Ectopic Pregnancy on Ultrasound: Diagnosis and Treatment

With thousands of ups and downs associated with pregnancy, being on the lookout for risks like ectopic pregnancy on ultrasound is crucial.

Any pregnancy in which implantation occurs somewhere other than the uterine cavity is considered an ectopic pregnancyRead on to know about the diagnosis and treatment for the same.

Ectopic Pregnancy on Ultrasound

In the past, ectopic pregnancy was a major cause of maternal mortality. 1However, today’s earlier diagnosis of ectopic pregnancy on ultrasound and management have significantly decreased this condition’s mortality and morbidity.

Here we will deal with the basic understanding of ectopic pregnancy on ultrasound.

1. Incidence and Site

As a quick refresher of fundamental anatomy, the introitus2 is the vaginal canal, where the uterus’s cervix enters the body.

A second ectopic pregnancy which is one of the important risk factors increases the risk by 12% after the first one. The fallopian tube (95%) is the most frequent location. The ampulla contains around 80% of the tubal ectopics, the isthmus 12%, the fimbrial end 6%, and the interstitial and corneal region 2%.

The ovary, cervix, and abdominal cavity are other locations. Ectopic pregnancy3 in a pre-existing scar (5%) is becoming more common as cesarean sections are performed more frequently.

Anatomy of uterus
Image by Bianca Van Dijk from Pixabay/Copyright 2021

2. Aetiology

Any factor that causes delayed transport or entrapment of the fertilized ovum through the fallopian tube favours plantation in the tube and can give rise to a tubal pregnancy.4

There are a few key risk factors, including:

  1. Pelvic inflammatory disease
  2. Congenital Factors
  3. Salpingitis Isthmica Nodosa
  4. Previous Tubal Surgery
  5. Assisted Reproductive Technology ( in vitro fertilization)
  6. Intrauterine Devices
  7. Cigarette Smoking
  8. Detection of Previous Ectopic Pregnancies on Ultrasound

3. Natural Course of Tubal Pregnancy

  • Tubal absorption (very early cases)
  • Tubal abortion
  • Tubal rupture
  • Intra abdominal hemorrhage
  • Pelvic haematocoele or hematoma and chronic ectopic
  • Secondary abdominal pregnancy
  • Secondary Intraligamentous pregnancy

4. Clinical Features

Many times, the conventional symptoms may not be present, therefore it’s crucial to maintain a high level of suspicion and consider the possibility of an ectopic pregnancy. 5Clinically suspected ectopic pregnancy on ultrasound may be detected by an ordinary first-trimester ultrasound.

The classic triad of amenorrhea, irregular vaginal bleeding, and abdominal pain indicate an ectopic pregnancy. Ectopic pregnancy is not likely to result in severe vaginal bleeding like a miscarriage. It’s not always necessary to have amenorrhea.

Until proven otherwise, irregular or abnormal bleeding in a sexually active woman that is accompanied by abdominal pain or pelvic pain should be considered a sign of an ectopic pregnancy. Fainting attacks are also common. An intraperitoneal bleed is typically the cause of abdominal or pelvic pain.

There can also be shoulder discomfort, which results from blood building up in the subdiaphragmatic area, which in turn stimulates the phrenic nerve and hurts the shoulder tip.

5. Diagnosis of Ectopic Pregnancy on Ultrasound

Pelvic ultrasounds should be carried out to identify an intra- or extra-uterine pregnancy6 when a patient exhibits symptoms that point to ectopic pregnancy or when hormone tests reveal an abnormal pregnancy. The preferred method of evaluation of ectopic pregnancy on ultrasound is transvaginal imaging.

Documenting the presence of an intrauterine pregnancy, whether it is normal or abnormal, is the aim of first-trimester screening.

In the first trimester, ultrasound can distinguish between normal and abnormal pregnancies7 with great sensitivity and specificity. The double decidual sac sign can be seen at around 5 weeks.

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Photo by Omar Lopez on Unsplash/Copyright 2017

When the gestational sac measures 10 mm, or at around 5.5 weeks, it is possible to see the secondary yolk sac with a transvaginal ultrasound.

Additionally, at around 5–6 weeks, when the gestational sac measures more than 18 mm or when the fetal pole measures 5 mm or more, transvaginal ultrasound should also detect the presence of embryonic heart activity.

5.1) Ruptured Ectopic Pregnancy

In a ruptured ectopic pregnancy, the patient may exhibit shock-like symptoms such as pallor, tachycardia, hypotension, and cold, clammy extremities. All of the symptoms of intraabdominal bleeding may be seen during an abdominal examination.

If an intraperitoneal hemorrhage8 is present, the Cullen sign, which is a bluish discolouration of the skin around the umbilicus, may be present. The abdomen may be distended with tenderness, guarding, rigidity and shifting dullness.

