropriate approach to treat EP. Guidelines are planned and their completion has been announced for 2020 [7].

To obtain a rapid and correct diagnosis of an ectopic pregnancy in a rare location, it is important to be aware of the potential sites of implantation. Locations outside the uterus, tubes and ovaries are of particular interest, as they present a significant diagnostic challenge in emergency gynecological medicine because of the number of different potential implantation sites [8]. In 2007, Molinaro and Barnhart published a study “Ectopic pregnancies in unusual locations” [6]; in 2014 the Cochrane Foundation initiated a protocol for a not yet published systematic review [8]; and in 2016, Parker and Srinivas summarized the approaches for the management of non-tubal ectopic pregnancies [3]. These publications were almost exclusively based on case reports. We were unable to find a review which collected and summarized the known cases of non-tubal and non-ovarian EP. Case reports on rare locations were therefore collected for this review. As a review of the literature already existed [6], we selected the year 2007 as our chronological starting point. The aim of our literature search was to provide a comprehensive summary of the publications published since 2007 on rare locations of extrauterine pregnancies, their presenting symptoms, diagnosis and treatment.

Methods

Inclusion and exclusion criteria

A systematic search was carried out in the three online databases PubMed, Livivo and Google Scholar. English-language and German-language case reports from January 2007 onward which described an ectopic pregnancy in an unusual location were included in our review. Reports about uterine implantation sites (cervical and intramural pregnancies as well as scar pregnancies) were excluded as were ampullary, isthmic and interstitial tubal pregnancies and ovarian pregnancies. Pregnancies which occurred after hysterectomy and heterotopic pregnancies were not included.

Search strategy

The search was carried out in June 2019 for the period 2007 – 2019 using the MeSH terms “ectopic pregnancy” and “case report” and a filter for German-language and English-language publications. The subcategories “tubal pregnancy,” “cornual pregnancy,” “angular pregnancy,” “ovarian pregnancy” and “scar pregnancy” were excluded from the search results using the operator “NOT.”

This study complies with the statute of the Charité on ensuring good scientific practice.

Results

After carrying out a systematic literature search, a total of 115 suitable case reports from 113 publications were included in the study and their full text was analyzed ([Fig. 1]). Based on anatomical sites and pathophysiology, cases were divided into intraperitoneal and extraperitoneal EP locations. Intraperitoneal implantation sites included all locations on the uterine serosa, the uterine ligaments, the liver, spleen, and bowel including the mesentery and the peritoneum of the pelvic wall, the diaphragm and the inguinal canal. Reported extraperitoneal sites of EP implantation included sites on the large arteries, in the area of the pancreas and the kidneys, in rectovaginal and paravesical spaces and in the obturator foramen.

Fig. 1 Flow chart showing the process and results of the literature search in the three databases.

As regards the pathogenesis of intraperitoneal EP, it is important to distinguish between primary and secondary abdominal pregnancy. With primary abdominal pregnancy, it is assumed that fertilization and implantation of the ovum occurs in the peritoneal space as a result of the anatomical conditions at the open distal portion of the uterine tube. In the case of secondary abdominal pregnancies, it is assumed that a secondary implantation in the peritoneal cavity occurs after rupture of a primary tubal pregnancy [3]. The pathogenesis of retroperitoneal EP, however, has not been conclusively established. Peritoneal fistulas following surgery [9] and lymphatic pathways [10] have been postulated as possible routes.

Presenting symptoms, diagnosis and treatment are summarized below, with cases grouped according to the location of the implantation site.

A) Implantation in the uterine serosa and the pouch of Douglas ([Table 1])

Table 1 Implantation in the uterine serosa and the pouch of Douglas.

No.	Source	Age	GP score	GW	β-HCG	Symptoms	Diagnostic procedure	Intervention	Placental management	Previous medical history
Abbreviations: GP score = gravidity and parity score [14], GW = week of gestation at the time of diagnosis, β-HCG in mIU/mL, if not stated otherwise, Diagnostic procedure = final procedure carried out to obtain the diagnosis, (L)AbP = (lower) abdominal pain, VB = vaginal bleeding, X = asymptomatic, BP = back pain, Vom. = vomiting, Resp. = respiratory problems, exLap/Ltm = exploratory laparoscopy/laparotomy, Sono = abdominal/transvaginal ultrasound scan, MRI = magnetic resonance imaging, Lap/Ltm = surgical treatment with laparoscopy/laparotomy, MTX = methotrexate, IVF(-ET) = in vitro fertilization (with embryo transfer), ICSI = intracytoplasmic sperm injection
1	Abdelrahman, 2017, South Sudan [15]	25	G2P0	35	–	AbP	exLtm	Ltm, live birth	Partial resection	–
2	Bhoil, 2016, India [16]	29	G2P2	34	–	AbP	MRI	Ltm, live birth	Resection	–
3	Bohiltea, 2015, Romania [17]	23	G0P0	23	–	AbP	exLtm	Ltm	Resection, uterine wedge resection	IVF
4	Cho, 2015, Taiwan [18]	31	G0P0	–	40 100	VB	Sono	Lap, MTX	Left in situ	–
5	Dabiri, 2014, USA [19]	27	G2P01	33	–	AbP	exLtm	Ltm, live birth	Resection, hysterectomy	–
6	Dassah, 2009, Ghana [20]	21	G0P0	22	–	LAbP	Sono	Ltm	Resection	–
7	Gayer 2012, USA [21]	30	G2P1	19	–	X	MRI	Ltm	–	–
8	Gidiri, 2015, Zimbabwe [22]	40	G4P3	21	–	LAbP, BP	Sono	Ltm	Resection	–
9	Gidiri, 2015, Zimbabwe [22]	37	G2P0 + 1	35	–	AbP	Sono	Ltm, live birth	Left in situ	Myomectomy
10	Hailu, 2017, Ethiopia [4]	26	G4P2	37	–	AbP, Vom.	exLtm	Ltm, live birth	Resection	–
11	Hishikawa, 2016, Japan [23]	32	G3P1	–	120,60	AbP	exLap	Lap	Resection	–
12	Isah, 2008, Nigeria [24]	30	G0P0	39	–	VB	Sono	Ltm, live birth	Resection	–
13	Kim, 2013, Korea [25]	28	G1P0	18	–	X	Sono	Ltm (34th GW) live birth	Resection	Previous EP
14	Marcelin, 2018, France [26]	25	G2P0	27	–	–	MRI	Ltm	Left in situ, embolization, Lap because of abscess formation	–
15	Miyauchi, 2015, Japan [5]	36	G1P1	5	2 050	LAbP	exLap	Ltm	Resection	–
16	Mengistu, 2015, Ethiopia [27]	32	G3P2	36	–	Resp.	MRI	Ltm, live birth	Resection, hysterectomy	–
17	Muehlparzer, 2011, Austria [28]	26	–	34	–	LAbP	exLtm	Ltm with live birth	Resection, hysterectomy, salpingectomy	–
18	Nassali, 2016, Botswana [29]	26	G0P0	41	–	AbP	exLtm	Ltm with live birth	Resection	–
19	Nkusu, 2008, Cameroon [30]	30	G5P5	at term	–	AbP	Sono	Ltm	Resection	–
20	Panagiotakis, 2009, USA [31]	24	G0P0	7	–	AbP	exLap	Lap, MTX	Left in situ	–
21	Parekh, 2008, India [32]	31	–	15	–	LAbP	Sono	Ltm	Resection, hemostasis	–
22	Patel, 2016, USA [33]	26	G0P0	16	–	LAbP	MRI	Ltm, MTX	Left in situ, re-Ltm with resection	–
23	Pieh-Holder, 2012, USA [34]	39	G1P0	25	–	X	MRI	Ltm, live birth	Left in situ, embolization	Myomectomy
24	Pradhan, 2013, India [35]	35	G0P0	26	–	AbP, Resp.	Autopsy	–	–	–
25	Promsonthi, 2007, Thailand [36]	41	G2P2	40	–	X	exLtm	Ltm, live birth	Left in situ, abscess formation, Ltm, hysterectomy, salpingo-oophorectomy	–
26	Rohilla, 2018, India [37]	27	Multipara	40	–	X	Sono	Ltm, live birth	Resection, salpingo-oophorectomy	–
27	Sib, 2018, Burkina Faso [38]	22	G4P2	at term	–	X	Sono	Ltm	Resection, salpingectomy	–
28	Shih, 2007, Taiwan [39]	33	G0P0	20 days post ET	901	X	Sono	Lap	Resection by Ltm	IVF-ET
29	Tucker, 2017, USA [40]	28	G2P1	22	–	X	exLap	Ltm	Resection	–
30	Yanaihara, 2017, Japan [41]	37	P0	6	–	X	exLap	Lap	Resection	ICSI
31	Yoder, 2016, USA [42]	30	G2P1	33 days post ET	12 400 pg/mL	X	exLap	Lap	Resection	IVF-ET
32	Zhang, 2008, China [43]	30	G3P1	38	–	AbP, Vom.	exLtm	Ltm, live birth	Resection, hysterectomy	–

