Ectopic pregnancy Radiology

Radiological features of ectopic pregnancy

1. IMAGING IN ECTOPIC PREGNANCY By Dr Sajan Varma

2. NORMAL EARLY PREGNANCY The double decidual sac sign (DDSS) is seen in early pregnancy when the yolk sac or embryo is still not visualised. It consists of the decidua parietalis (lining the uterine cavity) and decidua capsularis (lining the gestational sac) and is seen as two concentric rings surrounding an anechoic gestational sac. Where the two adhere is the decidua basalis, and is the site of future placental formation. Intratradecidual sac sign (IDSS)-As per this sign, site of implantation is seen as an early gestational sac or an intrauterine fluid collection or an echogenic area in a markedly thickened decidua on one side of the uterine cavity.

3. INTRAUTRINE SAC WITH NO APPRECIABLE FETAL POLE

4. NORMAL EARLY PREGNANCY A decidual reaction is feature seen in very early pregnancy where there is a thickening of the endometrium around the gestational sac more tha n 2mm A double bleb sign is a sonographic feature where there is visualisation of a gestational sac containing a yolk sac and amniotic sac giving an appearance of two small bubbles . The embryonic disc is located between the two bubbles. It is an important feature of an intrauterine pregnancy and thus distinguishes a pregnancy from a pseudogestational sac or decidual cast cyst .

5. THE DOULBE BLEB SIGN IS SEEN BECAUSE OF THE YOLK SAC WITHIN THE AMNIOTIC SAC

6. INTRODUCTION Ectopic pregnancy refers to the implantation of a fertilised ovum outside of the uterine cavity. The overall incidence is 1-2% of pregnancies. The risk is as high as 18% for first trimester pregnancies with bleeding. There is an increased incidence associated with in-vitro fertilisation (IVF) pregnancies.

7. ECTOPIC PREGNANCY:CLINICAL PRESENTATION The classic presentation is the traid of abdominal pain vaginal bleeding & Adnexal mass  B ut this is present in about 45% of cases of ectopic pregnancy In rest of the cases the symptoms may not be necessarily severe as there may be only mild pelvic pain and PV spotting in a patient in early pregnancy (5-9 weeks of amenorrhoea)  Nonetheless, monitoring of haemodynamic status is crucial, as haemorrhage following rupture can be life threatening.

8. LOCATION tubal ectopic: 93-97% ampullary ectopic: most common ~70% of tubal ectopics and ~65% of all ectopics isthmal ectopic: ~12% of tubal ectopics and ~11% of all ectopics fimbrial ectopic: ~11% of tubal ectopics and ~10% of all ectopics interstitial ectopic/cornual ectopic: 3-4%; also essentially a type of tubal ectopic ovarian ectopic: ovarian pregnancy; 0.5-1% cervical ectopic: cervical pregnancy; rare <1% scar ectopic: site of previous Caesarian section scar; rare abdominal ectopic: rare ~1.4%

9. LOCATIONS

10. ULTRASOUND The most reliable sign of ectopic pregnancy is visualisation of an extra-uterine gestation, but this is not seen in 15-35% of ectopic pregnancies The ultrasound exam should be performed both transabdominally and transvaginally. A transvaginal scan is important for diagnostic sensitivity. empty uterine cavity or no evidence of intrauterine pregnancy pseudogestational sac or decidual cyst: may be seen in 10-20% of ectopic pregnancies decidual cast thick echogenic endometrium

11. Sac with contents seen in the right adnexa Both ovaries Utreus with absence of a sac Fetal cardiac activity

12. FALLOPAIN TUBE AND OVARY simple adnexal cyst: 10% chance of an ectopic complex extra-adnexal cyst/mass: 95% chance of a tubal ectopic (if no IUP) an intra-adnexal cyst/mass is more likely to be a corpus luteum solid hyperechoic mass is possible, but non-specific tubal ring sign- 95% chance of a tubal ectopic if seen described in 49% of ectopics and in 68% of unruptured ectopics ring of fire sign: can be seen on colour Doppler in a tubal ectopic, but can also be seen in a corpus luteum absence of colour Doppler flow does not exclude an ectopic live extrauterine pregnancy (i.e. extra-uterine fetal cardiac activity): 100% specific, but only seen in a minority of cases

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14. TVS IMAGES SHOWING A GESTATIONAL SAC IN THE RIGHT ADNEXA

15. ANOTHER CASE OF ECTOPIC PREGNANCY ON TVS SHOWING A GESTATIONAL SAC IN THE RIGHT ADNEXA WITH APPRECIABLE FETAL POLE

16. DOUGHNUT / BAGEL SIGN WITH DECIDUAL CAST IN THE UTERUS

17. TVS IMAGE SHOWING A GESTATIONAL SAC IN THE LEFT ADNEXA WITH FREE FLUID IN THE PELVIS

18. CONFIRMATION OF AN ECTOPIC PREGNANCY IN THE LEFT ADNEXA WITH NO INTRAUTERINE SAC

19. RING OF FIRE SIGN

20. ANOTHER ECTOPIC SITE WITH IMPLANTATION AT LSCS SCAR

21. PERITONEAL CAVITY free pelvic fluid or haemoperitoneum in the pouch of Douglas the presence of free intraperitoneal fluid in the context of a positive beta HCG and empty uterus is ~70% specific for an ectopic pregnancy ~63% sensitive for ectopic pregnancy not specific for ruptured ectopic (seen in 37% of intact tubal ectopics) live pregnancy: 100% specific, but only seen in a minority of cases In patients receiving in vitro fertilisation (IVF), it is important not to be completely reassured by the presence of a live intrauterine pregnancy, as there is a possibility of a coexisting ectopic pregnancy in 1:500 (i.e. heterotopic pregnancy). In patients not receiving IVF, the risk of heterotopic pregnancy is 1:30,000.