A vaginal examination may show a normal or enlarged uterus with tenderness when the cervix is moved. Additionally, the fornices may be tender, and an adnexal mass may occasionally be felt to be tender. There can be fullness in the pouch of Douglas due to a pelvic hematoma.

5.2) Unruptured Ectopic Pregnancy

A clinical examination might be inconclusive in this case. Then, additional investigations are required. You will have a positive pregnancy test while testing urine for human chorionic gonadotropin9.

When a patient is at a higher risk for an ectopic pregnancy, a high index of suspicion is required.

Unruptured ectopic pregnancy on ultrasound is done mainly by transvaginal sonography and serial serum human chorionic gonadotropin are the two primary diagnostic tools, and they accurately predict ectopic pregnancy with a positive predictive value of 95%.

To distinguish between an ectopic pregnancy and an atypical intrauterine pregnancy, curettage may occasionally be necessary. Excluding a typical intrauterine pregnancy is the first step in making the diagnosis of ectopic pregnancy on ultrasound.

i) Transvaginal Ultrasound

The key to diagnosing ectopic pregnancy on ultrasound is the presence of an intrauterine gestational sac on transvaginal ultrasound. A pseudo sac can occasionally be visible in an ectopic pregnancy as a result of a hemorrhage brought on by the separation of a decidual cast.

The most reliable way to differentiate between a true intrauterine sac and a pseudo sac 10is the presence of the yolk sac within the true sac.

When searching for an ectopic pregnancy on ultrasound, the corpus luteum is a helpful indicator; it will typically be on the ipsilateral side.

The most common finding of ectopic pregnancy on ultrasound is an Empty uterus and the mass between the uterus and ovary.

Tubal Ectopic Pregnancy on Ultrasound: Adnexa
  • Complex or solid mass between the uterus and ovary is the most common feature seen in ectopic pregnancy on ultrasound
  • Empty gestational sac surrounded by a ring
  • Yolk sac and embryo in a gestational sac
  • Embryo with cardiac activity 100% Diagnostic of ectopic pregnancy on ultrasound but seen only in 10%
  • Ring of fire on colour Doppler

ii) Serum Beta Human Chorionic Gonadotropin (hCG)

Serum ß-hCG testing is carried out when the diagnosis is uncertain. It is most likely an ectopic pregnancy if the blood ß-human chorionic gonadotropin levels are greater than 1500–2000 IU/L and an intrauterine pregnancy is not seen on TVS.

The discriminating zone is the point at which an intrauterine gestational sac should be visible. It is regarded as 1500 IU/L with TVS.

An intrauterine pregnancy should be visualized at the discriminatory cut-off of 1500-2000 IU/L depending on the operator and equipment used, with nearly 100% sensitivity. The lack of a typical intrauterine pregnancy at this cut-off suggests an abnormal pregnancy.

There are, however, some exceptions to this assumption since 15% of normal pregnancies will not exhibit a doubling. This typically pertains to serum ß-human chorionic gonadotropin levels that are lower. Thus, serial values are crucial.

Multiple embryos may be present in pregnancies following in-vitro fertilization, which is another issue. In light of this, there may be two intrauterine pregnancies or a heterotopic pregnancy with elevated serum ß-hCG levels and no sac seen on TVS.

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Image by Michal Jarmoluk from Pixabay/Copyright 2017

Before beginning medical therapy, it is crucial to determine the pregnancy’s site. Keep in mind that hCG may be secreted by germ cell tumours, which is another factor to take into account. Thus, a positive pregnancy test does not necessarily mean that a woman is pregnant.

5.3) Contraindications for Ultrasonography

Transvaginal ultrasonography has just one absolute contraindication, whereas there is none for a transabdominal ultrasound.

Transvaginal imaging is contraindicated in patients who have recently undergone gynecologic surgery, which is extremely uncommon for women who could be in their first trimester.

When deciding how the imaging should be carried out, special factors should be taken into account. Transvaginal ultrasonography may be more beneficial for these patients because obesity may reduce the diagnostic efficacy of ectopic pregnancy on ultrasound by transabdominal imaging.

Patients who have experienced vaginal injuries may find it painful to use the transvaginal method. An additional consideration is the patient’s age. Younger patients may have never had a pelvic exam before, and transvaginal ultrasounds can make these patients feel anxious.

Transvaginal ultrasonography could be used as a backup plan after transabdominal imaging for the diagnosis of ectopic pregnancy on ultrasound, in some cases.

6. Treatment

There are different management options:

  1.  Medical management
  2.  Surgical Management
  3. Surgically administered medical management
  4.  Expectant management

6.1) Medical Management

When a tubal pregnancy has not ruptured, methotrexate is currently being utilized more frequently for medical care. It is a folic acid antagonistic anti-neoplastic medication that is highly effective against the growing trophoblast.

