Ultrasound to detect haemothorax after chest injury

Ultrasound to detect haemothorax after chest injury

Report by Kirsty McEwan, Medical Student

Checked by Peter Thompson, Consultant

Guy, Kings and St Thomas' Medical School, London, UK

Abstract

A short cut review was carried out to establish whether ultrasonography is as sensitive and specific as chest x ray or computed tomography (CT) scan in detecting haemothorax after chest trauma. Thirty‐nine papers were found using the reported searches, of which six presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are shown in table 3. It is concluded that ultrasonography is more sensitive and as specific as chest x ray at detecting haemothorax in patients with chest trauma.

Table 3.

Author, date, country	Patient group	Study type	Outcomes	Key results	Study weaknesses
Rothlin et al, 1993, Switzerland	Adults (aged 15–88 years) with blunt thoracic or abdominal injuries. Ultrasound scan by surgeons compared to the patients' clinical outcome and other diagnostic techniques	Prospective study	Clinical utility of ultrasound to detect haemothorax	Sensitivity 81%	Poor gold standard.Not performed by emergency physicians.Some of the beginner surgeons initially forgot to check for haemothorax, accounting for 5 of the 11 cases of false negative reports by ultrasound. Some of the effusions developed only after the first 24 h and therefore would not have been visible on the initial ultrasound scan
Ma et al, 1995, USA	245 adult (18 years +) patients presenting to the emergency department with major blunt or penetrating torso trauma. Diagnosis with ultrasound was compared to a combination of results of other diagnostic techniques including CT scan, supine chest x ray, formal two‐dimensional echocardiography or tube thoracostomy	Diagnostic cohort	Clinical utility of rapid ultrasound assessment at detecting the presence of haemothorax	Sensitivity 96%, specificity 100%, accuracy 99%	Composite gold standard
Ma and Mateer, 1997, USA	240 adults (aged 18 years+) presenting to the emergency department with a major blunt or penetrating torso trauma. Accuracy of ultrasound compared with that of initial plain supine chest x ray for the detection of haemothorax using a combination of CT and tube thoracostomy as the gold standard	Retrospective analysis of a prior prospective study	Clinical utility of ultrasound vs initial plain supine chest x ray for the detection of haemothorax	Sensitivity 96.2% vs 96.2%,specificity 100% vs 100%,accuracy 99.6% vs 99.6%	The same patients as reference 2
Sisley et al, 1998, USA	Patients with suspected blunt or penetrating torso injury who required a chest radiograph for a complete evaluation	Prospective study	Clinical utility of ultrasound vs supine chest x ray at detecting the presence of haemothorax	Sensitivity 97.5% vs 92.5%,specificity 99.7% vs 99.7%,PPV 97.5% vs 97.4%,NPV 99.7% vs 99.1%	The results of ultrasound were compared to those of supine chest x ray rather than them both being compared to an independent “gold standard”. Emergency physicians did not perform the ultrasound scan
Abboud and Kendall, 2003, USA	Blunt trauma patients who underwent CT scan of their chest as part of their clinical assessment	Prospective study	Clinical utility of ultrasound	Sensitivity 12.5%, specificity 98.4%	None of the haemothoraces detected by CT but not on ultrasound were large enough to be clinically relevant. The interval between the ultrasound scan and the CT scan was up to 4 h
Brooks et al, 2004, UK	Patients triaged to the resuscitation room with thoracic trauma (blunt or penetrating).Ultrasound findings were compared against a combination of other diagnostic methods including supine chest x ray, intercostal drain, CT or tube thoracotomy	Prospective study	Clinical utility of ultrasound at detecting the presence of haemothorax	Sensitivity 92%,specificity 100%,accuracy 98%,PPV 100%,NPV 98%	Composite gold standard

CT, computed tomography; NPV, negative predictive value; PPV, positive predictive value.

Three‐part question

[In adults with thoracic trauma] does [emergency department ultrasonography have better clinical utility than chest x ray] at [diagnosing haemothorax]?

Clinical scenario

A patient arrives in the emergency department after suffering thoracic trauma. A member of the team suggests using ultrasound to search for the presence of haemothorax, as an extension of the usual FAST assessment. You wonder how accurate the ultrasound would be compared to either the usual initial supine chest x ray or to a CT scan which could be performed later in the patient's assessment.

Search strategies

Medline 1966 to present (accessed 29 May 2007) using the OVID interface: [thorax.mp or thoraxic.mp or thoracic.mp or emergancy.mp or chest.mp or pulmonary diseases.mp or thoracic lesions.mp or chest disease.mp]AND [radiography.mp or diagnosis/ or diagnosis, computer assisted/ or diagnosis, differential/ or “diagnostic techniques and procedures”/ or diagnostic imaging/ or radiography or radiography, thoracic/ or tomography, x‐ray/ or ultrasonography/ or diagnostic techniques, cardiovascular/ or diagnostic techniques, respiratory system/ or diagnostic tests, routine/ or realy diagnosis or computed tomography.mp or CT.mp or thoracic CT.mp] AND [ultrasound.mp or ultrasonography.mp or explode ultrasonography/ or sonography.mp or radiological diagnosis.mp or ultrasonographic.mp or thoracic radiological procedures.mp or emergency ultrasound.mp or transthoracic ultrasound.mp or thoracic ultrasound.mp] AND [Hemathorax.mp or hemothorax.mp or haemathorax.mp or haemothorax.mp or traumatic effusion.mp].

The Cochrane Library Issue 2 2007: (hemothorax):ti,ab,kw OR (haemothorax):ti,ab,kw

Outcome

Altogether 39 papers were found in Medline, of which 34 were irrelevant or of insufficient quality. Twenty‐five papers were found in Cochrane—the only relevant paper had already been found in Medline. A further paper was found by scanning the references of relevant papers. All relevant papers are summarised in table 3.

Comments

Ultrasound is a sensitive, specific and accurate technique for detecting haemothorax in thoracic trauma patients. CT does detect some haemothoraces not seen on ultrasound; however, in a clinical situation, the two methods are performed on different patient populations and so are not directly comparable. The most clinically relevant diagnostic imaging method with which to compare ultrasound is the supine chest radiograph as they both are performed in the initial assessment of the patient. When compared directly to the supine chest x ray, ultrasound is shown to be more specific at detecting the presence of the haemothorax and is at least as specific and accurate. It also has the added advantage of being able to be performed in much less time, making it a useful diagnostic tool for the early diagnosis of haemothorax. However, it cannot replace the chest x ray as many other injuries can be shown on the chest x ray that cannot be demonstrated by ultrasound.

Clinical bottom line

Ultrasound is a sensitive, specific and accurate method to detect the presence of haemothorax in trauma patients. It cannot, however, replace chest radiography because there is additional information on the x ray that ultrasound cannot provide.