This patient had sustained his diaphragmatic injury 8 years previously, which was missed at initial presentation, most probably due to its asymptomatic nature. This is not the first case report, nor will it be the last, of delayed presentation of traumatic diaphragmatic hernia. In fact, there is a case that reports the repair of a diaphragmatic hernia as late as 45 years following the initial trauma.1
Although it is well established that areas such as South Africa have a greater prevalence of thoraco-abdominal injuries, the Home Office latest figures show that almost one in five offences of attempted murder, grievous bodily harm or robbery in the UK involved knives or sharp instruments.2
Penetrating diaphragmatic injuries from bullets or knives can cause small holes, often <1 cm in diameter.3
The negative intrathoracic pressure that this generates is thought to cause gradual herniation of organs into the thorax. The “interval” phase of herniation, defined as occult diaphragmatic herniation,4
is often asymptomatic or manifests as vague dyspeptic symptoms or upper abdominal discomfort. Therefore, it is not uncommon for presentations of such cases to be delayed.
There may be benefit in following up this group of patients with penetrating thoraco-abdominal injuries, with regards to minimising the risk of developing a diaphragmatic hernia at a later stage. The longer the delay in diagnosis, the greater the morbidity and hospital stay, with mortality figures5
reaching up to 30% in cases with bowel strangulation associated with diaphragmatic hernia.6,7
For this reason, it is important to identify an appropriate imaging technique for this surveillance.
Visualisation of the diaphragm is difficult because of its thinness, its domed contour, and its continuity with the soft tissues of the abdomen.8
Furthermore, different techniques have their own limitations. Plain radiography is often the first investigation of choice, but it is recognised that this may be normal in the initial phases of herniation.9
Although some studies have reported10
that chest radiography is diagnostic of traumatic diaphragmatic injury in 68% of cases, many other studies report poorer rates of only 20–40%.11–14
These rates suggest that chest radiography alone may not be a good investigation for the early recognition of a diaphragmatic hernia following injury.
Barium studies may be used to diagnose thoracic herniation of the stomach, small intestine and colon.9
One study in patients with penetrating injuries reports the sensitivity of contrast radiographs as 72–78%. Furthermore, with the addition of ultrasonography the sensitivity is 82%.15
Although CT is a very useful and reliable tool for detecting diaphragmatic hernias, evaluation of the diaphragm integrity on dome and costal attachments may not be possible on standard axial CT images.9
Multislice helical CT with sagittal, coronal, and three dimensional reformatted images is more likely to be effective at detecting subtle changes that indicate diaphragmatic injury at follow-up. One study reports that the sensitivity of helical CT for detecting left sided diaphragmatic rupture is 78% and specificity is 100%.16
Alternatively, magnetic resonance (MR) imaging, which is known to be sensitive for soft tissue, could be used. MR would not only identify the hernial orifice as a diaphragmatic discontinuity, but could also reveal other abdominal organ injuries.17
Although both CT and MRI would be likely to detect early signs of a traumatic diaphragmatic hernia, the poor cost effectiveness makes them inappropriate methods to routinely follow-up all patients who have had a chest or abdominal injury.
There is less evidence for the use of laparoscopy, in comparison to other imaging techniques, to diagnose suspected diaphragmatic hernia in high risk patients at the time of initial presentation. However, laparoscopy would also have the benefit of correcting the hernia at the time of diagnosis, avoiding laparotomy in up to 55% of patients.18
- It is the clinician’s role to maintain a high index of suspicion with these patients at initial presentation, and to arrange subsequent imaging to diagnose the development of a diaphragmatic hernia at an early stage.
- Various imaging techniques have been evaluated for their usefulness in diagnosing traumatic diaphragmatic hernia when a patient presents with symptoms.
- A technique with a high sensitivity to identify patients with early signs of a diaphragmatic hernia at follow-up is required. However, there is lack of evidence to support the use of any particular imaging technique for this purpose.
- Further studies are required to identify the best technique, taking into consideration its cost effectiveness, as well as its sensitivity and specificity.