It stops folic acid from turning into folinic acid. A side effect of methotrexate is a reduction in corpus luteum progesterone production, which results from a direct impairment of trophoblastic HCG synthesis. Before administering methotrexate, an intrauterine pregnancy must be ruled out.

Single-dose and multiple-dose regimens are the two most often used regimens.

i) Criteria for Selection for Medical Management

  • Hemodynamically stable
  • Compliant with follow-up
  • No intrauterine pregnancy on Ultrasound
  • Size of ectopic mass <4cm
  • No tubal rupture
  • B-hCG level preferably <5000 IU/L
  • No fetal cardiac activity is preferred

Surgery is advised if medical treatment is unsuccessful or a tubal rupture develops. Orthostatic hypotension, declining hematocrit, and acute and prolonged discomfort might all be signs that surgery is necessary

6.2) Surgical Management

For surgery, laparoscopy is typically preferred. The only exception is if the patient is in shock, in which case rapid exploratory laparotomy11 and resuscitation may be required. Blood should always be available. A laparoscopy would be preferred if the patient is hemodynamically stable and it is possible.

Laparotomy and laparoscopy are both capable of performing salpingectomy and conservative surgery. Laparoscopy is unquestionably preferable since it can shorten hospital stays and ease postoperative pain.

Additionally, compared to laparotomy, laparoscopy results in fewer adhesions. When a woman hasn’t finished her family, conservative measures are advised.

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Image by marionbrun from Pixabay/Copyright 2015

6.3) Surgically Administered Medical Management

Under ultrasound guidance, direct injection of a drug is given into the ectopic pregnancy. Methotrexate, potassium chloride, hyperosmolar glucose and PGF2α have been used.

6.4) Expectant Management

This is a treatment option for clinically asymptomatic, ectopic pregnancy diagnosed on ultrasound women with initial serum B hCG levels below the discriminating zone and subsequently declining values.

7. Other Sites of Ectopic Pregnancy

1) Heterotopic Pregnancy

An intraabdominal pregnancy and an ectopic pregnancy coexist in this situation.

The discovery of an intrauterine pregnancy, which provides a false sense of certainty, frequently causes a delay in the diagnosis. Serial monitoring of serum ß-hCG is not helpful.

i) High Index of Suspicion for Heterotopic Pregnancy

  • Women who become pregnant as a result of assisted reproduction
  • women who experience persistent pelvic pain during an intrauterine pregnancy
  • Women with a persistently high B hCG after miscarriage or termination of pregnancy

ii) Management

The mainstay of treatment is a laparoscopic salpingectomy. Hyperosmolar glucose or potassium chloride injections administered locally under ultrasound supervision are an additional alternative.

2) Interstitial, Cornual and Angular Pregnancy

i) Interstitial Pregnancy

Implantation in the proximal interstitial region of the fallopian tube is what is referred to as an interstitial pregnancy, the risk factors for tubal pregnancy are the same. Past ipsilateral salpingectomy is an additional risk factor.

Pregnancies may rupture between 8 and 16 weeks if undiagnosed, which is later than with ectopic pregnancies that are more distal.

-Ultrasound Criteria for Diagnosis
  • Empty uterine cavity
  • The gestational sac is located in the interstitial or intramural part of the tube more than 1 cm from the endometrial echo.
  • Thin <5mm myometrial mantle on all sides.
  • The interstitial line sign is a thin echogenic line extending from the uterine cavity to the periphery of the gestational sac and represents the interstitial part of the fallopian tube.

3D ultrasound or MRI may give more information and differentiate from angular or intrauterine pregnancies.


The round ligament will appear to have an expanded protuberance during laparoscopy or laparotomy.

The ipsilateral tube, the surrounding myometrium, 12and the pregnancy are all removed together during a corneal resection. Cornuostomy is an alternative. If detected early, systemic methotrexate in multiple doses may be a possibility.

iii) Cornual Pregnancy

Pregnancy in a bicorn uterus’s rudimentary horn is known as corneal pregnancy. The rudimentary horn and tube of the affected side can be removed if the disease is caught early enough.

If not treated promptly, rupture with severe intraperitoneal bleeding is unavoidable at 12 to 20 weeks.

-Criteria for Ultrasound
  • Visualization of a single fallopian tube interstitial segment within the main uterine body.
  • Myometrium surrounds the entire gestational sac, which is separate from the uterus.
  • The gestational sac’s vascular pedicle connects it to the unicornuate uterus.

