Diagnosis and Management of Ectopic Pregnancy: Green-top Guideline No. 21.

Abstract

BJOG: An International Journal of Obstetrics & GynaecologyVolume 123, Issue 13 p. e15-e55 RCOG Green-top GuidelineFree Access Diagnosis and Management of Ectopic Pregnancy Green-top Guideline No. 21 Correction(s) for this article Erratum Volume 124Issue 13BJOG: An International Journal of Obstetrics & Gynaecology pages: e314-e314 First Published online: November 22, 2017 First published: 03 November 2016 https://doi.org/10.1111/1471-0528.14189Citations: 145AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL This guideline replaces The Management of Tubal Pregnancy, which was published in 2004. Executive summary of recommendations Diagnosis of ectopic pregnancy How is a tubal pregnancy diagnosed? What are the ultrasound criteria? Transvaginal ultrasound is the diagnostic tool of choice for tubal ectopic pregnancy. [New 2016] Grade of recommendation: B Tubal ectopic pregnancies should be positively identified, if possible, by visualising an adnexal mass that moves separate to the ovary. [New 2016] Grade of recommendation: D What biochemical investigations should be carried out? A serum progesterone level is not useful in predicting ectopic pregnancy. [New 2016] Grade of recommendation: B A serum beta-human chorionic gonadotrophin (β-hCG) level is useful for planning the management of an ultrasound visualised ectopic pregnancy. [New 2016] Grade of recommendation: C How is a cervical pregnancy diagnosed? What are the ultrasound criteria? The following ultrasound criteria may be used for the diagnosis of cervical ectopic pregnancy: an empty uterus, a barrel-shaped cervix, a gestational sac present below the level of the internal cervical os, the absence of the ‘sliding sign’ and blood flow around the gestational sac using colour Doppler. [New 2016] Grade of recommendation: D What biochemical investigations should be carried out? A single serum β-hCG should be carried out at diagnosis. [New 2016] Grade of recommendation: D How is a caesarean scar pregnancy diagnosed? What are the ultrasound criteria? Clinicians should be aware that ultrasound is the primary diagnostic modality, using a transvaginal approach supplemented by transabdominal imaging if required. [New 2016] Grade of recommendation: D Defined criteria for diagnosing caesarean scar pregnancy on transvaginal scan have been described. [New 2016] Grade of recommendation: D Magnetic resonance imaging (MRI) can be used as a second-line investigation if the diagnosis is equivocal and there is local expertise in the MRI diagnosis of caesarean scar pregnancies. [New 2016] Grade of recommendation: D What biochemical investigations should be carried out? No biochemical investigations are needed routinely. [New 2016] Grade of recommendation: ✓ How is an interstitial pregnancy diagnosed? What are the ultrasound criteria? The following ultrasound scan criteria may be used for the diagnosis of interstitial pregnancy: empty uterine cavity, products of conception/gestational sac located laterally in the interstitial (intramural) part of the tube and surrounded by less than 5 mm of myometrium in all imaging planes, and presence of the ‘interstitial line sign’. [New 2016] Grade of recommendation: D Sonographic findings in two-dimension can be further confirmed using three-dimensional ultrasound, where available, to avoid misdiagnosis with early intrauterine or angular (implantation in the lateral angles of the uterine cavity) pregnancy. [New 2016] Grade of recommendation: D Supplementation with MRI can also be helpful in the diagnosis of interstitial pregnancy. [New 2016] Grade of recommendation: D What biochemical investigations should be carried out? A single serum β-hCG should be carried out at diagnosis to help with management. In some cases, a repeat serum β-hCG in 48 hours may be useful in deciding further management. [New 2016] Grade of recommendation: ✓ How is a cornual pregnancy diagnosed? What are the ultrasound criteria? The following ultrasound scan criteria may be used for the diagnosis of cornual pregnancy: visualisation of a single interstitial portion of fallopian tube in the main uterine body, gestational sac/products of conception seen mobile and separate from the uterus and completely surrounded by myometrium, and a vascular pedicle adjoining the gestational sac to the unicornuate uterus. [New 2016] Grade of recommendation: D What biochemical investigations should be carried out? A single serum β-hCG should be carried out at diagnosis to help with management. In some cases, a repeat serum β-hCG in 48 hours may be useful in deciding further management. [New 2016] Grade of recommendation: ✓ How is an ovarian pregnancy diagnosed? What are the ultrasound criteria? There are no specific agreed criteria for the ultrasound diagnosis of ovarian ectopic pregnancy. [New 2016] Grade of recommendation: D What