Gastrointestinal ultrasound ileus study (GUILE)

Interventions: Participants (recruited patients presenting for elective colorectal resection) will undergo a series of ultrasound (US) scans whilst in hospital. These will occur in the anaesthetic room on the day of surgery and post operatively on the ward at times outlined in the US protocol below. They will be performed by a combination of anaesthetists, colo-rectal surgeons and ultrasonographers and last approximately 15minutes each. US scans will be performed in a fasted state and also after a fluid challenge which involves scanning the gastric antrum at 40 minutes after oral ingestion of 250mls water. If there is lack of gastric emptying at 40 minutes, a further scan will be performed at 60 minutes post ingestion of water.
Standardised US Protocol
1.Gastric Antrum: Using a portable US machine (low-frequency probe) subjects will be placed in the right lateral decubitus position. Imaging is in the epigastric region in a parasagittal orientation. The cross-sectional area of the gastric antrum is measured and the gastric volume calculated.
2.Terminal Ileum (Resource and skill set dependent*, exploratory imaging): Using a low-frequency probe, the distal ileum will be located, the luminal diameter and wall thickness measured. In addition, peristaltic waves in the terminal ileum, which will be categorised as absent, normal or dysfunctional.
3.US timepoints:
Day 0 (Preoperatively) - Fasted gastric antrum US
Postoperative Day 2: i. Fasted US with fluid challenge (7-9am). Baseline and at 40-60mins ii. Spot US (2-4pm). Baseline and 40-60mins post fluid challenge
Postoperative Day 1: Resource dependent scanning only (fasted and with fluid challenge)
Postoperative Days 3 and 4: Selective scanning only in those who have demonstrated delayed gastr
Primary outcome(s): Proportion of patients with delayed gastric emptying on day 2 post operatively (defined by gastric residual volume >1.5ml/kg, 40minutes after ingestion of water on an empty stomach). This will be assessed by a series of abdominal ultrasounds scans. [Day 2 Post operatively]
Study Design: Purpose: Screening;Duration: Cross-sectional;Selection: Defined population;Timing: Prospective