Pitfall: Ruptured cornual ectopic pregnancy

Images Nick Sidler, text Genevieve Carbonatto

A 32 year old woman presents to the ED with her husband and 5.00 am. The woman is clearly unwell. She is directed straight to the resuscitation bay. Her husband tells you that shortly before 4.00 am she awoke with severe acute abdominal pain. He says she is pregnant – around 8 weeks. She is responsive but pale and peripherally cool. Her BP is 78/48, HR 110. Bloods are taken and an urgent VBG shows a Hb of 105. Her abdomen is peritonic to examination.  This is clearly a ruptured ectopic until proven otherwise. Obstetrics and gynecology are called, the on call anaesthetist is called. Within  5 minutes of her lying down in the resuscitation bay you do a scan

This is what you see in the RUQ

No fluid in the pouch of Douglas. You explore the inferior border of the kidney

There appears to be a sliver of free fluid at the edge of the liver. You explore the tip of the liver

There is a small amount of fluid visible at the tip of the liver.

You then scan her pelvis. This is her pelvis in the longitudinal plane 

You scan the pelvis in the transverse plane

The obstectrics and gynecology registrar looks at your scans as says this is not a ruptured ectopic because there is no free fluid in the pelvis and only a small amount in the RUQ.

Your response is to explain the pelvic scan to her.

The pelvis is full of echogenic clotted blood which is why it does not appear anechoic. The echogenic blood is surrounding the uterus and filling the entire pelvis. You can see this is blood because it has a mixed echogenicity. It is not bowel because it is not moving, and there is no dirty shadowing from gas. The reason why there is no fluid in the RUQ is because the woman has just been laid supine and therefore free fluid from her pelvis has not yet moved to her RUQ. A scan in 10 minutes will show more fluid.

You have also identified the possible ectopic. Having said that, this is irrelevant in the context of the empty uterus and the pelvis full of blood.

Meanwhile the patient’s BP is deteriorating. Her repeat Hb is 55. The massive transfusion protocol is activated. She is urgently transferred to theatre where a ruptured cornual ectopic is removed. In theatre the uterus is found to be surrounded by approximately  3 l of clotted blood. She makes a good recovery.

Discussion

2 points can be taken from this case:

  1. Irrespective of the ultrasound findings, this young, pregnant, haemodynamically unstable patient with a peritonic abdomen has a ruptured ectopic pregnancy until proven otherwise
  2. If ultrasound is to be used to guide management then credentialing is paramount. Bad decision making and delay in treatment can be the product of poor understanding of ultrasound in some cases.

Cornual ectopics can cause massive catastrophic bleeding. They are situated in the interstitial part of the fallopian tube which is the proximal portion that lies within the muscular wall of the uterus. It is 0.7 mm wide and approximately 1–2 cm long, with a slightly tortuous course, extending obliquely upward and outward from the uterine cavity. (1) Cornual pregnancies tend to present later than other ectopic pregancies because of myometrial distensibility at this site. They present between 7 and 12 weeks. They can also grow for longer because of the plentiful blood supply from the myometrium . They therefore become larger and more vascularised as the trophoblastic tissue invades the myometrium(2)

Because of the abundant blood supply in the cornual region from both uterine and ovarian vessels, rupture occurring after 10 –  12 weeks of gestation often leads to severe catastrophic  haemorrhage and even death. The mortality rate is 6 – 7 times higher than that of  ectopic pregnancies.

Teaching point : The greatest pitfall of ultrasound in the context of  an ectopic pregnancy is not recognising that blood in the pelvis clots quickly. The second greatest pitfall is not to recognise that if a  patient has been sitting  for a while or standing and is then examined immediately supine, there may not be free fluid in Morison’s pouch simply because the blood has not had time to flow to the RUQ from the pelvis. Ultrasound can be used sequentially. Re examine the patient 10 minutes later to see whether there has been any accumulation of fluid.

References

  1. The Obstetrician & Gynaecologist  10.1576/toag.9.4.249.27355 www.rcog.org.uk/tog   online 2007;9:249–255   Review Management of cornual (interstitial) pregnancy Authors Radwan Faraj / Martin Steel
  2. Callen’s Ultrasonography in Obstectrics and Gynecology 6th edition

 

 

 

 

 

 

 

 

 

 

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