Presenting symptoms

• Abdominal pain (14/32 cases), particularly in the lower abdomen; abdominal pain and respiratory problems (1/32); abdominal pain and vomiting (2/32); abdominal pain and back pain (1/32)

• Asymptomatic (10/32)

• Vaginal bleeding (2/32)

• Respiratory problems (1/32)

• Not specified (1/32)

Diagnosis and diagnostic procedures

• Earliest diagnosis made in the 5th week of gestation (GW) post last menstrual period, latest diagnosis in the 41st GW

• Diagnosed by ultrasound scan (11/32), exploratory laparoscopy (6/32), exploratory laparotomy (8/32), MRI (6/32) or at autopsy (1/21)

Intervention

• Surgical treatment with laparotomy (25/32), with additional administration of MTX in one case

• Surgical treatment with laparoscopy (6/32) with additional administration of MTX in 2 cases

• Not specified (2/32)

Placental management

• Resection of the placenta (23/32), with additional organ removal in 7 cases

• Placenta left in situ (7/32), with re-laparotomy with resection additionally performed in 2 cases

• Not specified (1/32) (autopsy)

It is worth noting that in many cases the pregnancy was already far advanced at diagnosis and many of the patients were asymptomatic. In 14/32 cases, a live infant was delivered by laparotomy. The most common site of implantation was the posterior uterine wall.

B) Implantation on the broad ligament of uterus ([Table 2])

Table 2 Implantation in and on the broad ligament of uterus.

No.	Source	Age	GP score	GW	β-HCG	Symptoms	Diagnostic procedure	Intervention	Placental management	Previous medical history
Abbreviations: GP score = gravidity and parity score, GW = week of gestation at diagnosis, β-HCG in mIU/mL, Diagnostic procedure = final procedure carried out to obtain the diagnosis, (L)AbP = (lower) abdominal pain, VB = vaginal bleeding, X = asymptomatic, Dys. = dysuria, Vom. = vomiting, exLap/Ltm = exploratory laparoscopy/laparotomy, Sono = abdominal/transvaginal ultrasound scan, MRI = magnetic resonance imaging, Lap/Ltm = surgical treatment with laparoscopy/laparotomy, MTX = methotrexate, IUI = intrauterine insemination, IUD = intrauterine device
1	Abdul, 2008, Nigeria [44]	29	G7P6	22	–	X	Sono	Ltm	Resection, salpingo-oophorectomy	–
2	Abdul, 2008, Nigeria [44]	33	G7P6	20	–	X	Sono	Ltm	Resection, salpingo-oophorectomy	–
3	Akhtar, 2011, Pakistan [45]	35	G3P2	37	–	AbP	Sono	Ltm, live birth, MTX	Left in situ	–
4	Atis, 2014, Turkey [46]	34	Multipara	8	10 290	LAbP, VB	Sono	Ltm	Resection	–
5	Cosentino, 2017, Italy [47]	35	G3P1	12	–	X	Sono	Lap	Resection, salpingo-oophorectomy	–
6	Dahab, 2011, Saudi Arabia [48]	23	G0P0	40	75 542	LAbP, Dys.	Sono	Ltm, live birth	Resection	–
7	Gudu, 2015, Ethiopia [49]	35	P2	37	–	AbP, VB	Sono	Ltm, live birth	Resection, salpingectomy	–
8	Kar 2011, India [50]	31	G0P0	8	9 470	X	Sono	MTX + Lap	Resection	IUI, endometriosis
9	Kim, 2016, Tanzania [51]	27	G3P2	13	–	AbP	MRI	Ltm	Resection, salpingo-oophorectomy, partial omentectomy	HIV positive
10	Nayar, 2016, Portugal [52]	25	G0P0	6	24 719	AbP, VB	Sono	Lap	Resection, salpingectomy
11	Parulekar, 2011, India [53]	22	G2P1	5	1 250	LAbP	exLap	Lap	Resection	Lost IUD
12	Phupong, 2016, Thailand [54]	27	G2P1	37	–	X	exLtm	Ltm, live birth	Resection, hysterectomy, salpingo-oophorectomy	–
13	Rama, 2015, India [55]	23	G2P1	12	–	AbP, VB, Vom.	exLtm	Ltm	Resection, salpingo-oophorectomy	–
14	Sassi, 2017, Tunisia [56]	32	G2P1	5	26 784	LAbP	Sono	Lap	Resection	–
15	Seckin, 2011, Turkey [57]	28	G0P0	39	–	AbP	exLtm	Ltm, live birth	Left in situ, re-Ltm because of abscess formation	–
16	Shamaash, 2017, Egypt [58]	25	G2P0 + 1	17	–	X	exLtm	Ltm	Resection, salpingectomy	–
17	Sheethal, 2017, India [59]	28	G0P0	37	–	X	exLtm	Ltm, live birth	Resection	–
18	Yasutake, 2013, Japan [60]	34	G2P1	8	13 195	X	Sono	Lap → Ltm, MTX	Left in situ	–

Presenting symptoms

• Abdominal pain (6/18), particularly in the lower abdomen

• Abdominal pain and vaginal bleeding (4/18)

• Asymptomatic (8/18)

Diagnosis and diagnostic procedures

• Earliest diagnosis made in the 5th GW, latest diagnosis in the 39th GW with the birth of a healthy neonate

• Diagnosed by ultrasound scan (11/18), exploratory laparotomy (5/18), MRI (1/18) or exploratory laparoscopy (1/18)

Intervention

• Surgical treatment with laparotomy (13/18), with additional administration of MTX in 2 cases

• Surgical treatment with laparoscopy (5/18), with additional administration of MTX in 1 case

Placental management

• Placental resection (15/18), combined with organ removal in 9 cases

• Placenta left in situ (3/18)

Some cases required a salpingectomy to remove the placenta and/or achieve hemostasis. It should be noted that some ectopic pregnancies were continued almost to term, with delivery of a live infant (6/18).

C) Implantation in and on the liver ([Table 3])

Table 3 Implantation in and on the liver.

No.	Source	Age	GP score	GW	β-HCG	Symptoms	Diagnostic procedure	Intervention	Placental management	Previous medical history
Abbreviations: GP score = gravidity and parity score, GW = week of gestation at diagnosis, β-HCG in mIU/mL, Diagnostic procedure = final procedure carried out to obtain the diagnosis, * = in the subhepatic space adjoining the gallbladder, (L)AbP = (lower) abdominal pain, EgP = epigastric pain, RUAP = right upper abdominal pain, RSP = right shoulder pain, VB = vaginal bleeding, Vom. = vomiting, exLap/Ltm = exploratory laparoscopy/laparotomy, Sono = abdominal/transvaginal ultrasound scan, CT = computed tomography scan, MRI = magnetic resonance imaging, Lap/Ltm = surgical treatment with laparoscopy/laparotomy
1	Brouard, 2015, USA [61]	20	G4P4	37	–	X	exLtm	Ltm, live birth	Left in situ	–
2	Chin, 2010, Singapore [62]	30	G2P1	5	1 292	EgP, syncope, RSP	exLap	Lap, MTX	Resection	–
3	Guo, 2016, China [63]	31	–	–	81 418	abd. swelling	MRI	Ltm	Resection	–
4	Hao, 2016, China [64]	31	G2P1	6		AbP, abd. swelling	PET-CT	Ltm	–	–
5	Hu, 2014, China [65]	32	G3P2	8		EgP	MRI	Ltm	–	–
6	Kuai, 2013, China [66]	33	G4P2	6	186	RUAP, RSP	MRI	Ltm	Resection	–
7	Ma, 2013, China [67]	31	G6P2	8	23 824	RUAP	exLtm	Ltm, MTX	Left in situ, embolization	–
8	Moores, 2010*, UK [68]	23	G1P0	12	–	RUAP, RSP	Sono	KCl, MTX	Left in situ	–
9	Qiao, 2013, China [69]	31	G3P2	10	95 700	X	MRI	Ltm	Resection, partial resection of the liver	Tubal ligation
10	Ramphal, 2010, South Africa [70]	18	–	19	–	X	Sono	Ltm in the 34th GW, live birth	Left in situ	–
11	Sibetcheu, 2017, Cameroon [71]	24	G4P1	8	3 000	RUAP, VB	Sono	MTX	Left in situ	–
12	Wang, 2012, Japan [72]	33	G0P0	7	8 988	AbP, VB	CT	Ltm	Resection	–
13	Yadav, 2012, India [73]	25	G2P1	18		RUAP, Vom.	Sono	Ltm	Resection, embolization, unsuccessful hemostasis	–
14	Zhao, 2017, China [74]	21	G0	14	135 755	VB	MRI	MTX, Lap	Resection	–