biochemical investigations should be carried out? A single serum β-hCG should be carried out at diagnosis to help with management. In some cases, a repeat serum β-hCG in 48 hours may be useful in deciding further management. [New 2016] Grade of recommendation: ✓ How is an abdominal pregnancy diagnosed? What are the ultrasound criteria? Defined ultrasound criteria can be used to diagnose an abdominal pregnancy. [New 2016] Grade of recommendation: D MRI can be a useful diagnostic adjunct in advanced abdominal pregnancy and can help to plan the surgical approach. [New 2016] Grade of recommendation: D What biochemical investigations should be carried out? A high index of suspicion is based upon an elevated serum β-hCG level in combination with ultrasound findings. [New 2016] Grade of recommendation: D How is heterotopic pregnancy diagnosed? What are the ultrasound criteria? A heterotopic pregnancy is diagnosed when the ultrasound findings demonstrate an intrauterine pregnancy and a coexisting ectopic pregnancy. [New 2016] Grade of recommendation: D What biochemical investigations should be carried out? A serum β-hCG level is of limited value in diagnosing heterotopic pregnancy. [New 2016] Grade of recommendation: D Management options What are the surgical, pharmacological or conservative treatment options for tubal pregnancy? A laparoscopic surgical approach is preferable to an open approach. Grade of recommendation: A In the presence of a healthy contralateral tube, salpingectomy should be performed in preference to salpingotomy. [New 2016] Grade of recommendation: B In women with a history of fertility-reducing factors (previous ectopic pregnancy, contralateral tubal damage, previous abdominal surgery, previous pelvic inflammatory disease), salpingotomy should be considered. [New 2016] Grade of recommendation: C If a salpingotomy is performed, women should be informed about the risk of persistent trophoblast with the need for serum β-hCG level follow-up. They should also be counselled that there is a small risk that they may need further treatment in the form of systemic methotrexate or salpingectomy. Grade of recommendation: ✓ Systemic methotrexate may be offered to suitable women with a tubal ectopic pregnancy. It should never be given at the first visit, unless the diagnosis of ectopic pregnancy is absolutely clear and a viable intrauterine pregnancy has been excluded. [New 2016] Grade of recommendation: B Expectant management is an option for clinically stable women with an ultrasound diagnosis of ectopic pregnancy and a decreasing β-hCG level initially less than 1500 iu/l. Grade of recommendation: B What are the surgical, pharmacological or conservative treatment options for cervical pregnancy? Medical management with methotrexate can be considered for cervical ectopics. [New 2016] Grade of recommendation: D Surgical methods of management are associated with a high failure rate and should be reserved for those women suffering life-threatening bleeding. [New 2016] Grade of recommendation: D What are the surgical, pharmacological or conservative treatment options for caesarean scar pregnancy? Women diagnosed with caesarean section scar pregnancies should be counselled that such pregnancies are associated with severe maternal morbidity and mortality. [New 2016] Grade of recommendation: D Medical and surgical interventions with or without additional haemostatic measures should be considered in women with first trimester caesarean scar pregnancy. [New 2016] Grade of recommendation: D There is insufficient evidence to recommend any one specific intervention over another for caesarean scar pregnancy, but the current literature supports a surgical rather than medical approach as the most effective. [New 2016] Grade of recommendation: D What are the surgical, pharmacological or conservative treatment options for interstitial pregnancy? Nonsurgical management is an acceptable option for stable interstitial pregnancies. [New 2016] Grade of recommendation: D Expectant management is only suitable for women with low or significantly falling β-hCG levels in whom the addition of methotrexate may not improve the outcome. [New 2016] Grade of recommendation: D A pharmacological approach using methotrexate has been shown to be effective, although, there is insufficient evidence to recommend local or systemic approach. [New 2016] Grade of recommendation: D Surgical management by laparoscopic cornual resection or salpingotomy is an effective option. [New 2016] Grade of recommendation: D Alternative surgical techniques could include hysteroscopic resection under laparoscopic or ultrasound guidance. [New 2016] Grade of recommendation: D There is insufficient evidence on safety and complications in future pregnancies to recommend other nonsurgical methods. [New 2016] Grade of recommendation: D What are the surgical, pharmacological or conservative treatment