Each bariatric surgical procedure presents a different spectrum of complications. The most common procedures with their associated complications are as follows [11]:

GB includes procedures involving both adjustable and nonadjustable band placement.

Whilst the technique is in decline, many patients have implanted bands in situ.

Complications include:

– Gastric leak is the most common complication with an incidence of 1–10% of patients in published gastroplasty series [12]. The incidence can rise to 16–20% following repeat operative surgery [12]. Gastric leak has been defined by the UK Surgical Infection Study Group as “the leak of luminal contents from a surgical join between two hollow viscera” and is classified based on the timing of the leak during the post-operative period, namely, early (≤3 days after surgery), intermediate (≥4 and ≤7 days after surgery), and late (≤8 days after surgery) [13].

Classically leaks tend to appear between 5 and 6 days after surgery because of a lack of mural/anastomotic integrity. The typical location of gastric leak is the proximal third of the stomach, close to the gastro-oesophageal junction (85.7%), and less commonly occurs in the distal third (14.3%) [12]. Gastric leak management is still relatively empiric without accepted guidelines [13].

RYBP includes both gastrojejunal anastomosis and enteroenteric anastomoses with both anastomoses susceptible to complications, which include:

Interventional radiology (IR) plays an important role in the minimally invasive management of various post-operative bariatric surgical complications particularly when further surgical re-intervention increases the complication risk to the patient.

Since the advent of IR techniques, diagnostic imaging technology along with IR equipment has undergone rapid technological advances. In particular, developments in IR techniques and equipment have led to various safe and effective procedures. For example, manufacturing advances have resulted in a variety of catheters and guide wires with characteristics such as torsional strength, diameter, hydrophilic properties, and specific shape to the type of procedure undertaken.

In parallel, equipment used to guide interventional procedures has advanced with in particular the cross-sectional techniques of ultrasound (US) and computed tomography (CT) now widely available allowing the precise placement of interventional equipment. Multimodality imaging is also now routinely used during interventional procedures with more recent developments facilitating image fusion such as the overlay of 3D cross-sectional datasets with fluoroscopy. These advances have also been associated with the significant reduction in radiation exposure to both patients and staff.

The type of interventional procedure performed will depend on the specific post-operative complication, with IR techniques most commonly used to aspirate and drain collections, embolise/stent bleeding vessels, dilate anastomotic strictures, and more recently facilitate GI tract stent placement following leaks.

In addition, IR can play an important role in delayed complications including choledocholithiasis formation in patients following RYGB (Table 6.2).

Percutaneous drainage (PD) of post-operative collections is the first-line therapy for patients who do not have other indications for immediate surgery. This is particularly true for the post-operative bariatric patient with a well-contained collection.

Primary SG may have a leak rate of up to 9% with an increase in incidence of up to 13% following revision surgery.

Whilst authors have recommended immediate surgical re-intervention in order to close the anastomotic defect, other minimally invasive techniques may be used with Corona et al. reporting that PD has been the stand-alone procedure in 58% of patients in their unit with gastric leak after SG [15].

Whilst PD is generally safe and effective, procedures require careful planning in order to determine the optimum access pathway to a collection. In particular, a pathway should be direct and straightforward and avoid inadvertent injury to adjacent structures and organs. Pre-procedure planning and guidance are in most cases performed using either US or CT. The choice of modality depends on various parameters including collection characteristics, operator choice, and imaging availability.

US offers a number of advantages such as real-time imaging, no ionising radiation, accurate assessment of collection contents due to high-contrast resolution, and equipment mobility allowing procedures to be performed in the IR suite or at the patient’s bedside. The modality however is very operator dependent particularly in obese patients, and collections containing gas may be poorly visualised. In addition, enteric leaks that occur from anastomoses following gastric bypass procedures commonly present in anatomical locations adjacent/deep to gas-filled organs including the stomach, duodenum, small bowel, and colon making ultrasound guidance challenging or impossible. Therefore, whilst US can be used in large and superficial collections, CT plays an important role in this group of patients.

Despite the disadvantage of requiring ionising radiation, CT is widely used when feasible in the bariatric patient in order to plan the access pathway to a collection. The modality allows accurate assessment of the collection position, depth, and adjacent structures thus facilitating the calculation of the optimal angle/direction for the access pathway. The standard CT scanner however has a maximum allowed patient weight of around 160 kgs with a bore of 70 cms, thus restricting the use of the modality in this group of patients. In response to this drawback, a number of manufacturers have developed dedicated bariatric machines allowing up to 300 kgs bodyweight with an enlarged bore of 80 cms.

The majority of 21/22 gauge needle systems however require insertion of an initial 0.018 inch guide wire followed by a coaxial dilator thus adding to the complexity of the procedure.

The typical manufacturing needle length is 15–20 cm, which may be inadequate to reach a deep collection in the bariatric patient. The use of a 55 cm Colapinto needle (Cook Incorporated, Bloomington, IN) will however allow access to most collections.

Pigtail catheters are preferred because the design allows a reduced risk of accidental displacement. The choice of catheter size can be determined by the needle aspiration test, which dictates that if fluid can be easily aspirated through a 10 mL syringe (1 mL in 1 s) using an 18 gauge needle, then an 8.5 F catheter diameter will be effective.

Complex collections however may require a catheter size of up to 16 F.

The two standard techniques for percutaneous collection drainage are the trocar or “one-step” and Seldinger or “two-step” procedures.

Trocar technique : This uses a catheter mounted on a central trocar and stylet.

Following subcutaneous infiltration of local anaesthetic, a direct puncture with the mounted catheter is used to access the collection. The central stylet is then removed, and aspiration is performed to confirm correct catheter tip location. The catheter is then advanced over the trocar into the collection. The technique is only suitable for large and superficial collections.

Seldinger technique : The technique is more appropriate and in most cases much safer for use in bariatric patients. Following subcutaneous infiltration of local anaesthetic, an appropriate needle (usually 18 gauge) is introduced into the collection under image guidance. After successful aspiration, a guide wire is then inserted through the needle into the collection, and following needle removal, the tract is dilated over the wire to the required diameter prior to wire-guided placement of the catheter. If a smaller needle diameter is initially used to puncture the collection, then either further guide wire exchanges can be used to upsize the tract or a second 18 gauge needle can be introduced adjacent to the initial needle (Fig. 6.1).

Both techniques require appropriate final catheter fixation to the skin with a range of devices available. Importantly an adequate specimen must be sent to microbiology and free drainage of collection contents confirmed into the catheter bag.

Collections containing viscid contents require regular flushing using 10–20 mL of saline once or twice daily in order to maintain catheter patency.