Tubal Ectopic Pregnancy

The fallopian tube is the most common site (95%) for ectopic pregnancy. The majority (70%) of tubal pregnancies occur mostly in the ampulla, followed by the isthmus and fimbria. The most common ultrasound finding in a tubal ectopic pregnancy is an adnexal mass separate from the ovary, seen in about 90% of cases. This is confirmed by demonstrating that the mass moves separately from the ovary on manipulation of the probe.

The diagnosis is more specific when a yolk sac (as in our case) or living embryo is detected. When neither of these is seen, demonstration of the tubal ring sign is helpful. The tubal ring sign refers to a hyperechoic ring surrounding an extrauterine gestational sac, and is often seen in association peripheral hypervascularity of the hyperechoic ring (the "ring of fire" sign). The ring of fire sign is helpful when a definite ectopic pregnancy cannot be identified, and color Doppler images demonstrate an adnexal ring of fire sign.

The dreaded complication of a tubal ectopic pregnancy is rupture. Clinical signs and symptoms may be unimpressive, and pain may even decrease or disappear following tubal rupture.

Ultrasound findings are likewise nonspecific, and no finding at transvaginal ultrasound has been shown to be a reliable indicator of rupture. The presence of echogenic fluid within the Morrison pouch and the cul-de-sac should, however, raise concern for rupture.

Ectopic pregnancies may be managed expectantly, medically, or surgically.

Expectant management is based on the observation that some tubal ectopic pregnancies resolve spontaneously. Asymptomatic patients with an ectopic pregnancy with falling beta-hCG levels initially < 1,000 mIU/l can be expectantly managed. Patients are followed up with twice weekly beta-hCG and weekly transvaginal scans. At the 7-day follow-up ultrasound, the size of the adnexal mass should decrease and beta-hCG should fall by at least 50%. The beta-hCG is followed until it drops to < 20 mIU/l.

Methoterxate may be considered in patients with low initial beta-hCG and progesterone levels and the absence of ectopic cardiac activity. The size of the ectopic is also considered, with treatment recommended with a sac size < 3.5 cm if cardiac activity is present or sac size < 4.0 cm if cardiac activity is absent. It must be noted, however, that the size of the ectopic pregnancy, volume of hematoma, and the presence of free pelvic blood do not seem to influence the success or failure of methoterxate therapy.

Surgical management may include salpingostomy or salpingectomy. Salpingostomy involves making a linear incision in the fallopian and flushing out the ectopic pregnancy. Salpingostomy is considered when the contralateral fallopian tube is abnormal and we wish to preserve at least one side. The main complication is the risk of retention of trophoblastic tissue, which is higher with laparoscopy than laparotomy, and which can be minimized with prophylactic methotrexate.

Indications for salpingectomy include: a normal contralateral fallopian tube, patient at higher risk of complications with salpingostomy, severely damaged ipsilateral fallopian tube (making attempts at preservation with salpingostomy irrelevant), recurrent ectopic pregnancy on the same side, uncontrolled bleeding after salpingostomy, tubal pregnancy > 5 cm, a heterotopic pregnancy, and in patients who do not desire continued fertility.

References

• Frates MC, Brown DL, Doubilet PM, Hornstein MD. Tubal rupture in patients with ectopic pregnancy: diagnosis with transvaginal US.Radiology. 1994 Jun;191(3):769-72.
• Lin EP, Bhatt S, Dogra VS. Diagnostic clues to ectopic pregnancy. Radiographics. 2008 Oct;28(6):1661-71.
• Nama V, Manyonda I. Tubal ectopic pregnancy: diagnosis and management. Arch Gynecol Obstet. 2009 Apr;279(4):443-53. Epub 2008 Jul 30.