It could be mistaken for an interstitial pregnancy during a laparoscopy or laparotomy. The round ligament will have a rudimentary horn-like attachment lateral to the sac. The round ligament will be medial to the sac during an interstitial pregnancy. The rudimentary horn has to be removed.

iii) Angular Pregnancy

This is characterized as intrauterine implantation in one of the uterus’ lateral angles, medial to the uterotubal junction and the round ligament. Because these pregnancies might last till term, this distinction is crucial.

3. Abdominal Pregnancy

When an early tubal rupture or abortion results in abdominal pregnancy, the fertilized ovum implants on the peritoneum and grows there. The fetus develops in the peritoneal cavity during abdominal pregnancy.

Most fetuses die, and fetal salvage is uncommon. Most pregnant women who are having an abdominal baby experience severe nausea and stomach pain, especially when the fetus moves.

Fetal components can be superficial and often present incorrectly. By showing the uterus separately or the lack of uterine outline over the fetus, ultrasound can be helpful.

i) Management

As soon as the problem is identified, the fetus must be removed via laparotomy. Laparoscopy could be an option for very early-stage abdominal pregnancies.

4. Intraligamentous Pregnancy

This uncommon occurrence results from the trophoblast’s passage between the two layers of the wide ligament and penetration of the tubal wall.

Therefore, a tubal pregnancy is typically a secondary cause. Clinical observations resemble an abdominal pregnancy.

5. Cervical Pregnancy

The pregnancy implants in the endocervical canal, just below the internal oz. Prior dilatation and curettage or a prior cesarean section are the typical predisposing variables.

Vaginal bleeding without pain is the most typical symptom. They are typically discovered by chance during a regular ultrasound or when removing a suspected abortion. Blood flow around the sac as shown on a colour doppler is an indicator of a genuine cervical pregnancy.

Diagnosing cervical ectopic pregnancies through ultrasound is done by standard first-trimester scans.

-Criteria for ultrasound

  • Empty uterus Barrel-shaped cervix
  • Hourglass shape of the uterus
  • Ballooned-out cervical canal
  • Gestational sac below the level of internal oz.
  • Blood flow around the sac (c.f.miscarriage)
  • Absence of sliding sign (c.f. miscarriage)
  • Closed internal oz.


Due to the severe bleeding during an evacuation, hysterectomy was the only option in the past. Methotrexate therapy in several doses is a viable medical option today. If it doesn’t work, evacuation is the next step after radiological uterine artery embolization.

6. Ovarian Pregnancy

A pregnancy implanted in the ovary is extremely uncommon, early-stage rupture is the typical outcome. Surgery is used to treat the condition, and typically an ovariotomy is required. Ovarian ectopic pregnancies on ultrasound, detected early may be treated with methotrexate.

Since the diagnosis of ectopic pregnancy on ultrasound is challenging, surgery and histopathology are typically used to confirm the diagnosis.

7. Caesarean Scar Ectopic Pregnancy

Image by Engin Akyurt from Pixabay/copyright 2017

Implantation into the myometrial defect present at the location of the prior uterine incision is referred to as a cesarean scar pregnancy. One in 2000 pregnancies is estimated to be ongoing, viable, or failing.

There are two distinct categories. The first kind advances into the uterine cavity and may become viable, but there is a chance of significant bleeding from the implantation site.

The second variety advances to the uterine surface, posing the risk of first-trimester rupture and hemorrhage. A cesarean scar ectopic pregnancy is predisposed by a cesarean delivery scar defect (CDSD), isthmocoele, or richer.

i) Diagnostic Criteria on Ultrasound

  • Empty uterine cavity
  • Empty endocervical canal
  • A gestational sac or trophoblastic mass is located at the level of the internal oz. And embedded in the site of the previous scar
  • A thin or non-existent layer of myometrium between the bladder and gestational sac
  • Doppler revealed significant trophoblastic/placental circulation.

Frequently Asked Questions

1. When is ectopic pregnancy serious?

If you experience any of the early indications of a pregnancy that is ectopic, such as severe pelvic or abdominal discomfort followed by bleeding, you should seek immediate medical care.

2. How many weeks is ectopic dangerous?

The fetus finally succumbs since tissues outside the uterus are unable to provide the required blood flow and support. Usually, the fetus’s protective structure ruptures between six and sixteen weeks.

3. How many hours is ectopic surgery?

It usually takes thirty minutes to an hour, but if a laparotomy is required to be performed, it can take longer.


Over the past 20 years, there has been a noticeable rise in the prevalence of ectopic pregnancy on a global scale.

This is mostly caused by the prevalence of STDs, pelvic inflammatory disease, and increased use of assisted reproductive technology. Thankfully, early treatment can be highly beneficial, so, if you have any of the symptoms mentioned above, consult a doctor soon.

Also, check out a detailed guide on implantation bleeding.

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