Presenting symptoms

• Abdominal pain (4/14), particularly in the right upper quadrant

• Abdominal pain radiating into the right shoulder (3/14)

• Abdominal pain and vaginal bleeding (2/14)

• Vaginal bleeding (1/14)

• Asymptomatic (3/14)

• Abdominal swelling (1/14)

Diagnosis and diagnostic procedures

• Earliest diagnosis made in the 5th GW, latest diagnosis in the 37th GW with the birth of a healthy neonate

• Diagnosed by MRI (5/14), ultrasound scan (4/14), exploratory laparotomy (2/14), exploratory laparoscopy (1/14), CT (1/14) or PET-CT scan (1/14)

Intervention

• Surgical treatment with laparotomy (10/14), with additional administration of MTX in one case

• Surgical treatment with laparoscopy (2/14), with additional administration of MTX in both cases

• Feticide with potassium chloride (1/14) and administration of MTX

• Only administration of MTX (1/14)

Placental management

• Placental resection (7/14), combined with partial organ resection in 1 case

• Placenta left in situ (5/14)

• Not specified (2/14)

MRI and abdominal ultrasound were essential for diagnosis in those cases where the site of implantation was in the liver. In some cases, a live infant was delivered by laparotomy.

D) Implantation on the greater omentum ([Table 4])

Table 4 Implantation on the greater omentum.

No.	Source	Age	GP score	GW	β-HCG	Symptoms	Diagnostic procedure	Intervention	Placental management	Previous medical history
Abbreviations: GP score = gravidity and parity score, GW = week of gestation at diagnosis, β-HCG in mIU/mL, Diagnostic procedure = final procedure carried out to obtain the diagnosis, (L)AbP = (lower) abdominal pain, EgP = epigastric pain, VB = vaginal bleeding, Vom. = vomiting, exLap/Ltm = exploratory laparoscopy/laparotomy, Sono = abdominal/transvaginal ultrasound scan, CT = computed tomography scan, MRI = magnetic resonance imaging, Lap/Ltm = surgical treatment with laparoscopy/laparotomy, Pelv OP = prior history of pelvic surgery
1	Allen, 2007, UK [75]	31	G2P0 + 1	14	–	EgP, Vom., diarrhea	Sono	Ltm	Resection	Chlamydia
2	Bajis, 2018, Australia [76]	37	G2P2	4	1 480	LAbP, VB, syncope	Sono	Lap × 2	Resection	–
3	Behjati, 2009, UK [77]	27	G2P1	–	12 709	LAbP, syncope	exLap	Ltm	Resection, partial omentectomy	–
4	Chen, 2015, China [78]	18	G0P0	6	460	LAbP	CT	Lap	Resection, partial omentectomy	–
5	Chopra, 2009, India [79]	29	G4P3	6	–	AbP	Sono	Ltm	Resection	–
6	da Silva, 2008, Brazil [80]	36	G3P3	13	–	LAbP	exLtm	Ltm	Resection, partial omentectomy	–
7	Maiorana, 2014, Italy [81]	24	G1P0	8	8 047	LAbP	exLap	Lap	Resection	–
8	Seol, 2010, Korea [82]	26	G2P0	–	–	LAbP	exLap	Lap	Resection, partial omentectomy	–
9	Srinivasan, 2014, USA [83]	20	G2P1	8	1 057	LAbP	exLap	Lap	Resection, partial omentectomy	–
10	Takeda, 2016, Japan [84]	34	G2P0	8	–	–	MRI	Lap	Resection, partial omentectomy
11	Tanase, 2013, Japan [85]	32	G1P0	5	–	LAbP	exLap	Lap	Resection, partial omentectomy	Pelv OP
12	Yip, 2016, Singapore [86]	31	–	6	11 803	EGP	Sono	Lap → Ltm	Resection	–

Presenting symptoms

• Abdominal pain (10/12), often located in the lower abdomen, in one case with syncope

• Abdominal pain and vaginal bleeding with syncope (1/12)

• Not specified (1/12)

Diagnosis and diagnostic procedures

• Earliest diagnosis made in the 4th GW, latest diagnosis in the 14th GW

• Diagnosed by exploratory laparoscopy (5/12), ultrasound scan (4/12), MRI (1/12), exploratory laparotomy (1/12), or CT (1/12).

Intervention

• Surgical treatment with laparoscopy (7/12)

• Exploratory treatment with laparotomy (5/12)

Placental management

• Placental resection 12/12, combined with partial omentectomy in 7 cases.

E) Implantation on the bowel and mesenteries ([Table 5])

Table 5 Implantation on the bowel and mesenteries.

No.	Source	Age	GP score	GW	β-HCG	Symptoms	Diagnostic procedure	Intervention	Placental management	Previous medical history
Abbreviations: GP score = gravidity and parity score, GW = week of gestation at diagnosis, β-HCG in mIU/mL, Diagnostic procedure = final procedure carried out to obtain the diagnosis, (L)AbP = (lower) abdominal pain, BP = back pain, SP = shoulder pain, VB = vaginal bleeding, Resp. = respiratory problems, exLap/Ltm = exploratory laparoscopy/laparotomy, Sono = abdominal/transvaginal ultrasound scan, MRI = magnetic resonance imaging, Lap/Ltm = surgical treatment with laparoscopy/laparotomy, Pelv OP = prior history of pelvic surgery, PID = pelvic inflammatory disease
1	Anozie, 2016, Nigeria [11]	35	G6P5	at term	–	AbP, Resp.	Sono	Ltm, live birth, MTX	Left in situ	–
2	Baffoe, 2011, Ghana [12]	31	G3P1	38	–	AbP, VB	exLtm	Ltm, live birth	Left in situ	–
3	Demendi, 2011, Hungary [87]	28	G3P2	17		LAbP	Sono	Ltm, MTX	Left in situ, embolization
4	Pichaichanlert, 2017, Thailand [88]	32	G1P1	15	–	blutiger Stuhl	exLtm	Ltm	Resection, partial bowel resection, re-anastomosis	Pelv OP, PID
5	Salathiel, 2016, Chad [89]	30	G8L5	19	–	AbP, VB	exLtm	Ltm	Resection, hysterectomy	–
6	Thompson, 2011, UK [90]	27	–	8	–	LAbP	exLtm	Ltm	Resection, appendectomy	–
7	Tolefac, 2017, Cameroon [13]	22	G3P0	25	–	abd. swelling	exLtm	Ltm, live birth	Left in situ
8	Trail, 2018, UK [91]	26	G4P2	6	1 647	LAbP, SP	exLap	Lap, MTX	Left in situ
9	Yildizhan, 2009, Turkey [92]	34	G2P1	13	–	AbP, BP, VB	MRI	Ltm	Resection	–

Presenting symptoms

• Abdominal pain (4/9)

• Abdominal pain and vaginal bleeding (3/9)

• Hematochezia (1/9)

• Abdominal swelling (1/9)

Diagnosis and diagnostic procedure

• Earliest diagnosis made in the 6th GW, latest diagnosis in the 38th GW with the birth of a neonate

• Diagnosed by exploratory laparotomy (5/9), ultrasound scan (2/9), exploratory laparoscopy (1/9) or MRI (1/9).

Intervention

• Surgical treatment with laparotomy (8/9), with additional administration of MTX in two cases

• Surgical treatment with laparoscopy and administration of MTX (1/9)

Placental management

• Placenta left in situ (5/9)

• Placental resection (4/9), with additional removal of organs in 3 cases

In the three cases who were delivered of a live infant, in addition to implanting on the bowel and its mesenteries, the placenta was also connected to the uterine serosa [11], [12], [13].

F) Implantation on and in the spleen ([Table 6])

Table 6 Implantation on and in the spleen.