options for cornual pregnancy? Cornual pregnancies should be managed by excision of the rudimentary horn via laparoscopy or laparotomy. [New 2016] Grade of recommendation: D What are the surgical, pharmacological or conservative treatment options for ovarian pregnancy? Definitive surgical treatment is preferred if laparoscopy is required to make the diagnosis of ovarian ectopic pregnancy. [New 2016] Grade of recommendation: D Systemic methotrexate can be used to treat ovarian ectopic pregnancy when the risk of surgery is high, or postoperatively in the presence of persistent residual trophoblast or persistently raised β-hCG levels. [New 2016] Grade of recommendation: D What are the surgical, pharmacological or conservative treatment options for abdominal pregnancy? Laparoscopic removal is an option for treatment of early abdominal pregnancy. [New 2016] Grade of recommendation: D Possible alternative treatment methods would be systemic methotrexate with ultrasound-guided fetocide. [New 2016] Grade of recommendation: D Advanced abdominal pregnancy should be managed by laparotomy. [New 2016] Grade of recommendation: D What are the surgical, pharmacological or conservative treatment options for heterotopic pregnancy? The intrauterine pregnancy must be considered in the management plan. [New 2016] Grade of recommendation: B Methotrexate should only be considered if the intrauterine pregnancy is nonviable or if the woman does not wish to continue with the pregnancy. [New 2016] Grade of recommendation: D Local injection of potassium chloride or hyperosmolar glucose with aspiration of the sac contents is an option for clinically stable women. [New 2016] Grade of recommendation: D Surgical removal of the ectopic pregnancy is the method of choice for haemodynamically unstable women and is also an option for haemodynamically stable women. [New 2016] Grade of recommendation: D Expectant management is an option in heterotopic pregnancies where the ultrasound findings are of a nonviable pregnancy. [New 2016] Grade of recommendation: D Do rhesus D (RhD)-negative women with an ectopic pregnancy require anti-D immunoglobulin? Offer anti-D prophylaxis as per national protocol to all RhD-negative women who have surgical removal of an ectopic pregnancy, or where bleeding is repeated, heavy or associated with abdominal pain. [New 2016] Grade of recommendation: D What are the long-term fertility prospects following an ectopic pregnancy? In the absence of a history of subfertility or tubal pathology, women should be advised that there is no difference in the rate of fertility, the risk of future tubal ectopic pregnancy or tubal patency rates between the different management methods. [New 2016] Grade of recommendation: D Women with a previous history of subfertility should be advised that treatment of their tubal ectopic pregnancy with expectant or medical management is associated with improved reproductive outcomes compared with radical surgery. [New 2016] Grade of recommendation: C Women receiving methotrexate for the management of tubal ectopic pregnancy can be advised that there is no effect on ovarian reserve. [New 2016] Grade of recommendation: D Women undergoing treatment with uterine artery embolisation and systemic methotrexate for nontubal ectopic pregnancies can be advised that live births have been reported in subsequent pregnancies. [New 2016] Grade of recommendation: D Women undergoing laparoscopic management of ovarian pregnancies can be advised that their future fertility prospects are good. [New 2016] Grade of recommendation: D What support and counselling should be offered to women undergoing treatment for ectopic pregnancy? Women should be advised, whenever possible, of the advantages and disadvantages associated with each approach used for the treatment of ectopic pregnancy, and should participate fully in the selection of the most appropriate treatment. Grade of recommendation: D Women should be made aware of how to access support via patient support groups, such as the Ectopic Pregnancy Trust, or local bereavement counselling services. [New 2016] Grade of recommendation: D Muscle relaxation training may be of use to women undergoing treatment for ectopic pregnancy with methotrexate. [New 2016] Grade of recommendation: C It is recommended that women treated with methotrexate wait at least 3 months before trying to conceive again. [New 2016] Grade of recommendation: D Service and training What is the most appropriate setting for management of women with an ectopic pregnancy? Providers of early pregnancy care should provide a 7-day early pregnancy assessment service with direct access for women referred by general practitioners and accident and emergency departments, i.e. along current NHS recommendations. Available facilities for the management of suspected ectopic pregnancy should include diagnostic and therapeutic algorithms, transvaginal