22. T2W MR IMAGE SHOWING AN ABDOMINAL PREGNANCY

23. ECTOPIC PREGNANCY IS A PHYSIOLOGY TURNED INTO PATHOLOGY. THEREFORE, IF IMAGING SEEMS INADEQUATE WE NEED TO LOOK FOR THE PHYSIOLOGY

24. NON- SPECIFIC FINDINGS (PHYSIOLOGICAL) Serum beta HCG levels tend to increase at a slower rate. Whereas a normal doubling rate in early pregnancy is approximately 48 hours, an increase of 50% or less in 48 hours is strongly suggestive of a non-viable (either intra- or extra-uterine) pregnancy. T he bets HCG threshold for TAS is 1800 mIU /ml and for TVS is 500-1000 mIU /ml, thereby if the threshold level reaches and there is no intrauterine pregnancy identified, an ectopic pregnancy is presumable.(2 days’ repeat test for beta HCG rules out a living or dead/dying gestation) Other than this there can be local tenderness on TVS probe and presence of hemorrhagic fluid in the pelvis

25. NON- SPECIFIC FINDINGS (continued…) Serum progesterone levels are generally lower in a non-viable (including ectopic) pregnancy ; a progesterone of 5 ng /ml or less is strongly associated with pregnancy failure, whereas in a viable pregnancy, progesterone is usually 20 ng /ml or more . Other signs include those of blood loss and shock and for how long the bleeding has been present but more important is how fast it is as it can endanger the life of the patient.

26. PSEUDOGESTATIONAL SAC A pseudogestational sac or pseudosac is a small amount of intrauterine fluid in the setting of a positive pregnancy test and abdominal pain that could be erroneously interpreted as a true gestational sac in ectopic pregnancy. The sign was originally reported before the use of transvaginal ultrasound imaging But in a woman with a positive beta-hCG, any intrauterine sac-like fluid collection seen on ultrasound is highly likely to be a gestational sac

27. ULTRASOUND FEATURES generally irregularly-shaped with pointed edges and/or filled with debris, sometimes referred to as ' beaking ’. centrally located in the endometrial cavity, rather than eccentrically located within the endometrium. It does not demonstrate a yolk sac. A double decidual layer is compatible with intrauterine pregnancy, but lack of this sign is not specific for pseudogestational sac that may be surrounded by a thick decidual layer. It should be distinguished from an intradecidual sign, which is also a sign of an early pregnancy.

28. ULTRASOUND IMAGES SHOWING A FLUID FILLED SAC IN THE UTERUS WITH BEAKING EDGES

29. ANEMBRYONIC PREGNANCY  is a form of a failed early pregnancy, where a gestational sac develops, but the embryo does not form. The term blighted ovum was used before for the same. It is common intrauterine and very rarely ectopic. On Ultrasound- when there is no embryo seen on TVS in a gestational sac with mean sac diameter (MSD) ≥25 mm Or there is no embryo on follow-up TVS- ≥11 days after scan showing gestational sac with yolk sac, but no embryo, or ≥ 2 weeks after a scan showing gestational sac without yolk sac or embryo  A fall in the Beta HCG levels is also an indicator.

30. TVS IMAGE SHOWING AN INTRAUTERINE SAC WITHOUT A FETAL POLE

31. ON CT An ectopic pregnancy can be an incidental finding or as a tool to confirm the diagnosis after a TVS examination fails A cystic lesion can be seen at the site of the ectopic pregnancy with enhancement of it’s wall on contrast administration In case of a ruptured ectopic there can be a large volume of high density fluid throughout the abdomen keeping up with a haemoperitoneum . The solid organs can enhance normally.

32. CT IMAGE IN A CASE OF RUPTURED ECTOPIC PREGNANCY SHOWING CYSTIC LESION IN THE LEFT ADNEXA

33. CORONAL AND SAG IMAGES OF THE SAME CASE DEMONSTRATING FLUID IN THE PERITONEUM WITH HU VALUES CONSISTENT WITH ACUTE BLOOD

34. ON MRI An ectopic pregnancy can found in women with acute abdominal pain and PV bleeding and shows a cystic lesion in the adnexa that can be initially considered neoplastic. Co-relation with the beta HCG levels and clinical findings can be needed to establish a diagnosis of an ectopic pregnancy It shows a hyperintense cystic lesion on T2W and hypo to iso -intense on T1 weighted images

35. MR IMAGES SHOWING A CYSTIC LESION IN THE LEFT ADNEXA WITH HETEROGENOUS INTENSITIES WITHIN

36. HETEROTROPIC PREGNANCY Usually its 1 per 30,000 (for a naturally conceived pregnancy). The incidence among patients with assisted reproduction is higher and is thought to be around 1-3:100. Thus it is necessary especially in a IVF pregnancy to screen the adnexal regions and other sites to rule out presence of another gestational sac in the early pregnancy

37. TVS IMAGE SHOWING TWO GESTATIONAL SACS – HETEROTROPIC PREGNANCY

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