No.	Source	Age	GP score	GW	β-HCG	Symptoms	Diagnostic procedure	Intervention	Placental management	Previous medical history
Abbreviations: GP score = gravidity and parity score, GW = week of gestation at diagnosis, β-HCG in mIU/mL, Diagnostic procedure = final procedure carried out to obtain the diagnosis, * = subsplenic, (L)AbP = (lower) abdominal pain, LUAP = left upper abdominal pain, VB = vaginal bleeding, Vom. = vomiting, X = asymptomatic, exLap/Ltm = exploratory laparoscopy/laparotomy, Sono = abdominal/transvaginal ultrasound scan, CT = computed tomography scan, Lap/Ltm = surgical treatment with laparoscopy/laparotomy, MTX = methotrexate, GA = gonadotropin analogs, PCOS = polycystic ovary syndrome
1	Biolchini, 2010, Italy [93]	41	G3P-	4	8 980	LUAP	CT	Lap	Resection, splenectomy	–
2	Gao, 2017, China [94]	27	G0P0	8	119 027	AbP, VB, dizziness	Sono	Ltm	Resection, splenectomy	–
3	Greenbaum, 2016, USA [95]	27	G2P2	4	1 865	LUAP, Vom.	exLap	Ltm	Resection, splenectomy	–
4	Klang, 2016, Israel [96]	35	G3P1	–	71 000	X	CT	KCl, MTX	Left in situ	GA, PCOS
5	Perez 2008*, USA [97]	36	G1P0	–	–	LAbP	exLap	Lap	Resection	Unicornuate uterus, renal agenesis
6	Python, 2016, USA [98]	21	G1	5	8 476	AbP, VB	CT	MTX	Left in situ	–
7	Rathore, 2017, Turkey [99]	23	G1P1	4	6 565	LUAP, Vom.	exLtm	Ltm	Resection, splenectomy	–
8	Wu, 2017, Japan [100]	27	G1P0	8	119 027	AbP	Sono	Ltm	Resection, splenectomy	–
9	Wu, 2018, China [101]	29	G3P2	8	16 669	VB, AbP	Sono	Ltm	Resection, splenectomy

Presenting symptoms

• Abdominal pain (5/9), particularly in the left upper abdomen

• Abdominal pain and vaginal bleeding (3/9)

• Asymptomatic (1/9)

Diagnosis and diagnostic procedures

• Earliest diagnosis made in the 4th GW, latest diagnosis in the 8th GW

• Diagnosed by ultrasound scan (3/9), CT scan (3/9), exploratory laparoscopy (2/9), or exploratory laparotomy (1/9)

Intervention

• Surgical treatment with laparotomy (5/9)

• Surgical treatment with laparoscopy (2/9)

• Feticide with potassium chloride and administration of MTX (1/9)

• Only administration of MTX (1/9)

Placental management

• Placental resection (7/9), combined with splenectomy in 6 cases

• Placenta left in situ (2/9)

G) Implantation on the peritoneum of the abdominal/pelvic wall ([Table 7])

Table 7 Other rare intraperitoneal implantation sites.

No.	Source	Age	GP score	GW	β-HCG	Symptoms	Diagnostic procedure	Intervention	Placental management	Previous medical history
Abbreviations: GP score = gravidity and parity score, GW = week of gestation at diagnosis, β-HCG in mIU/mL, Diagnostic procedure = final procedure carried out to obtain the diagnosis, (L)AbP = (lower) abdominal pain, RUAP = right upper abdominal pain, RSP = right shoulder pain, VB = vaginal bleeding, exLap/Ltm = exploratory laparoscopy/laparotomy, Sono = abdominal/transvaginal ultrasound scan, CT = computed tomography scan, Lap/Ltm = surgical treatment with laparoscopy/laparotomy, MTX = methotrexate
Abdominal wall
1	Anderson, 2009, USA [102]	26	G4P1	3	8 979	AbP, VB	CT	MTX	Left in situ	–
2	Borton, 2015, UK [103]	38	G2P0	7	2 208	AbP, VB	exLap	MTX	Left in situ	PID, endometriosis
3	Gorry, 2012, UK [104]	32		8	–	AbP, VB	exLap	Lap	Left in situ	–
4	Irani, 2016, USA [105]	36	G0P0	4	998	AbP	exLap	Lap	Resection	IVF
5	Lee, 2015, Cameroon [106]	21	G2P2	36	–	LAbP	Sono	Ltm, MTX	Left in situ, re-Ltm because of abscess formation	–
Diaphragm
1	Chen, 2019, China [107]	33	G – P1	12	3 129	RUAP, RSP	CT	Lap	Resection	–
Inguinal canal
1	Noguchi, 2014, Japan [108]	45	G5P4	8	3 090	Swelling and pain in the right groin	Sono	Ltm	Resection	Endometriosis

Presenting symptoms

• Abdominal pain (2/5)

• Abdominal pain and vaginal bleeding (3/5)

Diagnosis and diagnostic procedures

• Earliest diagnosis made in the 3rd GW, latest diagnosis in the 36th GW with the delivery of a dead infant

• Diagnosed by exploratory laparoscopy (3/5), ultrasound scan (1/5) or CT scan (1/5)

Treatment

• Surgical treatment with laparoscopy (2/5)

• Surgical treatment with laparotomy and the administration of MTX (1/5)

• In 2 cases only administration of MTX

Placental management

• Placenta left in situ (4/5); one of these cases required re-laparotomy because of abscess formation

• Placental resection (1/5)

H) Implantation in the paraaortic/paracaval retroperitoneal space ([Table 8])

Table 8 Extraperitoneal implantation sites.

No.	Source	Age	GP score	GW	β-HCG	Symptoms	Diagnostic procedure	Intervention	Placental management	Previous medical history
Abbreviations: GP score = gravidity and parity score, GW = week of gestation at diagnosis, β-HCG in mIU/mL, Diagnostic procedure = final procedure carried out to obtain the diagnosis, (L)AbP = (lower) abdominal pain, VB = vaginal bleeding, X = asymptomatic, EgP = epigastric pain, exLap/Ltm = exploratory laparoscopy/laparotomy, Sono = abdominal/transvaginal ultrasound scan, CT = computed tomography scan, Lap/Ltm = surgical treatment with laparoscopy/laparotomy, MTX = methotrexate, IVF = in vitro fertilization, ET = embryo transfer, IUI = intrauterine insemination
Paraaortic and paracaval
1	Iwama, 2008, Japan [109]	31	G1P0	10	45 369	AbP	MRI	MTX, Ltm	Resection	EP, IVF, salpingectomy
2	Jiang, 2014, China [110]	33	G3P2	7	–	AbP	MRI	MTX, Ltm	Resection
3	Ouassour, 2017, Morocco [111]	35	G4P2	7	29 386	X	Sono	Ltm	Resection	EP, salpingectomy
4	Pak, 2018, USA [112]	30	G4P3	8	40 532	AbP	exLtm	Ltm	Resection	–
5	Wang, 2017, China [9]	32	G4P1	5	10 652	X	CT	Lap	Resection	Salpingectomy
6	Yang, 2018, China [113]	34	G2P0	7	6 803	AbP, VB	CT	Ltm	Resection	–
7	Zhang, 2018, China [114]	29		9	16 453	LAbP	Sono	Emb., MTX, Ltm	Resection	–
Rectovaginal space
1	Martinez, 2011, Spain [115]	37	G2P1	29 days after IUI	7 787	LAbP	Sono	Lap, MTX	Resection	IUI
2	Yang, 2017, China [116]	32	G5P1	6	1 880	LAbP	exLap	Lap	Resection	–
Obturator foramen
1	Lin, 2008, China [117]	19	G1P0	7	267	LAbP, VB	exLap	Ltm	Resection
2	Persson, 2010, Sweden [10]	33	G3P1	27 days after ET	18 032	VB	Sono	Lap × 2	Resection	EP, ET
Renal fascia
1	Chishima, 2013, Japan [118]	33	G3P2	7	3 100	AbP	CT	Ltm	Resection	–
Pancreas
1	Guan, 2015, China [119]	30	G1P0	5	2 500	EgP	MRI	MTX, Lap	Resection pancreatectomy, splenectomy	–
Paravesical space
1	Meire, 2007, Netherlands [120]	30	G3P1	20	–	LAbP	exLtm	MTX, Ltm	Resection	–

Presenting symptoms

• Abdominal pain (4/7)

• Abdominal pain and vaginal bleeding (1/7)

• Asymptomatic (2/7)

Diagnosis and diagnostic procedures

• Earliest diagnosis made in the 5th GW, latest diagnosis in the 10th GW

• Diagnosed by ultrasound scan (2/7), CT scan (2/7), MRI (2/7), or exploratory laparotomy (1/7)

Treatment

• Surgical treatment with laparotomy (6/7), with additional administration of MTX in 3 cases

• Surgical treatment with laparoscopy (1/7)

Placental management

• Placental resection (7/7)

Implantation sites of retroperitoneal EP were often found in the paraaortic, paracaval or paravesicular space and usually required surgical resection by laparotomy.

