You are near the end of a night shift and things are looking up: no patients on the tracking board, the last two admissions just went upstairs, and triage is empty. But it’s 6:08 am and you have a sneaking suspicion that something will happen before your 7 am sign-out. Sure enough, five minutes later, the triage nurse brings back two parents and their 14-year-old daughter who is complaining of right lower quadrant pain.
The history is simple. She was fine when she went to bed, but awoke at 6:43 am with severe abdominal pain that radiates to her right flank and right thigh. The pain then got worse and she vomited clear fluid three times. She denies any fever, change in bowel habits, dysuria, or hematuria, and her last menstrual period ended 17 days ago. She has never experienced anything like this before, and her past medical history and family history are both unremarkable. On exam she is writhing on the bed, intermittently crying and moaning in pain. Her vital signs show a blood pressure of 112/66, temperature of 37°C, pulse 93, and respiratory rate 16. Her physical exam is unremarkable except for a soft abdomen that is tender to palpation and percussion in the right lower quadrant.
Her clinical picture is concerning, but a repeat set of vital signs are stable. You order an IV, a CBC, a BMP, a pregnancy test, and a comprehensive pelvic ultrasound. Unfortunately, the ultrasound tech has to be called in from home, and they are likely to ask if it can wait until 8 am when the next shift begins. Your differential diagnosis includes the possibility of a ruptured ectopic pregnancy, ruptured ovarian cyst, ruptured tubo-ovarian abscess, or ovarian torsion, and you know that the pelvic scan will be the rate limiting step in getting this patient the definitive care she may need. The solution? Perform a bedside ultrasound yourself while waiting for the comprehensive scan by radiology. You return to the room with your machine and politely ask the parents to step out. While the machine is warming up you ask them if their daughter has a boyfriend and if they think there could be any chance that she is sexually active, qualifying it with the statement. “Please don’t take it the wrong way, but I wouldn’t be doing my job if I didn’t ask.” You then ask their permission to speak to their daughter alone and in confidentiality to which they answer “yes.” After speaking to the patient privately, you invite the parents into the room and inform them that you are going to do a brief screening ultrasound while they are waiting for the comprehensive scan, to evaluate for any findings or changes that would require immediate attention.
Image 1 Image 2
Even though your 14-year-old patient denied being sexually active, you know it’s better to be safe than sorry. You first check Morrison’s pouch (Image 1) — no free fluid. That’s a relief. Also there is no evidence of hydronephrosis from a distal kidney stone or mass compressing on the right ureter. You next turn your attention and the probe to the pelvis and right lower quadrant. Finding an appendix is a challenge you are not up to yet, but you get a good view of the uterus and right ovary. (Image 2)
What do you see? Do you think this is an ectopic pregnancy?
While scanning, you visualize a normal uterus in a transverse view and follow the broad ligament and ovarian ligament laterally in an attempt to visualize the right ovary. Just medial to the internal iliac vessels, you note a large right ovarian cyst (image at left). The large right ovarian cyst in the setting of this patient’s clinical presentation makes you highly suspicious for ovarian torsion. You make an early call to the OB on-call to let her know your concerns and you have one of your favorite types of phone conversations— no questions from the consultant, just a simple, “I’ll be right in.”
The patient’s urinalysis and pregnancy test come back unremarkable. Here complete blood count was unremarkable except for a white blood cell count of 12.8 and her metabolic panel was normal except for a glucose of 220. The ultrasound tech and the gynecologist arrive simultaneously. The comprehensive ultrasound showed a 7.1 cm right ovarian cyst with no blood flow to the right ovary and a mild amount of adjacent free fluid. She is taken immediately to the OR, but unfortunately, despite the excellent and timely care that you provided, when the ovary is detorsed in the OR it does not reperfuse and she requires a salpingo-oophorectomy.
Pearls & Pitfalls for imaging the pelvis
Pearls & Pitfalls for imaging the pelvis
>>Know your limitations: This speaks for itself. Ultrasound should be used as an adjunct to help clarify findings elicited by history and physical exam. One ED-based retrospective review demonstrated that 3 of 9 OT cases were missed using Doppler flow studies (Annals EM 2001; 38: 156-159). However, when used correctly, it can greatly improve diagnostic accuracy, and help guide patient management. There is no substitute for hands-on practice to improve your skills. Your department should have a quality improvement program whereby EP scans are over-read by an EP trained in ultrasound or by a physician in radiology.
