**1. Introduction**

Abdominal trauma has varied clinical presentations, most of which are subtle, and patients may appear stable at presentation [1]. The injuries sustained are not easily identified by surface appearance or examination. Abdominal trauma is usually not found as an isolated injury, but rather as part of polytrauma cases [2]. A patient with intoxication, altered sensorium due to head injury, severe injuries over the limbs or thorax may have sustained trauma to the abdomen, which may go undetected due to the distracting nature of the other symptoms. A high index of suspicion is required in such cases. Any trauma sustained between the nipple line to the pelvis warrants a search for intraperitoneal organ injury. Point of care ultrasonography (POCUS) is a powerful tool that can aid in the search.

#### **1.1 Relevant anatomy**

Abdomen holds complex structures along with a large potential space. Knowledge of anatomy is key to identifying the possible organs involved. In general, the abdomen is divided into nine regions (**Figure 1**) for purposes of evaluation. However, this

#### **Figure 1.** *Surface anatomy and regions of abdomen [3].*

division studies the abdomen only from the anterior aspect. A more inclusive division of abdominal regions for trauma cases would be into four regions–lower chest, anterior abdomen, and flank and posterior abdomen. Based on the mechanism and location of the injury, the likely structures to be affected can be ascertained based on this division (**Table 1**). Retroperitoneum and pelvic structures can also be injured, however, are not well imaged by ultrasonography. POCUS can then be utilized effectively by screening these suspected structures with care, instead of performing an extensive abdominal scan that would delay the time and outcome for the patient.


**Table 1.** *Four abdominal regions.*

*POCUS in Abdominal Trauma: Old Gadget, New Insights DOI: http://dx.doi.org/10.5772/intechopen.107049*

**Figure 2.** *Ultrasound probes – Linear (a) and curvilinear (b) [4].*

The ultrasound machine is usually equipped with three basic probes - curvilinear, linear, and phased array probes (**Figure 2**). A curvilinear probe is of low frequency, allowing deeper imaging with a wide-angle view. A linear probe is of high frequency and visualizes superficial structures. By convention, the ultrasound probes when used in a sagittal or coronal plane have the pointer/marker toward the head end of the patient. In the transverse plane, the pointer is to be facing the right of the patient.