Discussion

A total of 115 case reports from 113 publications were analyzed for this literature review. The most commonly reported EP implantation sites were the uterine serosa (32/115 or 27.8%), the broad ligament of uterus (18/115 or 15.7%), the liver (14/115 or 12.2%) and the greater omentum (12/115 or 10.4%). Other possible locations for peritoneal EP were the serosa of the bowel, spleen or abdominal wall. There are reports of individual cases with implantation on the diaphragm [107] and in the inguinal canal [108]. A number of retroperitoneal EP sites were found, particularly in the paraaortic and paracaval space but also in the rectovaginal space, on the obturator foramen, in the paravesical space or in the vicinity of the pancreas or kidney.

As regards rare EP implantation sites, their symptoms and the diagnostic procedures used to determine EP, these data largely correspond to the information collated by Molinaro and Barnhart [6]. However, the data on EP implantation sites in the liver and in the retroperitoneal space were not yet available to Molinaro and Barnhart [6] and have been added here. Various abdominal implantation sites were briefly cited in the above-mentioned review by Parker and Srinivas [3]. Our review added a summary of a number of additional case reports to their more limited data, including reports covering implantation on the diaphragm, in the inguinal canal, at the obturator foramen, on a renal capsule and on the pancreas.

For clinical practice, the symptoms of the affected patient are crucial. The most commonly reported symptom was abdominal pain, with fewer reports of vaginal bleeding. However, there are also a number of reports of abdominal ectopic pregnancies occurring in asymptomatic patients, with a total of 24/115 (20.9%) patients in our review reporting no symptoms. Abdominal symptoms and a β-HCG serum value of more than 1500 mU/mL with no intrauterine pregnancy visible on imaging are indications for an EP and must be immediately investigated further with additional diagnostic procedures or by exploratory laparoscopy [93]. The importance of carrying out laparoscopic inspection of both the lower and the upper abdominal region must be emphasized (comprehensive inspection) [98]. In the case reports which we found during our search, the most common intervention was surgical resection by laparotomy, particularly in cases of advanced pregnancy, surgery in the retroperitoneal space, and in countries with more limited medical resources. However, there are also reports of the successful management of specific cases of EP in rare locations [52], [62], [85], [93].

The appropriate strategy for placental management is disputed in the literature and decisions must be made on a case-by-case basis according to the individual implantation site, the risk of bleeding, the patientʼs clinical condition, the physicianʼs surgical experience and the available medical resources [28], [62]. Implantations on the omentum, spleen or liver are associated with a higher risk of bleeding, while the risk of bleeding appears to be lower if the placenta is located on the uterine serosa [37]. According to some authors, the extent of placental adhesion can be determined preoperatively using MRI [121]. Provided that placental blood supply can be safely disrupted, then resection of the placenta is recommended [37], [40], [57]. Otherwise the placenta can be left in situ, after the umbilical cord and fetal membranes have been removed [4]. A postoperative course of antibiotics to prevent infection combined with abdominal drainage to detect bleeding are recommended [87]. Imaging procedures and changes in β-HCG values can be used to monitor resorption of the placenta [22], [23], [30]. Varying doses of methotrexate were administered in some cases to hasten trophoblast degeneration [18], [31], [67], [87].

Reports of an abdominal EP resulting in the birth of a viable infant are rare in the literature. Their prevalence is estimated to be less than 0.01% of all hospital births [30]. Many authors refer to pregnancies after the 20th GW as advanced abdominal pregnancies; it has been suggested that conservative management could be considered in these cases after weighing up the maternal risk of bleeding [37]. In our case series, the majority of live infants were delivered to patients with placental implantation on the external serosa of the uterine wall. This was also observed by Rohilla et al. in her review of advanced abdominal pregnancies [37]. Individual cases who underwent planned conservative management of an abdominal EP with elective laparotomy and the birth of a healthy infant in the 34th GW have been described [25], [70].

Conclusion

This literature review makes it clear that in the event of a positive pregnancy test, an “empty” uterus, and abdominal pain with or without vaginal bleeding in women of childbearing age, it is important not only to investigate for tubal pregnancy as the most common ectopic pregnancy site but also to consider the possibility of ectopic pregnancies in rarer ectopic sites. At the same time, the relatively high percentage of asymptomatic patients and the often very late diagnosis highlight the importance of obtaining a detailed abdominal vaginal ultrasound scan. Abdominal CT or MRI imaging may provide additional useful information. While this is available in highly developed industrialized countries, CT imaging and MRI can be a problem in countries with more limited healthcare resources [13]. MRI is the best method of obtaining a diagnosis and planning the treatment of an EP located in the intra- or extraperitoneal space [3], [6], [65], [110]. The appropriate placental management strategy and the possibility of achieving a live birth must always be considered on case-by-case basis and weighed up after carefully assessing the maternal morbidity risk.

Future studies on rare EP locations should focus on previously unknown risk factors in this group of EP patients, using retrospective case-control studies. The pathogenesis of retroperitoneal implantation of ectopic pregnancy is still unknown and also merits further study.

