Morrison’s Pouch: Answer 1.1

morrisons-pouch-redo1

Although we had many submissions – there were NO WINNERS this week

A 75-year-old woman presents with left lower extremity swelling and pain behind the knee for the past few days.  She has been taking ibuprofen and was referred from her PMD, who was concerned that she may have a DVT.  The patient has a history of hypertension and diabetes.  She smokes cigarettes daily.   Her vital signs are within normal limits.  On physical exam, her legs are symmetric in size, her dorsalis pedis pulses are 2+ and symmetric, there is no erythema, but she is tender to palpation in the popliteal fossa.

Questions:

1.  What is the diagnosis?
2. Which veins of the lower extremity are visualized in the DVT examination?
3. Name a finding seen on ultrasound exam that is consistent with the diagnosis of DVT?

Answers:
1.  Baker’s cyst
2. from the exam includes the veins from the iliofemoral junction to the popliteal fossa.
3. Veins that are not completely compressable are indicative for a DVT.

This patient’s leg veins were fully compressible, so a DVT was ruled out.  The ultrasound exam demonstrated a Baker’s cyst, which explains the pain she is having behing her knee.  The patient was discharged with pain medications and instructions to follow-up with her PMD for a repeat ultrasound in 1-week.

baker2-labelled

pop2-labelled4 saph2-labeled4 split2-labeled3

Discussion:
As ED physicians, we are using ultrasound with increasing frequency to evaluate the lower extremity for DVT, Baker’s cyst, and abscesses.  A Baker cyst is a synovial cyst that is located posterior to the medial femoral condyle, between the tendons of the medial head of the gastrocnemius and semimembranous muscles. It usually communicates with the joint by way of a slitlike opening at the posteromedial aspect of the knee capsule just superior to the joint line. An extension of the knee joint, a Baker cyst is lined with a true synovium.  The common symptoms of baker cysts include localized swelling and pain, and decreased range of motion of the extremity. Baker cysts commonly resolve following rest; analgesics and extremity elevation help to reduce swelling and pain. If symptoms persist, an orthopedic surgeon can excise the cyst.

Over the past decade, emergency ultrasound is well established in its use to detect lower extremity DVT.  The exam is traditionally performed by ultrasounding from the iliofemoral vein junction to the popliteal vein. After identifying these vessels, the vein is followed and compressed at 1-centimeter intervals. Full collapse indicates that no DVT is present, while partial or incomplete collapse is diagnostic of DVT.
Several studies have shown that ED ultrasound interpertation is equivalent to formal ultrasound studies. A 2000 study showed ED ultrasound exams and formal ultrasound studies agreeing in 110 of 112 cases of possible DVT. Of the two discrepancies, one was a false positive ED reading. The other was an ED-positive exam that was initially read as negative by formal ultrasound but later shown to be DVT-positive by venography. Another study done in 2004 showed that 154 of 156 DVTs were diagnosed by ED ultrasound, the remaining two being false positive results.

In addition, the ED evaluation of DVT saves time in correctly diagnosing the presence or absence of DVT, prevents a potentially unstable patient from having to leave the ED department for a study, and ensures the timely diagnosis even when an ultrasound technician is unavailable.

This case prepared by Dr Sam Lee, PGY-1 Emergency Medicine Resident, Detroit Receiving Hospital

Bibliography

  1. Blaivas, Lambert, Harwood, Wod, Konicki. Lower-extremity Doppler for Deep Vein Thrombosis – can emergency physicians be accurate and fast? Academic Emergency Medicine. Feb 2000. Vol. 7, number2. pgs. 120-1262.
  2. Stephen A. Shiver MD and Michael Blaivas. Acute Lower extremity pain in an adult patient secondary to bilateral popliteal cysts. Journal of EM: Volume 34, issue 3, April 2008. pgs 315-3183.
  3. Theodoro, Blaivas, Duggal, Snyder, Lucas. Real-time B-mode Ultrasound in the emergency department saves time in the diagnosis of Deep Vein Thrombosis American Journal of EM Vol 22, no. 3, may 2004. pgs. 197-200

“Morrison’s Pouch” is an educational module that utilizes ultrasound video clips from case presentations in the Emergency Department.  The section is hosted by Dr. Daniel Morrison, Director of Emergency Medicine Ultrasound for Detroit Medical Center, and case presentations are submitted by the EM residents of Detroit Receving Hospital.

Follow

Get every new post delivered to your Inbox.

Join 96 other followers