ultrasound and serum β-hCG estimations. Grade of recommendation: ✓ Women should have access to all appropriate management options for their ectopic pregnancy. If local facilities do not provide all options, then clear referral pathways should exist to allow them to access appropriate care. [New 2016] Grade of recommendation: ✓ What are the training implications for those managing women with ectopic pregnancy? Clinicians undertaking the surgical management of ectopic pregnancy must have received appropriate training. Laparoscopic surgery requires appropriate equipment and trained theatre staff. Grade of recommendation: ✓ Clinicians undertaking ultrasound for the diagnosis of ectopic pregnancy must have received appropriate training. [New 2016] Grade of recommendation: ✓ Clinicians undertaking medical management via ultrasound-guided needle techniques must have received appropriate training. [New 2016] Grade of recommendation: ✓ If clinicians undertaking surgical management of ectopic pregnancy cannot carry out the full range of surgical procedures, appropriately experienced support must be available if necessary. [New 2016] Grade of recommendation: ✓ Virtual reality simulators can be used as a training tool for salpingectomy. [New 2016] Grade of recommendation: D 1 Purpose and scope The purpose of this guideline is to provide evidence-based guidance on the diagnosis and management of ectopic pregnancies. This guideline will cover the following ectopic pregnancies: tubal, cervical, caesarean scar, interstitial, cornual, ovarian, abdominal and heterotopic. The diagnosis and management of pregnancy of unknown location (PUL) will not be covered. The management of PUL is discussed in the National Institute for Health and Care Excellence (NICE) guideline.1 2 Introduction and background epidemiology An ectopic pregnancy is any pregnancy implanted outside of the endometrial cavity. In the UK, the incidence is approximately 11/1000 pregnancies, with an estimated 11 000 ectopic pregnancies diagnosed each year.2 The incidence of ectopic pregnancy in women attending early pregnancy units is 2–3%.3, 4 Unfortunately, women still die from ectopic pregnancy, with six maternal deaths reported between 2006 and 2008. However, the case fatality rate has decreased over recent years, suggesting that earlier diagnosis and treatment may have made an impact.2 Risk factors for ectopic pregnancy include tubal damage following surgery or infection, smoking and in vitro fertilisation.5-9 However, the majority of women with an ectopic pregnancy have no identifiable risk factor. 3 Identification and assessment of evidence This guideline was developed in accordance with standard methodology for producing Royal College of Obstetricians and Gynaecologists (RCOG) Green-top Guidelines. MEDLINE, EMBASE and the Cochrane Library were searched. The search was restricted to articles published between 1995 and July 2015 and limited to humans and the English language. The databases were searched using the relevant Medical Subject Headings (MeSH) terms and this was combined with a keyword search. Search terms included ‘ectopic pregnancy’, ‘tubal pregnancy’, ‘interstitial pregnancy’, ‘cornual pregnancy’, ‘cervical pregnancy’, ‘caesarean scar pregnancy’, ‘ovarian pregnancy’, ‘abdominal pregnancy’, ‘heterotopic pregnancy’, ‘pregnancy of unknown location’ and ‘extrauterine pregnancy’. The National Guideline Clearinghouse, NICE Evidence Search and Trip were also searched for relevant guidelines. Where possible, recommendations are based on available evidence. Areas lacking evidence are highlighted and annotated as ‘good practice points’ (GPP). Further information about the assessment of evidence and the grading of recommendations may be found in Appendix I. 4 Diagnosis of ectopic pregnancy How is a tubal pregnancy diagnosed? 4.1.1 What are the ultrasound criteria? Transvaginal ultrasound is the diagnostic tool of choice for tubal ectopic pregnancy. Grade of recommendation: B Tubal ectopic pregnancies should be positively identified, if possible, by visualising an adnexal mass that moves separate to the ovary. Grade of recommendation: D The majority of tubal ectopic pregnancies should be visualised on transvaginal ultrasound. Transvaginal ultrasound has reported sensitivities of 87.0–99.0% and specificities of 94.0–99.9% for the diagnosis of ectopic pregnancy.3, 10-13 The majority of ectopic pregnancies will be visualised on the initial ultrasound examination.14-18 The remainder will initially be classified as a PUL. Not all ectopic pregnancies initially classified as a PUL are ‘missed’ on the initial scan. Some of these ectopic pregnancies are just too small and too early in the disease process to be visualised on the initial ultrasound examination.19 Laparoscopy is no longer the gold standard for diagnosis. False-negative laparoscopies (3.0–4.5%) have been reported when the procedure is performed