• References/Literatur

• 1 National Institute for Health and Care Excellence. Ectopic pregnancy and miscarriage: diagnosis and initial management 2019. Online (last access: 30.05.2019): https://www.nice.org.uk/guidance/ng126
• 2 Cecchino GN, Araujo Junior E, Elito Junior J. Methotrexate for ectopic pregnancy: when and how. Arch Gynecol Obstet 2014; 290: 417-423 doi:10.1007/s00404-014-3266-9
• 3 Parker VL, Srinivas M. Non-tubal ectopic pregnancy. Arch Gynecol Obstet 2016; 294: 19-27 doi:10.1007/s00404-016-4069-y
• 4 Hailu FG, Yihunie GT, Essa AA. et al. Advanced abdominal pregnancy, with live fetus and severe preeclampsia, case report. BMC Pregnancy Childbirth 2017; 17: 243 doi:10.1186/s12884-017-1437-y
• 5 Miyauchi A, Yamada M, Furuya M. et al. Peritoneal pregnancy with massive hemoperitoneum in early gestation: two case reports. Clin Case Rep 2015; 3: 431-437 doi:10.1002/ccr3.266
• 6 Molinaro TA, Barnhart KT. Ectopic pregnancies in unusual locations. Semin Reprod Med 2007; 25: 123-130 doi:10.1055/s-2007-970051
• 7 Arbeitsgemeinschaft der wissenschaftlichen Medizinischen Fachgemeinschaften (AWMF). Angemeldetes Leitlinienvorhaben: Extrauteringravidität (17.01.2019). Online (last access: 30.05.2019): https://www.awmf.org/leitlinien/detail/anmeldung/1/ll/015-076.html
• 8 Shen L, Fu J, Huang W. et al. Gynaecology and Fertility Group. Interventions for non-tubal ectopic pregnancy. Online Protocol. Cochrane Database Syst Rev 2014;
• 9 Wang L, Tong X, Li H. et al. Case Report An early extra peritoneal ectopic pregnancy successfully treated with laparoscopy: a case report. Int J Clin Exp Med 2017; 10: 3855-3859
• 10 Persson J, Reynisson P, Masback A. et al. Histopathology indicates lymphatic spread of a pelvic retroperitoneal ectopic pregnancy removed by robot-assisted laparoscopy with temporary occlusion of the blood supply. Acta Obstet Gynecol Scand 2010; 89: 835-839 doi:10.3109/00016341003623779
• 11 Anozie OB, Esike CU, Eze JN. et al. Advanced abdominal ectopic pregnancy: a case report. Open J Obstet Gynecol 2016; 6: 360
• 12 Baffoe P, Fofie C, Gandau BN. Term abdominal pregnancy with healthy newborn: a case report. Ghana Med J 2011; 45: 81-83
• 13 Tolefac PN, Abanda MH, Minkande JZ. et al. The challenge in the diagnosis and management of an advanced abdominal pregnancy in a resource-low setting: a case report. J Med Case Rep 2017; 11: 199 doi:10.1186/s13256-017-1369-1
• 14 Creinin MD, Simhan HN. Can we communicate gravidity and parity better?. Obstet Gynecol 2009; 113: 709-711 doi:10.1097/AOG.0b013e3181988f8f
• 15 Abdelrahman S, Deeter M, Muthusami A. et al. A live term intra-abdominal pregnancy in a Field Hospital: a case report. J Surg Case Rep 2017; 2017: rjx062 doi:10.1093/jscr/rjx062
• 16 Bhoil R, Aggarwal N, Jhobta A. et al. Advanced abdominal pregnancy with successful outcome. Intern Emerg Med 2016; 11: 877-878 doi:10.1007/s11739-015-1339-9
• 17 Bohiltea R, Radoi V, Tufan C. et al. Abdominal pregnancy – Case presentation. J Med Life 2015; 8: 49-54
• 18 Cho FN, Chen SN, Chang YH. et al. Alternative management of a sizable cul-de-sac ectopic pregnancy. Taiwan J Obstet Gynecol 2015; 54: 206-207 doi:10.1016/j.tjog.2014.10.006
• 19 Dabiri T, Marroquin GA, Bendek B. et al. Advanced extrauterine pregnancy at 33 weeks with a healthy newborn. Biomed Res Int 2014; 2014: 102479 doi:10.1155/2014/102479
• 20 Dassah ET, Odoi AT, Opoku BK. Advanced twin abdominal pregnancy: diagnostic and therapeutic challenges. Acta Obstet Gynecol Scand 2009; 88: 1291-1293 doi:10.3109/00016340903281006
• 21 Gayer G. Images in clinical medicine. Abdominal ectopic pregnancy. N Engl J Med 2012; 367: 2334 doi:10.1056/NEJMicm1111814
• 22 Gidiri MF, Kanyenze M. Advanced abdominal ectopic pregnancy: lessons from three cases from Zimbabwe and a literature appraisal of diagnostic and management challenges. Womens Health (Lond) 2015; 11: 275-279 doi:10.2217/whe.15.3
• 23 Hishikawa K, Fukuda T, Inoue H. et al. Laparoscopic Management of Abdominal Pregnancy with Local Injection of Vasopressin Solution: A Case Report. Am J Case Rep 2016; 17: 637-640 doi:10.12659/ajcr.898554
• 24 Isah AY, Ahmed Y, Nwobodo EI. et al. Abdominal pregnancy with a full term live fetus: case report. Ann Afr Med 2008; 7: 198-199
• 25 Kim MJ, Bae JY, Seong WJ. et al. Sonographic diagnosis of a viable abdominal pregnancy with planned delivery after fetal lung maturation. J Clin Ultrasound 2013; 41: 563-565 doi:10.1002/jcu.22010
• 26 Marcelin C, Kouchner P, Bintner M. et al. Placenta embolization of advanced abdominal pregnancy. Diagn Interv Imaging 2018; 99: 265-266 doi:10.1016/j.diii.2017.12.001
• 27 Mengistu Z, Getachew A, Adefris M. Term abdominal pregnancy: a case report. J Med Case Rep 2015; 9: 168 doi:10.1186/s13256-015-0635-3
• 28 Muehlparzer L, Arzt W, Ebner T. et al. Secondary abdominal pregnancy with live birth. Acta Obstet Gynecol Scand 2011; 90: 288 doi:10.1111/j.1600-0412.2010.01041.x
• 29 Nassali MN, Benti TM, Bandani-Ntsabele M. et al. A case report of an asymptomatic late term abdominal pregnancy with a live birth at 41 weeks of gestation. BMC Res Notes 2016; 9: 31 doi:10.1186/s13104-016-1844-6
• 30 Nkusu Nunyalulendho D, Einterz EM. Advanced abdominal pregnancy: case report and review of 163 cases reported since 1946. Rural Remote Health 2008; 8: 1087
• 31 Panagiotakis A, Brown M, Asulin Y. et al. A Case Report of Successful Treatment of an Abdominal Ectopic Pregnancy with Methotrexate. J Minim Invasive Gynecol 2009; 16: S126
• 32 Parekh VK, Bhatt S, Dogra VS. Abdominal pregnancy: an unusual presentation. J Ultrasound Med 2008; 27: 679-681
• 33 Patel C, Feldman J, Ogedegbe C. Complicated abdominal pregnancy with placenta feeding off sacral plexus and subsequent multiple ectopic pregnancies during a 4-year follow-up: a case report. J Med Case Rep 2016; 10: 37 doi:10.1186/s13256-016-0808-8
• 34 Pieh-Holder KL, Scardo JA, Costello DH. Lactogenesis failure following successful delivery of advanced abdominal pregnancy. Breastfeed Med 2012; 7: 543-546 doi:10.1089/bfm.2011.0131
• 35 Pradhan M, Sreenivas M, Singh B. et al. Sudden death in advanced abdominal pregnancy: a case report and discussion of the related medicolegal issues. Med Sci Law 2013; 53: 90-92 doi:10.1258/msl.2012.012014
• 36 Promsonthi P, Herabutya Y. Uterocutaneous fistula in term abdominal pregnancy. Eur J Obstet Gynecol Reprod Biol 2007; 132: 239-241 doi:10.1016/j.ejogrb.2006.04.041
• 37 Rohilla M, Joshi B, Jain V. et al. Advanced abdominal pregnancy: a search for consensus. Review of literature along with case report. Arch Gynecol Obstet 2018; 298: 1-8 doi:10.1007/s00404-018-4743-3
• 38 Sib SR, Ouedraogo I, Sanogo M. et al. A full term abdominal pregnancy with an isthmic tubal implantation of the placenta. BMC Pregnancy Childbirth 2018; 18: 448 doi:10.1186/s12884-018-2071-z
• 39 Shih CC, Lee RK, Hwu YM. Cul-de-sac pregnancy following in vitro fertilization and embryo transfer. Taiwan J Obstet Gynecol 2007; 46: 171-173 doi:10.1016/s1028-4559(07)60013-8
• 40 Tucker K, Bhardwaj NR, Clark E. et al. Delayed diagnosis and management of second trimester abdominal pregnancy. BMJ Case Rep 2017; 2017: bcr2017221433 doi:10.1136/bcr-2017-221433
• 41 Yanaihara A, Ohgi S, Motomura K. et al. An abdominal ectopic pregnancy following a frozen-thawed ART cycle: a case report and review of the literature. BMC Pregnancy Childbirth 2017; 17: 108 doi:10.1186/s12884-017-1294-8
