The site of ectopic pregnancy can affect the clinical syndrome of patients. Compared with tubal pregnancy, ovarian pregnancy is easier to rupture, which leads to a higher shock rate and needs more emergency management [4]. The mortality rate of abdominal pregnancy is eight times higher than tubal pregnancy with a mortality rate of 0.5–18% as for late diagnosis and treatment [5–6]. Having a clear picture of the distribution of ectopic pregnancy can help us make clinical decisions better when we encountered a patient considering ectopic pregnancy.
But the site of ectopic pregnancy has been little studied. Most studies are focusing on the trend of ectopic pregnancy ratio of all female population or focusing on the mortality rate of one specific type of ectopic pregnancy. Tubal pregnancy is the most common type of ectopic pregnancy. According to former studies, about 95% ectopic pregnancy is tubal pregnancy [7], ovarian pregnancy makes up about 0.5%-3% of ectopic pregnancy with an incidence rate of 1/7000–1/40,000 live births[8–10], abdominal pregnancy makes up about 1.3% with incidence rate ranges from 1 in 10000 to 30000 pregnancies [11–12], cervical pregnancy comprises about 1% with incidence rate varies between 1 in 2,500 and 1 in 12,422 pregnancies[13–14], while cesarean scar pregnancy makes up about 6% of ectopic pregnancy with its incidence rate is about from 1 in 2500 to 1 in 1800 of pregnancies[15–16]. Most studies just focus on a specific type of ectopic pregnancy, and we can only get general information about the ectopic pregnancy distribution. According to our data, tubal pregnancy consists of 84.70% of ectopic pregnancy, which is lower than the 95% from former studies. The proportion of ovarian pregnancy, abdominal pregnancy, cervical pregnancy, cesarean scar pregnancy and cornual pregnancy are close to former studies.
According to the study of Bouyer [17] at the year 2001, interstitial pregnancy accounts for 2.4% of ectopic pregnancy, isthmic pregnancy consists of 12%, ampullary pregnancy accounts for 70%, fimbrial pregnancy makes up 11.1%, ovarian pregnancy accounts for 3.2% and abdominal pregnancy comprises 1.3%. According to our data, interstitial pregnancy consists of 3.39%, isthmic pregnancy makes up 4.82%, ampullary pregnancy accounts for 89.21%, fimbrial pregnancy accounts for 2.58%.
With the increase of cesarean delivery rate in China, the incidence rate of cesarean scar pregnancy has been increasing during the recent years. Cesarean scar pregnancy is a special type of ectopic pregnancy in which embryo implants at cesarean scar. Cesarean scar pregnancy can lead to severe complications, such as severe hemorrhage and uterine rupture [18]. According to the study of Li Hong-Tian [19], during the year 2008–2018, the cesarean delivery rate increased from 28.8–36.7%.
The proportion of tubal pregnancy shows a decreasing trend, the proportion of cesarean scar pregnancy and cornual pregnancy shows an increasing trend. From the year 2012–2015 to the year 2016–2019, the proportion of cesarean scar pregnancy to ectopic pregnancy increased from 5.74–11.81%, which reminds us the cesarean delivery rate should be decreased to decrease the morbidity of cesarean scar pregnancy.
From the year 2012–2015 to the year 2016–2019, the ratio of tubal pregnancy to ectopic pregnancy decreased from 90.06–80.98%. It may be because of the rise of women’s health awareness, which leads to the decrease of the rate of pelvic inflammatory disease and tubal diseases. According to the study of Kreisel K [20], the ratio of emergency department visits due to pelvic inflammatory disease decreased from 0.57% in 2006 to 0.41% in 2013. In addition, patients are more willing to treat tubal infertility, which also leads to the decrease of tubal diseases.
The ratio of cornual pregnancy to ectopic pregnancy increased from 1.89–3.58%, which may be related to the increase of intrauterine operation and the damage of endometrium due to intrauterine operation. It’s important to decrease the unnecessary intrauterine operation.
Cesarean scar pregnancy means the fertilized ovum implants at the cesarean scar. After implantation, trophocyte can invade into myometrium and grow there, which may lead to uterine rupture or massive bleeding. If keeping growing, cesarean scar pregnancy can develop into placenta previa, placenta implantation and dangerous placenta previa, bringing giant risks to pregnant women [21]. Cesarean scar pregnancy is highly related to cesarean delivery history, but the pathogenesis is still unclear, its pathogenesis is maybe the broadening of scar, fibrosis and ischemia of uterine wall, poor healing of scar [22]. According to former studies, the high-risk factors of cesarean scar pregnancy are abortion history, multiple cesarean delivery history, the way of suture and the intervals with last cesarean delivery [23]. The scar sickness of patients with double-layer suture is thicker than patients with one-layer suture [24]. It’s in accord with the data at my hospital. 72.78%(246/338) patients had cesarean delivery once, 25.15%(85/338) had cesarean delivery twice, and 2.07%(7/338) had cesarean delivery three times. 80.18%(271/338) had aborted before.
According to the study of So Yun Kim [25], the mean age of cesarean scar pregnancy is 35.7 ± 3.8 years old, the mean gestational age at diagnosis is 6.5 ± 1.1 weeks and the mean hCG before treatment is 30,785 (range 550 − 155,356) U/L. According to Lanrong Luo [26], the mean age of cesarean scar pregnancy is 34.16 ± 4.4 years old. According to my data, the mean age is 32.90 ± 4.80 years old, 67.16%(227/338) patients are between 30 ~ 39 years old, the mean gestational age is 6.67 ± 1.82 weeks, which is close to former study.
The diagnosis of cesarean scar pregnancy is mainly through ultrasound tests, especially transvaginal ultrasound combined with transabdominal ultrasound, Magnetic Resonance Imaging can be used to clarify the relationship between gestation sac and other organs when necessary. Its main clinical manifestations are amenorrhea, abdominal pain and vaginal bleeding [27], like other kinds of ectopic pregnancies. According to my data, the most common clinical manifestations are amenorrhea(98.52%), abdominal pain(25.74%) and vaginal bleeding(67.76%), the most common sign is hysterauxesis(46.75%).
The main treatment methods of cesarean scar pregnancy are suction curettage, suction curettage + uterine arterial embolization, hysteroscopy, hysteroscopy + uterine arterial embolization and laparoscope. Uterine arterial embolization can highly reduce the possibility of massive hemorrhage. It can also be treated by conservative treatment methods, using methotrexate localized or systematic [28]. At my hospital, 40.23%(126/338) patients were treated by suction curettage, 37.28%(126/338) patients were treated by suction curettage + uterine arterial embolization. Suction curettage and suction curettage + uterine arterial embolization are the dominating treatment methods.