There are diverse causes that contribute to abdominal distention and increase diagnostic complexity. This study showed a simple protocol, FASK, had efficacy and timeliness for the ED patients with abdominal distention. It could be an effective screening tool for the timely detection of ascites and distended urinary bladder, followed by proper management. The diagnostic accuracy of the protocol was 99% with high sensitivity and specificity, whatever the level of the performer. With the early intervention of the FASK protocol, the majority of patients could be discharged soon after proper management without further advanced imaging. It suggested that the introduction of PoCUS in patients with abdominal distention using a designated protocol could lessen LOS, facilitate the management process, and preserve safety. To our best of knowledge, this is the first study regarding the application of the PoCUS in non-critical patients with abdominal distention.
PoCUS is frequently used for critical patients, however, it has a positive impact on non-critical patients . This study also demonstrated the introduction of a simple US protocol with an easily accessible US machine could make incorporating PoCUS into the daily practice easy. In addition to being an extension of physical examination, PoCUS could play an important role in diagnosis and management in ED settings. Safety and timeliness, two domains of quality of care , would be preserved by using PoCUS.
Although US would be operator-dependent , no association could be identified between diagnostic accuracy and the level of the performer. Senior sonographers could achieve US images with better quality in this study, It could be explained that this protocol included two fundamental, simple US scanning techniques in US training. Also, junior sonographers performed the FASK protocol under the supervision of the instructors. The gap between the green hands and the experienced sonographers could be compensated. Therefore, the high accuracy, whatever the level of the sonographers could be explained.
Ascites can be easily identified by physical examination if the volume is greater than 1500 mL . However, small amounts of fluid are not easily detected, or an increased adipose tissue may confound the diagnosis . It would be safer with US-guided paracentesis [22, 23]. By contrast, paracentesis would be withheld if small amounts of ascites were detected. Also, urinary retention, often misdiagnosed as bowel obstruction or an abdominal tumor, is easily diagnosed by US . In this study, more than 70% of the patients had ascites or a distended urinary bladder by using US, being the causes for their abdominal distention. Only 16% of the patients needed advanced imaging, such as CT for further evaluation.
The FAST examination is a commonly performed PoCUS examination to evaluate trauma patients in the ED. Besides detecting free fluid in the peritoneal cavity, indicating internal bleeding following trauma , the sonographer should be able to identify liver, kidney, spleen, and urinary bladder. The FAST examination can also provide valuable information in managing non-trauma patients and altering these patients’ clinical course . In this study, the FASK protocol included combinations of the FAST examination and the renal US. The simple protocol could be an effective, timely screening tool for patients with abdominal distention.
There was a certain percentage of the patients receiving CT following PoCUS. These patients experienced longer LOS and a lower discharge rate. The results showed that a certain percentage of patients needed further investigation besides PoCUS. It might be explained by the spirit of the PoCUS. PoCUS is the focused sonographic examination performed by the treating provider to inform clinical decision-making . It is used to answer simple, binary (yes/no) questions . Differences exist between PoCUS and comprehensive sonographic examination performing by established specialists , as well as CT. Also, these patients had longer door-to-US time and LOS, compared with those receiving US only. Possibly these patients were complicated to need more time for history taking, physical examination, and early management. Moreover, these patients had a lower rate of ED discharge and a higher probability of hospital admission.
There were several limitations. First, this was a retrospective, observational study with a non-random sample. Selection bias existed that the results were obtained from the formal US documentations. Some sonographic examinations without documentation were not included in the analysis. Besides, because PoCUS had become commonly used in EDs, ethical concerns raised about conducting a randomized controlled trial for PoCUS. Difficulties exist in estimating LOS without the introduction of US. Second, this study was conducted in a single center with an active US training program. The distribution of the causes of abdominal distention would vary from hospitals to hospitals. The external validity of the study results needs further verification. Third, the imaging quality was scored based on the still images in the US report. The still images could represent the quality of the sonographic examination partially. Dynamic evaluation of structures or position change of the patient may add significant information . However, due to volume limitations, the US reporting system in our hospital could upload the still images. Fourth, the discharge/admission diagnosis having ascites or distended urinary bladder was used as a standard for accuracy. However, the underlying etiology for ascites or distended urinary bladder was not the main aim of the study. This study focused on the simple PoCUS protocol that would help in the quality of care and the management process. Last, this protocol could not detect loculated ascites outside the Morison’s pouch, splenorenal recess, and the pelvis, as in 2 patients in this study.