• 42 Yoder N, Tal R, Martin JR. Abdominal ectopic pregnancy after in vitro fertilization and single embryo transfer: a case report and systematic review. Reprod Biol Endocrinol 2016; 14: 69 doi:10.1186/s12958-016-0201-x
• 43 Zhang J, Li F, Sheng Q. Full-term abdominal pregnancy: a case report and review of the literature. Gynecol Obstet Invest 2008; 65: 139-141 doi:10.1159/000110015
• 44 Abdul MA, Tabari AM, Kabiru D. et al. Broad ligament pregnancy: a report of two cases. Ann Afr Med 2008; 7: 86-87
• 45 Akhtar N. Ectopic pregnancy and full term live birth: a case report. J Postgrad Med Inst 2011; 25: 181-182
• 46 Atis A, Gunduz O, Tolga Karacan KA. A Rare Form of Ectopic Pregnancy on Mesoovarium, Case Report. J Clin Case Rep 2014; 4: 359
• 47 Cosentino F, Rossitto C, Turco LC. et al. Laparoscopic Management of Abdominal Pregnancy. J Minim Invasive Gynecol 2017; 24: 724-725 doi:10.1016/j.jmig.2017.01.023
• 48 Dahab AA, Aburass R, Shawkat W. et al. Full-term extrauterine abdominal pregnancy: a case report. J Med Case Rep 2011; 5: 531 doi:10.1186/1752-1947-5-531
• 49 Gudu W, Bekele D. A pre-operatively diagnosed advanced abdominal pregnancy with a surviving neonate: a case report. J Med Case Rep 2015; 9: 228 doi:10.1186/s13256-015-0712-7
• 50 Kar S. Primary abdominal pregnancy following intra-uterine insemination. J Hum Reprod Sci 2011; 4: 95-99 doi:10.4103/0974-1208.86091
• 51 Kim MC, Manyanga H, Lwakatare F. Secondary abdominal pregnancy in human immunodeficiency virus-positive woman. Obstet Gynecol Sci 2016; 59: 535-538 doi:10.5468/ogs.2016.59.6.535
• 52 Nayar J, Nair SS. Broad Ligament Pregnancy – Success Story of a Laparoscopically Managed Case. J Clin Diagn Res 2016; 10: Qd04-QD05 doi:10.7860/jcdr/2016/19293.8136
• 53 Parulekar SV. Face to face: misplaced intrauterine device and abdominal ectopic pregnancy. J Postgrad Med 2011; 57: 223-224 doi:10.4103/0022-3859.85217
• 54 Phupong V, Uthaisan J, Tantbirojn P. Undiagnosed term intraligamentous pregnancy: A case report and literature review. J Obstet Gynaecol 2016; 36: 432-434 doi:10.3109/01443615.2015.1101432
• 55 Rama C, Lepakshi G, Raju SN. Broad Ligament ectopic pregnancy. Journal of Clinical and Scientific Research 2015; 4: 45-48 doi:10.15380/2277-5706.JCSR.14.013
• 56 Sassi A, Dimassi K, Ben Slama S. et al. A broad ligament pregnancy successfully managed by laparoscopy. J Obstet Gynaecol 2018; 38: 423-424 doi:10.1080/01443615.2017.1342231
• 57 Seckin B, Turkcapar FA, Tarhan I. et al. Advanced intraligamentary pregnancy resulting in a live birth. J Obstet Gynaecol 2011; 31: 260-261 doi:10.3109/01443615.2011.553691
• 58 Shamaash AH, Abbas AM. Undiagnosed asymptomatic second trimester broad ligament ectopic pregnancy: a case report and mini-review. Proc Obstet Gynecol 2017; 7: 1-8
• 59 Sheethal CH, Powar A. Full term viable secondary broad ligament pregnancy – A rare case. Case Rep Womens Health 2017; 13: 4-5 doi:10.1016/j.crwh.2016.10.003
• 60 Yasutake N, Tsunematsu R, Oishi H. et al. Successfully treated abdominal pregnancy causing hemoperitoneum using combined surgical and systemic methotrexate therapy: a case report and review of cases treated at Kyushu University Hospital. Gynecol Obstet Invest 2013; 76: 188-192 doi:10.1159/000353980
• 61 Brouard KJ, Howard BR, Dyer RA. Hepatic Pregnancy Suspected at Term and Successful Delivery of a Live Neonate With Placental Attachment to the Right Lobe of the Liver. Obstet Gynecol 2015; 126: 207-210 doi:10.1097/aog.0000000000000703
• 62 Chin PS, Wee HY, Chern BS. Laparoscopic management of primary hepatic pregnancy. Aust N Z J Obstet Gynaecol 2010; 50: 95-98 doi:10.1111/j.1479-828X.2009.01113.x
• 63 Guo B, Li D. Hepatobiliary and Pancreatic: Ectopic pregnancy in the liver: another rare cause of space occupying lesion. J Gastroenterol Hepatol 2016; 31: 1514 doi:10.1111/jgh.13396
• 64 Hao J, Cheng Z, Hu N. et al. Imaging of Hepatic Ectopic Pregnancy by 18F-FDG PET/CT. Clin Nucl Med 2016; 41: 697-698 doi:10.1097/rlu.0000000000001307
• 65 Hu S, Song Q, Chen K. et al. Contrast-enhanced multiphasic CT and MRI of primary hepatic pregnancy: a case report and literature review. Abdom Imaging 2014; 39: 731-735 doi:10.1007/s00261-014-0101-5
• 66 Kuai XP, Wang SY, Qiu JM. Ectopic pregnancy implanted in the liver under the diaphragm. Taiwan J Obstet Gynecol 2013; 52: 586-587 doi:10.1016/j.tjog.2013.10.024
• 67 Ma J, Zhou C, Duan Z. et al. Successful management of primary hepatic pregnancy with selective hepatic artery embolization and intra-arterial methotrexate infusion. Int J Gynaecol Obstet 2013; 122: 78-79 doi:10.1016/j.ijgo.2013.02.019
• 68 Moores KL, Keriakos RH, Anumba DO. et al. Management challenges of a live 12-week sub-hepatic intra-abdominal pregnancy. BJOG 2010; 117: 365-368 doi:10.1111/j.1471-0528.2009.02450.x
• 69 Qiao JC, Chang ZG, Wei JM. et al. Hepatic ectopic pregnancy treated successfully by hepatectomy. Chin Med J 2013; 126: 4806-4807
• 70 Ramphal SR, Moodley J, Rajaruthnam D. Hepatic pregnancy managed conservatively. Trop Doct 2010; 40: 121-122 doi:10.1258/td.2009.090218
• 71 Sibetcheu Tchatou A, Tchounzou R, Mbuagbaw L. et al. Successful medical treatment of a hepatic pregnancy: a case report. J Med Case Rep 2017; 11: 70 doi:10.1186/s13256-017-1227-1
• 72 Wang C, Cheng L, Zhang Z. et al. Imaging diagnosis of hepatic ectopic pregnancy: A report of one case. Intractable Rare Dis Res 2012; 1: 40-44 doi:10.5582/irdr.2012.v1.1.40
• 73 Yadav R, Raghunandan C, Agarwal S. et al. Primary hepatic pregnancy. J Emerg Trauma Shock 2012; 5: 367-369 doi:10.4103/0974-2700.102417
• 74 Zhao RF, Huang SR, Xu LL. et al. Successful Management of a Live 14-week Primary Hepatic Ectopic Pregnancy Combined with a Residual Horn of the Uterus Using Laparoscopy. Chin Med J 2017; 130: 3013-3014 doi:10.4103/0366-6999.220298
• 75 Allen WL, Subba B, Yoong W. et al. Chronic abdominal pregnancy following rupture from a bicornuate uterus. Arch Gynecol Obstet 2007; 275: 393-395 doi:10.1007/s00404-006-0249-5
• 76 Bajis R, Paterson D, McElhinney B. Primary omental ectopic pregnancy: a case report. J Obstet Gynaecol 2019; 39: 560-561
• 77 Behjati S, Bamfo JE, Bates AW. et al. A near miss: lessons from a case of omental pregnancy. J Obstet Gynaecol 2009; 29: 559-560 doi:10.1080/01443610902984946
• 78 Chen L, Qiu L, Diao X. et al. CT findings of omental pregnancy: a case report. Jpn J Radiol 2015; 33: 499-502 doi:10.1007/s11604-015-0449-7
• 79 Chopra S, Keepanasseril A, Suri V. et al. Primary omental pregnancy: case report and review of literature. Arch Gynecol Obstet 2009; 279: 441-442 doi:10.1007/s00404-008-0730-4
• 80 da Silva BB, de Araujo EP, Cronemberger JN. et al. Primary twin omental pregnancy: report of a rare case and literature review. Fertil Steril 2008; 90: 2006.e13-2006.e15 doi:10.1016/j.fertnstert.2008.03.038
• 81 Maiorana A, Incandela D, Giambanco L. et al. Omental pregnancy: case report and review of literature. Pan Afr Med J 2014; 19: 244 doi:10.11604/pamj.2014.19.244.3661
• 82 Seol HJ, Kim T, Lee SK. Successful laparoscopic management of primary omental pregnancy. Arch Gynecol Obstet 2010; 281: 163-165 doi:10.1007/s00404-009-1100-6
• 83 Srinivasan A, Millican S. Laparoscopic management of an abdominal pregnancy. Case Rep Obstet Gynecol 2014; 2014: 562731 doi:10.1155/2014/562731
