**7. Bowel**

The assessment of bowel by POCUS in neonates remains an emerging practice despite the availability of clinical data in neonates for more than a decade. POCUS can show dynamic intestinal peristalsis as well as characterize the physical nature and perfusion of bowel that can be used to assess bowel integrity and viability. The newborn can be affected by a variety of congenital and acquired bowel conditions that may lead to significant bowel dysfunction or even death. Early recognition of the signs of impending bowel injury or the progression of bowel damage is essential. Intestinal peristalsis can be quantified by counting cumulative motility events over time to give an objective assessment of bowel movement [27]. Identifying peristalsis can assist in the routine management of neonatal feeding or bowel assessment but more studies are required to validate its utility for clinical outcomes (**Figure 6**). Some other studies have demonstrated that gastroesophageal reflux can be evaluated by POCUS both identifying anatomic risk factors as well as visualizing the bolus but this has not gained traction in clinical practice yet [28, 29].

NEC quick diagnostics and implementation of appropriate treatment are crucial [34–36]. Diagnosis is based on clinical presentation, laboratory testing and imaging. Traditionally, the gold standard for imaging evaluation of the neonatal intestine is the intestinal gas pattern on plain abdominal radiographs; however interpretation can be challenging with intestinal gas pattern being nonspecific [37–39], and significant overlap between radiographic signs of NEC

Current Neonatal Applications of Point-of-Care Ultrasound

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The usefulness of abdominal ultrasound in the diagnosis of NEC has been known since 1984 as evidenced in a number of studies [41–43]. Studies have looked at ultrasound being an adjunct to diagnose and manage infants with NEC. It allows for an earlier detection of typical signs of NEC, with more rapid disease management. When compared with abdominal radiographs in predicting NEC, studies showed that they can depict bowel distension, to some extent bowelwall thickness, pneumatosis intestinalis, portal venous air and free abdominal air which ultrasound could easily depict as well. More importantly, abdominal ultrasound provides important additional information regarding viability of bowel wall viability and free fluid, which might aid in diagnosis and management of NEC [44, 45]. With color Doppler specific suspicious loops of bowel can be interrogated to reveal if they are perfused or not which enables the identification of non-viable bowel with a high degree of certainty. The gradual progression of NEC can be identified by POCUS from the initial hyperemia and swelling of bowel wall to the dilatation with increased disease and then thinning of bowel wall with loss of perfusion or blood flow. Therefore, nonviable bowel will no longer have any blood flow present (**Figure 7 Epelman diagram)**. The detection of portal venous gas is much easier by POCUS than by radiographs [46].

For performing bowel ultrasound a linear probe of 8–15 MHz probe (higher frequency for higher resolution and lower depth targeting superficial structures). Features that are key include: (a) bowel wall thickening >2.6 mm, (b) increase in bowel wall echogenicity, (c) portal venous air, (d) pneumatosis Intestinalis and free air and (e) intra-abdominal fluid.

and other intestinal pathology [40].

**Figure 6.** Normal bowel appearance.

**7.1. Procedure and features**

Recent data suggest that dedicated abdominal ultrasound examination may be of utility in the diagnosis and management of infants with necrotizing enterocolitis (NEC). Advantages of ultrasound include assessment of peristalsis, vascular perfusion, bowel-wall thickening, and abdominal fluid. Absence of ionizing radiation is an added benefit. A recent meta-analysis showed that bowel ultrasound is increasingly being recognized as an important imaging tool for evaluating NEC that provides additional detail over plain abdominal radiographs [30]. There are still only few studies with small case series and heterogeneous gestational age population that have investigated the comparison between plain radiographs and abdominal ultrasound in predicting the outcomes of patients with NEC.