too early in the development of an ongoing ectopic pregnancy.20, 21 Evidence level 2++ An inhomogeneous or noncystic adnexal mass is the most common finding in around 50–60% of cases.4, 10, 12, 13, 19 An empty extrauterine gestational sac will be present in around 20–40% of cases.4, 10, 19 While an extrauterine gestational sac containing a yolk sac and/or embryonic pole that may or may not have cardiac activity will be present in around 15–20% of cases.4, 10, 19 There is no specific endometrial appearance or thickness to support a diagnosis of tubal ectopic pregnancy. In up to 20% of cases, a collection of fluid may be seen within the uterine cavity, classically referred to as a ‘pseudosac’.22-24 The key is to distinguish this from an early intrauterine gestational sac. The intradecidual and double decidual signs can be used to diagnose an early intrauterine pregnancy. The intradecidual sign is described as a fluid collection with an echogenic rim located ‘within a markedly thickened decidua on one side of the uterine cavity’.25 The double decidual sign is described as an intrauterine fluid collection surrounded by ‘two concentric echogenic rings’.26 However, in practice, it can be very difficult to distinguish a ‘pseudosac’ which is just a collection of fluid in the endometrial cavity from an early intrauterine sac. The presence of a ‘pseudosac’ alone cannot be used to diagnose an ectopic pregnancy and in fact, a small anechoic cystic structure is more likely to be an early sac rather than a ‘pseudosac’. A study27 has shown that a woman with a positive pregnancy test, an intrauterine smooth-walled anechoic cystic structure and no adnexal mass has a 0.02% probability of ectopic pregnancy, while the probability of intrauterine pregnancy in such a patient is 99.98%. Free fluid is often seen on ultrasound, but is not diagnostic of ectopic pregnancy. A small amount of anechoic fluid in the pouch of Douglas may be found in both intrauterine and ectopic pregnancies. Echogenic fluid has been reported in 28–56% of ectopic pregnancies.28, 29 It may signify tubal rupture, but most commonly is due to blood leaking from the fimbrial end of the fallopian tube. Evidence level 3 4.1.2 What biochemical investigations should be carried out? A serum progesterone level is not useful in predicting ectopic pregnancy. Grade of recommendation: B A serum beta-human chorionic gonadotrophin (β-hCG) level is useful for planning the management of an ultrasound visualised ectopic pregnancy. Grade of recommendation: C A meta-analysis30 has confirmed that a single β-hCG level cannot be used in isolation to predict an ectopic pregnancy. Evidence level 1– There is a common misconception that a single low serum β-hCG level (e.g. less than 1000 iu/l) means that an ectopic pregnancy is unlikely. However, this is a false assumption and in modern practice many ectopic pregnancies have a β-hCG value below this level.31 Evidence level 2+ The initial serum β-hCG level is a key prognostic indicator for the success of conservative management (expectant and medical) in cases of ultrasound visualised tubal ectopic pregnancies.32 Evidence level 2– How is a cervical pregnancy diagnosed? 4.2.1 What are the ultrasound criteria? The following ultrasound criteria may be used for the diagnosis of cervical ectopic pregnancy: an empty uterus, a barrel-shaped cervix, a gestational sac present below the level of the internal cervical os, the absence of the ‘sliding sign’ and blood flow around the gestational sac using colour Doppler. Grade of recommendation: D Cervical pregnancies are rare, accounting for less than 1% of all ectopic gestations.33 Defined criteria have been described for diagnosing cervical ectopic pregnancies.34, 35 The following ultrasound criteria have been described in the diagnosis of cervical ectopic pregnancy: Empty uterine cavity. A barrel-shaped cervix. A gestational sac present below the level of the internal cervical os. The absence of the ‘sliding sign’. Blood flow around the gestational sac using colour Doppler. The ‘sliding sign’ enables cervical ectopic pregnancies to be distinguished from miscarriages that are within the cervical canal. When pressure is applied to the cervix using the probe, in a miscarriage, the gestational sac slides against the endocervical canal, but it does not in an implanted cervical pregnancy.34 Evidence level 3 4.2.2 What biochemical investigations should be carried out? A single serum β-hCG should be carried out at diagnosis. Grade of recommendation: D A single serum β-hCG carried out at the time of ultrasound diagnosis is useful in deciding management options. A serum β-hCG level greater than 10 000 iu/l is associated with a decreased chance of successful methotrexate treatment.36 Evidence level 3 How is a caesarean scar pregnancy diagnosed? 