• 84 Takeda A, Nakamura H, Hayashi S. et al. Primary Omental Pregnancy: Successful Laparoendoscopic Single-site Partial Omentectomy After Diagnosis by Diffusion-weighted Magnetic Resonance Imaging. J Minim Invasive Gynecol 2016; 23: 6-7 doi:10.1016/j.jmig.2015.04.009
• 85 Tanase Y, Yoshida S, Furukawa N. et al. Successful laparoscopic management of a primary omental pregnancy: case report and review of literature. Asian J Endosc Surg 2013; 6: 327-329 doi:10.1111/ases.12056
• 86 Yip SL, Tan WK, Tan LK. Primary omental pregnancy. BMJ Case Rep 2016; 2016: bcr2016217327 doi:10.1136/bcr-2016-217327
• 87 Demendi C, Langmar Z, Banhidy F. et al. Successful operative management of an intact second trimester abdominal pregnancy with additional preoperative selective catheter embolization and postoperative methotrexate therapy. Med Sci Monit 2011; 17: Cs53-Cs55 doi:10.12659/msm.881752
• 88 Pichaichanlert A, Luvira V, Tipsunthonsak N. Abdominal Pregnancy in the Small Intestine Presenting as Acute Massive Lower Gastrointestinal Hemorrhage. Case Rep Surg 2017; 2017: 8017937 doi:10.1155/2017/8017937
• 89 Salathiel DT, Anicet Z, Madoue GB. et al. Abdominal pregnancy discovered during laparotomy for complications after attempted abortion. South Sudan Medical Journal 2016; 16: 14
• 90 Thompson RJ, Hawe MJ. A rare pathological trinity: an appendiceal ectopic pregnancy, acute appendicitis and a carcinoid tumour. Ir J Med Sci 2011; 180: 579-580 doi:10.1007/s11845-009-0283-y
• 91 Trail CE, Watson A, Schofield AM. Case of hepatic flexure ectopic pregnancy medically managed with methotrexate. BMJ Case Rep 2018; 2018: bcr2017220480 doi:10.1136/bcr-2017-220480
• 92 Yildizhan R, Kolusari A, Adali F. et al. Primary abdominal ectopic pregnancy: a case report. Cases J 2009; 2: 8485 doi:10.4076/1757-1626-2-8485
• 93 Biolchini F, Giunta A, Bigi L. et al. Emergency laparoscopic splenectomy for haemoperitoneum because of ruptured primary splenic pregnancy: a case report and review of literature. ANZ J Surg 2010; 80: 55-57 doi:10.1111/j.1445-2197.2009.05176.x
• 94 Gao H, Yuan T, Ding Y. et al. Primary splenic pregnancy with hemorrhagic shock. J Obstet Gynaecol Res 2017; 43: 1342-1345 doi:10.1111/jog.13348
• 95 Greenbaum A, Miskimins R, Coffman B. et al. Management of splenic ectopic pregnancy presenting with massive haemoperitoneum. BMJ Case Rep 2016; 2016: bcr2016218291 doi:10.1136/bcr-2016-218291
• 96 Klang E, Keddel N, Inbar Y. et al. Splenic Pregnancy: A New Minimally Invasive Approach to Treatment. Cardiovasc Intervent Radiol 2016; 39: 1339-1342 doi:10.1007/s00270-016-1403-5
• 97 Perez A, Caban-Martinez AJ, Alvarez W. et al. Subsplenic ectopic pregnancy adjacent to a rudimentary uterine horn. Int J Gynaecol Obstet 2008; 102: 78-79 doi:10.1016/j.ijgo.2008.02.014
• 98 Python JL, Wakefield BW, Kondo KL. et al. Ultrasound-Guided Percutaneous Management of Splenic Ectopic Pregnancy. J Minim Invasive Gynecol 2016; 23: 997-1002 doi:10.1016/j.jmig.2016.05.004
• 99 Rathore R, Shilpi S, Chopra R. et al. Primary Splenic Pregnancy- A Rare but Imperative Cause of Hemoperitoneum – Case Report and Review of Literature. Turk Patoloji Derg 2019; 35: 242-246 doi:10.5146/tjpath.2017.01403
• 100 Wu BQ, Zhu F, Jiang Y. et al. Case of spontaneous splenic rupture caused by ectopic pregnancy in the spleen. J Obstet Gynaecol Res 2017; 43: 1778-1780 doi:10.1111/jog.13440
• 101 Wu L, Jiang X, Ni J. Successful diagnosis and treatment of early splenic ectopic pregnancy: A case report. Medicine 2018; 97: e0466 doi:10.1097/md.0000000000010466
• 102 Anderson PM, Opfer EK, Busch JM. et al. An Early Abdominal Wall Ectopic Pregnancy Successfully Treated with Ultrasound Guided Intralesional Methotrexate: A Case Report. Obstet Gynecol Int 2009; 2009: 3 doi:10.1155/2009/247452
• 103 Borton Z, Landon AG, Singh S. A painless pelvic wall ectopic pregnancy. BMJ Case Rep 2015; 2015: bcr2015211529 doi:10.1136/bcr-2015-211529
• 104 Gorry A, Morelli ML, Olowu O. et al. Laparoscopic management of abdominal ectopic pregnancy using FLOSEAL Hemostatic Matrix. Int J Gynaecol Obstet 2012; 117: 83-84 doi:10.1016/j.ijgo.2011.11.003
• 105 Irani M, Elias RT, Pereira N. et al. Abdominal ectopic pregnancy with undetectable serum beta-human chorionic gonadotropin 9 days following blastocyst transfer. J Obstet Gynaecol Res 2016; 42: 1886-1888 doi:10.1111/jog.13127
• 106 Lee C. Abdominal pregnancy in a low-resource setting. Obstet Gynecol 2015; 125: 1039-1041 doi:10.1097/aog.0000000000000706
• 107 Chen L, Liu J, Shu J. et al. Successful laparoscopic management of diaphragmatic pregnancy : a rare case report and brief review of literature. BMC Pregnancy Childbirth 2019; 19: 99 doi:10.1186/s12884-019-2248-0
• 108 Noguchi D, Matsumoto N, Kamata S. et al. Ectopic pregnancy developing in a cyst of the canal of Nuck. Obstet Gynecol 2014; 123: 472-476 doi:10.1097/aog.0000000000000099
• 109 Iwama H, Tsutsumi S, Igarashi H. et al. A case of retroperitoneal ectopic pregnancy following IVF-ET in a patient with previous bilateral salpingectomy. Am J Perinatol 2008; 25: 33-36 doi:10.1055/s-2007-1004829
• 110 Jiang W, Lv S, Sun L. et al. Diagnosis and treatment of retroperitoneal ectopic pregnancy: review of the literature. Gynecol Obstet Invest 2014; 77: 205-210 doi:10.1159/000353691
• 111 Ouassour S, Filali AA, Raiss M. et al. Retroperitoneal Ectopic Pregnancy: Diagnosis and Therapeutic Challenges. Case Rep Surg 2017; 2017: 9871865 doi:10.1155/2017/9871865
• 112 Pak JO, Durfee JK, Pedro L. et al. Retroperitoneal Ectopic Pregnancy. Obstet Gynecol 2018; 132: 1491-1493 doi:10.1097/aog.0000000000002965
• 113 Yang Y, Liu Z, Song L. et al. Diagnosis and surgical therapy of the retroperitoneal ectopic pregnancy: A case report. Int J Surg Case Rep 2018; 49: 21-24 doi:10.1016/j.ijscr.2018.05.027
• 114 Zhang M, Qin LL. A case of retroperitoneal para-aortic ectopic pregnancy detected by sonography. J Clin Ultrasound 2018; 46: 412-414 doi:10.1002/jcu.22554
• 115 Martínez-Varea A, Hidalgo-Mora JJ, Payá V. et al. Retroperitoneal ectopic pregnancy after intrauterine insemination. Fertil Steril 2011; 95: 2433.e1-2433.e3 doi:10.1016/j.fertnstert.2011.02.026
• 116 Yang M, Cidan L, Zhang D. Retroperitoneal ectopic pregnancy: a case report and review of the literature. BMC Pregnancy Childbirth 2017; 17: 358 doi:10.1186/s12884-017-1542-y
• 117 Lin JX, Liu Q, Ju Y. et al. Primary obturator foramen pregnancy: a case report and review of literature. Chin Med J 2008; 121: 1328-1330
• 118 Chishima F, Kato-Suzuki E, Ichikawa G. et al. Rare case of primary peritoneal pregnancy infiltrated into the Gerotaʼs fascia of the right kidney. J Obstet Gynaecol Res 2013; 39: 1073-1076 doi:10.1111/j.1447-0756.2012.02057.x
• 119 Guan Z, Li HF, Guo LL. et al. Management of pancreatic ectopic pregnancy. Taiwan J Obstet Gynecol 2015; 54: 629-631 doi:10.1016/j.tjog.2015.08.022
• 120 Meire I, van Heusden A, Roukema MS. et al. A retroperitoneal pregnancy of an anencephalic fetus. J Obstet Gynaecol 2007; 27: 518-519 doi:10.1080/01443610701465071
• 121 Lockhat F, Corr P, Ramphal S. et al. The value of magnetic resonance imaging in the diagnosis and management of extra-uterine abdominal pregnancy. Clin Radiol 2006; 61: 264-269 doi:10.1016/j.crad.2005.10.013