NEC is one of the most severe gastrointestinal conditions affecting neonates. The risk increases with degree of prematurity and in those with low birth weight [31–35]. Although risk factors have been identified, the etiology is still not well recognized. Despite significant advances in neonatal care, mortality in NEC remains high (between 20 and 60% in a group of most immature neonates) and maintained at the same level. Therefore, in cases of clinically suspected

**Figure 6.** Normal bowel appearance.

through the chest is possible due to the cartilaginous sternum. Although there is air inside and around the ETT and the entry is at a steep angle to the ultrasound probe, the tip of the probe can be identified with a white or hyperechoic line. The ideal location for the tip of the ETT is midway between the thoracic inlet and the carina. Identifying the distance of the tip of the ETT from the carina can be accurately measured. In a recent publication of an extensive database literature search on studies relating to US use for ETT position confirmation found nine studies which collectively reported a > 80% visualization of the ETT tip by US [22]. Also, US interpretation of the ETT position correlated with the XR position in 73–100% of cases. US appears comparable to XR determining ETT position in this population. As US is more easily available and is safer than CXR, it may be a better modality for confirming proper placement of ETT in neonates when time is critical. There are no current data yet on identifying tip location during placement of the

The assessment of bowel by POCUS in neonates remains an emerging practice despite the availability of clinical data in neonates for more than a decade. POCUS can show dynamic intestinal peristalsis as well as characterize the physical nature and perfusion of bowel that can be used to assess bowel integrity and viability. The newborn can be affected by a variety of congenital and acquired bowel conditions that may lead to significant bowel dysfunction or even death. Early recognition of the signs of impending bowel injury or the progression of bowel damage is essential. Intestinal peristalsis can be quantified by counting cumulative motility events over time to give an objective assessment of bowel movement [27]. Identifying peristalsis can assist in the routine management of neonatal feeding or bowel assessment but more studies are required to validate its utility for clinical outcomes (**Figure 6**). Some other studies have demonstrated that gastroesophageal reflux can be evaluated by POCUS both identifying anatomic risk factors as well as visualizing the bolus but this has not gained trac-

Recent data suggest that dedicated abdominal ultrasound examination may be of utility in the diagnosis and management of infants with necrotizing enterocolitis (NEC). Advantages of ultrasound include assessment of peristalsis, vascular perfusion, bowel-wall thickening, and abdominal fluid. Absence of ionizing radiation is an added benefit. A recent meta-analysis showed that bowel ultrasound is increasingly being recognized as an important imaging tool for evaluating NEC that provides additional detail over plain abdominal radiographs [30]. There are still only few studies with small case series and heterogeneous gestational age population that have investigated the comparison between plain radiographs and abdominal

NEC is one of the most severe gastrointestinal conditions affecting neonates. The risk increases with degree of prematurity and in those with low birth weight [31–35]. Although risk factors have been identified, the etiology is still not well recognized. Despite significant advances in neonatal care, mortality in NEC remains high (between 20 and 60% in a group of most immature neonates) and maintained at the same level. Therefore, in cases of clinically suspected

ETT and so more clinical data may be required before widespread adoption.

**7. Bowel**

70 Current Topics in Intensive Care Medicine

tion in clinical practice yet [28, 29].

ultrasound in predicting the outcomes of patients with NEC.

NEC quick diagnostics and implementation of appropriate treatment are crucial [34–36]. Diagnosis is based on clinical presentation, laboratory testing and imaging. Traditionally, the gold standard for imaging evaluation of the neonatal intestine is the intestinal gas pattern on plain abdominal radiographs; however interpretation can be challenging with intestinal gas pattern being nonspecific [37–39], and significant overlap between radiographic signs of NEC and other intestinal pathology [40].

The usefulness of abdominal ultrasound in the diagnosis of NEC has been known since 1984 as evidenced in a number of studies [41–43]. Studies have looked at ultrasound being an adjunct to diagnose and manage infants with NEC. It allows for an earlier detection of typical signs of NEC, with more rapid disease management. When compared with abdominal radiographs in predicting NEC, studies showed that they can depict bowel distension, to some extent bowelwall thickness, pneumatosis intestinalis, portal venous air and free abdominal air which ultrasound could easily depict as well. More importantly, abdominal ultrasound provides important additional information regarding viability of bowel wall viability and free fluid, which might aid in diagnosis and management of NEC [44, 45]. With color Doppler specific suspicious loops of bowel can be interrogated to reveal if they are perfused or not which enables the identification of non-viable bowel with a high degree of certainty. The gradual progression of NEC can be identified by POCUS from the initial hyperemia and swelling of bowel wall to the dilatation with increased disease and then thinning of bowel wall with loss of perfusion or blood flow. Therefore, nonviable bowel will no longer have any blood flow present (**Figure 7 Epelman diagram)**. The detection of portal venous gas is much easier by POCUS than by radiographs [46].