4.3.1 What are the ultrasound criteria? Clinicians should be aware that ultrasound is the primary diagnostic modality, using a transvaginal approach supplemented by transabdominal imaging if required. Grade of recommendation: D Defined criteria for diagnosing caesarean scar pregnancy on transvaginal scan have been described. Grade of recommendation: D Magnetic resonance imaging (MRI) can be used as a second-line investigation if the diagnosis is equivocal and there is local expertise in the MRI diagnosis of caesarean scar pregnancies. Grade of recommendation: D Caesarean scar pregnancy is defined as implantation into the myometrial defect occurring at the site of the previous uterine incision. The prevalence of caesarean scar pregnancy is estimated to be approximately 1 in 2000 pregnancies and these pregnancies may be ongoing potentially viable pregnancies or miscarriages within the scar.37 The diagnostic criteria described for diagnosing caesarean scar implantation on transvaginal ultrasound include: Empty uterine cavity.38 Gestational sac or solid mass of trophoblast located anteriorly at the level of the internal os embedded at the site of the previous lower uterine segment caesarean section scar.39 Thin or absent layer of myometrium between the gestational sac and the bladder.38, 40 Evidence of prominent trophoblastic/placental circulation on Doppler examination.41 Empty endocervical canal.38 Thirteen percent of reported cases of caesarean scar pregnancy were misdiagnosed as intrauterine or cervical pregnancies at presentation.42 The true prevalence of caesarean scar pregnancies is likely to be somewhat higher than estimated in the literature as some cases will end in the first trimester,either by miscarriage or termination, and go unreported and undiagnosed. There is a spectrum of severity associated with pregnancies implanted into caesarean section scars and the natural history is uncertain. Vial et al.43 proposed that there are two different types of pregnancies implanted in a caesarean scar: the first type progressing into the uterine cavity as the gestational sac grows and develops, so with the potential to reach a viable gestational age, but with the risk of massive bleeding from the implantation site; and the second with progression deeper towards the serosal surface of the uterus with the risk of first trimester rupture and haemorrhage. Given that there are also varying appearances of caesarean section scars on the uterus and that placental development evolves over time as the pregnancy progresses, all of these factors can cause difficulty in the diagnosis of caesarean scar pregnancy. The diagnostic criteria have not been subject to validation and are derived from descriptive case series,38-44 so to minimise the risk of false-positive diagnosis, we recommend that all nonemergency cases of suspected scar pregnancy are referred to a regional centre to confirm the diagnosis. The MRI features of caesarean scar pregnancy are essentially the same as those described on ultrasound, but ultrasound is more readily available and cheaper.44, 45 Evidence level 3 4.3.2 What biochemical investigations should be carried out? No biochemical investigations are needed routinely. Grade of recommendation: ✓ A serum β-hCG level may be useful as a baseline prior to monitoring if conservative treatment is contemplated, but it does not have a role in the diagnosis of caesarean scar pregnancy. How is an interstitial pregnancy diagnosed? 4.4.1 What are the ultrasound criteria? The following ultrasound scan criteria may be used for the diagnosis of interstitial pregnancy: empty uterine cavity, products of conception/gestational sac located laterally in the interstitial (intramural) part of the tube and surrounded by less than 5 mm of myometrium in all imaging planes, and presence of the ‘interstitial line sign’. Grade of recommendation: D Sonographic findings in two-dimension can be further confirmed using three-dimensional ultrasound, where available, to avoid misdiagnosis with early intrauterine or angular (implantation in the lateral angles of the uterine cavity) pregnancy. Grade of recommendation: D Supplementation with MRI can also be helpful in the diagnosis of interstitial pregnancy. Grade of recommendation: D Interstitial pregnancy occurs when the ectopic pregnancy implants in the interstitial part of the fallopian tube. The reported incidence varies between 1.0% and 6.3% of ectopic pregnancies.46-48 The interstitial part of the fallopian tube is about 1–2 cm in length and traverses the muscular myometrium of the uterine wall, opening via the tubal ostium into the uterine cavity.49 Evidence level 3 Ultrasound criteria have been described for the diagnosis of interstitial pregnancy.50 These include: Empty uterine cavity. Products of conception/gestational sac located laterally in the interstitial (intramural) part of the tube and surrounded by less than 5 mm of myometrium in all imaging planes. The ‘interstitial line sign’, which is a thi