>>Improve your odds by combining the US with a good history. The same retrospective review (above) revealed 25% had an ovarian cyst history, 75% presented initially to the ED. 70% had nausea or vomiting and pain was most consistently described as “sharp” in 70% with a mean duration of 8.7 days of pain prior to presentation. OT was considered in the admitting differential diagnosis in only 47% of patients and only 30% had surgery within 24-hours.
>>Transabdominal Scan: Transabdominal imaging is usually adequate as a bedside screening study. Limitations include patient habitus, discomfort, or an empty urinary bladder. Use the curved array 2.5 to 3.5 MHz transducer or phased array transducer on most patients. This can be followed by a comprehensive pelvic ultrasound with the transvaginal probe by you or the ultrasound technician if no emergent findings are detected immediately. Attempt to visualize the uterus, the vesicouterine pouch between the bladder and the uterus, the cul-de-sac (Pouch of Douglas) between the uterus and rectum, and the ovaries bilaterally. Often times, the ovaries are difficult to visualize on a transabdominal scan and will need to be evaluated using a transvaginal approach. A full bladder will serve as a better acoustic window for the transabdominal approach, but should be emptied before a transvaginal scan.
>>Transvaginal Scan: Use a 5 to 7.5 MHz transducer and the proper probe sheath. Patient discomfort can be minimized by allowing the patient to insert the transvaginal probe herself. Ensure that you have a chaperone for your full exam. Orientation can be difficult if you are just starting to utilize this application. Make sure the indicator marker is pointed towards the ceiling during the first part of the scan. In the standard sagittal view, a longitudinal view of the uterus will be visualized. Scan systematically through the entire uterus and cervix, noting abnormalities such as masses, cysts, free fluid, or collections within the endometrial stripe (Stay tuned for future articles on ultrasound evaluation of intrauterine pregnancies and ectopic pregnancies). Turn the probe 90° so that the indicator marker to pointed towards the patient’s right. Attempt to find the ovaries lying just medial to the iliac vessels. Scan systematically through both ovaries and the uterus again in this orientation. Note the size and orientation of the ovaries, and evaluate for any cysts, masses, fluid collections, or free fluid. If you are comfortable with the application, evaluate both ovaries for blood flow and confirm your findings with the comprehensive scan by the ultrasound technician.
>>Ectopic Pregnancy: The first place you should look is Morrison’s pouch. If there is free fluid there in the right clinical scenario, you have not only an ectopic pregnancy until proven otherwise, but you also have a rupture with hemoperitoneum. A cornual ectopic, which is the most dangerous type, is also the closest to the uterus. Don’t be fooled into thinking it’s an IUP.
>>Placental Abruption: Ultrasound is only 40% sensitive for placental abruption. If there is concern the patient must go to Labor & Delivery for toco-cardiographic monitoring.
>>Free Fluid: Free fluid in the pelvis or abdomen should be considered blood until proven otherwise. Blood and ascitic fluid may look the same on ultrasound. Consider the clinical scenario, but usually you should assume it’s blood unless you know it’s not. Turn down the far gain when looking for free fluid behind the bladder. This will help compensate for the acoustic enhancement that occurs distal to fluid filled structures. Fluid collections will most frequently take the form of “dog-ears” or a “bow tie”.
>>The Uterus: The uterus is usually the most easily visualized structure in the pelvis and is a good starting point. Look for it first. An empty bladder or retroverted uterus may make imaging a challenge.
>>The Ovaries: The ovaries can be a real challenge to find without proper experience. Sometimes the ultrasound tech can’t even find them. Look lateral and slightly superior to the uterus. Simple cysts less than 2.5cm in greatest diameter are usually considered normal.
>>Don’t expect miracles. Doppler evaluation of the ovarian vascularity is challenging for several reasons:
a) ovaries have dual blood supplies.
b) ovary may torse and detorse during clinical and ultrasonographic evaluation resulting in a false-negative study.
c) the common presence of large ovarian mass can complicate Doppler interrogation. Successful operative detorsion is rare (9% in the above retrospective review).
Brady Pregerson, MD
, oversees QI for ED Ultrasound at Cedars-Sinai Medical Center in Los Angeles. Check out more from Dr. Pregerson at www.ERPocketBooks.com
Teresa Wu, MD, the Director of Simulation Education & Research at Orlando Regional Medical Center, completed her ultrasound fellowship at Stanford University Medical Center.